Planet Musings

July 03, 2009

Terence Tao — Benford’s law, Zipf’s law, and the Pareto distribution

A remarkable phenomenon in probability theory is that of universality – that many seemingly unrelated probability distributions, which ostensibly involve large numbers of unknown parameters, can end up converging to a universal law that may only depend on a small handful of parameters. One of the most famous examples of the universality phenomenon is the central limit theorem; another rich source of examples comes from random matrix theory, which is one of the areas of my own research.

Analogous universality phenomena also show up in empirical distributions – the distributions of a statistic ${X}$ from a large population of “real-world” objects. Examples include Benford’s law, Zipf’s law, and the Pareto distribution (of which the Pareto principle or 80-20 law is a special case). These laws govern the asymptotic distribution of many statistics ${X}$ which

(i) take values as positive numbers;
(ii) range over many different orders of magnitude;
(iiii) arise from a complicated combination of largely independent factors (with different samples of ${X}$ arising from different independent factors); and
(iv) have not been artificially rounded, truncated, or otherwise constrained in size.

Examples here include the population of countries or cities, the frequency of occurrence of words in a language, the mass of astronomical objects, or the net worth of individuals or corporations. The laws are then as follows:

Benford’s law For ${k=1,\ldots,9}$ , the proportion of ${X}$ whose first digit is ${k}$ is approximately ${\log_{10} \frac{k+1}{k}}$ . Thus, for instance, ${X}$ should have a first digit of ${1}$ about ${30\%}$ of the time, but a first digit of ${9}$ only about ${5\%}$ of the time.
Zipf’s law The ${n^{th}}$ largest value of ${X}$ should obey an approximate power law, i.e. it should be approximately ${C n^{-\alpha}}$ for the first few ${n=1,2,3,\ldots}$ and some parameters ${C, \alpha > 0}$ . In many cases, ${\alpha}$ is close to ${1}$ .
Pareto distribution The proportion of ${X}$ with at least ${m}$ digits (before the decimal point), where ${m}$ is above the median number of digits, should obey an approximate exponential law, i.e. be approximately of the form ${c 10^{-m/\alpha}}$ for some ${c, \alpha > 0}$ . Again, in many cases ${\alpha}$ is close to ${1}$ .

Benford’s law and Pareto distribution are stated here for base ${10}$ , which is what we are most familiar with, but the laws hold for any base (after replacing all the occurrences of ${10}$ in the above laws with the new base, of course). The laws tend to break down if the hypotheses (i)-(iv) are dropped. For instance, if the statistic ${X}$ concentrates around its mean (as opposed to being spread over many orders of magnitude), then the normal distribution tends to be a much better model (as indicated by such results as the central limit theorem). If instead the various samples of the statistics are highly correlated with each other, then other laws can arise (for instance, the eigenvalues of a random matrix, as well as many empirically observed matrices, are correlated to each other, with the behaviour of the largest eigenvalues being governed by laws such as the Tracy-Widom law rather than Zipf’s law, and the bulk distribution being governed by laws such as the semicircular law rather than the normal or Pareto distributions).

To illustrate these laws, let us take as a data set the populations of 235 countries and regions of the world in 2007 (using the CIA world factbook); I have put the raw data here. This is a relatively small sample (cf. my previous post), but is already enough to discern these laws in action. For instance, here is how the data set tracks with Benford’s law (rounded to three significant figures):

${k}$	Countries	Number	Benford prediction
1	Angola, Anguilla, Aruba, Bangladesh, Belgium, Botswana, Brazil, Burkina Faso, Cambodia, Cameroon, Chad, Chile, China, Christmas Island, Cook Islands, Cuba, Czech Republic, Ecuador, Estonia, Gabon, (The) Gambia, Greece, Guam, Guatemala, Guinea-Bissau, India, Japan, Kazakhstan, Kiribati, Malawi, Mali, Mauritius, Mexico, (Federated States of) Micronesia, Nauru, Netherlands, Niger, Nigeria, Niue, Pakistan, Portugal, Russia, Rwanda, Saint Lucia, Saint Vincent and the Grenadines, Senegal, Serbia, Swaziland, Syria, Timor-Leste (East-Timor), Tokelau, Tonga, Trinidad and Tobago, Tunisia, Tuvalu, (U.S.) Virgin Islands, Wallis and Futuna, Zambia, Zimbabwe	59 ( ${25.1\%}$ )	71 ( ${30.1\%}$ )
2	Armenia, Australia, Barbados, British Virgin Islands, Cote d’Ivoire, French Polynesia, Ghana, Gibraltar, Indonesia, Iraq, Jamaica, (North) Korea, Kosovo, Kuwait, Latvia, Lesotho, Macedonia, Madagascar, Malaysia, Mayotte, Mongolia, Mozambique, Namibia, Nepal, Netherlands Antilles, New Caledonia Norfolk Island, Palau, Peru, Romania, Saint Martin, Samoa, San Marino, Sao Tome and Principe, Saudi Arabia, Slovenia, Sri Lanka, Svalbard, Taiwan, Turks and Caicos Islands, Uzbekistan, Vanuatu, Venezuela, Yemen	44 ( ${18.7\%}$ )	41 ( ${17.6\%}$ )
3	Afghanistan, Albania, Algeria, (The) Bahamas, Belize, Brunei, Canada, (Rep. of the) Congo, Falkland Islands (Islas Malvinas), Iceland, Kenya, Lebanon, Liberia, Liechtenstein, Lithuania, Maldives, Mauritania, Monaco, Morocco, Oman, (Occupied) Palestinian Territory, Panama, Poland, Puerto Rico, Saint Kitts and Nevis, Uganda, United States of America, Uruguay, Western Sahara	29 ( ${12.3\%}$ )	29 ( ${12.5\%}$ )
4	Argentina, Bosnia and Herzegovina, Burma (Myanmar), Cape Verde, Cayman Islands, Central African Republic, Colombia, Costa Rica, Croatia, Faroe Islands, Georgia, Ireland, (South) Korea, Luxembourg, Malta, Moldova, New Zealand, Norway, Pitcairn Islands, Singapore, South Africa, Spain, Sudan, Suriname, Tanzania, Ukraine, United Arab Emirates	27 ( ${11.4\%}$ )	22 ( ${9.7\%}$ )
5	(Macao SAR) China, Cocos Islands, Denmark, Djibouti, Eritrea, Finland, Greenland, Italy, Kyrgyzstan, Montserrat, Nicaragua, Papua New Guinea, Slovakia, Solomon Islands, Togo, Turkmenistan	16 ( ${6.8\%}$ )	19 ( ${7.9\%}$ )
6	American Samoa, Bermuda, Bhutan, (Dem. Rep. of the) Congo, Equatorial Guinea, France, Guernsey, Iran, Jordan, Laos, Libya, Marshall Islands, Montenegro, Paraguay, Sierra Leone, Thailand, United Kingdom	17 ( ${7.2\%}$ )	16 ( ${6.7\%}$ )
7	Bahrain, Bulgaria, (Hong Kong SAR) China, Comoros, Cyprus, Dominica, El Salvador, Guyana, Honduras, Israel, (Isle of) Man, Saint Barthelemy, Saint Helena, Saint Pierre and Miquelon, Switzerland, Tajikistan, Turkey	17 ( ${7.2\%}$ )	14 ( ${5.8\%}$ )
8	Andorra, Antigua and Barbuda, Austria, Azerbaijan, Benin, Burundi, Egypt, Ethiopia, Germany, Haiti, Holy See (Vatican City), Northern Mariana Islands, Qatar, Seychelles, Vietnam	15 ( ${6.4\%}$ )	12 ( ${5.1\%}$ )
9	Belarus, Bolivia, Dominican Republic, Fiji, Grenada, Guinea, Hungary, Jersey, Philippines, Somalia, Sweden	11 ( ${4.5\%}$ )	11 ( ${4.6\%}$ )

Here is how the same data tracks Zipf’s law for the first twenty values of ${n}$ , with the parameters ${C \approx 1.28 \times 10^9}$ and ${\alpha \approx 1.03}$ (selected by log-linear regression), again rounding to three significant figures:

${n}$	Country	Population	Zipf prediction	Deviation from prediction
1	China	1,330,000,000	1,280,000,000	${+4.1\%}$
2	India	1,150,000,000	626,000,000	${+83.5\%}$
3	USA	304,000,000	412,000,000	${-26.3\%}$
4	Indonesia	238,000,000	307,000,000	${-22.5\%}$
5	Brazil	196,000,000	244,000,000	${-19.4\%}$
6	Pakistan	173,000,000	202,000,000	${-14.4\%}$
7	Bangladesh	154,000,000	172,000,000	${-10.9\%}$
8	Nigeria	146,000,000	150,000,000	${-2.6\%}$
9	Russia	141,000,000	133,000,000	${+5.8\%}$
10	Japan	128,000,000	120,000,000	${+6.7\%}$
11	Mexico	110,000,000	108,000,000	${+1.7\%}$
12	Philippines	96,100,000	98,900,000	${-2.9\%}$
13	Vietnam	86,100,000	91,100,000	${-5.4\%}$
14	Ethiopia	82,600,000	84,400,000	${-2.1\%}$
15	Germany	82,400,000	78,600,000	${+4.8\%}$
16	Egypt	81,700,000	73,500,000	${+11.1\%}$
17	Turkey	71,900,000	69,100,000	${+4.1\%}$
18	Congo	66,500,000	65,100,000	${+2.2\%}$
19	Iran	65,900,000	61,600,000	${+6.9\%}$
20	Thailand	65,500,000	58,400,000	${+12.1\%}$

As one sees, Zipf’s law is not particularly precise at the extreme edge of the statistics (when ${n}$ is very small), but becomes reasonably accurate (given the small sample size, and given that we are fitting twenty data points using only two parameters) for moderate sizes of ${n}$ .

This data set has too few scales in base ${10}$ to illustrate the Pareto distribution effectively – over half of the country populations are either seven or eight digits in that base. But if we instead work in base ${2}$ , then country populations range in a decent number of scales (the majority of countries have population between ${2^{23}}$ and ${2^{32}}$ ), and we begin to see the law emerge, where ${m}$ is now the number of digits in binary, the best-fit parameters are ${\alpha \approx 1.18}$ and ${c \approx 1.7 \times 2^{26} / 235}$ :

${m}$	Countries with ${\geq m}$ binary digit populations	Number	Pareto prediction
31	China, India	2	1
30	”	2	2
29	“, United States of America	3	5
28	“, Indonesia, Brazil, Pakistan, Bangladesh, Nigeria, Russia	9	8
27	“, Japan, Mexico, Philippines, Vietnam, Ethiopia, Germany, Egypt, Turkey	17	15
26	“, (Dem. Rep. of the) Congo, Iran, Thailand, France, United Kingdom, Italy, South Africa, (South) Korea, Burma (Myanmar), Ukraine, Colombia, Spain, Argentina, Sudan, Tanzania, Poland, Kenya, Morocco, Algeria	36	27
25	“, Canada, Afghanistan, Uganda, Nepal, Peru, Iraq, Saudi Arabia, Uzbekistan, Venezuela, Malaysia, (North) Korea, Ghana, Yemen, Taiwan, Romania, Mozambique, Sri Lanka, Australia, Cote d’Ivoire, Madagascar, Syria, Cameroon	58	49
24	“, Netherlands, Chile, Kazakhstan, Burkina Faso, Cambodia, Malawi, Ecuador, Niger, Guatemala, Senegal, Angola, Mali, Zambia, Cuba, Zimbabwe, Greece, Portugal, Belgium, Tunisia, Czech Republic, Rwanda, Serbia, Chad, Hungary, Guinea, Belarus, Somalia, Dominican Republic, Bolivia, Sweden, Haiti, Burundi, Benin	91	88
23	“, Austria, Azerbaijan, Honduras, Switzerland, Bulgaria, Tajikistan, Israel, El Salvador, (Hong Kong SAR) China, Paraguay, Laos, Sierra Leone, Jordan, Libya, Papua New Guinea, Togo, Nicaragua, Eritrea, Denmark, Slovakia, Kyrgyzstan, Finland, Turkmenistan, Norway, Georgia, United Arab Emirates, Singapore, Bosnia and Herzegovina, Croatia, Central African Republic, Moldova, Costa Rica	123	159

Thus, with each new scale, the number of countries introduced increases by a factor of a little less than ${2}$ , on the average. This approximate doubling of countries with each new scale begins to falter at about the population ${2^{23}}$ (i.e. at around ${4}$ million), for the simple reason that one has begun to run out of countries. (Note that the median-population country in this set, Singapore, has a population with ${23}$ binary digits.)

These laws are not merely interesting statistical curiosities; for instance, Benford’s law is often used to help detect fraudulent statistics (such as those arising from accounting fraud), as many such statistics are invented by choosing digits at random, and will therefore deviate significantly from Benford’s law. (This is nicely discussed in Robert Matthews’ New Scientist article “The power of one“; this article can also be found on the web at a number of other places.) In a somewhat analogous spirit, Zipf’s law and the Pareto distribution can be used to mathematically test various models of real-world systems (e.g. formation of astronomical objects, accumulation of wealth, population growth of countries, etc.), without necessarily having to fit all the parameters of that model with the actual data.

Being empirically observed phenomena rather than abstract mathematical facts, Benford’s law, Zipf’s law, and the Pareto distribution cannot be “proved” the same way a mathematical theorem can be proved. However, one can still support these laws mathematically in a number of ways, for instance showing how these laws are compatible with each other, and with other plausible hypotheses on the source of the data. In this post I would like to describe a number of ways (both technical and non-technical) in which one can do this; these arguments do not fully explain these laws (in particular, the empirical fact that the exponent ${\alpha}$ in Zipf’s law or the Pareto distribution is often close to ${1}$ is still quite a mysterious phenomenon), and do not always have the same universal range of applicability as these laws seem to have, but I hope that they do demonstrate that these laws are not completely arbitrary, and ought to have a satisfactory basis of mathematical support.

— 1. Scale invariance —

One consistency check that is enjoyed by all of these laws is that of scale invariance – they are invariant under rescalings of the data (for instance, by changing the units).

For example, suppose for sake of argument that the country populations ${X}$ of the world in 2007 obey Benford’s law, thus for instance about ${30.7\%}$ of the countries have population with first digit ${1}$ , ${17.6\%}$ have population with first digit ${2}$ , and so forth. Now, imagine that several decades in the future, say in 2067, all of the countries in the world double their population, from ${X}$ to a new population ${X' := 2X}$ . (This makes the somewhat implausible assumption that growth rates are uniform across all countries; I will talk about what happens when one omits this hypothesis later.) To further simplify the experiment, suppose that no countries are created or dissolved during this time period. What happens to Benford’s law when passing from ${X}$ to ${X'}$ ?

The key observation here, of course, is that the first digit of ${X}$ is linked to the first digit of ${X' = 2X}$ . If, for instance, the first digit of ${X}$ is ${1}$ , then the first digit of ${X'}$ is either ${2}$ or ${3}$ ; conversely, if the first digit of ${X'}$ is ${2}$ or ${3}$ , then the first digit of ${X}$ is ${1}$ . As a consequence, the proportion of ${X}$ ’s with first digit ${1}$ is equal to the proportion of ${X'}$ ’s with first digit ${2}$ , plus the proportion of ${X'}$ ’s with first digit ${3}$ . This is consistent with Benford’s law holding for both ${X}$ and ${X'}$ , since

$\displaystyle \log_{10} \frac{2}{1} = \log_{10} \frac{3}{2} + \log_{10} \frac{4}{3} ( = \log_{10} \frac{4}{2} )$

(or numerically, ${30.7\% = 17.6\% + 12.5\%}$ after rounding). Indeed one can check the other digit ranges also and that conclude that Benford’s law for ${X}$ is compatible with Benford’s law for ${X'}$ ; to pick a contrasting example, a uniformly distributed model in which each digit from ${1}$ to ${9}$ is the first digit of ${X}$ occurs with probability ${1/9}$ totally fails to be preserved under doubling.

One can be even more precise. Observe (through telescoping series) that Benford’s law implies that

$\displaystyle {\Bbb P}( \alpha 10^n \leq X < \beta 10^n \hbox{ for some integer } n ) = \log_{10} \frac{\beta}{\alpha} \ \ \ \ \ (1)$

for all integers ${1 \leq \alpha \leq \beta < 10}$ , where the left-hand side denotes the proportion of data for which ${X}$ lies between ${\alpha 10^n}$ and ${\beta 10^n}$ for some integer ${n}$ . Suppose now that we generalise Benford’s law to the continuous Benford’s law, which asserts that (1) is true for all real numbers ${1 \leq \alpha \leq \beta < 10}$ . Then it is not hard to show that a statistic ${X}$ obeys the continuous Benford’s law if and only if its dilate ${X' =2X}$ does, and similarly with ${2}$ replaced by any other constant growth factor. (This is easiest seen by observing that (1) is equivalent to asserting that the fractional part of ${\log_{10} X}$ is uniformly distributed.) In fact, the continuous Benford law is the only distribution for the quantities on the left-hand side of (1) with this scale-invariance property; this fact is a special case of the general fact that Haar measures are unique (see e.g. these lecture notes).

