The title statement is almost meaningless. It would be better just to say "simulating reality takes a LONG time".<p>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 does your approximation reproduce whatever it is that you're attempting to model? In some cases, very well. For instance, I'm not going to get exact energy levels of a large system, but the system will qualitatively evolve in the same fashion that the experimental system does (which then guides the experimental counterpart to the research). I don't know the details of this brain simulation, but there is certainly some aspect of it that is not being reproduced anywhere close to real-life, and hopefully this isn't what they're interested in (and I'm sure they know that, but I don't think the article author does).<p>The very best simulations of reality that we can perform handle at most just a few H/He/C atoms. And an issue called the fermion-sign problem means that the computational power necessary to simulate larger systems scales exponentially with the number of particles. Unfortunately what that means is -- short of developing quantum computers (which are polynomial order for the sign problem) -- we aren't ever going to simulate more than a few atoms with near-perfect accuracy, and certainly nothing like a human brain.<p>EDIT: Didn't mean for my comment to sound so negative. Obviously, the researchers know exactly what they're doing. I was just trying to dispel the impression that we're close to simulating the human brain.
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.<p>This matters, for example, if we want to simulate neuronal plasticity or the effect of antidepressants. We're an incredibly long way from a full simulation, which would also require integration with the rest of the nervous system.
If Moore's law were to continue to hold, this would mean the same simulation could operate in real-time on an 83K processor cluster in approximately 25 years or on one processor in about 50 years. Of course, this simulation is 1% of the neurons that a human brain has, and I don't know if scaling up to a full-brain would be linear (This probably depends on the average length of axons in the brain.). This completely unrealistic estimate also assumes no improvements in algorithms, etc..<p>Perhaps a more interesting question is whether or not the brain can really be simulated by a classical computer at all. If quantum mechanics plays a role in the function of the brain we will need a quantum computer to do the job. A classical simulation of a quantum brain would be a very odd beast indeed! It might exhibit behavior that seems like intelligence but somehow falls short.
At what point does this become unethical (if ever)?<p>Before you answer, please consider how certain you are that you are not a simulation.<p>Edit: I don't know the answer, and there probably is a large gray area. But I do know this starts to make me uncomfortable the more accurate it gets. Time to go reread Egan's Axiomatic again, I guess.
I found the article misleading. Real brain activity was not simulated.<p>From the press release (emphasis mine):<p>"The nerve cells were <i>randomly connected</i> and the simulation itself was not supposed to provide new insight into the brain"
Unfortunately, that's only for a number of cells equivalent to 1% of a human brain. A full brain's worth of simulation would take 2.5 days....although that much is probably not necessary. It will fall soon enough, though.
Maybe we are simply taking the wrong approach.<p>How many gears from a mechanical computer does it take to simulate a micro processor?<p>If we were to one day to closely simulate the brain, I am sure the method will not involve computers as we know them today.
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?
Yes we are very far away from the human brain on many levels. However, I don't like this kind of article because it doesn't make sense on the software level.<p>Mathematically, we could figure out how much computing power we would need to match the human brain (24 bytes per synapse * number of synapse, etc).<p>I think I would be more interested in what was the specific of their experiment.<p>- What kind of software were they running?<p>- Was the software bug-free(yeah right)?<p>- Was the software optimized?<p>- Caching?
Recent research has shown glial cells, the uncelebrated insulator of the axon, in fact provide significant chemical signaling and modulation to the process of neural activity. Only phenotypical changes have been observed, it's not understood yet. Suffice to say that computational limits aside, we still couldn't simulate a brain because we wouldn't know what to make.
These attempts at brain simulation perplex me to no end.<p>Simulating a lump of tissue is definitely useful, it's when they start talking about simulating a complete brain that I get lost.<p>A brain doesn't happen overnight. It is the result of a long developmental process encompassing embryology, learning and experience acquisition.<p>How do they plan to wire the whole thing?<p>Micro- and macroscopic connections are well understood, it is the so-called meso-scale (in between) that is troublesome.<p>There will never be a non-destructive way to do extract the information of a live brain, and I'm not sure there will ever be a way to extract it at all. The current methods[0] allow to extract either the wiring or the genes expression.<p>[0] <a href="http://www.brain-map.org/" rel="nofollow">http://www.brain-map.org/</a>
This has been done before with a full human brain scale model in 2005. It took 50 days on 27 processor for that simulation. It's always good to have more research being produced, but this linked article is a bit short on information.<p><a href="http://izhikevich.org/human_brain_simulation/Blue_Brain.htm" rel="nofollow">http://izhikevich.org/human_brain_simulation/Blue_Brain.htm</a>
I would imagine that the analogue nature of the brain is going to always entail a lot of approximation on simulation. I am not sure you could even accurately simulate even 1 neuron.<p>Disclaimer: this is completely out of my field - just a layman speculating.
How many Moore law doublings before it is real time? Seems like ~23 generations or ~35 years. Of course, if you leave out the bits constantly thinking about sex, we might get there a lot faster :)
This assumes that the neuron is the level of granularity that we need to simulate?<p>Is there any research on what other chemical/electrical interactions might be necessary to simulate the brain?