Simulating 1 second of real brain activity takes 40 minutes and 83K processors • Hacker News Board

Re: Simulating 1 second of real brain activity takes 40 minutes and 83K processors

#51

Post by Dylan16807 » Mon, Aug 05, 2013, 1:20 AM UTC

pmr_ wrote: post #42

Dylan16807 wrote: post #31

Earlier quoted context omitted.

Why would they debate? It's very easy to test for [sentience or fake sentience programmed by a sentient]. Unless the aliens think we're robots they can do a mirror test or something. But such a test does not work in a possibly-tainted environment. A neural net that seems to communicate might just have a hidden encoding of ELIZA. You can err on the side of assuming sentience if you want, but don't think it's out of se…

> It's [sentience is] very easy to test for. Isn't that only true if you assume that our definition of sentience is universal or that there is no higher development of consciousness? It seems to me that it doesn't even require a very skilled science fiction/fantasy writer to develop such a concept or ability.

As long as you assume whatever you're testing moves around or communicates instead of constantly naval-gazing, I'd bet even crazy-alien intelligence can be seen to be intelligent.

Sure there might be higher levels, but we're not talking about higher levels?

Re: Simulating 1 second of real brain activity takes 40 minutes and 83K processors

#52

Post by gwern » Mon, Aug 05, 2013, 1:37 AM UTC

Dylan16807 wrote: post #24

gwern wrote: post #13

Earlier quoted context omitted.

> To put this claim in perspective, we are still unable to simulate a single cell by modeling everything we know from biochemistry, even if we ignore molecular dynamics. Mostly this is because we don't know what many genes and the proteins they encode do. To me, this mostly shows that naive beliefs about difficulty aren't really accurate ('but it should it harder to simulate a brain than a cell, because it's bigger r…

Why does it show that the belief isn't accurate? This isn't simulating a brain, it's simulating the connections in a brain and pretending the neurons are about as complex as wires. That is a model that is possibly correct, but there's certainly no evidence it's correct.

It shows, at a minimum, that 'simulating' is not a binary either-or proposition, and that the higher-level a simulation, the easier/more efficient the simulation can be, and so it is perfectly possible to have a high-level simulation of a 'big' thing which is easier to run than a low-level simulation of a 'small' thing - both of these points, as obvious as they may seem to you or me, are badly underappreciated by a lot of people.

Re: Simulating 1 second of real brain activity takes 40 minutes and 83K processors

#53

Post by gwern » Mon, Aug 05, 2013, 1:38 AM UTC

dnautics wrote: post #27

gwern wrote: post #13

Earlier quoted context omitted.

> To put this claim in perspective, we are still unable to simulate a single cell by modeling everything we know from biochemistry, even if we ignore molecular dynamics. Mostly this is because we don't know what many genes and the proteins they encode do. To me, this mostly shows that naive beliefs about difficulty aren't really accurate ('but it should it harder to simulate a brain than a cell, because it's bigger r…

I happen to work in the synthetic biology lab at the venter institute, although not on this project - two of our researchers are coauthors on this paper - and my personal opinion is that this paper is a joke. Note that the guys who made the simulation didn't even pick the correct organism. The cell that we have synthetic control over is M. mycoides, not M. genitalium. Lest this seem like a nit-pickey detail, until th…

What did your colleagues make of your criticism?

Re: Simulating 1 second of real brain activity takes 40 minutes and 83K processors

#54

Post by pmr_ » Mon, Aug 05, 2013, 1:38 AM UTC

Dylan16807 wrote: post #51

pmr_ wrote: post #42

Earlier quoted context omitted.

> It's [sentience is] very easy to test for. Isn't that only true if you assume that our definition of sentience is universal or that there is no higher development of consciousness? It seems to me that it doesn't even require a very skilled science fiction/fantasy writer to develop such a concept or ability.

As long as you assume whatever you're testing moves around or communicates instead of constantly naval-gazing, I'd bet even crazy-alien intelligence can be seen to be intelligent. Sure there might be higher levels, but we're not talking about higher levels?

You were explicitly talking about testing sentience (which does not require "moves around" or "communicates"). Sentience is simply a concept we have come up with to differentiate organisms. It wouldn't seem surprising to me if something more evolved used a different concept more appropriate to their physiology or philosophy. Hence I think you need to be careful if we are about to apply our concepts to classify something.

