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Richard Feynman and the Connection Machine (1989)

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Re: Richard Feynman and the Connection Machine (1989)

#41

Post by JamesLeonis »

sillysaurus3 wrote: post #32

Someone please explain how to do this. It's been a lifelong mystery that has always fascinated me: > By the end of that summer of 1983, Richard had completed his analysis of the behavior of the router, and much to our surprise and amusement, he presented his answer in the form of a set of partial differential equations. To a physicist this may seem natural, but to a computer designer, treating a set of boolean circui…

I think the "in respect to time" and "amount of bit" part is the continuum. You can then think of your communication as a stream and rate. Their computer had a million cores in it's original design, but each could only talk with ~20 nearest neighbors. Weirdly information might begin to mimic simple fluid dynamics in this environment.

I suspect that's why Feynman could build those equations as well as discover that they only needed the 5 buffers. Though I can fully sympathize with the program manager in not wanting to reason in terms of differentials.

Re: Richard Feynman and the Connection Machine (1989)

#42

Post by dfox »

sillysaurus3 wrote: post #32

Someone please explain how to do this. It's been a lifelong mystery that has always fascinated me: > By the end of that summer of 1983, Richard had completed his analysis of the behavior of the router, and much to our surprise and amusement, he presented his answer in the form of a set of partial differential equations. To a physicist this may seem natural, but to a computer designer, treating a set of boolean circui…

Just today I was reminded of this paragraph when we thought about completely different discrete optimalization problem with the expectation that there must be some way to solve it analytically instead of numerically.

But in case of CM router, “the average number of 1 bits in a message address.” is surprisingly useful quantity, because for the most straightforward implementation of hypercube routing the number of one bits in address is equal to number of links the message must traverse. The algorithm is essentially this: find address bit set to one, clear it and send the message down the link with same number as was the order of that bit, if address is all zeros, message has reached the destination (the same thing can be implemented without changing the address seen on wire by each router XORing its node ID with address in message and getting the same bitvector, but I believe most implementations actually modify the message address in each router).

Re: Richard Feynman and the Connection Machine (1989)

#43

Post by PhasmaFelis »

jschwartzi wrote: post #28
bane wrote: post #4

Earlier quoted context omitted.

Feynman is great, very amusing and obviously brilliant. But I've also worked with folks like him before who end up as fish out of water in fields they don't know the conventions for and can't be bothered to learn. Lots of time is wasted trying to figure out how to get the rest of the company to communicate with the lone genius, and it's obvious that they're smart enough to go away for a week and learn enough of the f…

On the flip side, it's also frustrating to know you're right about something, but because your co-workers don't have the same education as you they completely ignore you.

They are both real problems. Anecdotally, I've seen a lot more cases of specialists failing to communicate effectively than of non-specialists ignoring well-expressed advice. It's kind of endemic among techies, unfortunately.

Re: Richard Feynman and the Connection Machine (1989)

#44

Post by cr0sh »

jabl wrote: post #12

I came across this a long time ago, but read it again, and laughed out loud several times. It's a good read. It's also amusing to think of how "small" science was only just a few decades ago. I guess that's what exponential growth is.. (plus, I guess, survivor bias) Here we have one of the greatest physicists of the 20th century working at a startup for a bunch of wet-eared kids from MIT. But oh, looking at the wikip…

> I came across this a long time ago, but read it again, and laughed out loud several times. It's a good read.

I've read it before as well, but read it again recently due to this HN post (before it moved up in the stack, sometime last week).

While I always find it an amazing and amusing recollection of the period, at the end I always find a bit of "smoke" in my eyes, knowing that we have lost one of the greats of our age, and that I will never be able to say to him personally how much I have enjoyed reading and listening to his words.

Fortunately, though, we do still have those - and they seem to continue to inspire people - which is really something.

Re: Richard Feynman and the Connection Machine (1989)

#45

Post by [deleted] »

CuriouslyC wrote: post #27
aj7 wrote: post #7

Cellular automata-- a dead end.

Cellular automata are just a subclass of graph evolution algorithms constrained to a regular grid comprised of homogeneous nodes. Neural networks are also graph evolution algorithms, and logical programs can be modeled this way as well. Cellular automata are just a toy branch of a tree that is thriving like crazy.

[deleted]

Re: Richard Feynman and the Connection Machine (1989)

#46

Post by leephillips »

mark_l_watson wrote: post #17

Both of a friend's parents worked on the Manhattan Project. Feynman was a character. I was fortunate to be able to write code for version 1 of the Connection Machine (that was the SIMD device) and I would prototype code on my Mac in Star Lisp. Good times that I am grateful for.

Me too, at the Naval Research Laboratory. Did you use C*? (This was a version of C designed for the CM, with parallel operators.)

Re: Richard Feynman and the Connection Machine (1989)

#47

Post by kordless »

I love this part:

"Feynman had a proposed solution to the anisotropy problem which he attempted (without success) to work out in detail. His notion was that the underlying automata, rather than being connected in a regular lattice like a grid or a pattern of hexagons, might be randomly connected. Waves propagating through this medium would, on the average, propagate at the same rate in every direction."

Re: Richard Feynman and the Connection Machine (1989)

#48

Post by sethev »

bane wrote: post #4
andyjohnson0 wrote: post #2

A nice essay. This paragraph stood out for me: "By the end of that summer of 1983, Richard had completed his analysis of the behavior of the router, and much to our surprise and amusement, he presented his answer in the form of a set of partial differential equations. To a physicist this may seem natural, but to a computer designer, treating a set of boolean circuits as a continuous, differentiable system is a bit st…

Feynman is great, very amusing and obviously brilliant. But I've also worked with folks like him before who end up as fish out of water in fields they don't know the conventions for and can't be bothered to learn. Lots of time is wasted trying to figure out how to get the rest of the company to communicate with the lone genius, and it's obvious that they're smart enough to go away for a week and learn enough of the f…

You're making a big assumption that he could have achieved the same result using the techniques that failed for the rest of the team.

Re: Richard Feynman and the Connection Machine (1989)

#49

Post by YZF »

sillysaurus3 wrote: post #32

Someone please explain how to do this. It's been a lifelong mystery that has always fascinated me: > By the end of that summer of 1983, Richard had completed his analysis of the behavior of the router, and much to our surprise and amusement, he presented his answer in the form of a set of partial differential equations. To a physicist this may seem natural, but to a computer designer, treating a set of boolean circui…

There aren't enough details about but there are a lot of touch points between discrete mathematics and calculus. If you read Knuth's AOCP you'll see a lot of other examples where things like integrals are used in discrete math problems...

Re: Richard Feynman and the Connection Machine (1989)

#50

Post by yardie »

mark_l_watson wrote: post #17

Both of a friend's parents worked on the Manhattan Project. Feynman was a character. I was fortunate to be able to write code for version 1 of the Connection Machine (that was the SIMD device) and I would prototype code on my Mac in Star Lisp. Good times that I am grateful for.

Please, go on. I've been fascinated with Connection Machines ever since I saw one at a university auction. Which also had plenty of SGI gear and Next slabs as well.
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