It is also easy to see that Zipf’s law and the Pareto distribution also enjoy this sort of scale-invariance property, as long as one generalises the Pareto distribution

$\displaystyle {\Bbb P}( X \geq 10^m ) = c 10^{-m/\alpha} \ \ \ \ \ (2)$

from integer ${m}$ to real ${m}$ , just as with Benford’s law. Once one does that, one can phrase the Pareto distribution law independently of any base as

$\displaystyle {\Bbb P}( X \geq x ) = c x^{-1/\alpha} \ \ \ \ \ (3)$

for any ${x}$ much larger than the median value of ${X}$ , at which point the scale-invariance is easily seen.

One may object that the above thought-experiment was too idealised, because it assumed uniform growth rates for all the statistics at once. What happens if there are non-uniform growth rates? To keep the computations simple, let us consider the following toy model, where we take the same 2007 population statistics ${X}$ as before, and assume that half of the countries (the “high-growth” countries) will experience a population doubling by 2067, while the other half (the “zero-growth” countries) will keep their population constant, thus the 2067 population statistic ${X'}$ is equal to ${2X}$ half the time and ${X}$ half the time. (We will assume that our sample sizes are large enough that the law of large numbers kicks in, and we will therefore ignore issues such as what happens to this “half the time” if the number of samples is odd.) Furthermore, we make the plausible but crucial assumption that the event that a country is a high-growth or a zero-growth country is independent of the first digit of the 2007 population; thus, for instance, a country whose population begins with ${3}$ is assumed to be just as likely to be high-growth as one whose population begins with ${7}$ .

Now let’s have a look again at the proportion of countries whose 2067 population ${X'}$ begins with either ${2}$ or ${3}$ . There are exactly two ways in which a country can fall into this category: either it is a zero-growth country whose 2007 population ${X}$ also began with either ${2}$ or ${3}$ , or it was a high-growth country whose population in 2007 began with ${1}$ . Since all countries have a probability ${1/2}$ of being high-growth regardless of the first digit of their population, we conclude the identity

$\displaystyle {\Bbb P}( X' \hbox{ has first digit } 2, 3 ) = \frac{1}{2} {\Bbb P}( X \hbox{ has first digit } 2, 3 ) \ \ \ \ \ (4)$

$\displaystyle + \frac{1}{2} {\Bbb P}( X \hbox{ has first digit } 1 )$

which is once again compatible with Benford’s law for ${X'}$ since

$\displaystyle \log_{10} \frac{4}{2} = \frac{1}{2} \log_{10} \frac{4}{2} + \frac{1}{2} \log \frac{2}{1}.$

More generally, it is not hard to show that if ${X}$ obeys the continuous Benford’s law (1), and one multiplies ${X}$ by some positive multiplier ${Y}$ which is independent of the first digit of ${X}$ (and, a fortiori, is independent of the fractional part of ${\log_{10} X}$ ), one obtains another quantity ${X'=XY}$ which also obeys the continuous Benford’s law. (Indeed, we have already seen this to be the case when ${Y}$ is a deterministic constant, and the case when ${Y}$ is random then follows simply by conditioning ${Y}$ to be fixed.)

In particular, we see an absorptive property of Benford’s law: if ${X}$ obeys Benford’s law, and ${Y}$ is any positive statistic independent of ${X}$ , then the product ${X'=XY}$ also obeys Benford’s law – even if ${Y}$ did not obey this law. Thus, if a statistic is the product of many independent factors, then it only requires a single factor to obey Benford’s law in order for the whole product to obey the law also. For instance, the population of a country is the product of its area and its population density. Assuming that the population density of a country is independent of the size of that country (which is not a completely reasonable assumption, but let us take it for the sake of argument), then we see that Benford’s law for the population would follow if just one of the area or population density obeyed this law. It is also clear that Benford’s law is the only distribution with this absorptive property (if there was another law with this property, what would happen if one multiplied a statistic with that law with an independent statistic with Benford’s law?). Thus we begin to get a glimpse as to why Benford’s law is universal for quantities which are the product of many separate factors, in a manner that no other law could be.

As an example: for any given number ${N}$ , the uniform distribution from ${1}$ to ${N}$ does not obey Benford’s law; for instance, if one picks a random number from ${1}$ to ${999,999}$ then each digit from ${1}$ to ${9}$ appears as the first digit with an equal probability of ${1/9}$ each. However, if ${N}$ is not fixed, but instead obeys Benford’s law, then a random number selected from ${1}$ to ${N}$ also obeys Benford’s law (ignoring for now the distinction between continuous and discrete distributions), as it can be viewed as the product of ${N}$ with an independent random number selected from between ${0}$ and ${1}$ .

Actually, one can say something even stronger than the absorption property. Suppose that the continuous Benford’s law (1) for a statistic ${X}$ did not hold exactly, but instead held with some accuracy ${\varepsilon > 0}$ , thus

$\displaystyle \log_{10} \frac{\beta}{\alpha} - \varepsilon \leq {\Bbb P}( \alpha 10^n \leq X < \beta 10^n \hbox{ for some integer } n ) \leq \log_{10} \frac{\beta}{\alpha} + \varepsilon \ \ \ \ \ (5)$

for all ${1 \leq \alpha \leq \beta < 10}$ . Then it is not hard to see that any dilated statistic, such as ${X' = 2X}$ , or more generally ${X'=XY}$ for any fixed deterministic ${Y}$ , also obeys (5) with exactly the same accuracy ${\varepsilon}$ . But now suppose one uses a variable multiplier; for instance, suppose one uses the model discussed earlier in which ${X'}$ is equal to ${2X}$ half the time and ${X}$ half the time. Then the relationship between the distribution of the first digit of ${X'}$ and the first digit of ${X}$ is given by formulae such as (4). Now, in the right-hand side of (4), each of the two terms ${{\Bbb P}( X \hbox{ has first digit } 2, 3 )}$ and ${{\Bbb P}( X \hbox{ has first digit } 1 )}$ differs from the Benford’s law predictions of ${\log_{10} \frac{4}{2}}$ and ${\log_{10} \frac{2}{1}}$ respectively by at most ${\varepsilon}$ . Since the left-hand side of (4) is the average of these two terms, it also differs from the Benford law prediction by at most ${\varepsilon}$ . But the averaging opens up an opportunity for cancelling; for instance, an overestimate of ${+\varepsilon}$ for ${{\Bbb P}( X \hbox{ has first digit } 2, 3 )}$ could cancel an underestimate of ${-\varepsilon}$ for ${{\Bbb P}( X \hbox{ has first digit } 1 )}$ to produce a spot-on prediction for ${X'}$ . Thus we see that variable multipliers (or variable growth rates) not only preserve Benford’s law, but in fact stabilise it by averaging out the errors. In fact, if one started with a distribution which did not initially obey Benford’s law, and then started applying some variable (and independent) growth rates to the various samples in the distribution, then under reasonable assumptions one can show that the resulting distribution will converge to Benford’s law over time. This helps explain the universality of Benford’s law for statistics such as populations, for which the independent variable growth law is not so unreasonable (at least, until the population hits some maximum capacity threshold).

Note that the independence property is crucial; if for instance population growth always slowed down for some inexplicable reason to a crawl whenever the first digit of the population was ${6}$ , then there would be a noticeable deviation from Benford’s law, particularly in digits ${6}$ and ${7}$ , due to this growth bottleneck. But this is not a particularly plausible scenario (being somewhat analogous to Maxwell’s demon in thermodynamics).

The above analysis can also be carried over to some extent to the Pareto distribution and Zipf’s law; if a statistic ${X}$ obeys these laws approximately, then after multiplying by an independent variable ${Y}$ , the product ${X'=XY}$ will obey the same laws with equal or higher accuracy, so long as ${Y}$ is small compared to the number of scales that ${X}$ typically ranges over. (One needs a restriction such as this because the Pareto distribution and Zipf’s law must break down below the median.) These laws are also stable under other multiplicative processes, for instance if some fraction of the samples in ${X}$ spontaneously split into two smaller pieces, or conversely if two samples in ${X}$ spontaneously merge into one; as before, the key is that the occurrence of these events should be independent of the actual size of the objects being split. If one considers a generalisation of the Pareto or Zipf law in which the exponent ${\alpha}$ is not fixed, but varies with ${n}$ or ${k}$ , then the effect of these sorts of multiplicative changes is to blur and average together the various values of ${\alpha}$ , thus “flattening” the ${\alpha}$ curve over time and making the distribution approach Zipf’s law and/or the Pareto distribution. This helps explain why ${\alpha}$ eventually becomes constant; however, I do not have a good explanation as to why ${\alpha}$ is often close to ${1}$ .

— 2. Compatibility between laws —

Another mathematical line of support for Benford’s law, Zipf’s law, and the Pareto distribution are that the laws are highly compatible with each other. For instance, Zipf’s law and the Pareto distribution are formally equivalent: if there are ${N}$ samples of ${X}$ , then applying (3) with ${x}$ equal to the ${n^{th}}$ largest value ${X_n}$ of ${X}$ gives

$\displaystyle \frac{n}{N} = {\Bbb P}( X \geq X_n ) = c X_n^{-1/\alpha}$

which implies Zipf’s law ${X_n = C n^{-\alpha}}$ with ${C := (Nc)^\alpha}$ . Conversely one can deduce the Pareto distribution from Zipf’s law. These deductions are only formal in nature, because the Pareto distribution can only hold exactly for continuous distributions, whereas Zipf’s law only makes sense for discrete distributions, but one can generate more rigorous variants of these deductions without much difficulty.

In some literature, Zipf’s law is applied primarily near the extreme edge of the distribution (e.g. the top ${0.1\%}$ of the sample space), whereas the Pareto distribution in regions closer to the bulk (e.g. between the top ${0.1\%}$ and and top ${50\%}$ ). But this is mostly a difference of degree rather than of kind, though in some cases (such as with the example of the 2007 country populations data set) the exponent ${\alpha}$ for the Pareto distribtion in the bulk can differ slightly from the exponent for Zipf’s law at the extreme edge.

The relationship between Zipf’s law or the Pareto distribution and Benford’s law is more subtle. For instance Benford’s law predicts that the proportion of ${X}$ with initial digit ${1}$ should equal the proportion of ${X}$ with initial digit ${2}$ or ${3}$ . But if one formally uses the Pareto distribution (3) to compare those ${X}$ between ${10^m}$ and ${2 \times 10^m}$ , and those ${X}$ between ${2 \times 10^m}$ and ${4 \times 10^m}$ , it seems that the former is larger by a factor of ${2^{1/\alpha}}$ , which upon summing by ${m}$ appears inconsistent with Benford’s law (unless ${\alpha}$ is extremely large). A similar inconsistency is revealed if one uses Zipf’s law instead.

However, the fallacy here is that the Pareto distribution (or Zipf’s law) does not apply on the entire range of ${X}$ , but only on the upper tail region when ${X}$ is significantly higher than the median; it is a law for the outliers of ${X}$ only. In contrast, Benford’s law concerns the behaviour of typical values of ${X}$ ; the behaviour of the top ${0.1\%}$ is of negligible significance to Benford’s law, though it is of prime importance for Zipf’s law and the Pareto distribution. Thus the two laws describe different components of the distribution and thus complement each other. Roughly speaking, Benford’s law asserts that the bulk distribution of ${\log_{10} X}$ is locally uniform at unit scales, while the Pareto distribution (or Zipf’s law) asserts that the tail distribution of ${\log_{10} X}$ decays exponentially. Note that Benford’s law only describes the fine-scale behaviour of the bulk distribution; the coarse-scale distribution can be a variety of distributions (e.g. log-gaussian).

by Terence Tao at July 03, 2009 11:15 PM

July 03, 2009

Gordon Watts — LHC News

Sorry if this is old news…

CERN management recently had a council meeting. These meetings take place between the council and the CERN directory general. Big funding changes, new projects, major schedule changes, a new country wants to join CERN, etc., all have to be approved by this council. As you might imagine the recent council meetings have been dominated by the “schedule changes” (I don’t actually know as a function of time if that is true, but I would imagine).

What is nice about the current CERN DG is that he usually immediately sends a message out to the public and the the CERN folks. Much better than reading about an updated CERN LHC schedule in the Geneva newspaper. Even better, a presentation to all of CERN (and an open webcast) is schedule. The last one just happened (there is a video link and slides link at the top of the agenda, just under the main agenda title).

Everyone is eager for data. I’ve discussed what I think are some of the pressures on the accelerator division previously. This meeting is a continuing part of that conversation.

It is clear they are doing a huge amount of work. They have a lot done. A huge amount. From a physicist’s point of view, the most frustrating thing about Steve Myers’ talk was there is no date and no energy. It wasn’t clear to me what the plan was until someone asked a question at the very end of the talk. Basically – they will have measured the splices (electrical connections) in all of the LHC in early August. Those splices are what caused the disaster last September – so it is important that all of them be carefully measured. And once they have measured everything – then they can start a discussion with the experiments on start up schedule and energy.

Next time something on the trade offs…

by gordonwatts at July 03, 2009 05:49 PM

Secret Blogging Seminar — Bleg: book recommendations for an undergraduate

Following Emily’s advice, I recently signed up to be mentor in the AWM Mentor Network. It’s been pretty good thus far (I recommend it to any of you who would like to do some menting), but I got a request from my mentee that I thought some of our audience might have better ideas about than me.

What math books would you suggest for relatively casual summer reading for an undergraduate math major finishing their third year? This is not the sort of thing I think about a lot, but I know a reasonable number of readers have a lot more experience with young mathematicians than I do.

by Ben Webster at July 03, 2009 03:01 PM

Chad Orzel — Two-Word Lyrics: Independence Day Edition

I have a new appreciation for Cathy and Amanda and the rest of the infant room staff at the day care center, after two days of chasing a fully recovered SteelyKid around the house because she still had a couple of coxsackie virus blisters on her hands. They're earning the money we're paying them.

She's back in day care today, but my brains have turned to cheese, so here's a lyrics-guessing game. Same drill as before: each of these two-word phrases identifies a song; if you know it and want to guess, leave your guess in the comments, and include a two-word phrase from a different song for other people to guess.

This should be a little easier than usual, as today's songs have a seasonally appropriate theme:

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Secret Blogging Seminar — Three geometric constructions of the irreducible representations of GL_n

The past few weeks there has been a summer school and conference on geometric representation theory and extended affine Lie algebras at University of Ottawa. As part of this event, I gave a week long lecture series entitled “three geometric constructions of the irreducible representations of $GL_n$ “. Specifically I discussed the Borel-Weil theorem, Ginzburg’s construction using Springer fibres, and the geometric Satake correspondence. I focused on $GL_n$ to keep the root system combinatorics and the geometry as elementary as possible.

The typed lecture notes from my talk are now available. If you do read them, please let me know if you have any comments/corrections. (You can also find videos of the talks.)

The other lectures at the summer school were given by Neher, Kang, Wang, Savage, and Chari. I recommend reading their notes/watching their videos if you want to learn more about geometric representation theory, crystals, and affine Lie algebras.

by Joel Kamnitzer at July 03, 2009 11:18 AM

Clifford Johnson — Michael Jackson and D-Branes

Well, I bet you have not read any articles connecting Michael Jackson and research in string theory before. No, even though I spend a lot of time and effort trying to bring science into everyday conversations people have about the broader culture, I cannot claim credit for this one. I was reading an excellent article* in the Village Voice written by Greg Tate, and to my surprise, there it was. It is by far the most thoughtful and insightful of any of the articles on Michael Jackson that I've read, and I'd already concluded that before noticing any mention of physics. I strongly recommend it, especially if you don't know what all the fuss is about, or if you think that the fuss is only about some pop music. Tate examines not just the impact of Jackson on the culture, and where he sits in the pantheon of black people who have made such impact (he's mostly focusing on America), but also the role of adversity and struggle in focusing talent in a way that produces people who create at such a high level and which such seismic effect. He [...]

by Clifford at July 03, 2009 10:56 AM

Backreaction — This and That

The Economist has a nice article on The Underworked American:
"Americans like to think of themselves as martyrs to work. They delight in telling stories about their punishing hours, snatched holidays and ever-intrusive BlackBerrys. At this time of the year they marvel at the laziness of their European cousins, particularly the French. Did you know that the French take the whole of August off to recover from their 35-hour work weeks? [...]

But when it comes to the young the situation is reversed. American children have it easier than most other children in the world, including the supposedly lazy Europeans [...]