Re: Simulating 1 second of real brain activity takes 40 minutes and 83K processors

#55

Post by marcosdumay » Mon, Aug 05, 2013, 1:50 AM UTC

Xcelerate wrote: post #49

The title statement is almost meaningless. It would be better just to say "simulating reality takes a LONG time". My research is in molecular dynamics. I simulate systems up to 1 billion atoms on Kraken & Titan. HUGE approximations are made in simulating these systems, but depending on what exactly it is you're studying, these simulations still provide useful results. That is the key to all these studies: how well do…

If we have a reliable model for how synapses fire, we can simulate the brain. Whatever problems quantum mechanics impose on molecular simulation is not relevant, the same way that you don't need to simulate the nucleons on your molecules even if you need precise energy measurements.

Re: Simulating 1 second of real brain activity takes 40 minutes and 83K processors

#56

Post by dekhn » Mon, Aug 05, 2013, 1:52 AM UTC

Xcelerate wrote: post #49

The title statement is almost meaningless. It would be better just to say "simulating reality takes a LONG time". My research is in molecular dynamics. I simulate systems up to 1 billion atoms on Kraken & Titan. HUGE approximations are made in simulating these systems, but depending on what exactly it is you're studying, these simulations still provide useful results. That is the key to all these studies: how well do…

Generally, the people doing brain simulations like to claim that they can use a massively reduced representation (little more than a graph model that pushes signals around with some constants) and yet, somehow, the simulation is inherently capable of reproducing something complex about thought. I'm not sure how they get to this conclusion, but it's a massive reductionism. It would be nice if it were true- it would mean that for a reasonable expenditure, we could build a machine that, basically, "thought" and had a "mind" and we could convince ourselves that it was "living" much like we think of other humans.

To date nobody has come up with a really compelling disproof that they are more or less correct- thought and mind seem to be best explained as "emergent behavior of a complex system".

Now, whether can we bootstrap a thinking mind by running complex simulations on computers remains to be seen. I'd like to believe there is some interesting physics going on in brains we can't simulate with straightforward physical models, but there really isn't any good evidence for that.

Re: Simulating 1 second of real brain activity takes 40 minutes and 83K processors

#57

Post by dekhn » Mon, Aug 05, 2013, 1:54 AM UTC

jfoutz wrote: post #39

moocowduckquack wrote: post #36

Earlier quoted context omitted.

How would you plan on simulating all the variety of states, reactions and solutions involving plain old water without worrying about hydrogen and oxygen atoms?

Again, i would assert that a cell is 70% water. some tiny fraction of water that's actually used in a reaction would just be special cased, and modeled independently. My understanding of "solution" is stuff floating in water. If there's some value in breaking out each atom, i'm all for it, but i kind of suspect the spherical cow is good enough in that case. Even if i'm wrong there, each atom would introduce at least…

Note that cells are in fact completely packed- everything is grinding against everything else. THere's water there, but it's not a bunch of free solutes.

Re: Simulating 1 second of real brain activity takes 40 minutes and 83K processors

#58

Post by dekhn » Mon, Aug 05, 2013, 1:56 AM UTC

foobarbazqux wrote: post #23

deletes wrote: post #15

Earlier quoted context omitted.

To correctly model a cell you would need to simulate every atom and there are about 10^11 to 10^14 (!) of them in a single cell. I think an interesting number would be how many atoms does it take to simulate one atom reasonably well. Then you could get correct results for some ( really ) small biological functions.

Usually people modeling cells don't consider molecular dynamics, they consider concentrations of proteins, ions, and metabolites. A full MD simulation would obviously be superior, but useful predictions could be made without it. It's hard to say which is the better approach. On the one hand you have MD from which you could technically build an accurate model "from scratch", folding all of your own proteins as part of…

I used to do explicit MD with waters, etc, the whole shebang.

Massive waste of cycles. Never gonna make a useful prediction.

Reduced representations that contain the minimum of complexity to express the phenomena of interest are far more useful.

Re: Simulating 1 second of real brain activity takes 40 minutes and 83K processors

#59

Post by marcosdumay » Mon, Aug 05, 2013, 1:56 AM UTC

jjjeffrey wrote: post #5

Does anyone know what it means to simulate brain activity? Is the brain being emulated in any meaningful way? Or is it just modeling the physical behavior of neurons?

From the article, those were simulation of our neurons, randomly connected. The intention was to test the machine and software.

Re: Simulating 1 second of real brain activity takes 40 minutes and 83K processors

#60

Post by tensor » Mon, Aug 05, 2013, 2:12 AM UTC

aa0 wrote: post #37

ceejayoz wrote: post #9

Earlier quoted context omitted.

If I'm a simulation, I'd prefer to exist and have a legal right to continue doing so.

If you were a simulation, you might not have free will. To even propose that you'd have a decision beyond state-machine-dynamics is a world away.

You might not have free will as a meat brain.