### The Passing of Michael Atiyah and Andrew Ranicki

#### Posted by Simon Willerton

*guest post by ***Bruce Bartlett**

Michael Atiyah, the celebrated geometer, passed away on Friday 11
January. He was 89 years old. He achieved mathematical fame for the
Index Theorem which he proved with Isadore Singer in 1963, his work
with Hirzebruch on K-theory, the “Woods Hole” fixed point theorem with
Raoul Bott, his classic paper “The Yang-Mills equations over Riemann
surfaces” also with Bott, and many other things. He famously also
“poached” Edward Witten from theoretical physics into mathematics, and
the subjects have never been the same since.

Atiyah had a great passion for mathematics, especially the beauty of
geometry. His ideas were the driving force behind the subject for many
years. For me personally, I found his approach hugely inspirational.
Graeme Segal, who was a student of his, said “He could hypnotize you
into believing you understood something. He would make you think that
everything was possible, and there were all these wonderful ideas, and
you could put them together and do something with them.” I have heard
many others make similar remarks. I am very sad that he is gone.

At this time I cannot help but also sadly remember the untimely death
of Andrew Ranicki last year, another Edinburgh topologist. I met
Andrew only on a few occasions (I was introduced to him by Simon, my
thesis advisor) but he left a huge impression on me.
Andrew had a sparkle in his eye, a huge booming laugh and a tremendous
unselfish interest in meeting others and finding out what they were
doing. A kind and generous man with a massive spirit. You can just see
all of that in a glance in this picture:

For instance, his passion is born out in his website, which is
still easily the best collection of books, videos, papers and
information on algebraic topology anywhere.

Andrew only made a single
post at the n-category cafe. This was about the Michael and Lily Atiyah Portrait Gallery at Edinburgh, which he was
instrumental in establishing in 2013. However, judging from the
enthusiasm and generosity he displayed in sharing the magic of
algebraic topology through his website, and one or two conversations I
had with him, I got the impression that he heartily approved of this
blog.

His death came as a shock to me in February 2018 and I will always
miss him greatly.

Posted at January 21, 2019 12:20 PM UTC
TrackBack URL for this Entry: https://golem.ph.utexas.edu/cgi-bin/MT-3.0/dxy-tb.fcgi/3081

### Re: The Passing of Michael Atiyah and Andrew Ranicki

I never talked to Atiyah, though his paper Topological quantum field theory influenced me greatly and ultimately led James Dolan and me to formulate the cobordism hypothesis. Earlier, when I was in grad school, I spent a lot of time trying to understand the Atiyah-Singer index theorem, mostly using Gilkey’s book and the nice volume edited by Richard Palais. During this time Quillen was using his eternal course on homological algebra to try to construct a “just plain calculus” proof of the index theorem. It was inspiring to watch someone lecture over and over on the same subject, often getting stuck, but continuing to move forward.

I had some great conversations with Andrew Ranicki, whose contributions to topology were always a bit over my head. I remember him saying once that we need to set up a version of Napster for scientific papers. That’s what LibGen amounts to.

### Re: The Passing of Michael Atiyah and Andrew Ranicki

I have met both Sir Michael, as I used to refer to him, and one of his best friends, Andrew. Sir Michael influenced me greatly at first, because the first mathematics talk I had ever gone to was given by him, and this is how I learned for instance about stereographic projection, and about the beautiful problem on configurations of points.

I got the chance to be invited to visit Sir Michael, first in February 2017. This is how I also met Andrew. By the way, Andrew was very modest, and he insisted that I call him Andrew, as opposed to my “Prof. Ranicki”. I do remember his laugh quite well by the way. It was quite special.

Back to Sir Michael, he was a very generous man, in the sense that he did share many of his ideas with me, particularly on the problem I have mentioned. He shared his philosophy with me. He liked to understand things deeply. He kind of thought that some proofs, particularly formulas, may prove something, but without explaining what was really going on. He was so full of ideas, and he could summarize entire fields very succinctly.

I did visit a second time in July 2018, and was lucky to get invited to the celebration of Lily Atiyah’s life and work. Sadly she had passed away if I remember correctly about 3 weeks after Andrew had passed away. The celebration of Lily’s life was itself a well organized and moving event.

I have a lot to write, but I just wanted to express how grateful I am to Sir Michael, and how lucky I am to have met both Sir Michael and Andrew.

## Re: The Passing of Michael Atiyah and Andrew Ranicki

I never talked to Atiyah, though his paper Topological quantum field theory influenced me greatly and ultimately led James Dolan and me to formulate the cobordism hypothesis. Earlier, when I was in grad school, I spent a lot of time trying to understand the Atiyah-Singer index theorem, mostly using Gilkey’s book and the nice volume edited by Richard Palais. During this time Quillen was using his eternal course on homological algebra to try to construct a “just plain calculus” proof of the index theorem. It was inspiring to watch someone lecture over and over on the same subject, often getting stuck, but continuing to move forward.

I had some great conversations with Andrew Ranicki, whose contributions to topology were always a bit over my head. I remember him saying once that we need to set up a version of Napster for scientific papers. That’s what LibGen amounts to.