Did you notice we're in the middle of a global pandemic? Here's California's reaction: Drive Through Doctors, see "The Doctor Will See You At The Next Window."

Nature has a special on Science Journalism, accompanying the 6th World Conference of Science Journalists from 30 June-2 July 2009 in London, and to "shine a spotlight on the profession in changing times." It contains several interesting pieces, for example Boyce Rensberger's essay "Science journalism: Too close for comfort." (Thanks to George for sending the link!) Rensberger's essay is a brief historical account "to reflect on how far the profession has come since its beginning." (Occasionally a bit too far?) He closes with saying
"We are obviously now in the 'Digital Age', and the very definition of journalism is changing in uncertain directions. Science journalism has moved from working for the glory of the scientific establishment to taking back its independence and exercising a new responsibility to the public. Now, traditional news outlets are withering, leaving many journalists to self-publish online with total independence and a direct connection to the public. But scientists too can use the web, bypassing journalists altogether and taking their science — and their agendas — directly to the public. It is becoming increasingly difficult for readers to tell which sources are disinterested and which have an axe to grind.

If science journalists are to regain relevance to society, not only must they master the new media, they must learn enough science to analyse and interpret the findings — including the motives of the funders. And, as if that were not enough, they must also anticipate the social impacts of potential new technologies while there is still time to make a difference."

Also recommendable is the editorial "Filling the void" (comments in square brackets added):
"[S]cientists are blogging in ever increasing numbers [are they?], and the most popular blogs draw hundreds of thousands of readers each month [#visitors not equal #readers]. These blogging scientists not only offer expertise for free, but have emerged as an important resource for reporters. A Nature survey of nearly 500 science journalists shows that most have used a scientist's blog in developing story ideas [sure, it's all our own fault] ...

Sadly, these activities live on the fringe of the scientific enterprise. Blogging will not help, and could even hurt, a young researcher's chances of tenure [Who want's tenure anyway?]. Many of their elders still look down on colleagues who blog, believing that research should be communicated only through conventional channels such as peer-review and publication [petroglyphs!]. Indeed, many researchers are hesitant even to speak to the popular press, for fear of having their carefully chosen words twisted beyond recognition [once bitten, twice shy].

But in today's overstressed media market, scientists must change these attitudes if they want to stay in the public eye. They must recognize the contributions of bloggers [YES!] and others [others??], and they should encourage any and all experiments that could help science better penetrate the news cycle. Even if they are reluctant to talk to the press themselves, they should encourage colleagues who do so responsibly [pass the buck]. Scientists are poised to reach more people than ever, but only if they can embrace the very technology that they have developed [the spirits that we called...]"

See also our earlier post Do we need Science Journalists?

Paul Fendley was offended by a "the" in Lee Smolin's book "The Trouble With Physics" and thus offers us Five Problems in Physics without the Definite Article. It must totally suck to be a writer. Thanks to Matt for the link.
You find my top 10 unsolved problems in physics here. Note absence of definite article. Now do I qualify to write a book or what?

by Bee at July 03, 2009 10:42 AM

Secret Blogging Seminar — Continued Fractions and Hyperelliptic Curves

I recently read a charming little paper: Quasi-elliptic integrals and periodic continued fractions, by van der Poorten and Tran. Most of us who have taken a number theory course of some kind learned how to solve Pell’s equation: $x^2 - D y^2 =1$ where $D$ is a nonsquare positive integer. The usual method is to compute the continued fraction
$\displaystyle{\sqrt{D} = a_0 + \frac{1}{a_1 + \frac{1}{a_2 + \frac{1}{\cdots}}}}$ .
One then defines the convergents of $\sqrt{D}$ by
$\displaystyle{x_0/y_0 = a_0}$
$\displaystyle{x_1/y_1 = a_0 + \frac{1}{a_1}}$
$\displaystyle{x_2/y_2 = a_0 + \frac{1}{a_1+\frac{1}{a_2}}}$ etcetera.

Then $x_i^2 - D y_i^2$ tends to be very small and, if you compute long enough, for some $i$ you will have $x_i^2 - D y_i^2=1$ .

What van der Poorten and Tran do is to ask what happens if $D$ is not an integer, but a polynomial $D(t) = t^{2g+2} + d_{2g+1} t^{2g+1} + \cdots + d_1 t + d_0$ . Before I get into details, I want to tell you about something gorgeous that I won’t explain at all. Using the methods in their paper, van der Poorten and Trap can discover identities like
$\displaystyle{ \int \frac{3 x dx}{\sqrt{x^4+2x}} = \log \left( x^3+1+x \sqrt{x^4+2x} \right)}.$
Isn’t that pretty?

It turns out that the continued fraction algorithm for $\sqrt{D(t)}$ is actually much prettier than for integers. Everything should be understood in terms of the curve $C$ cut out by $y^2 = D(t)$ . This is a curve of genus $g$ , with two points at infinity. (One of these points is the limit of $(t, \sqrt{D(t)})$ and the other is the limit of $(t, -\sqrt{D(t)})$ .) I’ll call these two points $\infty_{+}$ and $\infty_{-}$ . The theory is controlled by the line bundles $\mathcal{O}(k \infty_+ + \ell \infty_-)$ . In particular, there are nontrivial solutions to $x(t)^2 - D(t) y(t)^2 =1$ if and only if the continued fraction is periodic, if and only if $\mathcal{O}(k \infty_+) = \mathcal{O}(k \infty_-)$ for some $a >0$ .

Below the fold, I’ll explain what is meant by the continued fraction algorithm for an algebraic function, and tell you some of the other nice results from the paper.

Given any power series $Y(t) = Y_k t^k + Y_{k-1} t^{k-1} + \cdots$ in $t^{-1}$ , we define the continued fraction of $Y(t)$ .

Define $[Y(t)] := \sum_{i=0}^k Y_k t^k$ . Set $a_0 = [Y]$ and define $F_1$ by $Y = a_0 + 1/F_1$ . Then set $a_1 = [F_1]$ and $F_1 = a_1 + 1/F_2$ . Continuing in this way, we get a sequence $a_i$ of polynomials, a sequence $F_i$ of power series, and a continued fraction
$\displaystyle{Y = a_0 + \frac{1}{a_1+\frac{1}{a_2+\frac{1}{\cdots}}}}$ .
We can also define the convergents $x_i/y_i$ as before; they do converge to $Y$ in the sense that each ratio $x_i/y_i$ agrees with $Y$ to a higher order than the ratio does.

In particular, suppose that $D(t)$ is a polynomial of the form $t^{2g+2} + d_{2g+1} t^{2g+1} + \cdots + d_1 t + d_0$ .
Then $\sqrt{D(t)}$ is a power series in $t^{-1}$ :
$\displaystyle{\sqrt{D(t)}} = t^{g+1} + (1/2) d_{2g+1} t^g + \cdots.$
So we can define the continued fraction of $\sqrt{D(t)}$ .
We keep the notations $a_i(t)$ , $F_i(t)$ , $x_i(t)$ and $y_i(t)$ from above.

I’ll explain just one key idea from the paper. Let’s think about the zeroes and poles of $F_i(t)$ . Since $a_i(t)$ is a polynomial in $t$ , its only poles are at $\infty_{\pm}$ , and it has a pole of the same order at both $\infty$ ’s. So, other than $\infty_{\pm}$ , the function $F_i(t) - a_i(t)$ has the same poles as $F_i$ . Then $F_{i+1} = 1/(F_i - a_i)$ has zeroes at the poles of $F_i - a_i$ .

That’s what happens away from $\infty_{\pm}$ . Suppose that $F_i(t)$ has a pole of order $p > 0$ at $\infty_{+}$ , and a zero of order $q > 0$ at $\infty_{-}$ . Then $a_i(t)$ has a pole of order $p$ at both $\infty$ ’s. The difference $F_i(t) - a_i(t)$ has a zero of order $\geq 1$ at $\infty_{+}$ and a pole of order $p$ at $\infty_{-}$ . So $F_{i+1}$ has a pole of order $\geq 1$ at $\infty_{+}$ and a zero of order $p$ at $\infty_{-}$ .

Summing up the last two paragraphs, let the poles of $F_i$ be $P + p \infty_{+}$ and let the zeroes be $Q + q \infty_{-}$ . Then the poles of $F_{i+1}$ are $R+r \infty_{+}$ , for some $R$ and some $r \geq 1$ and the zeroes are $P + p \infty_{-}$ . (Here $P$ , $Q$ and $R$ are supported away from $\infty_{\pm}$ .) In other words, there is a sequence of positive integers $p_i$ and a sequence of divisors $P_i$ such that the poles of $F_i$ are $P_i + p_i \infty_{+}$ while the zeroes are $P_{i-1} + p_{i-1} \infty_{-}$ .

Note that $p_i$ is the degree of $a_i$ . Note also that $P_i + p_i \infty_{+} \equiv P_{i-1} + p_{i-i} \infty_{-}$ in the Picard group, so
$P_i \equiv P_0 + p_0 \infty_{-} + \sum p_j (\infty_{-} - \infty_{+}) - p_{i} \infty_{+}$ .

It’s not too hard to work out what happens if the coefficients of $D(t)$ are chosen generically. The first $a_0$ has degree $g+1$ and all the other $p_i$ are $1$ . A bit of effort checks that $P_1$ has degree $g$ (exercise!), so all of $P_i$ have degree $g$ and, in fact, $P_i \equiv (g+i) \infty_{-} - i \infty_{+}$ in the Picard group. You may remember that a generic divisor of degree $g$ has a unique effective representative in PIcard; $P_i$ is that unique representative. So, we have just found an explicit way to write down an arithmetic progression in $Pic^g(C)$ , where $C$ is a hyperelliptic curve.

Of course, the fun comes in the nongeneric case. In that case, the $p_i$ can skip around. It’s really fun when $\infty_{+} - \infty_{-}$ is torsion in the Picard group or, in other words, when there is a unit $x(t) + y(t) \sqrt{D(t)}$ in the coordinate ring of $C$ . Then, eventually, the sequence in Picard will repeat. It turns out, when this happens, the corresponding approximation $x_i(t)/y_i(t)$ gives your unit!

There are plenty of other ideas in the paper. What is the analogue of the result that the $x_i/y_i$ are the best approximations to $\sqrt{D}$ ? The $F_i$ are all of the form $(A_i + \sqrt{D})/B_i$ : how do we relate the polynomials $A_i$ and $B_i$ to the divisors $P_i$ ? And how did I come up with that integral above? All this and more, so read the paper!

by David Speyer at July 03, 2009 10:21 AM

Chad Orzel — How to Teach Physics to Your Dog Contest Winners

After a long baby-induced delay, we are finally ready to announce the winners of the How to Teach Physics to Your Dog Caption Contest and Poetry Contest. I've obtained a few more copies of the bound galleys from the publisher, so we'll be giving two awards in each contest category: one for each photo, one for Cuttlefish poetry, and one for non-Cuttlefish poetry.

And the winners are:

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US/LHC Blog — Surely you are joking Mr Florez!

Surely you are joking Mr Florez!

I was sitting on the airplane from the US to Brussels. There was a technical problem and the monitors for the TV don’t work. It had been an hour already and people started getting impatient, and with all reason. It was late and we hadn’t eaten! A child started to cry, which made things even more tense. Suddenly, the lady sitting right next to me introduced herself. She was about 60 years old and had a strong accent. I asked her where she was originally from and she responded, Israel. I introduced myself and we started the normal conversation that two bored people usually have in a airplane. She looked at me and ask me, “So, Mr Florez what do you do?” I told her that I am a Ph. D student in Particle Physics. Then she asked me my most feared question…oh what is that about?

I smiled and gently tried to explain to her the basic idea. She smiled and with interest asked me, “How are you going to use this LHC that you are telling me about? What is the practical application of it for the society?” I took a deep breath and told her I have to be honest — in terms of practical application in the short term, nothing! She laughed hard and said, “Surely you are joking Mr Florez.” Then, I remembered Feynman’s book and smiled!

At that moment I thought that is interesting how people expect a material reward from every job. Probably, it is something natural in our common sense. I told her that, as scientist, I am curious about the world and the universe around me. I want to know the basic principles of nature to get an idea of how this universe works–not necessarily to apply that knowledge to build something to satisfy or solve a need of humanity. If it happens, it’s an extra reward. But, does that mean that I am selfish person? I am a student and I have been able to learn so much from other scientists. I must say that without their guidance I couldn’t have made much progress in my profession. Science has done amazing things for humanity and great scientific inventions have improved our lives. For instance, the beloved World Wide Web was invented at CERN, the laboratory where the LHC is being build.

I might say that thanks to the studies in particle physics, we have thousands of professionals with great skills in physics, programming, electronics and other areas. Right now, future generations of scientist (including me) are being educated and surely will bring development and science to our countries. Probably we can find amazing things that we will apply in technology in the future. But, for now, this is not the main goal of our experiment. We just want to understand why we are here and how this universe works!

Finally the plane is ready to leave. But, a half hour later, when they tried to play the movie, the TV’s didn’t work….it was a long flight without movies. Very sad…….

by Andres Florez at July 03, 2009 09:09 AM

Edinburgh Mathematical Physics Group — News from The Planck Scale

I recently returned from Wrocław (a.k.a. Breslau) where I attended the first three days of the XXV Max Born Symposium: the Planck scale. (I am not in the habit of leaving conferences before they are finished, but there were no other direct flights from Wrocław to Edinburgh before my return to Japan on Saturday.) [...]

by jmf at July 03, 2009 09:09 AM

Chad Orzel — In Which I Cave In to the Current Social Media Fad-of-the-Moment, Purely for Book-Publicity Purposes, You Understand, Not Because I Need Another Time-Waster

http://twitter.com/orzelc

That is all.

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David Hogg — dwarf galaxies in the mid-infrared

Ronin and I finished her thesis chapter / paper on the ultra-low-luminosity dwarf galaxies observed with SDSS and Spitzer. Our co-author has one week to respond and then we submit it! Congratulations Ronin.

by Hogg at July 03, 2009 08:36 AM

Chad Orzel — links for 2009-07-03

Setshot: Basketball for the Aging and Infirm: Rosters: Managing the list

"Overall, I like administering the list because I can virtually guarantee that any time I want to play, there will be others to play with. I also like the fact that I have some control over who gets on the list, and more importantly, who is excluded from it. Now don't get me wrong—this isn't some velvet rope thing, and it certainly isn't as exclusive as this basketball list. I invited almost all the regular players at the gym. However, I was also able to subtly exclude a few bad apples by intentionally failing to mention the list when they were around."

(tags: sports basketball ethics society blogs)
Physics Buzz: Physics, Fireworks, Fun

"The Fourth of July is this Saturday, and I can't resist trying to inject a little physics fun into the holiday celebration. My apologies to those of you who just wanted to sit in your backyard, eat a burger, and enjoy some fireworks without mentally calculating the trajectory of your bottle rocket or trying to guess at the chemical composition of your Roman candle."

(tags: science physics chemistry blogs physics-buzz)
Cocktail Party Physics: i think it's time

""Time, I think, is a little bit like love. It's accessible to all of us; it is intuitively experienced by all of us in the same way; yet it retains its mystery at whatever level you weigh in on it. It is a mysterious force that we all can experience and share." That's how journalist and session moderator John Hockenberry opened "Time Since Einstein," at the World Science Festival in New York a few weeks back."

(tags: science physics blogs cocktail-party time philosophy)
When are highly-anxious women most anxious? When you least expect it : Cognitive Daily

Which makes sense, because it's much more anxiety-inducing that way...

(tags: social-science psychology gender cog-daily blogs science society)
New Study Shows Clothes Don't Make The Professor - The Daily Californian

"The study, which surveyed four psychology classes at North Hennepin Community College in Minnesota, concluded that the clothing instructors wear has little effect on how students perceive them over longer periods of time. "

(tags: academia society culture education social-science clothing news)

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US/LHC Blog — Life at CMS

So as my internship was drawing to a close (already…?) I was looking back on what I’ve been doing over the past month and a half… and a strange paradox made itself instantly clear: I feel like I still know very little (~nothing) about what is going on at the experiment, and yet if I were to travel back in time to a month and a half ago to talk to myself about what I had done and what I knew of the experiment, my past self would’ve been impressed at everything my present self knows. I guess that’s how you can tell how steep the learning curve is, and at CERN, when you’re working everyday alongside some of the most brilliant people in the world, qualifying the learning curve as “very steep” already sounds like a euphemism.

