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Comment by scottlocklin | Hacker News Reader

These papers are such unutterable horse shit it makes my head spin. You know what: Kriging on the data set (or any other kind of functional approximator) would do the same thing a hell of a lot computationally faster on the 3-4 shitty solutions they demonstrated. As a bonus; it's more likely to conserve angular momentum and energy.

The fact that HN weebs gobble this horse shit up as if it were pate de fois gras is also depressing.

TLDR: physics nerds do an unimpressive thing with neural nets. You want to look at something impressive and still mysterious involving physics and neural doohickeys: why do echo state networks (reservoir computers that are effectively projections onto a random hyperplane) reproduce chaotic time series, most famously Mackey-Glass, so well?

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In the paper: "The physical setup allows the initial conditions to be described by 2 parameters and the evolution of the system by 3 parameters"

Let's see, 3 input parameters, relying on a ton of pre-computed data, no ability to extrapolate beyond the precomputed numbers...they've invented the world's shittiest lookup table.

The 3 body problem (any classical mechanics where energy is conserved) takes place in a symplectic space:

https://en.wikipedia.org/wiki/Symplectic_geometry

If your integrator isn't built to respect the symmetries of symplectic space it is going to give qualitatively wrong answers as t -> infinity. A non-symplectic geometry might do a better job if you want to track the Earth around the sun for 1000 years, but if you use a non-symplectic integrator who knows where the Earth ends up in a billion years.

"Deep networks" are the new hypnotic induction phase to induce willing suspensions of disbelief. Maybe there is some "emperor's new clothes" going on. Usually if somebody makes a bogus claim people will think "the person making the claim is stupid", but if a person makes a bogus claim today involving a deep network, the reader tends to assume that they are too stupid to understand it.

You are probably right.

Neural doohickeys find real uses in computational chemistry. Accurate ab initio solvers (many-body Schrödinger equation) are very slow and everything else is just heuristic-, quasi- approximation mixed with semi-empirical tricks.

When someone makes even marginally better heuristic improvement, it's more likely that they sell it or start a company than post paper in arxiv. There is serious money to be made.

Tell us how you really feel scott

He’s not wrong...

As soon as I read that first sentence I said "Has to be Scott Locklin"

Same. But I figured it out in the second paragraph.

> The fact that HN weebs gobble this horse shit up as if it were pate de fois gras is also depressing.

Looking through the comments here, that doesn't seem to be the case.

HN has always seemed to me to be a great place to get a cold shower against all AI/NN hype, generally where I go to for a sober evaluation.

I dont think the comments will reflect "gobbling up"

HN may provide a good reality check for AI/NN (I'm not equipped to say). But HN is not a physics site, and it's really not such a good place to go for a reality check on physics. (Not really a criticism. HN doesn't claim to be a physics site.)

For the small minority who are going to say "I'm really smart and I've taken some physics classes" ... please consider how far "I'm really smart and I've taken some programming classes" would get you on HN.

Not that that's a real physics paper, but HN has many former physicists; for example, my Ph.D. thesis had the words "three body problem" in it, and it wasn't about Chinese science fiction.

Yeah we were doing numerical linear algebra before everyone though it was the key to replacing call centers (well in my case after, but the field generally)

So the tech companies hired a bunch of us

For sure there are physicists reading HN. Absolutely. My claim, which I probably expressed clumsily, is that the majority of commenters here are not physicists.

I think there is quite a large overlap in audience - quite a few of the readers here will have PhDs in physics in a way that few internets forums will.

There are physics people on HN. I'll stick by my claim that the crowd here is not a physics crowd. I'm confident that among web sites HN scores well above average on physics ... but discussions of physics on an average web site aren't something I really want to even think about.

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