An interesting paper in somewhat the opposite direction, but still building on Landauer's work is "Ultimate physical limits to computation": https://arxiv.org/abs/quant-ph/9908043 The end of the abstract: > [...] quantitative bounds are put to the computational power of an `ultimate laptop' with a mass of one kilogram confined to a volume of one liter.
Ultimate physical limits to computation
Seth Lloyd
1999 · arXiv
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From the abstract
Computers are physical systems: what they can and cannot do is dictated by the laws of physics. In particular, the speed with which a physical device can process information is limited by its energy and the amount of information that it can process is limited by the number of degrees of freedom it possesses. This paper explores the physical limits of computation as determined by the speed of light $c$, the quantum scale $\hbar$ and the gravitational constant $G$. As an example, quantitative bounds are put to the computational power of an `ultimate laptop' with a mass of one kilogram confined to a volume of one liter.
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> Suppose that there is a network that is never partitioned, and machines connected to that network that never fail. In that case consistency and availability should be perfect. You mean, in that case tolerance to partition and availability should be perfect. > Perhaps someday we may be able to say that the odds of enough partitions or machine failures to make the system unavailable are lower than the odds of you getting struck by lightning, at which point you will have for practical purposes defeated the constraints of the CAP theorem. So this is the really interesting question. All the CAP theorem says is that (C,A,P) != (1.0,1.0,1.0). How close to (1.0,1.0,1.0) could…
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we make (C,A,P)? If infinitely close, then we have achieved perfection by the limit, and the CAP theorem is rather pointless. If not, then what is the numeric limit? As you speculate, maybe the numeric limit on C x A x P is so close to 1.0 that the odds of seeing a consistency, availability, or partitioning problem are much smaller than getting hit by lightning. Then again, maybe not. Who knows? ;) To avoid sounding like a total crackpot, here is an interesting paper that explores the physical limits of computation: http://arxiv.org/pdf/quant-ph/9908043v3
Maybe read https://arxiv.org/pdf/quant-ph/9908043.pdf before you think about computers operating on 2*140 objects and try to be less aggressive in your comments.
I'd be curious if anyone with understanding of memory transistor density has an idea of what sort of physical footprint and power requirements 128-bit addressable memory would look like, because I'm having a hard time picturing even a distributed, shared virtual memory space realistically exceeding 16 exabytes. It looks like the Fugaku ARM cluster with 158,000 nodes uses < 5 PiB for 40 MW. As an aside, man does reading something from @sgi.com on USENET take me back to a better time. Title should probably note [1995] [0] https://www.fujitsu.com/global/about/innovation/fugaku/speci... [1] Also https://arxiv.org/abs/quant-ph/9908043 "Ultimate physical limits to computation"
In the Perfect Imperfection by Jacek Dukaj [0] has something called "Remy's curve" [1]. On the curve you can find: - Ultimate Computer is the computer using the best hardware as allowed by the physical constants of our universe. See also physics of computation. - Inclusions are in essence 'pocket universes'. They are created for specific entities to run hardware in a dedicated universe with physical constants different from ours, allowing for better performance than those in our universe - Ultimate Inclusion is the inclusion with the best possible set of physical constants in the entire multiverse Seth Lloyd wrote a paper "Ultimate physical limits to computation" [2]. [0] https://en.wikipedia.org/wiki/Perfect_Imperfection [1] https://en.wikipedia.org/wiki/Perfect_Imperfection#/media/Fi... [2] https://arxiv.org/abs/quant-ph/9908043
It seems likely that Moore’s Law will someday be resurrected, perhaps in a weaker form, but I wouldn't bet heavily on any particular invention being the one that resurrects it. I say it seems likely because Landauer's limit works out to about 0.003 attojoules per bit erasure at room temperature, while current top-efficiency processors use on the order of 100–200 picojoules per instruction — say, about 1 picojoule per bit erasure. So we're about 10 orders of magnitude from Landauer's limit, even before we switch to reversible computation, or drop Landauer's limit by a factor of 75 by operating our computers at the temperature of the cosmic background radiation. Other…
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fundamental limits on computation (Lloyd's "ultimate laptop": https://arxiv.org/abs/quant-ph/9908043) are even further off. In 2D, though, we're actually sort of close, in the sense that the transistors TSMC and Samsung are mass-producing are only about five orders of magnitude larger than the somewhat fundamental limit of single-atom transistors; https://news.ycombinator.com/item?id=20273007 says silicon atoms in an unstrained lattice are 0.235 nm apart, so a 10-nm-wide gate is 40 atoms across. Single-atom transistors have been working for decades in the lab (IBM Almaden, maybe?) so we know there aren't any fundamental limits to computation in between here and there.