Yet learning isn’t the only thing I had going for me all this time. My professors would no doubt be relieved to know that I also did (some) work for the experiment, from taking shifts to mounting, installing and databasing (for lack of a better word I made one up) temperature sensors. You know you’ve got something good going for you when, as you’re fighting to get that sensor installed in the midst of all those high voltage cables and razor sharp scraps of hard nylon and metal (there is a mortality rate for undergrads at CERN… though that information is classified), some average Joe on tour of the experiment decides to take a picture of you as you’re working and even asks his kid to stand in the picture with you. I guess they should’ve given me a nametag with “the summer student intern in his natural habitat” written on it… (A “no pictures please, it bothers the animals” sign would’ve been nice too)

I also got some pretty interesting questions asked to me about the experiment. You get all sorts of people on these tours, but I really want to share an excerpt from a particular conversation I had with an anonymous man while touring my own father around the CMS cavern:

Visitor: “So I’ve heard that, if we discover this Higgs particle, also known as the “God” particle, then it will have proven the existence of the Divine Creator?”

Me: “Not exactly… only that there exists one particle that gives mass to all the other particles.”

Visitor: “But… that MUST mean that there is a God, right?”

Me: “I don’t know… is the Higgs particle mentioned anywhere in the Bible?”

(Imagine my shock when I learned that it wasn’t…)

And speaking of interesting people on tour, there was a very important official from the Vatican that came through the CMS experiment, and I heard that he asked where CERN kept its antimatter. We were also honored by the presence of Bill Gates at CMS, who, to my great disappointment, didn’t help us out with our software problems. Yet the greatest fiasco of all was the visit, in one day, of the presidents of Poland and Mozambique. That day, the farmer who owns the fields adjacent to Point 5 woke up with the sudden urge to spray manure all over his land, and, the wind blowing in the direction that it was, the whole place was a stinking mess for the duration of the tour of these two eminent visitors. I think next time the French will be pushing for EU subsidies for their agriculture, the Polish representative might have something to say…

Stinking-up foreign leaders aside, CERN is full of its own array of diplomatic incidents. Going into a physics group meeting, I didn’t expect to understand much, and I didn’t… at least, not physics. Because nothing, not even my professor’s constant references to the “heated debates” that took place within those meetings, could’ve prepared me for what I was about to witness: a yelling standoff between physicists arguing in favor of or against different theories (in keeping with my tradition of euphemisms, I chose to use the word “yelling“ to describe what was going on in that meeting…). To quote my own physics professor, Dr Padley: “It is interesting for you to go to those meetings not so much for the informational content they may have, but for the cultural experience as well.” I think I might disagree on the use of the word “cultural” there, though I will grant that I’ve never before heard so many curse words in all those different languages…

Yet that is what truly amazes me about CERN. It’s hard enough that they have ridiculously large amounts of data coming in, from different detectors, detecting collisions taking place in the largest scientific experiment in the world, operating at energies never before probed by man, but they’ve got to work together with scientists from all over the world! When this experiment finally operates at optimal performance, it will have been an achievement unparalleled in the scientific community, but also a tremendous achievement at the human level, and will confirm once more the resounding truth: that physics is universal, and though we may often disagree with the grammar, it nonetheless makes for one impressive international language.

Amram Bengio

by Rice University at July 03, 2009 12:57 AM

July 02, 2009

Steinn Sigurðsson — the doctrinaire way

and so, my fine young friends...

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Chad Orzel — Thursday Baby Blogging 070209

SteelyKid has recovered her usual energy level, as you can tell by the giant debris field she's created in the living room:

Looking at her there, among the scattered toys with Appa, you might be saying "Boy, what a great big baby she is!" It's all a matter of perspective, though:

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US/LHC Blog — My research [Part 2] — effective theories

We now return to Part 2 of the 3-part series, “my research.” We left off at Act 3: Particle Physics, where we introduced high energy physics as the study of the smallest scales in nature and hailed the Standard Model as the current gold-standard for understanding our observations of those scales.

Intermission: Effective Theories

Before we go any further, we should take a brief intermission to discuss one of the overarching themes in theoretical physics: effective theories. This is just a fancy name for something you already understand intuitively: “physics at different scales decouple.”

Bumpiness by scale.

Okay, that still sounds like fancy-talk. An example is in order. When you drive in your car, you prefer flat roads and watch out for potholes and rocks that might make your ride bumpier. On a much smaller scale, however, we can zoom into the asphalt and see that it’s actually made of little bits of sand and gravel that are actually very bumpy. Because this bumpiness is so small, however, we don’t feel it. Similarly, one can zoom out and note that we’re actually driving on very bumpy geological features on a big rock (the Earth). We don’t feel this bumpiness either, because we’re so much smaller than it.

This is what we mean by “physics at different scales decouple.” This isn’t exact, of course, but it’s a general principle whose utility in particle physics will be made clear in a moment.

Scales and Sciece

Let’s first start by really placing physics in context; think of this as a summary of Part I. I think here a picture is worth a thousand words:

scalesscience

The point to take from this is that science is made up of a series of “effective theories” at different scales. For example, chemistry can describe all of the complicated behavior within a cell; but to describe the physiology of cows or elephants one needs a different kind of understanding of nature, biology.

You could similarly say that “chemistry is just applied physics,” but this really obscures the richness of chemistry that cannot be clearly described by physics alone. In the same way that driving in a car we don’t need to think about the bumpiness of the sand in the asphalt, chemists don’t need to worry about the subatomic phenomena underlying their work: all of this physics is packaged into “effective rules” about chemical reactions.

I think one of my professors said it best when he expressed that

… a chef does not need to know gauge theory.

This means that even though what is actually happening when you bake a cake is a series of very complicated organic/chemical reactions, which are themselves based on subatomic physics, the chef only needs to know a set of rules (a recipe) to bake a cake. The art of being able to make a good cake is not easily understood from the ‘fundamental’ chemical or physical theory underlying the recipe, but can easily be explained by Alton Brown on television.

Effective theories in physics

Let’s get back to physics. A useful analogy to start with is Newtonian mechanics.

We know that Newtonian mechanics is not a complete theory of all physics. At the very least we know that general relativity becomes effective at large scales and quantum mechanics takes over at small scales. Why, then, do generations of high school students have to learn “lies” like F=ma? Isn’t Newton wrong?

No! If you want to calculate the trajectory of a baseball (or even a NASA satellite), you would use Newtonian mechanics. Sure, there would be incredibly small corrections from quantum effects and from the curvature of space… but these are usually much smaller than the precision you care about for the baseball. Newtonian mechanics isn’t wrong — it works just fine. It’s just that it only works within a domain of validity, i.e. within a specific scale.

In this sense it is not a “complete” theory, but nobody ever promised it was.

The unreasonable success of the Standard Model

In very much the same way the Standard Model is incomplete. This doesn’t make it “wrong” any more than F=ma is wrong; it just means that we expect more if we keep digging. There are many good reasons to believe this. The Standard Model does not explain “known unknowns” like gravity, dark matter, the origin of neutrino masses; it has little to say about tantalizing theoretical ideas like supersymmetry or grand unification; and it seems to suffer from a fine-tuning problem in the Higgs sector.

Why then, did I claim that the Standard Model has passed all experimental tests?

That’s because the Standard Model is an effective theory that agrees with all observations of nature at the scale in which it is effective. The “experimental tests” which I refer to are primarily the so-called “precision electroweak” measurements at the LEP I and II detectors in CERN and at the Stanford Linear Collider at SLAC in the 1990s and the flavor experiments whose current state-of-the-art are the B factories at BABAR (SLAC) and BELLE (KEK).

[ In fact, we can turn this question upside down: how can we know that the Standard Model has passed any tests if we haven't even measured the properties of the Higgs boson? The answer is that we're not actually probing the Standard Model (so I lied a little)... we're probing an effective theory of the Standard Model without the Higgs. ]

At the LHC we hope to find hints to some of the outstanding questions of the Standard Model as we begin to probe scales that have heretofore been inaccessible. Hopefully we’ll find hints of “new physics,” but I’ll get to that in Part III.

David Hogg — abstracts, image modeling

I worked on abstracts for the Koposov and Wu papers that are being finished now in Heidelberg. Abstracts are the hardest parts of papers and therefore should be written first and constantly tinkered with as the paper is written and revised.

Marshall and I developed a plan to start image modeling, with the goal of finding faint lensing galaxies under the flux of bright, multiply-imaged quasars. This problem is a hard one in ground-based data, but essential if the lenses from PanSTARRS and LSST are going to be properly mined. The project is related to the image modeling projects of Lang and Bovy and myself; Marshall and I are hoping that we can join forces somehow. Among other big issues: Can we believe the surveys' pipeline-output PSF models, or do we have to fit for a set of perturbations or modifications around or away from those outputs? If we do have to fit, what basis functions make most sense?

by Hogg at July 02, 2009 04:41 PM

Cosmic Variance — arxiv Find: The Local Density of Dark Matter

One of the big hopes of particle- and astro-physicists over the next few years is to experimentally pin down the nature of dark matter. In a perfect world, we’ll make the dark matter particle at the LHC, observe gamma rays produced when dark matter annihilates in the galaxy, and detect it directly in experiments here on Earth. The world isn’t always perfect, but sometimes it’s even better, so everyone is sitting on the edges of their seats waiting to hear what the experiments tell us.

For the direct-detection strategy here on Earth, we build giant detectors and wait for ambient dark-matter particles to interact with something in the detector. If the dark matter is a weakly interacting massive particle (WIMP), that’s not so hard; the difficult part is distinguishing a purported signal from various backgrounds. To know what the signal should be, of course, we need to know how many dark matter particles are zipping through the laboratory. It should be a good number: roughly speaking, there would be about one weak-scale-sized dark matter particle per coffee-cup-volume in the universe, and in our galaxy these particles will typically be trucking along at around 300 kilometers per second.

Still, you’d like an accurate estimate of how much dark matter there is supposed to be in your detector. That’s what Riccardo Catena and Piero Ullio claim to have provided:

A novel determination of the local dark matter density
Authors: Riccardo Catena, Piero Ullio

Abstract: We present a novel study on the problem of constructing mass models for the Milky Way, concentrating on features regarding the dark matter halo component. We have considered a variegated sample of dynamical observables for the Galaxy, including several results which have appeared recently, and studied a 7- or 8-dimensional parameter space - defining the Galaxy model - by implementing a Bayesian approach to the parameter estimation based on a Markov Chain Monte Carlo method. The main result of this analysis is a novel determination of the local dark matter halo density which, assuming spherical symmetry and either an Einasto or an NFW density profile is found to be around 0.39 GeV cm$^{-3}$ with a 1-$\sigma$ error bar of about 7%; more precisely we find a $\rho_{DM}(R_0) = 0.385 \pm 0.027 \rm GeV cm^{-3}$ for the Einasto profile and $\rho_{DM}(R_0) = 0.389 \pm 0.025 \rm GeV cm^{-3}$ for the NFW. This is in contrast to the standard assumption that $\rho_{DM}(R_0)$ is about 0.3 GeV cm$^{-3}$ with an uncertainty of a factor of 2 to 3. A very precise determination of the local halo density is very important for interpreting direct dark matter detection experiments. Indeed the results we produced, together with the recent accurate determination of the local circular velocity, should be very useful to considerably narrow astrophysical uncertainties on direct dark matter detection.

So they’re claiming the density is about .39 GeV per cubic centimeter (where one GeV is about the mass of the proton), whereas the standard figure is something closer to .30 GeV per cubic centimeter. More importantly, they claim to trust their estimate to a precision of about 7%, while the usual number is supposed to be uncertain by a factor of 2 or 3.

I’m not expert enough to judge whether they are right, but it would certainly be very impressive to pin down the density to such high precision. They do assume spherical symmetry, however, which I suspect is not a very good assumption. There are ongoing arguments about how lumpy the distribution of galactic dark matter really is, and I can easily imagine that lumpiness can distort the local density by much more than 7%. But work like this is going to be very important in interpreting the results, if (when?) we do directly detect the dark matter.

by Sean at July 02, 2009 02:55 PM

Dave Bacon — New DARPA Director

DARPA, you know the people who invented the internet ("100 geniuses connected by a travel agent"), has a new director:

The Department of Defense (DoD) today announced the appointment of Regina E. Dugan as the 19th director of the Defense Advanced Research Projects Agency (DARPA). DARPA is the principal agency within the DoD for research, development, and demonstration of concepts, devices, and systems that provide highly advanced military capabilities for the current and future combat force. In this role of developing high-risk, high-payoff projects, DARPA compliments and balances the overall science and technology program of the DoD.

Go MechE's from Caltech! DARPA's last director Tony Tether ruffled a lot of feathers as it was widely perceived that the agency was shifting to short term research at the expense of the kind of groundbreaking work that had been funded in the past (See Peter Lee for details and recommendations for changes at DARPA.) Hopefully Dr. Dugan will take a different tack. That would certainly make a lot of computer science researchers a lot happier.

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US/LHC Blog — Outreach

Outreach activities are an important part of what we do. Not only do they inform the public what their tax dollars are being spent on and allow it to ask questions, but also reaches out to students when they are still thinking about a career; either when they are undergraduates or even earlier in high school.

Research is built around the concept of “apprenticeship”, and having good, motivated students is crucial. They do a lot of the “grunt work”, e.g., building and calibrating the detector, writing software, etc., but they also analyze data that lead to publications, and their dissertations ; undergraduates can also make important contributions.

One way to work with undergraduates is to be a host for a student in the REU program (Research Experience for Undergraduates). An undergraduate typically spends ten weeks during the summer with a research group at a university different from where they are enrolled as a student. This summer a colleague and I are hosting a student from Missouri University of Science & Technology; last year we worked with one from Vanderbilt University. He is reading ATLAS documentation to understand how “Missing Energy” is determined, learning how to use software tools, making plots, giving talks in local group meetings, etc. In other words, getting a first hand look at how research is done.

Another outreach activity I have been involved with since last year is called “Adopt-a-Physicist”. It is coordinated through the American Institute of Physics. Basically, one is “adopted” by high school students from around the country for a period of two weeks, and they ask questions (on a web-based forum) about whatever strikes their fancy, e.g., what my research is all about, what the life of a scientist is like, what my daily activities are, how much I get paid (not as much as I would like! Even Physicists like to own Porsches!), whether I have pets, etc. The adoptees have a Physics degree but are not necessarily in research. It is a very good way for students to learn the benefits of getting a science education. I received the following from one teacher whose class had adopted me, “…thanks for increasing their interest in a science related career. This interaction with you has definitely changed their view about scientists and they realized that scientists are real people leading a life a similar to theirs…” Maybe one or more of them will end up doing research. At the very least, it broadens their perception about science and scientists.

by Vivek Jain at July 02, 2009 01:48 PM

US/LHC Blog — Field trip

Today I and two colleagues took a rather exciting trip to visit the Paul Scherrer Institut, outside of Zurich. We’re engaged in some research on future pixel detectors there, so we have one postdoc stationed at PSI, and two students who are resident there for the summer. Since I was at going to be at CERN for a couple of weeks, I wanted to visit them and see what was going on there.

PSI is about three and a half hours away from Geneva by train, plus a short bus ride at the end. Swiss trains are, by my standards, very civilized! The first leg of the trip, from Geneva to Lausanne, goes along Lake Geneva, and the scenery is very pretty, as you can look across the lake and see the mountains on the other side. We went up last night, after a day of work at CERN, and had dinner on the train, which was on the expensive side but also quite pleasant.

PSI sits on both the east and west bank of the Aare River, with a bridge connecting the two sides. It’s essentially the Swiss general-purpose national laboratory. High-energy physics is only a small part of what they do. They also have a synchrotron light source with very stable beams, a proton source and a neutron beam. Our host for the day was Roland Horisberger, who is the leader of the CMS group there. PSI built the barrel pixel detector for CMS. With tens of millions of readout channels within a radius of 11 centimeters, it’s really a work of art. The truly amazing thing is that the entire barrel was built just by the group at PSI, which is only eight physicists. Suffice it to say that they are all very good at what they do, and what they do covers the gamut of detector design and construction — mechanical engineering, electrical engineering, chip design, and so forth. Now that they have built and installed the detector that will operate in CMS starting this fall, they are hard at work on improving their designs so they can start to build a replacement detector, which will be necessary because the large particle fluxes through the detector will ultimately damage it.

Our students are learning a tremedous amount from working with such a strong and knowledgeable team. I’ll have to visit again soon!

by Ken Bloom at July 02, 2009 12:18 PM

Joe Fitzsimons — The Canadians are coming

The list of accepted papers for FOCS has just been published. There appear to be 6 quantum related papers.

Two-message quantum interactive proofs are in PSPACE
Rahul Jain, Sarvagya Upadhyay and John Watrous.
Span programs and quantum query complexity: The general adversary bound is nearly tight for every boolean function
Ben Reichardt.
Optimal quantum strong coin flipping
André Chailloux and Iordanis Kerenidis.
The Quantum and Classical Complexity of Translationally Invariant Tiling and Hamiltonian Problems
Sandy Irani and Daniel Gottesman.
Universal Blind Quantum Computation
Anne Broadbent, Joseph Fitzsimons and Elham Kashefi.
A Probabilistic Inequality with Applications to Threshold Direct Product Theorems
Falk Unger.

