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Timeline for Motivation for $C^*$-algebras

Current License: CC BY-SA 4.0

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May 19, 2021 at 21:31 comment added jjcale One motivation is quantum statistical mechanics, see e.g. "Operator Algebras and Quantum Statistical Mechanics 1", springer.com/gp/book/9783540170938 .
May 19, 2021 at 17:03 history bumped CommunityBot This question has answers that may be good or bad; the system has marked it active so that they can be reviewed.
Apr 20, 2021 at 12:55 comment added user85913 Not an answer to "why C*-algebras?" but a comment on the more focused "why exotic group C*-algebras?": one perfectly reasonable answer is "to build interesting examples of C*-algebras". Another is that the K-theory of group C*-algebras (and crossed products) is a receptacle for interesting invariants: equivariant indices etc. Different C*-algebras attached to the same group can have different K-theory, and it appears that for some purposes the nicest K-theoretic properties are enjoyed by "exotic" algebras in between the two standard ones. See the work of Baum-Guentner-Willett and others.
Apr 20, 2021 at 9:32 comment added Emiel Lanckriet I am a student finishing my masters degree, but I have only learned about $C^*$-algebras in the last year. The question came from a fellow student who was also interested in the use of this area of mathematics. It is correct that I don't know a lot about the wider history of the subject, but I would say that the question is more "What did we gain from studying it?", than "Why did we start studying it?" although both are interesting questions.
Apr 19, 2021 at 16:29 comment added Nik Weaver @MatthewDaws very good point.
Apr 19, 2021 at 15:40 comment added Matthew Daws Can I read between the lines, and guess you are a student? May I ask: at what point in your education? It could be (I of course cannot know for sure) that the question, in response to a talk you gave, might have been more asking "Do you, as a student, know something of the wider history of this subject?" rather than (as I think people here might be tempted to read) "Why is this area of Mathematics important?" Just a guess...
Apr 19, 2021 at 12:24 comment added Branimir Ćaćić Seriously, if you’re interested in the original historical motivation for $C^\ast$-algebras, see Nik Weaver’s answer in his second link. Compare the Kadison–Singer problem, whose original formulation comes straight out of quantum mechanics as formulated in terms of $C^\ast$-algebras of bounded observables. [BTW, the recent solution of the Kadison–Singer problem depends crucially on Weaver’s reformulation of Anderson’s reformulation, if I understand the basic history correctly?]
Apr 19, 2021 at 10:58 comment added David Roberts I changed the notation, $C^*$ is the usual form, not $\mathbb{C}^*$
Apr 19, 2021 at 10:57 history edited David Roberts CC BY-SA 4.0
Mathematical formatting, tag
Apr 19, 2021 at 10:49 review Close votes
Apr 19, 2021 at 18:34
Apr 19, 2021 at 10:40 answer added ThiKu timeline score: 3
Apr 19, 2021 at 10:39 comment added Nik Weaver See What are the applications of operator algebras to other areas. My answer to States in C${}^*$-algebra and their origins in physics might help too.
Apr 19, 2021 at 10:27 history edited YCor
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Apr 19, 2021 at 9:47 review First posts
Apr 19, 2021 at 10:43
Apr 19, 2021 at 9:21 history asked Emiel Lanckriet CC BY-SA 4.0