A very famous and popular paper that's often cited when debating the simulation hypothesis. I'm squarely in the "not a simulation" camp for a few reasons. 1) Limits of computation. First, we need to find out whether or not the universe is computable. To me, it doesn't seem like it is[1] due to "funky" phenomena like quantum effects. 2) Consistency. It doesn't seem that a simulation ought to be as consistent as our universe appears to be. In fact, if there was a hyper-advanced society making simulations out there, the great majority of simulations would be failed attempts or bug-addled, inconsistent messes. So the probability of picking a random simulation that's perfect…
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quickly approaches zero. And yet, we live in a staggeringly consistent universe. 3) Meta-cognition. If you're making a simulation, why even give sims the capability of understanding what it means to be simulated? Make this very thought akin to contemplating a "square circle" -- a logical impossibility. And yet, there's an entire corpus out there discussing this very hypothesis: from Descartes' Demon to the Wachowski's Matrix. 4) Moral responsibility. Living in a simulation relinquishes me (and everyone else) of moral responsibility. This is deeply troubling, although not a particularly good argument against us living in a simulation. What is a good argument is thinking about the hyper-advanced species that built this simulation: why would they create morally-sensitive beings in a world where morality is irrelevant? That wouldn't make for a very good simulation. 5) Personal experience. I feel like I'm living in the real world, why would I doubt that? Everyone else seems to feel the same way. This is the same argument found in the "Other Minds Hypothesis" -- where we basically give the benefit of the doubt. [1] https://arxiv.org/abs/quant-ph/9908043
see also: "Ultimate physical limits to computation" http://arxiv.org/pdf/quant-ph/9908043v3.pdf "Limits on fundamental limits to computation" http://arxiv.org/pdf/1408.3821v2 "The physics of information processing superobjects: daily life among the Jupiter brains" http://diyhpl.us/~bryan/papers2/The%20physics%20of%20informa...
I've always found the idea of the universe being a simulation rather silly. There are estimated to be 10^80 particles in the observable universe. Assuming our universe is being simulated on an earth sized computer (this is mind bogglingly ridiculous to me) and that the simulation meets Bremermann's limit (also ridiculous, since we're 40 orders of magnitude away according to this http://arxiv.org/pdf/quant-ph/9908043v3.pdf), then it would take on the order of a whole earth day to simulate a single time step. Of course, perhaps the host universe doesn't have the same limitations. Such speculation seems pointless. Maybe solipsism is true. Maybe the simulation runs on magical fairy dust.
A note -- if you're linking to arXiv, it's better to link to the abstract (http://arxiv.org/abs/quant-ph/9908043, or http://arxiv.org/abs/quant-ph/9908043v3 for this particular version) rather than directly to the PDF. From the abstract, one can easily click through to the PDF; not so the reverse. And the abstract allows one to do things like see different versions of the paper, search for other things by the same authors, etc. Thank you!
There is another more fundamental limit, credited to Margolus and Levitin [1], which puts the maximum speed of a (quantum) gate at 2E / h operations per second for a system of energy E and Planck constant h. Given the energy of the sun quoted in the article, this puts the upper limit of bit flips per second at 2^193. Seth Lloyd's 'Ultimate physical limits to computation' [2] goes into further detail on this subject. However, the notion of zero energy dissipation (scalable quantum computers will likely need error correction, which implies bit erasure) on any real system is ludicrous, and I think the Landauer bound models reality better than Margolus-Levitin. [1] http://arxiv.org/abs/quant-ph/9710043 [2] http://arxiv.org/abs/quant-ph/9908043
Read this in the past and there's a few things that bother me * It's impossible to simulate a universe of our current resolution, because it would take more matter than the original universe. * You can't just simulate 'observable areas'. Everything needs to be simulated. * An infinite loop does not end, even in an infinitely powerful computer * A fun calculation from the ZFS folks: To fully populate a 128bit filesystem (ie permute all combinations) you a lot of energy. So much energy you could boil the world's oceans, See: * [1] Physical Limits of Computation: http://arxiv.org/pdf/quant-ph/9908043.pdf * [2] https://blogs.oracle.com/dcb/entry/zfs_boils_the_ocean_consu...