So what's notable about this list (aside from the fact that I'm on it)? Take a look at the authors. Four of the six accepted papers have Waterloo affiliated authors. I count 7 current affiliations to either IQC or PI, out of 12 authors, and Elham has spent time at IQC in the past. If any proof were needed that IQC lives up to its promise its the above list. Try to imagine one institute producing 2/3 of the papers in Nature or Science. Hard, no?

by Joe at July 02, 2009 11:54 AM

US/LHC Blog — LHC Status Update from Steve Myers

LHC Chief Steve Myers gave a very interesting talk on the LHC Status today to a packed auditorium here at CERN. The slides and video can be found here: http://indico.cern.ch/conferenceDisplay.py?confId=62277

Here is a brief summary of what I took to be the most important lessons from the talk (although of course you’ll learn more from going back to the original):

The LHC schedule has been delayed by about three weeks from what was forseen in February. That’s routine schedule slippage and no big deal as far as I’m concerned; if there are no other major issues than we will certainly be running this Fall.
The limiting factor in when and how the LHC starts are the measurements of the resistances of the welding between copper busbars at the connection between magnets, which only carry current when the superconducting wire isn’t superconducting. Some of them have resistances that are too high, and if one of these is affected during a quench, then both the copper and the superconducting wire can melt and cause a current arc. This is what happened last September, and was part of the chain of events that caused significant damage to the LHC. There are other busbars with resistances that are too high, and the highest one in the LHC will limit the total current in the magnets and therefore the accelerator energy.
So far about half the resistances in the accelerator have been fully checked. The rest are planned to be checked by early August, and if there are no significantly higher resistances are found than those seen so far, the LHC will probably be able to do an initial run with energy of about 4 TeV.
Once all these resistances have been measured, and in particular if higher values are found, the LHC experts will have to decide what the highest safe machine energy is. Then CERN, the LHC, and the experiments can decide together if it is better to run at that energy or wait longer in order to repair the worst resistances.
There have been significant upgrades to a variety of systems for preventing and reducing large-scale problems caused by future current arcs or other damage to the helium cryostats in the LHC magnets, although of course the goal is to avoid these in the future.

by Seth Zenz at July 02, 2009 11:40 AM

Chad Orzel — Poll: Threats and Menaces

SteelyKid's nearly over her coxsackie virus, but has just enough spots left that we can't take her to day care. Which means another day of baby wrangling, and another poll question chosen by the dog:

<a href="http://answers.polldaddy.com/poll/1753213/">What is the biggest single threat to your household security?</a><span style="font-size:9px;">(<a href="http://www.polldaddy.com">surveys</a>)</span>

Emmy is convinced that we're insufficiently serious about home defense.

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Dave Bacon — ArXiview 1.2 for iPhone OS 3.0 Out

ArXiview, my arXiv browsing iPhone app, has been updated for the new iPhone OS 3.0. New features include:

Search fields now accept boolean queries and exact phrase queries. Touch the little (i) icon to get info on this feature from the search page.
Search by identifier has been added.
There is now an in application emailer. So when you want to email yourself a reference the program doesn't quit out of the app.
Added the cond-mat category for quantum gases.
The app now sorts resorts in reverse chronological order.
A bunch of bug fixes (search by category in particular was acting buggy.) The bugs were mostly pointed out to me by Andrew. Thanks Andrew!

In the mean time, reviews of the app have appeared in a couple places. Over at MacWorld Kate Dohe reviews the app and pointed out the lack of boolean searching. This should now be all fixed up in the new version. The one feature that Kate requests that I have yet to find a good solution to is how to transfer the pdfs stored on the device to a local desktop. Next on my list.

Another review by Ian Douglas compared all three arXiv apps out there (one is $0.99 and the other is free or $0.99 depending on what the developer decided for that day. It's a great way to boost up your meter on the store: switch between free and paid. Free will boost your popularity meter and then you can get more from the paid! Score! Look for a "arXiview free for a day" promotion coming to this blog soon :) ) Ian puts my app on top:

Dave Bacon is the Quantum Pontiff of the quantum computing-themed blog of the same name. I like the blog very much and didn't want to give his app a bad review, which is why it was a great relief when I found it was the best of the three by quite a long way.

Woot! I think I owe him a beer.

Here is a review in French. Science librarians have also taken note: Mobile Libraries, the science librarian at Drexel physics, Science Libraries in Transition, and the Biomedical and Physical Science library at Michigan State. To name but a few.

An on the ITunes store itself there is finally a review up by ebitnet: "Of the three arxiv apps, this one is the best..." Thanks ebitnet! Does the nickname stand for entangled bit network?

On a similar note, I highly recommend Life as a Physicist who discusses issues with reading pdfs on small mobile displays. I've been playing around with some ideas for how to fix this for arXiv docs...we will see if this gets anywhere.

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Dave Bacon — Bacon Bubble

Okay, I'm calling it. We have officially reached the top of the Bacon loving bubble. Why? The dress made of Bacon indicator has been tripped. This indicator has a 50 percent probability of beating the magic 8 ball in predicting the top of past Bacon bubbles. I predict a hard landing for Bacon lovers everywhere. Until they shed their few extra pounds (a lagging indicator) we are entering a dark period for Bacon.

Hat tip: Jorge.

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Chad Orzel — A Literary Theory

There is a fairly prominent strain of SF fandom which vehemently rejects all but the most superficial forms of literary analysis. This mostly seems to be due to bad experiences with English Lit classes in high school and/or college, at least based on the long rants they used to uncork on Usenet, back in the day.

I suspect that it is this element of fandom that is responsible for godawful dreck like Mike Resnick's stories making it onto the Hugo Award ballot. Their rejection of the very idea of thinking about what's going on beneath the surface level of a story has left them incapable of spotting the point in any story with actual literary virtues. Instead, they end up favoring stories with trite and horribly obvious Morals, whose messages are pounded home with the force of a meteorite strike.

It's only a theory, of course, but it does seem to explain most of the ~~data~~ plural anecdotes.

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Chad Orzel — Hugo Voting

Just a reminder, if you're someone who's eligible to vote for this year's Hugo Awards, the deadline to do so is tomorrow. Of course, you probably already know that-- they sent out reminder emails last night. They want me to vote so badly, in fact, that I got four reminder emails last night, two with my own member number and voting PIN, and two with somebody else's...

I sent my vote in this morning. Once again, this was a year in which there was a huge gap between the category winners and the next-best nominees. It was awkwardly large, in fact-- not quite big enough to put "No Award" second, but big enough that I wanted some way to indicate that. I wonder how they would handle a ballot with no second-place vote, that went directly from "1" to "3"?

For those who care, my votes are below the fold:

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Backreaction — Giant Thistle

Do you recall the day you sat on the thistle? Would you have thought these things can outgrow you?

That plant is about 2m high. Would make for a nice Christmas tree.

by Bee at July 02, 2009 08:19 AM

Georg von Hippel — LATTICE 2009 programme online

The programme for the LATTICE 2009 conference in Beijing is up on the Web (here). This gives me the opportunity to remind my readers of the need for guest bloggers to cover the conference, since I will not attend this year.

by Georg at July 02, 2009 07:18 AM

n-Category Café Open Access to Taxpayer-Funded Research

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$n$ -Café regulars will know about Representative Conyer’s bill that would repeal the National Institute of Health’s public access policy and forbid other US funding agencies from mandating open access to research papers written with the help of federal grant money. Conyers’ argument in favor of this bill was hilariously misinformed. He wrote: “Journal publishers organize and pay for peer review with the proceeds they receive from the sale of subscriptions to their journals.”

But laughing at the folly of the world is not really much fun. Now some good news, for a change! A bill has been introduced that would do quite the opposite. It would ensure free, timely, online access to the published results of research funded by the National Science Foundation and ten other US federal agencies!

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A brief report:

On June 25, Senators Lieberman (I-CT) and Cornyn (R-TX) introduced the Federal Research Public Access Act (S.1373), a bill that would ensure free, timely, online access to the published results of research funded by eleven U.S. federal agencies.

S.1373 would require those agencies with annual extramural research budgets of $100 million or more to provide the public with online access to research manuscripts stemming from such funding no later than six months after publication in a peer-reviewed journal. The bill specifically covers unclassified research funded by agencies including: Department of Agriculture, Department of Commerce, Department of Defense, Department of Education, Department of Energy, Department of Health and Human Services, Department of Homeland Security, Department of Transportation, Environmental Protection Agency, National Aeronautics and Space Administration, and the National Science Foundation.

If you work at a university, now is the time to get the bigshots there to start lobbying for this bill. That’s what we’re doing here at the University of California!

n-Category Café Elsevier Pays for Favorable Book Reviews

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We all know how Elsevier has been running fake medical journals for the drug company Merck, devoted to saying good things about Merck products. But this isn’t all they’re up to.

For example, on a recent thread here at the $n$ -Café, Ben pointed out an interesting BBC news report. Apparently Elsevier offered Amazon gift certificates to academics who would write 5-star reviews of their textbook Clinical Psychology!

Caught red-handed, Elsevier blamed this action on an unnamed ‘rogue employee’. They did not say whether any disciplinary action would be taken.

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Let me quote the relevant portion of the BBC report:

It’s no surprise that the recent actions of science publisher Elsevier caused a storm. The firm offered a $25 (£15) Amazon voucher to academics who contributed to the textbook Clinical Psychology if they would go on Amazon and Barnes & Noble (a large US books retailer) and give it five stars. Elsevier was quick to disown the actions of its marketing employee and emphasise that it had all been a mistake.

“The company doesn’t pay for positive reviews,” says Tom Reller, director of corporate relations. “This was a recent employee error. We haven’t given out any gift cards under the programme.”

He emphases that the rogue employee had gone a long way beyond normal publishing practice.

“Encouraging interested parties to post book reviews isn’t outside the norm in scholarly publishing, nor is it wrong to offer to nominally compensate people for their time.

“But in all instances the request should be unbiased, with no incentives for a positive review, and that’s where this particular e-mail went too far.”

Does anyone know more about this incident, or similar incidents? It would be very interesting if this were not the only case of Elsevier paying for good book reviews.

Chad Orzel — links for 2009-07-02

Newton, P.I. | Cosmic Variance | Discover Magazine

"Happily, Tom Levenson (of The Inverse Square, and one of our honored guest bloggers) has provided us with a fascinating peek into a telling episode in Newton’s later life — his career as a criminal investigator. Not really “P.I.”, as Newton was acting in his capacity as a government official, the Warden of the Mint. The story is closer to something from Law and Order or CSI — remarkably close, in fact. "

(tags: history physics science books levenson blogs cosmic-variance)
Confessions of a Community College Dean: Strong Basis in Confusion

"As a hiring manager, I literally don't know what to do with [the Ricci decision]. I'm compelled by law to ferret out disparate impact, but forbidden by law from doing anything about it. Pre-emptive compliance with disparate impact will fail to meet the "strong basis" standard, since I can't prove I'd lose a lawsuit until I actually lost it. (As Kennedy put it, "[f]ear of litigation alone cannot justify an employer's reliance on race to the detriment of individuals who passed the examinations and qualified for promotions." (p.33) I can't just be afraid of losing; I have to actually lose.) "

(tags: academia law jobs diversity race society culture blogs dean-dad)
News: Supreme Court Punts - Inside Higher Ed

"[L]egal experts note that one category of case the justices tend to take is a dispute in which the federal appeals courts are coming up with different approaches to the same issue. And for that reason, many advocates for Christian students and advocates for gay students had expected that the Supreme Court this week would agree to resolve a legal dispute involving the anti-bias policies of many public colleges and Christian student groups that want the right to ignore parts of those policies"

(tags: education academia law religion society culture)
There, I Fixed It.

"The cunning of the human mind when presented with only duct tape and chip clips is nothing short of amazing."

(tags: blogs pictures silly experiment)
Backreaction: Why are modern scientists so dull? And why that question is nonsense.

"First, the starting point of the whole article is unwarranted. Where is the evidence that something is wrong with modern science? How do you know that we have too few "revolutionary" scientists and too many "normal" scientists? This lacking basis, incidentally, is the same problem I have with Lee Smolin's call for more "risky" research. While I am sympathetic to the argument and personally tend to agree, it's not a scientific statement and anecdotes can't replace data. How do we know it's worse today than yesterday? Who determines whether we need more "revolutionary scientists?" Will somebody calculate a percentage? Who? Based on what? And wouldn't one expect that to depend on the field of research? And on the status of that field?"

(tags: science academia blogs backreaction)
I just won the Association of British Science Writers' Best Newcomer award! : Not Exactly Rocket Science

Congratulations to Ed Yong.

(tags: blogs science prizes journalism)

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Room 538 — N-body simulation of DGP model

I am very happy to have Kwan Chuen Chan from Center for Particles Physics and Cosmology, New York University to talk about their new paper. He is a grad student at NYU, working with Roman Scoccimarro. His office is in Room 538 CCPP.
Keith

Thank Keith for inviting me to blog about our recent paper. In this post I will briefly talk about the paper that Roman Scoccimarro and I just uploaded to the arXiv. I will keep it brief and elementary, so for more details, please refer to the original paper arXiv:0906.4548.

Here is the abstract

Large-Scale Structure in Brane-Induced Gravity II. Numerical Simulations
Authors: K. C. Chan, Roman Scoccimarro
(Submitted on 24 Jun 2009)
Abstract: We use N-body simulations to study the nonlinear structure formation in brane-induced gravity, developing a new method that requires alternate use of Fast Fourier Transforms and relaxation. This enables us to compute the nonlinear matter power spectrum and bispectrum, the halo mass function, and the halo bias. From the simulation results, we confirm the expectations based on analytic arguments that the Vainshtein mechanism does operate as anticipated, with the density power spectrum approaching that of standard gravity within a modified background evolution in the nonlinear regime. The transition is very broad and there is no well defined Vainshtein scale, but roughly this corresponds to k_*= 2 h/Mpc at redshift z=1 and k_*=1 h/Mpc$ at z=0. We checked that while extrinsic curvature fluctuations go nonlinear, and the dynamics of the brane-bending mode $C$ receives important nonlinear corrections, this mode does get suppressed compared to density perturbations, effectively decoupling from the standard gravity sector. At the same time, there is no violation of the weak field limit for metric perturbations associated with $C$. We find good agreement between our measurements and the predictions for the nonlinear power spectrum presented in paper I, that rely on a renormalization of the linear spectrum due to nonlinearities in the modified gravity sector. A similar prediction for the mass function shows the right trends but we were unable to test this accurately due to lack of simulation volume and mass resolution. Our simulations also confirm the induced change in the bispectrum configuration dependence predicted in paper I.

DGP model is an extra-dimension model, which has one co-dimension, and ordinary matter lives on the 3-brane. The graviton propagator is modified in the infrared. One of the interesting properties of this model is that it exhibits self-accelerating solution. The hope was that the recent observed cosmic acceleration may be due to modification of gravity rather than the mysterious dark energy. However, both theoretically and observationally, this model is proved to be unfavorable. However, this model has inspired a bunch of more sophisticated models such as degravitation, galleon. One of the serious problem in modification of gravity is that it induces new degrees of freedom. The theory can usually be approximated as a scalar-tensor theory. But any scalar degree of freedom is likely to be highly constrained by current solar system experiments. There are two nice ways have been put forward to evade this kind of constraints. One of them is chameleon mechanism, which has been realized in $f(R)$ gravity. The other mechanism is called Vainshtein effect, which is incorporated in DGP and some massive gravity models. The scalar degree of freedom becomes strongly coupling and frozen because of the derivative self-interactions. The theory effectively becomes GR.

In this paper, using numerical simulations, we study this type of brane-induced gravity in the nonlinear regime, in particular the Vainshtein effect. We compute the cosmological observables: the power spectrum, bispectrum, mass function, and bias, which give us the signatures of the DGP model, and help us to differentiate modified gravity model from dark energy. In the companion paper arXiv:0906.4545 by Scoccimarro, the model is studied by perturbative calculations. Some of the results are checked against the numerical results in this work.

