Comments on: Why not von Neumann? http://mattleifer.info/2006/09/27/why-not-von-neumann/ Mathematics -- Physics -- Quantum Theory Thu, 21 Jan 2010 17:02:00 -0500 http://wordpress.org/?v=2.9.1 hourly 1 By: Scott Aaronson http://mattleifer.info/2006/09/27/why-not-von-neumann/comment-page-1/#comment-79 Scott Aaronson Sat, 30 Sep 2006 03:42:06 +0000 http://mattleifer.wordpress.com/2006/09/27/why-not-von-neumann/#comment-79 Maybe a better question is: why didn't von Neumann invent <i>classical</i> computational complexity theory? As you mentioned, that would certainly have been a first step toward inventing quantum computing! My own answer is simply that (1) von Neumann had a huge amount on his plate, and (2) he died in 1957. (Indeed, it was while he was dying in a hospital that Gödel sent him his famous letter about P vs. NP. But we don't know if von Neumann ever even saw this letter, let alone thought about it.) Some of von Neumann's papers from the fifties show that he <i>was</i> aware of computational scaling as an issue, and of polynomial scaling being better than exponential scaling. Probably, this was one of many things that he died before he was able to follow up on. Interestingly, Feynman did <i>not</i> have a particularly good appreciation of complexity -- if you read his <i>Lectures on Computation</i>, complexity never appears even once! And even in his famous 1982 talk on quantum computers, complexity only appears as one of many issues to be considered. Maybe a better question is: why didn’t von Neumann invent classical computational complexity theory? As you mentioned, that would certainly have been a first step toward inventing quantum computing!

My own answer is simply that (1) von Neumann had a huge amount on his plate, and (2) he died in 1957. (Indeed, it was while he was dying in a hospital that Gödel sent him his famous letter about P vs. NP. But we don’t know if von Neumann ever even saw this letter, let alone thought about it.)

Some of von Neumann’s papers from the fifties show that he was aware of computational scaling as an issue, and of polynomial scaling being better than exponential scaling. Probably, this was one of many things that he died before he was able to follow up on.

Interestingly, Feynman did not have a particularly good appreciation of complexity — if you read his Lectures on Computation, complexity never appears even once! And even in his famous 1982 talk on quantum computers, complexity only appears as one of many issues to be considered.

]]> By: Matthew Leifer http://mattleifer.info/2006/09/27/why-not-von-neumann/comment-page-1/#comment-77 Matthew Leifer Thu, 28 Sep 2006 03:53:04 +0000 http://mattleifer.wordpress.com/2006/09/27/why-not-von-neumann/#comment-77 Indeed, they've been having trouble filling that positon for some time. Indeed, they’ve been having trouble filling that positon for some time.

]]> By: William http://mattleifer.info/2006/09/27/why-not-von-neumann/comment-page-1/#comment-78 William Thu, 28 Sep 2006 03:36:34 +0000 http://mattleifer.wordpress.com/2006/09/27/why-not-von-neumann/#comment-78 At some point in my university career I was torn. I was interested in theoretical computer science, pure math (particularly functional analysis) and quantum mechanics. I decided the natural career path was to become John von Neumann. It's not an easy job, but I hear there is an opening. At some point in my university career I was torn. I was interested in theoretical computer science, pure math (particularly functional analysis) and quantum mechanics. I decided the natural career path was to become John von Neumann. It’s not an easy job, but I hear there is an opening.

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