Programming the Universe by Seth Lloyd (physics professor at MIT who likes to call himself a "quantum mechanic"). Here's a relevant paper by Lloyd titled "Ultimate physical limits to computation": http://arxiv.org/abs/quant-ph/9908043v3
It uses energy to do so— just like a heat pump can heat your home with greater output than electrical input, but not no electrical input. The more exciting detail is that computation itself doesn't increase entropy, at least not if reversible computing is use. Only errors or, rather, their correction do... So things may be more rosy than you might guess: http://arxiv.org/abs/quant-ph/9908043
Hm. It appears Blogspot ate my comments. So I guess I'll just paste it here. --- > The "for a time" bit is crucial. There is as Feynman said "plenty of room at the bottom" but it is by no means infinite given actually demonstrated physics. That means all growth curves that look exponential or more in the short run turn over and become S-curves or similar in the long run, unless we discover physics that we do not now know, as information and data processing under physics as we know it are limited by the number of particles we have access to, and that in turn can only increase in the long run by at most a cubic polynomial (and probably much less than that, since space is…
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mostly empty). Yes, but the fundamental limit is so ridiculously high that it might as well be infinite. Look at Seth Lloyd's bounds in http://arxiv.org/abs/quant-ph/9908043 . He can be off by many orders of magnitude and still Moore's law will have many doublings to go. (Incidentally, the only quasi-Singulitarian I am aware of who has claimed there will be an actual completed infinity is Frank Tipler, and as I understand it, his model required certain parameters like a closed universe which have since been shown to not be the case.) > As for "the Singularity" as a point past which we cannot predict, the stock market is by this definition an ongoing, rolling singularity, as are most aspects of the weather, and many quantum events, and many other aspects of our world and society. And futurists are notoriously bad at predicting the future anyway, so just what is supposed to be novel about an unpredictable future? WHAT. We have plenty of models of all of those events. The stock market has many predictable features (long-term appreciation of x% a year and fat-tailed volatility for example), and weather has even more (notice we're debating the long-term effects of global warming in the range of a few degrees like 0-5, and not, I dunno, 0-1,000,000). Our models are much better than the stupidest possible max-entropy guess. We can predict a hell of a lot. The point of Vinge's singularity is that we can't predict past the spike. Will there be humans afterwards? Will there be anything? Will world economic growth rates and population shoot upwards as in Hanson's upload model? Will there be a singleton? Will it simply be a bust and humanity go on much as it always has except with really neat cellphones? Max-ent is our best guess; if we want to do any better, then we need to actively intervene and make our prediction more likely to be right. > Even if there was such a thing as a "general intelligence" the specialized machines would soundly beat it in the marketplace. It would be very far from a close contest. And the humans? If there is a niche for humans, that same niche is available to the general intelligence, and since it can be self-improving and graft on the specialized machines better than humans ever will, it ought to dominate. The economic extinction of humanity? Seems like a Singularity to me. (The economy was driven by human desires before, but what do the machines compete for when the humans are gone? I certainly can't predict it.) > Nor does the human mind, as flexible as it is, exhibit much in the way of some universal general intelligence. Many machines and many other creatures are capable of sensory, information-processing, and output feats that the human mind is quite incapable of. And pray, how do we know of these feats? How were these machines constructed? (Whether I kill you with my bare hands or by firing a bullet, you are still dead.) 5678: > The null hypothesis would be: there does not exist an algorithm and a computer which achieves the goals of AGI. I await the proof, or a modicum of scientific evidence to support this. Shouldn't the null hypothesis be the Copernican hypothesis? - there is nothing special about humans. Every success of AI, every human function done in software, is additional Bayesian evidence that there is nothing special about humans. If there were something special, one ought to observe endless failure, much like trying to trisect the angle or prove the parallel axiom; but instead, one observes remarkably rapid progress. (Where was chemistry after its first 60 years? Feel free to set your starting point anywhere from the earliest Chinese alchemists to after Robert Boyle.) Kevembuangga: > More to the point, some singularitarians pretend to have a definition of "Universal Intelligence" which curiously enough isn't computable. :-) If you have an actual argument, please feel free to give it and not just engage in mockery. Were you aware that uncomputable algorithms are useful and can easily be made computable? (You can solve the Halting Problem for a Turing machine with bounded memory, for example. And every static analysis like type-checking, by Rice's theorem, is attempting something Turing-complete, but they're still not useless. When employing theorems, beware lest you prove something different from what you think you are proving.)
Agreed. Unfortunately the Nature article is behind a paywall but the original paper is available on arxiv: http://arxiv.org/abs/quant-ph/9908043
Keep following the thread.
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