The method we used is the N-body simulation, which is largely similar to the standard gravity one. However, in GR, the field equation in the subhorizon, non-relativistic regime is just the Poisson equation, now we need to solve a fully nonlinear partial differential equation. Let me write down the equations although I am not attempting to explain it in details
$\bar{\nabla}^2 \phi - \frac{1}{\eta} \sqrt{ - \bar{\nabla}^2 } \phi + \frac{1}{2 \eta} \bar{\nabla}^2 C + \frac{ 3 \eta^2 - 5 \eta + 1 }{2 \eta^2 (2 \eta -1) } \sqrt{ - \bar{\nabla}^2 } C = \frac{3}{2} \frac{\eta -1 }{\eta} \delta$
$(\bar{\nabla}^2 C)^2 + \alpha \bar{\nabla}^2 C - (\bar{ \nabla}_{ij} C)^2 + \frac{ 3 \beta (\eta -1) }{2 \eta-1 } \sqrt{ - \bar{\nabla}^2 } C = \frac{ 3( \eta -1 ) } {\eta } ( 1- \beta \bar{\nabla}^{-1} ) \delta,$
The first equation is analogous to the Poisson equation, but now we have one more field C, whose equation of motion is given by the second one. The nonlocal term like $\sqrt{ - \bar{\nabla}^2 } C$ can be easily handled in the Fourier space. The real headache comes from the nonlinear derivative terms $(\bar{\nabla}^2 C)^2$ and $(\bar{ \nabla}_{ij} C)^2$ . One of the major achievement in this paper is that we developed a convergent method to solve this set of equations consistently. It involves alternate use of relaxation and Fast Fourier transform (so we call it FFT-relaxation method). Although that is a main result of the paper, I am not going to talk about it in details so as not to get too technical and dry. But interested readers are welcome to read the original paper.

Let me get to the results. As I have mentioned, from the simulations we have measured the power spectrum, bispectrum, mass function and bias. Here I only show the power spectrum.
PDGP_Grun_z0
PDGP_GRH_z0
In the first figure we show the power spectrum from three different models, which are the fully nonlinear DGP model (nlDGP), linearized DGP model (lDGP) and the GR with the same expansion history as the DGP model (GRH), which essentially is the GR limit. In order to see the difference more clearly, we have shown the ratios of power spectrum from various models, $P_{\rm nlDGP} / P_{\rm lDGP}$ and $P_{\rm GRH} / P_{\rm nl DGP}$ in the lower figure. In the large scales (small k), the full nonlinear DGP model reduces to the linear one. More interestingly in the nonlinear regime (large k limit), the fully nonlinear DGP model approaches the GR with the same expansion history. This demonstrates that Vainshtein effect drives the model towards GR limit in the large k regime. The transition is broad and the limit is not yet fully attained in the range shown here.

OK, let me summarize some of the main results here. We have developed a convergent algorithm, FFT-relaxation method, to solve the fully nonlinear field equations in the DGP model. This enables to compute the observables like the power spectrum in the DGP model using numerical simulations. We have demonstrated the Vainshtein effect, and the Vainshtein radius at $z =0$ is about 1 h/Mpc. For more details, please refer to our original paper arXiv:0906.4548.

by keithkchan at July 02, 2009 12:05 AM

July 01, 2009

Doug Natelson — This week in cond-mat

There have been a number of exciting (to me, anyway) papers on the arxiv this past week. One in particular, though, seems like a neat illustration of a physical principal that crops up a lot in condensed matter physics.

arxiv:0906.5206 - Tanda et al., Aharonov-Bohm Effect at liquid-nitrogen temperature: Frohlich superconducting quantum device

There are several examples in condensed matter physics of "special" (I'll explain what I mean in a second) electronic ground states that are "gapped", meaning that the lowest energy excited states for the many-electron system are separated from the ground state by an energy range where there are no allowed states. When I say that a ground state is special, I mean that it has some particular order parameter (or broken symmetry) that is distinct from that of the excited states. In this sense, a band insulator or semiconductor is not special - the many-body filled valence band states really don't have any different symmetries than the empty conduction band states. However, the superconducting ground state is special, with broken gauge symmetry (when compared to the normal metallic state) and a minimum energy (the gap energy) required to make any excitations (in this case, by breaking apart a Cooper pair). Fractional quantum Hall states are similarly gapped. The consequence of that energy gap is that the ground state can be very robust. In particular, the gap means that low energy (compared to the gap) inelastic processes cannot perturb the system, since there are no allowed final states around. This is one reason why it is possible to see macroscopic quantum effects in superconductors, as long as T is small compared to the gap.

The authors of this paper have decided to see whether such macroscopic quantum effects (detectable via quantum interference measurements analogous to the two-slit experiment) can survive in another gapped system. The distinction here is that the special state is something called a charge density wave (CDW), where the electronic density in a material (in this case tantalum trisulfide) spontaneously takes on a spatially periodic modulation. This gapped state kicks in at much higher temperatures than typical superconducting transitions. The authors have been able to measure quantum interference robustly in their device at liquid nitrogen temperatures, which is pretty impressive, and there is reason to believe that this could be extended to room temperature. The sample fabrication is very impressive, by the way. You can't just take a sheet of this stuff and punch a hole in it to make your ring-shaped interferometer. Instead, you have to actually curl a sheet up into a tube. Neat stuff, and quite surprising to me. I need to read up more about CDWs....

by Doug Natelson at July 01, 2009 10:29 PM

Chad Orzel — Baby Swimwear Note

Whoever came up with the idea of making little string bikinis in infant sizes should be beaten to death with Barbie dolls.

Seriously. The world does not need 6-9 month size versions of the useless "swimwear" that gets modeled in Sports Illustrated. We barely need the adult versions.

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Cosmic Variance — Newton, P.I.

When I was studying for my Ph.D., a fellow grad student and I asked our advisor if he could think of one single characteristic that was common to all of the best scientists he knew. Without too much hesitation, he answered: “Hard work.” That certainly wasn’t the answer we wanted to hear — you mean there isn’t some secret recipe to being brilliant? And of course hard work is not nearly enough to elevate you to the ranks of the world’s great scientists. But now that I have marinated for some time in the juices of experience myself, I see the truth of what he was getting at; there are a lot of smart people out there, so it makes sense that what elevates a few of them above their peers is an extraordinary focus on their work and a great amount of simple effort.

So it should come as no surprise that Isaac Newton, the greatest physicist of all time, was a relentless worker. In his days at Cambridge, when he focused on the workings of the natural world, he would spend as little time as possible on anything that drew him away from the researches in his rooms. Over the couple of years he was writing the Principia Mathematica, he took things to extremes, going for extended periods without food or sleep. (He also, apparently, died a virgin. Extremes come in many guises.)

Most contemporary physicists have heard that Newton eventually left Cambridge and more or less turned his back on scientific research, to take up activities in later life that we associate with varying degrees of disreputability: alchemy, religious studies, taking a bureaucratic position at the Royal Mint, using the Royal Society to attack his scientific rivals. Lots of us shrug and agree that many older scientists do all sorts of crazy things, and don’t wonder too much about the details.

Happily, Tom Levenson (of The Inverse Square, and one of our honored guest bloggers) has provided us with a fascinating peek into a telling episode in Newton’s later life — his career as a criminal investigator. Not really “P.I.”, as Newton was acting in his capacity as a government official, the Warden of the Mint. The story is closer to something from Law and Order or CSI — remarkably close, in fact. In Newton and the Counterfeiter, Levenson tells the tale of how Newton took up what should have been a cushy sinecure, and ended up devoting his extraordinary Newtonian powers to the pursuit and prosecution of one William Chaloner, the counterfeiter of the title. Poor Chaloner, suffice it to say, never knew what hit him.

I should say right up front that this is not a book about physics. Some time back Tom asked me to read some pages from his draft, to make sure the physics was coming out right, but he assured me that physics played a very minor role in the book. That baffled me a bit, because — well, it is Isaac Newton, right? But this is a work of biography and intellectual history, and offers a fascinating “street-level view” of the dawn of the Age of Reason. I can recommend it without hesitation to anyone who likes good stories, which I presume is just about anyone.

The book does begin with some stage-setting about Newton’s scientific work in Cambridge — it is Isaac Newton, right? But it picks up when our protagonist finally wrangles a position in London as Warden of the Mint. Not supposed to be a taxing job; one of the attractions for Newton was that he was going to have plenty of time available for his research. Mostly, at that time, on alchemy and religion — one of the enlightening chapters looks at how Newton actually went about his alchemical work, which is both engrossing and baffling to the modern reader.

History did not cooperate. The 1690’s was a transformative time for the English currency system, including the introduction of paper money, trade imbalances with the Continent, massive debts run up by William III’s wars in France, and an epidemic of counterfeiting and “coin-clipping,” by which people would shave off the edges of silver coins and melt them down to make new ones. In response, the Mint eventually gave in and undertook a comprehensive re-coinage — a program that was on track to become a complete fiasco until Newton stepped in. Remember that he was not simply an abstract theorist (although he was that); Newton was an extraordinarily careful experimenter, and he turned his practical side to the problem of re-coinage, with spectacular results.

But the real fun comes in when Newton takes on Chaloner, one of the most notorious counterfeiters of the day. I don’t want to give away too much, because you really should buy the book. Suffice it to say that where Newton was gifted with an extraordinary intellect and a relentless work ethic, Chaloner was gifted with what we would today call “balls.” No scheme was too audacious to be undertaken, no lie was too grandiose to be told, no collection of co-conspirators was too extensive to be betrayed or turned against each other. Chaloner was a colorful character, whose story would have made entertaining reading no matter what era he was born into. But he made one unforgivable mistake: he attracted the particular ire of Isaac Newton, who turned the full force of his powers to tracking this miscreant down and bringing him to justice. Chaloner’s own gifts notwithstanding, it was not a fair fight.

We tend to look at successful people and imagine that they are defined by their sphere of success. It’s hard for us today to think of Isaac Newton as anything other than a scientist. But he was good at what he did, whether it was piecing together the mysteries of classical mechanics or paying informers to spy on suspected criminals. Gil Grissom would approve — maybe not of all his methods, but certainly of his results.

by Sean at July 01, 2009 05:58 PM

Clifford Johnson — News From The Front, VII: What is Fundamental, Anyway?

One of the words I dislike most in my field - or more accurately, a common usage thereof - is "fundamental". This is because it is usually used as a weapon, very often by people in my area of physics (largely concerned with particle physics, high energy physics, origins questions and so forth), to dismiss the work of others as somehow uninteresting or irrelevant.

I don't like this. Never have. Not only is it often allied to a great deal of arrogance and misplaced swagger, it is often just plain short-sighted, since you never know where good ideas and techniques will come from. A glance at the history of physics shows just how much cross-pollination there is between fields in terms of ideas and techniques. You never know for sure where valuable insights into certain kinds of problems may come from. Fundamental physics is a term I used to hear used a lot to refer to particle physics (also called high energy physics a lot more these days). This was especially true some years back when I was an undergraduate in the UK, and it persisted in graduate school too, and is still in use today, although I think it is declining a bit in favour of less loaded terms. Somehow, a lot of particle physics is regarded as being all about the "what is everything made of at the very smallest scales" sort of question, first discussing atoms, and then atoms being made of electrons surrounding a nucleus, and the nucleus being made of protons and neutrons, and those in turn being made of quarks, and so on, in this was arriving at a list of "fundamental" particles. There's the parallel discussion about the "fundamental" forces (e.g., electromagnetism and the nuclear forces) being described in terms of exchanges of particles like photons, gluons, and W and Z particles and so forth. There's no real harm in the use of the term fundamental in this context, but this is about where the word gets elevated beyond its usefulness and starts becoming a hurdle to progress, and then a barrier.

Somehow, "fundamental", meaning "building block" gets turned, oddly, into "most important". The issue of what the smallest building blocks are gets elevated to the most important quest, when it is in reality only a component of the story. It is rather like saying that the most important things about the Taj Mahal are the beautiful stones, tiles, and other components from which it is constructed. Perspectives have evolved a bit since my salad days, with the rise of wider [...]

by Clifford at July 01, 2009 04:38 PM

BioCurious — Dead tree scrolls

I have long wondered who, exactly, still reads the dead tree copies of journals. I don’t know a soul who wanders over to a library to get the latest journal articles. The library is now where you go for only those journal articles that have (annoyingly) not yet found their way into a digital format that is Internet-accessible. I also don’t know many people who have subscriptions to dead tree copies of most journals. I’ll see the odd Science and Nature sitting around the coffee tables in various departments, but I don’t know many who prefer to read their favourite journals that way. Besides, Science and Nature are filled with enough news articles and op-eds that they really are science magazines with a more general appeal. Something like the Journal of the American Chemical Society? Definitely not.

Which is why I was quite happy to hear that the American Chemical Society is gradually moving to an entirely online distribution method. As per Nature News,

In 2010, ACS members will no longer be able to buy print subscriptions of journals, and the publications division will monitor print renewals from institutional subscribers. In general, Susan King [senior vice-president of the ACS’s journals publishing division] foresees a “move beyond print to an electronic-only scientific publishing environment”.

Not only is printing a dead tree version of a journal an incredible waste of money (which is obviously the real reason for the change by the ACS), it’s also an incredible waste of paper. Most journal articles are not interesting to most people. Online browsing of Tables of Contents and only printing out the articles you find interesting is a much better (from every perspective!) way of reading the scientific literature.

Of course, there will be a few dissenters. In this week’s Nature, Francois Diederich argues for the print editions of journals. As member of the German chemical society and a senior editor for Angewandte Chemie, he claims “there is a risk that the quality of these prestigious journals [Angewandte, JACS, etc] could gradually decline to the standard of many of today’s web-only journals.”

I’m having a lot of trouble coming up with a rational reason why this might be the case. How does the application of ink to paper by people and machines unrelated to the actual writing, editing, and production of the articles have anything to do with the quality of the science presented in a journal? In fact, abandoning the inconvenient medium of paper will allow for more informative Materials and Methods sections and (hopefully) a reduction in Supplemental Information. A return to well-described and documented methodology is one of the distinct advantages of moving to paperless scientific publishing.

I suspect the reason Diederich is so opposed to the idea is more his initial claim of convenience: “[printed journals] provide distinct advantages in letting me browse their content (during breakfast at home, for example) and readily take in information, without the lengthy opening of individual web pages, article by article.”

In an age of wireless Internet connections and mobile computing, this is not a compelling argument for the continual waste of both money and trees.

by PhilipJ at July 01, 2009 03:46 PM

Dave Bacon — Fido Left Behind

Over at my old blog one thread which keeps on giving is my missive about Dr. Wayne Dyer which now has over 2000 comments. I can always tell when it's PBS pledge drive time by the bump in traffic on my old website and the increase in comments on this post. Today I got a spam comment on the post. Now usually spam comments aren't to exciting (bad Viagra joke deleted), but this one is...well...different.

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Chad Orzel — Plagiarism, Garbling, and Superluminal Motion

I no longer recall who pointed me to this current.com post titled "Scientists Make Radio Waves Travel Faster Than Light "-- somebody on Facebook, I think. As it would be a pretty neat trick to make light move faster than light, I took a look. The opening is fairly standard semi-gibberish:

Scientist John Singleton insists that Albert Einstein wouldn't be mad at him, even though at first blush Singleton appears to have twisted the famous physicist's theories about light into a pretzel.

Most people think Einstein said that nothing can travel faster than the speed of light, but that's not really the case, Singleton said.

Einstein predicted that particles and information can't travel faster than the speed of light -- but phenomenon like radio waves? That's a different story, said Singleton, a Los Alamos National Laboratory Fellow.

Singleton has created a gadget that abuses radio waves so severely that they finally give in and travel faster than light.

This is fairly clearly the result of somebody not understanding the explanation they were given. What was really puzzling about the article, though, comes very near the end:

If Einstein were still alive, he probably wouldn't be all that surprised by the discovery, Perez said, even if it does seem on the surface to conflict with some of his theories.

That might not immediately seem odd, but this is actually the first mention of anybody named Perez. There's no earlier reference giving his first name or institutional affiliation. That's pretty unusual for what is otherwise a fairly professional-sounding article.

This happens because the post is incompetently copied from this article from a Santa Fe paper-- whoever appropriated it for current.com dropped a couple of paragraphs, including the one identifying Singleton's co-author, Mario Perez, also of Los Alamos National Laboratory.

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US/LHC Blog — Shifts

One of the chores that we have to face as summer interns at the CMS experiment is the half-dreaded, half-loved shifts. During these at time endless periods of time, we get to drive about 30 km away from the LHC main site in Meyrin to the so called point 5, or the location of the LHC ring where the CMS experiment is, in the town of Cessy.

A shift involves monitoring the different subdetectors of the experiment, making sure that the temperatures, humidity, voltages and many other parameters stay within the specified ranges. As shifters, we have limited possibilities as to what exactly we can do to fix any problems that might (and do) arise. In case, we are to let the shift experts know about any issues that arise. Sometimes, the problems are trivial, and one must just make a note of them and let it go. However, as Amram and Tico know very well, sometimes serious issues arise, and one has to have the guts to take drastic decisions, such as turning off the detector itself. (Not that we have access to the buttons that do this, but we’re around when this is done).

Last week, for instance, there was a general power failure at point 5. Some of the cooling cycles did not turn on again after power came on, while some of the wires carrying thousands of volts were quickly heating up. Before they cooked, said voltages had to be turned off.

In general these events are quite rare though. It is of course necessary to always have someone controlling each of the subsystems (Data Acquisition, Tracker, Pixels, the different calorimeters, the cathode strip chambers…), because whenever the experiment is running, someone will always have to on duty to check that the data acquisition process is running as smoothly as possible.However, spending 8 hours in a row sitting in a room with many screens, many of which don’t even change their display at all does get somewhat tedious at times…

Update: there is this cool website : http://cms.web.cern.ch/cms/Media/CMSeye/cam6.html. From there you can get a snapshot of the surface control room. It is updated every 5 minutes and if you’re lucky you might even see some of us there!

by Rice University at July 01, 2009 10:36 AM

Chad Orzel — Infinite Jest: My Favorite Footnote

The Infinite Summer people got me to start re-reading Infinite Jest, but I'm not really going to attempt to hold to their proposed reading schedule. Not because I find it hard to find time to read, but because I have trouble putting it down to go to sleep, let alone in order to keep pace with an online reading group.

I've been reading a bunch of the commentary that's already been posted (see here for an early round-up, and here for the thoughts of a bunch of political bloggers), and I have to admit, I find a lot of it baffling. There's a lot of hating on the footnotes, and while I will admit that the infamous filmography footnote is something that only really makes sense later, footnote 304 has also come in for a lot of derision. I find that incomprehensible, as footnote 304 is one of my favorite bits of the entire book-- it's an infodump presented in the form of an anecdote about a student plagiarizing a term paper from an overwrought academic article. This is one of many bits in this book that convince me I could never really make it as a novelist-- it's way better than anything I could hope to produce.

I'm also a little puzzled by the common complaints about the book starting slowly, and people feeling like they don't understand what's going on. This strikes me as kind of odd, as they're not even 100 pages into an 1100 page book-- you're not supposed to have a solid idea of the plot that early on.

Much as I hate fans-are-slans arguments, I wonder if this isn't an area where reading genre fiction helps-- I'm typing this in a room full of (mostly) SF books, many of them multi-volume epics running to thousands of pages. I'm not particularly intimidated by great big thick volumes whose plot arc isn't obvious early on-- I'm perfectly happy to roll with a book for a few hundred pages before I find out what the main plot is, provided it's entertaining along the way. And Infinite Jest is very good, right from the beginning.

Even the endnotes. I particularly recommend #304.

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Backreaction — Why are modern scientists so dull? And why that question is nonsense.

Bruce Charlton, Professor of Theoretical Medicine at the University of Buckingham, wrote an essay

I stumbled across this on Information Processing, you can download the PDF here.

After reading the paper, I felt the need to check the Elsevier logo on the PDF is not a fake. It isn't. The thing got published in the journal Medical Hypotheses, Volume 72, Issue 3, Pages 237-243. Prof. Carlton btw is Editor in Chief of this journal.

Summary

The argument the author puts forward can be roughly summarized as follows.

Modern scientists are "intellectually dull" and "lack scientific ambition." The reason for this, so Charlton, is a failure of the selective process in the academic system. He argues that the education of scientists is taking increasingly longer. As a result, being a scientist nowadays requires "an almost superhuman level of [...] perseverance - the ability to doggedly continue a course of action in pursuit of a goal, over a long period and despite difficulties, setbacks and the lack of immediate rewards (and indeed the lack of any guaranteed ultimate rewards)."

A near-synonym for this perseverance that he uses throughout the paper is the Big Five personality trait called "Conscientiousness". (The "Big Five" is a fairly common personality test that you can do yourself eg here). Besides Conscientiousness, Charlton writes, scientists today need to score high also on a second Big Five personality trait called "Agreeableness."

In the rest of the paper he argues that actually relevant for scientific success is a combination of three different factors: Most importantly, the IQ. And besides the IQ, creativity and "transcendental truth-seeking." If scientists are selected because of other qualities than these, then the average IQ of scientists isn't as high as it could be and their research not as revolutionary as should be. And that is then the reason why scientists are so agreeable, so conscientious, so uncreative. Or in one word: dull. That bothers Charlton because science has a need for "revolutionary scientists" (Greetings from Kuhn) and we thus have a lack of these people. Instead we have an overdose of the normal scientists. Revolutionary science is what the NSF calls "transformative research".

After elaborating on the importance of a high IQ, Charlton claims we should be looking for people with a low score of conscientiousness because "working on your own problem requires much less perseverance than working hard for many years at non-scientific problems, or working hard for many years at other people's scientific problems."

In one section Charlton writes that creativity has shown to be positively correlated with psychoticism, and even though "high levels of psychoticism are maladaptive," "low psychoticism would therefore be a desirable trait for normal scientists, but undesirable for revolutionary scientists." In the following section, he further makes a case for "asocial and awkward individuals," which he means to be the opposite of "agreeable". (This was the part of the paper that put off Chad, see discussion at Uncertain Principles.)

In the light of his elaboration, educational achievement is then no longer a reliable factor to determine a student's promise. Charlton thus talks into existence the following relation

Educational attainment ≈ IQ x Conscientiousness

Since he claims that low conscientiousness is what distinguishes the "revolutionary" scientist, one then wants to measure this factor. A tedious calculation yields

Conscientiousness ≈ Educational attainment/IQ

Thus, what one should measure is simply a student's IQ, and look at their grades. If their grades aren't as good as their IQ suggests, then they are "under-achievers" and thus promising revolutionary scientists. It is noteworthy that it does occur to the author such a procedure to select scientists has the slight problem that it's not so hard to fake bad grades. His comment is "[A] person could make themselves look like an 'underachiever' by deliberately messing up their exams [...] - however this would only be achievable at the cost of lowering their exam results, which is not often going to be a helpful thing to do so."

Leaving aside that the content of the sentence is close to nil, it neglects the fact that if you'd listen to Bruce Charlton, it would become a helpful thing to cheat on your exams.

Comments

Since, as you know, the failure of the academic system to select the most promising scientists is a pet topic of mine, this can't be left uncommented.

First, the starting point of the whole article is unwarranted. Where is the evidence that something is wrong with modern science? How do you know that we have too few "revolutionary" scientists and too many "normal" scientists? This lacking basis, incidentally, is the same problem I have with Lee Smolin's call for more "risky" research. While I am sympathetic to the argument and personally tend to agree, it's not a scientific statement and anecdotes can't replace data. How do we know it's worse today than yesterday? Who determines whether we need more "revolutionary scientists?" Will somebody calculate a percentage? Who? Based on what? And wouldn't one expect that to depend on the field of research? And on the status of that field?

Second, it is highly doubtful low conscientiousness is beneficial for "revolutionary" science. Charlton's argument is based on his believe that "self-chosen problems provide much more immediate reward," thus requiring a lower level of conscientiousness. Unfortunately, this claim is just bluntly wrong. If you chose a problem yourself, if you are "non-agreeable" and left to your own devices, you better score high on perseverance and conscientiousness, and have a high capability to cope with frustration. I have no clue how Charlton came up with this assertion. In contrast to most of the other claims that he makes, this one is not backed up by any reference.

Third, note Charlton's claim is not merely that revolutionary scientists do not necessarily need a high level of conscientiousness, but that they need a low one, meaning conscientiousness must be understood as actually being harmful to their research.

Forth, any claim that the most promising scientists can be identified by measuring some numbers assigned to their name by itself limits the possibility for revolutions. You may be oh-so sure measuring three relevant factors will reliably select the best scientists, but I might disagree. Who are you to decide what's good for science?

Fifth, and what about that thing called "transcendental truth-seeking?" Let us see what Charlton has to say about that: "A further vital ingredient is necessary: that elite scientists must have a vocational devotion to transcendental values of truth," and "Great revolutionary science is therefore a product of transcendental truth-seeking individuals working in a truth-seeking milieu," and "detecting truth-seeking, requires a scientific system that explicitly and in practice values transcendental truth-seeking." That sounds all well and fine, just that lacking any explanation what "trancendental truth-seeking" is supposed to mean, you could replace "truth" with "banana" and not change the scientific content of these statements. Charlton further claims that "science nowadays [...] lacks the living presence of such transcendental values." I occasionally feel like some of my colleagues values' are a little to transcendental. I guess that means I'm a very dull and normal scientist. Dooh.

Bottomline

The problem Charlton runs into is the same problem all other such attempts to fix the academic system run into. They attempt to define absolute criteria for "success" or "good research," and fail to see that the definition of such criteria itself will work against their goal. Whenever you define a criterion, whenever you fix a percentage, whenever you claim we need more of that and less of that, you are twisting knobs on a system that works best without any twisting. It works without method, and it works without measure.

I argued previously there is no better way to do science than to let scientists do it themselves and just to make sure the research process isn't affected by external pressures. Scientists themselves are well aware of the need for revolutionary science/risky projects/transformative research. They also know brilliant people can be complicated. They know the value of disagreement. They are smart people and most of them know who Kuhn, Feyerabend and Popper are. They are in academia because they are dedicated to science and truth-seeking. The problem is not that they don't know what to do. The problem is that "the system" does not allow them to follow their instincts and various sorts of pressure (most notably financial and time pressure) deviate their interests. This in turn has consequences for the selection process. In the long run this can lead to a detrimental population of the academic research environment.

More details in my earlier post We have only ourselves to judge each other.

For completeness, here's my Big 5 Results, and I'm INTJ.

by Bee at July 01, 2009 09:11 AM

US/LHC Blog — The things I learned in Kindergarten

I’m sure that many of you are aware that the LHC has several thousand people working on it and on all the experiments associated with it. When I tell my friends and family that I work on ATLAS, I’ve often been asked how do I work in a group of 2500 physicists? It’s not quite as straightforward as we just take a long time during roll call. So thought it would be worth mentioning it in this blog.

It all stems from the things you learned in kindergarten. I’ll start with the basics. Of course everyone on ATLAS doesn’t work with every other person. It’s comprised of several different detector components and areas of interest, each of which have their own working group. For example I work on the Liquid Argon (LAr) Calorimeter, so I’m a part of that detector group. I also work on physics associated with electrons and photons, so I’m in the e/gamma group. (photons are represented by the Greek letter gamma). There are groups for each part of the detector, each area of physics, for all the triggers, and for all the computing. A person is usually in a couple of these groups and often times the topics for discussion overlap. Although most of the time these groups work on topics independently, they’re all working toward the same goal, so it’s important to be able to work together. Which is the first lesson you learn in kindergarten. I was talking about this with my roommate and fellow blogger, Stephanie, who skipped kindergarten (off to learn more important things than sharing ;)). Now I don’t know how many of my colleagues skipped this important first step in academia, but I recently gave a presentation on behalf of one of the groups I work for, and I thought I’d share the experience.

In my years in graduate school, I’ve found that physicists are procrastinators. (Which was maybe the 2nd thing you learned in kindergarten… don’t procrastinate, or maybe don’t eat paste was 2nd… then 3rd was don’t procrastinate). I can’t pretend to be blameless, the deadline always seems a little farther away than it actually is. Needless to say this presentation was no different. About a week before, we started seriously talking about what we wanted to present (things like which data plots we wanted to show, how we wanted to show them, etc..). Which seemed like a reasonable amount of time in advance. There was enough material to present to make 2 presentations, so a fellow student and I were assigned to the tasks. So I diligently started working on my part thinking I have about 5 days to complete it. The first wrench in the process was when the other student wasn’t going to be able to present. So I’d have to combine both into one big talk. (Neither of which had been written, as of then).

I had been sent approximately 100 Power point slides to use in my 45 min talk. (This was a compilation of all the work that we’ve done over the course of 5 months or so… which may lead us into the 4th thing you learn in kindergarten: figuring out what is important stuff to know, and what isn’t. Example: the names of all 5 members of New Kids on the Block - important, your address and phone number - maybe not). I frantically sifted through the pages and pages of information trying to figure out what was most important as well as recreate the results that had been presented in our smaller group meeting a few days before.

Three days and one very stressful weekend later, brings us to the day of the presentation. Of course the results didn’t match up quite right (something we’re still trying to figure out), the errors on our numbers were big and finally right before the meeting started we decided to call the results preliminary and continue the work past the presentation.

At the end of the day, the everything went well, the analysis we are working on is complicated and there are a lot of subtle details that we didn’t realize were as important as they were. (lesson number 5: the world is complicated :)). At the end of the day, we needed everyone’s contribution to even get as far as we did, and that’s why working together is so important for a 2500 person experiment. Does it always work like a Swiss made clock? Maybe not, but after the presentation I did remember the last thing I learned in kindergarten: the importance of an afternoon nap.

On a different and much more sad note. During all the stress of preparing the talk, I learned that one of my favorite childhood entertainers had passed away. Even in France, MTV was doing a video tribute (which was the first time in a while I had seen music videos on MTV). I wanted to share this really touching link: MJ commercial

Until next time.

by Regina Caputo at July 01, 2009 09:05 AM

Backreaction — Hello from the SUSY 2009

As previously mentioned, I am here in Boston at the SUSY 2009, the 17th International Conference on Supersymmetry and the Unification of Fundamental Interactions. Since its inception 1993, the SUSY has become the meeting for everything around and everybody involved in physics beyond the Standard Model, from Supersymmetry and its breaking, via extra dimensions of any sort (large, universal, warped), String model building in general to Grand Unification and the phenomenology of Quantum Gravity (though mostly focussed on graviton and black hole production at the LHC). What was previously called the session on "alternatives" is now called "unconventional approaches." The word "alternative," it seems, is a bit worn out. The SUSY is a lively mix of experiment with theory, which is one of the reasons why I like it.

The meeting this year takes place at Northeastern University, where I had not been before. It is a nice place, very conveniently located, with a small but well maintained campus. (I took some photos, but unfortunately forgot the cable I need to upload them, so they will follow later). I had not known that Northeastern University was also where the first SUSY conference in 1993 was held.

On Friday we had the first session of plenary talks with updates from the LHC and TeVatron, and a reception in the evening to get to say hello to familiar and unfamiliar faces. Every time I'm at the SUSY there seem to be more people. Maybe it's me getting old, but there are really a lot of young postdocs around this year many of whom are enthusiastic about their research and I'm sure they will make interesting contributions during their career. Most of them were crammed in the parallel sessions during the weekend. I too delivered my talk this afternoon (slides here), squeezed between SUSY breaking and degenerate vacua. I think it went reasonably well.

This evening, we also had a public lecture by Frank Wilczek from MIT (Nobel Prize 2004 together with David Gross and David Politzer). Titled "Anticipating a New Golden Age," Wilczek explained what the LHC (The World's Largest Microscope) is and what it does, including the LHC Rap. He then went on to explain what Supersymmetry is and how it helps with the unification of the gauge couplings, expressing his conviction that Nature is giving us a clear sign that Supersymmetry is part of her workings (that part of the talk being identical to what he told at SciFoo last summer). He finished with the inspirational note that it's not only an exciting time to be a physicist, but an exiting time to be a thinking being - even if you are not actively working on these theories, we might be very close to unraveling some fundamental truth about reality. It was a very nice talk and I think the audience enjoyed it.

by Bee at July 01, 2009 08:28 AM

Backreaction — Quantum To Cosmos

Today Perimeter Institute announced the “Quantum to Cosmos: Ideas for the Future” festival that will take place October 15 to 25. And I'm so sorry I can't be here because it sounds tremendously exciting! The most important thing first: there is a website where you can find a lot of information

q2cfestival.com

This afternoon in the Theater of Ideas, after a welcome by our director Neil Turok, John Matlock (Director of Communications) and Richard Epp (Scientific Outreach) briefly outlined the event, followed by several VIPs in suits who said a lot of nice words, including the mayor of Waterloo, two guys who are ministers of something, a women from TVO, and Mike Lazaridis himself.

The Quantum to Cosmos festival will celebrate the 10th anniversary of PI’s inception, and simultaneously contribute to Canada’s National Science & Technology week, and be part of the International Year of Astronomy. As Mike added later, it isn't only PI's 10th anniversary, but also the 10th anniversary of the BlackBerry.

There are more than 50 events planned, including exhibits, cultural performances and film screenings, plus there will be quite an effort be made to allow a larger online community to take part in the festival by providing podcasts, live streaming and live blogging, supported by the media partner TVO. The festival is on Facebook, on Twitter on MySpace and on Friendfeed. A lot of interesting speakers will be here for the event, including Larry Abbott, Sean Carroll and Katherine Freese.

After the announcement we had a reception in the atrium. The guy with the camera has been sneaking around

and I took a couple of photos. Here is Neil waving with his arms

Robin Blume-Kohout and Achim Kempf

And here you can make a little bit of crowd-spotting. In the picture: two of our faculty members, Rob Spekkens and Rob Myers, Jon Henson, Dario Benedetti, the mayor of Waterloo, Simone Speziale, Constantinos Skordis, Samuel Vazquez, Nicolas Menicucci, and, so I belive, Jon Walgate.

(Close-up of the two Robs here). And here is the charme of the Institute, Sarah Croke, who is presently also our Postdoc Representative

I am afraid I will miss them all.

With that, I wish you all a great weekend!

by Bee at July 01, 2009 08:28 AM

Backreaction — Perimeter Institute Grows

We're running out of space! If you visit Perimeter Institute these days, you'll find desks crammed into every single corner in the corridors. Yet, still more people are being hired. One of the hotly discussed topics in the last months has thus been the upcoming building expansion. Luckily noise and dirt will start after I've left. Here is the official press release, with all significant quotes and digits:

Waterloo, Ontario, Canada, June 18, 2009 - Today, Neil Turok, Director of the Perimeter Institute for Theoretical Physics, welcomed the new investment of $10,012,043 from Canada Foundation for Innovation (CFI) supporting a major expansion of the Institute's world class facility.

"The CFI's support of cutting-edge research infrastructure has transformed Canada's research landscape and increased the country's international competitiveness," said Dr. Eliot Phillipson, President and CEO of the CFI. "Investments like these have allowed Perimeter Institute to become a destination of choice for some of the world's top research talent."

Perimeter's existing building in Waterloo, made possible by a past CFI investment in 2002, exceeded expectations and is operating at capacity. It must now be expanded to achieve the Institute's goal of becoming a world-leading centre promoting major scientific breakthroughs. This new CFI funding will support a 55,000 square foot expansion, in the form of a purpose-built facility designed by the Governor General Award winning firm Teeple Architects.

Plans allow for Perimeter to double its individual and group research spaces, including a new world-class research training space, all with state-of-the-art IT infrastructure enabling complex calculations and the analysis of large data sets as well as remote collaboration with international colleagues. The expanded facility has been designed as the world's ultimate environment for physicists to conceive, visualize and understand the nature of reality, from the subatomic world to the entire universe.

The potential payoff of this expansion of Perimeter Institute is immense. Just one major discovery in theoretical physics is literally capable of changing the world, as when Maxwell discovered a unified description of electricity and magnetism, and Marconi applied his ideas to send the first radio signals. Today, quantum theory is paving the way for the computers and communication systems of tomorrow, which will
vastly exceed the capabilities of current technologies. This historically proven cycle of innovation is fuelled by the foundational thinking that drives the research chain.

"The support received from federal partners like CFI is invaluable and will enable Perimeter Institute to become a leading global hub for theoretical physics research," said Neil Turok, Director of the Institute. "As a result, Perimeter Institute now provides an exceptional opportunity for major scientific progress, for Canada and for the world."

Funding for this project is part of a major $666,128,376 investment announced today by the CFI to support 133 projects at 41 institutions across the country. $247,664,977 was awarded under the Leading Edge Fund (LEF), designed to enable institutions to build on and enhance already successful and productive initiatives supported by past CFI investment.

Another $264,741,466 million was awarded under the New Initiatives Fund (NIF), designed to enhance Canada's capacity in promising new areas of research and technology development. Finally, $153,721,933 was awarded under the Infrastructure Operating Fund, which assists institutions with the incremental operating and maintenance costs associated with new infrastructure.

"Our community is an innovation leader, and we continue to build the intellectual capacity that will drive our future growth and prosperity," said Peter Braid, MP for Kitchener-Waterloo. "This funding for research infrastructure at the Perimeter Institute will ensure that Canada remains at the forefront of scientific discovery, and reinforces our reputation as a centre of excellence."

A complete list of projects funded today by the CFI can be found at: www.innovation.ca.

The Canada Foundation for Innovation (CFI) is an independent corporation created by the Government of Canada to fund research infrastructure. The CFI mandate is to strengthen the capacity of Canadian universities, colleges, research hospitals, and non-profit research institutions to carry out world-class research and technology development that benefits Canadians.

by Bee at July 01, 2009 08:28 AM

Backreaction — This and That

Some photos from the SUSY 2009 conference are online now, you can find them here. Here is one that caught me at the reception first day. And just in case, I'm the second from the left. Please don't ask me who these people are coz my brain has a black hole where other people store names.

Some more photos that I made, here's Boston

And here's the Curry Student Center at Northeastern University, the building where the parallel sessions took place, as well as some folks in the coffee break and the audience of the public lecture

I'm not on the group photo for no other reason than that I didn't know when it would be made.

Some other things:

Lee Smolin wrote a piece for PhysicsWorld titled "The Unique Universe". I don't know what to make out of it, so I'll restrain from commenting.

Martin Fenner asks Why do we go to conferences.

For quite convoluted reasons I found this article about Perimeter Institute in the Google cache. It's hilarious. I have the uncanny feeling somebody might be quiet unhappy I digged it out, but I can't resist sharing it. Let me quote you some lines
Faced with [Laurent] Freidel’s delirious state of distraction, his wife reportedly pleaded with a colleague: “Can’t you do something? He’s going insane.” [...]

Markopoulou-Kalamara is the only female faculty member at Perimeter. She makes efforts to tone down her exuberant European elegance to match the company she keeps—that is, variously aggressive, cavalier and nerdy male physicists. One of them, her husband Olaf Dreyer, had recently experienced an eureka moment. “He thinks he’s found the solution to quantum gravity,” she says. “He’s flipping out.” [...]

Every physicist at Perimeter has free use of a BlackBerry, though, as Smolin laments, “the phone bill isn’t covered.” [...]

Bilson-Thompson, 33, is a playful scientist who wears a perennial pony-tail and fleece [...] The Perimeter Institute, he says, encourages the same adventuresome pursuit of knowledge with a simple laissez-faire formula: “Take scientists, put them in a box and say, ‘OK you boffins, do your thing.’” [...]

Physicists are forever thinking they’ve “got it,” Markopoulou-Kalamara says. Or they are tormented because they don’t. This is the physicist’s bipolar yo-yo of euphoria and despair. “We need to have a psychiatrist in residence,” she says. “Somebody is always in a state of crisis over something.” [...]

As for Smolin, he said “Hello” when Susskind arrived for his visit at Perimeter in March, but got a tepid response. “It was in a tone that gave me the impression he had no interest in speaking to me,” he says.

Says Susskind, “I spend every day having lots of interesting conversations.” [...]

See what fun it is to be a theoretical physicist?

by Bee at July 01, 2009 08:27 AM

Christine Dantas — A little bit of cosmographic sanity

Finally, an interesting paper on dark energy. Cosmographic analysis of dark energy [http://arxiv.org/abs/0906.5407] Authors: Matt Visser (Victoria University of Wellington), Celine Cattoen (Victoria University of Wellington) Abstract: The Hubble relation between distance and redshift is a purely cosmographic relation that depends only on the symmetries of a FLRW spacetime, but does not intrinsically [...]

by ccdantas at July 01, 2009 07:23 AM

Chad Orzel — links for 2009-07-01

Acephalous: Infinite Summer: Morbid? Culturally Imperial? Morbidly Culturally Imperial?

"In the end, what’s interesting about the 25-year-old Klein’s post about the 46-year-old Foster Wallace’s novel is the notion that someone who was 18 years old when the Clash first performed in America and someone who was 18 years old the year Joe Strummer died can be said to belong to the same generation. How does that work? I’m tempted to blame it on the Internet"

(tags: blogs society culture literature music humanities acephalous)
Views: Books Aren't Everything - Inside Higher Ed

"Some in university presses view this as a time to rally around the book as the focal point of scholarship and academic publishing. Part of the argument revolves around university presses as purveyors of hard ideas — ideas that push culture forward. Intellectual rigor, the hallmark of any good university or college, is also the driving force in university press publishing. This rigor is best reflected in full-length discussion of particular subjects. Whatever the merits of books, this argument neglects to address fully the current financial and technological challenges. Disruptive technologies -- the Internet and digital information networks -- have made the printed book less important. Information gatherers have found an abundance of material on their desktops. More important, the psychology of getting information is driven by quick searching and the generation of instantaneous results. Trying to change users’ actions under continual technology improvements is futile."

(tags: publishing academia books inside-higher-ed information)
T.J. Houshmandzadeh Enjoys Ordering "The Houshmandzadeh" Just To See What Waiter Brings | The Onion - America's Finest News Source

"I will say the only time I ever regretted ordering it was at a Mexican place, as the prawns were spicier than I thought they would be."

(tags: food silly onion sports football)
2009

"No man is an island, so they say, although the small crustaceans and the bird which sat impassively on Dirk Manhope's chest as he floated lazily in the pool would probably disagree. "

(tags: writing literature silly)

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n-Category Café Laubinger on Lie Algebras for Frölicher Groups

$MathML-enabled post (click for more details).$

[guest post by Martin Laubinger in the context of Smootheology: the study of generalized smooth spaces]

I have posted a preprint which contains the central new result I obtained in my dissertation.

The result may not directly relate to higher category theory. Still, I would appreciate feedback and problems for further investigation:

Martin Laubinger
A Lie algebra for Frölicher groups
(arXiv)

Here is a short description: The category of Frölicher spaces is a cartesian closed category which contains the category of smooth finite-dimensional manifolds as a full subcategory. The same is true for the closely related category of diffeological spaces. However, it is easier to define tangent spaces to Frölicher spaces than to diffeological spaces. Many groups have natural Frölicher structures, including all Lie groups, but also certain groups of mappings such as $C^{∞} (M, G)$ or $Diff (M)$ , which can not be given a manifold structure in general. A basic question is whether the tangent space (in the Frölicher sense) at the identity of these groups can be equipped with a Lie bracket. I have been able to construct such a Lie bracket, but there is an additional condition which has to be verified. This condition is very natural, but I have not found a general proof. In my thesis, I did not have an example for a group which satisfies the extra condition, but in the meantime I verified the condition for the additive group $ℝ^{J}$ (product of the reals) if J is not too big. This is explained in detail in the preprint.

David Hogg — foreground and background modeling

I added text to the fitting-a-line document about foreground–background mixture modeling for robust fitting. This is a big favorite of mine because it is fast, simple, and very close to the right thing to do. It also resolves some of my issues of a few days ago.

by Hogg at July 01, 2009 03:45 AM

David Hogg — hypothesis confirmation

Phil Marshall showed up in Heidelberg today; he and Kasper Schmidt (MPIA) and I had lunch and discussed (among other things) the confirmation and rejection of hypotheses, which rarely—in the real world—goes according to either the Bayesian or the frequentist methodology. For example, the WMAP-1 paper was taken to be an awesome confirmation of the standard CDM model (and it was!) even though it had a bad chi-squared value (so frequentists were wrong to be excited) and it wasn't being competed against any serious alternative model (so Bayesians have nothing to say at all). I think this all comes down to message length, but I certainly haven't worked it all out yet.

by Hogg at July 01, 2009 03:41 AM

Georg von Hippel — Has Springer gone insane?

As a native of the beautiful city of Heidelberg, I am of course proud not just of my home town's world-famous university and castle, but also of the world-famous science publisher Springer ("Heidelberg-Tokyo-New York", as it says on their books). So I was particularly disappointed when I noticed that editing and production standards for Springer books seem to have declined a lot recently (have a look at the disfigured Feynman diagrams and numerous misprints in this book to see what I mean). But shoddy copyediting and poor production values are one thing, whereas blatantly wrong content is quite another thing altogether. Springer went there, though, and the story was brought to light by the indefatigable John Baez, the bane of all crackpots: Springer published an obvious crackpot book -- complete with elementary "proofs" of the Fermat-Wiles theorem and Goldbach's conjecture! As a native of Heidelberg, I hang my head in shame.

by Georg at July 01, 2009 03:11 AM

Dave Bacon — Power Tool Races

This last weekend we made it out to artopia in Seattle's Georgetown neighborhood. One of the cool event at artopia was the power tool races. That's right, power tool's or other appliances propelling themselves down a long track! Here, for instance, is my favorite, the Piña Collider:
Won the race, finishing perfectly at the end of the track, where the owner popped open the blender and poured himself a nice Piña Colida (this shot taken by Mrs. Pontiff, who is much better at aiming her iPhone than I am.)

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Clifford Johnson — Beach Time Baking!

It is the birthday of a friend today, with a party to be held at a beach. The instructions were to bring something French to eat. I was in a baking mood this morning and so I decided, after some thought and research, to make an apple cake as a birthday present. Apparently this is a typical French-style cake. Well, it is French enough for me, with its simple combination of fruit and cake.

(Interestingly it is roughly reminiscent of the apricot/peach upside-down cake I was planning to make when I was shopping in the market, but I could not get a definitive source to tell me whether that type of cake was of French origin or not, so I decided to use the apples instead. I can just eat the apricots and peaches for lunch each day this week.) Ok, here's how I made it. [...]

by Clifford at July 01, 2009 12:49 AM

Jonathan Shock — Empty sets

The lack of updates recently is due to being sucked slowly into an application black hole. I have a lot to get done in the next couple of weeks before going to China, including a whole lot of admin which has kept me up until 2 tonight (at least I found myself a nice new cafe in which to scribble) and a couple of projects which really deserve to be finished before people disappear for the summer. They're looking promising but still have a little way to go to completion.

I may come back here every now and then to vent stress, but don't expect too much from me over the next couple of weeks that fits into the categories of coherent or meaningful. I'll attempt to write when I'm back in England for a day, just before heading East on the 14th of July.

Until later, over and out.

by Jonathan Shock at June 30, 2009 07:00 PM

Planet Musings

Subscriptions

Info

July 03, 2009

Terence Tao — Benford’s law, Zipf’s law, and the Pareto distribution

July 03, 2009

Gordon Watts — LHC News

Secret Blogging Seminar — Bleg: book recommendations for an undergraduate

Chad Orzel — Two-Word Lyrics: Independence Day Edition

Secret Blogging Seminar — Three geometric constructions of the irreducible representations of GL_n

Clifford Johnson — Michael Jackson and D-Branes

Backreaction — This and That

Secret Blogging Seminar — Continued Fractions and Hyperelliptic Curves

Chad Orzel — How to Teach Physics to Your Dog Contest Winners

US/LHC Blog — Surely you are joking Mr Florez!

Edinburgh Mathematical Physics Group — News from The Planck Scale

Chad Orzel — In Which I Cave In to the Current Social Media Fad-of-the-Moment, Purely for Book-Publicity Purposes, You Understand, Not Because I Need Another Time-Waster

David Hogg — dwarf galaxies in the mid-infrared

Chad Orzel — links for 2009-07-03

US/LHC Blog — Life at CMS

July 02, 2009

Steinn Sigurðsson — the doctrinaire way

Chad Orzel — Thursday Baby Blogging 070209

US/LHC Blog — My research [Part 2] — effective theories

Intermission: Effective Theories

Scales and Sciece

Effective theories in physics

The unreasonable success of the Standard Model

Further Reading/Watching

David Hogg — abstracts, image modeling

Cosmic Variance — arxiv Find: The Local Density of Dark Matter

Dave Bacon — New DARPA Director

US/LHC Blog — Outreach

US/LHC Blog — Field trip

Joe Fitzsimons — The Canadians are coming

US/LHC Blog — LHC Status Update from Steve Myers

Chad Orzel — Poll: Threats and Menaces

Dave Bacon — ArXiview 1.2 for iPhone OS 3.0 Out

Dave Bacon — Bacon Bubble

Chad Orzel — A Literary Theory

Chad Orzel — Hugo Voting

Backreaction — Giant Thistle

Georg von Hippel — LATTICE 2009 programme online

n-Category Café Open Access to Taxpayer-Funded Research

n-Category Café Elsevier Pays for Favorable Book Reviews

Chad Orzel — links for 2009-07-02

Room 538 — N-body simulation of DGP model

July 01, 2009

Doug Natelson — This week in cond-mat

Chad Orzel — Baby Swimwear Note

Cosmic Variance — Newton, P.I.

Clifford Johnson — News From The Front, VII: What is Fundamental, Anyway?

BioCurious — Dead tree scrolls

Dave Bacon — Fido Left Behind

Chad Orzel — Plagiarism, Garbling, and Superluminal Motion

US/LHC Blog — Shifts

Chad Orzel — Infinite Jest: My Favorite Footnote

Backreaction — Why are modern scientists so dull? And why that question is nonsense.

US/LHC Blog — The things I learned in Kindergarten

Backreaction — Hello from the SUSY 2009

Backreaction — Quantum To Cosmos

Backreaction — Perimeter Institute Grows

Backreaction — This and That

Christine Dantas — A little bit of cosmographic sanity

Chad Orzel — links for 2009-07-01

n-Category Café Laubinger on Lie Algebras for Frölicher Groups

David Hogg — foreground and background modeling

David Hogg — hypothesis confirmation

Georg von Hippel — Has Springer gone insane?

Dave Bacon — Power Tool Races

Clifford Johnson — Beach Time Baking!

Jonathan Shock — Empty sets