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location New York City
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visits member for 3 years, 3 months
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I do not participate on this site any longer, except to respond to comments regarding my own text, if that text is unavailable in another form. I do not accept the political moderation atmosphere here, it is not compatible with open science. I participate at physicsoverflow.org.


Nov
22
awarded  Nice Question
Nov
21
comment Will free-fall object into black hole exceed speed of light $c$ before hitting black hole surface?
@mike4ty4: The coordinates where the objects freeze are degenerate on the horizon, there is no paradox. The objects freeze because the coordinate time stops, not because their intrinsic velocity is slow. It requires knowing the metric form at a horizon, something you can work out for Rindler space easily, because it's just flat Minkowski space in disguise.
Nov
18
comment How long would it take to travel through a wormhole?
@mike4ty4: Do I ever give a citation for anything? It's easy to see for yourself.
Nov
15
comment What is a tensor?
@Physikslover: This is just the classical index definition. The process of finding invariants is by raising and lowering indices using the metric tensor (which is just the identity for Euclidean space, so you can ignore up and down position) and taking arbitrary traces by contracting indices. With a two-tensor, there are lots of invariants T^a_a, the trace, T_ab T_ab (sum of squares of all components--- the "length"), T_abT_bcT_ca (a cubic invariant that doesn't have a name) etc. There is one other invariant, the epsilon tensor, which is used to construct chiral invariants like the cross prod.
Nov
13
awarded  Nice Answer
Nov
12
comment Is the universe linear? If so, why?
Or, say, let's not.
Nov
12
comment Is the universe linear? If so, why?
@mike4ty4: A quantum computer which factors an arbitrary 10,000 digit number is sufficient to rule out all classical 10^140 bit computers even with extra miracles (like order 10^sqrt(n) factoring realized easily in nature), so that's the condition I choose for saying "quantum mechanics is experimentally proved to be exponentially large". That's enough for me to say that you've proven quantum mechanics is exact for all intents and purposes, since exponentially large alternatives are not particularly interesting to me personally.
Nov
12
comment Will a ball slide down a lumpy hill over the same path it rolls down the hill?
@Physikslover: NO, there is no difficult part. The no-slip rolling-ball constrained Maupertuis action is identical to the sliding ball Maupertuis action, up to an overall rescaling which doesn't affect the trajectory (the only difference is the time taken to traverse the trajectory). That's why it's trivial in the Maupertuis formulation. I worked it out (in my head, in two seconds) before posting.
Nov
11
comment Is the universe linear? If so, why?
@mike4ty4: The difference between a computer simulating a classical universe and a computer simulating all the details of a quantum universe is exponential, so a classical computer needs 10^140 bits, while a classical computer simulating a quantum computer simulating the universe needs 10^(10^140) bits, which is like the difference between a googol an a googolplex (except even bigger). If Quantum Computation is fundamental, not classical computation, this would still require 10^140 qubits, which is reasonable. The question here is which is the right computation model, CM/QM.
Nov
11
comment Is the universe linear? If so, why?
@mike4ty4: Theories don't work like that--- we still observe things that are consistent with Newton, does that mean there is no relativity? The idea is that it is possible QM could be superseded by a smaller alternative, which would make the universe less computationally demanding. There's no real reason it must be so, but there's no real reason it can't be so, except quantum mechanics is very hard to reproduce from such a thing, and it can't happen without massive nonlocality. If you see real Quantum Computation, this rules out small computer universes forever, so I don't care. Many worlds.
Nov
11
comment Will a ball slide down a lumpy hill over the same path it rolls down the hill?
@Physikslover: In case you are an English non-native speaker, the reference is a JOKE. There is NO REFERENCE, nor can there be, it's completely obvious, despite the lengthy arguments in other answers, because of the existence of the timeless action principle (Maupertuis principle). Arguments in Physics ARE NEVER MADE WITH A REFERENCE, they are made from first principles, and I did so. This is an IMMEDIATE corrolary of the principle of Maupertuis, not because I say so, but because IT IS, an anyone can check it in ten seconds of thinking.
Nov
10
comment Will a ball slide down a lumpy hill over the same path it rolls down the hill?
@Qmechanic: Do you still think the same stupid things, with the benefit of hindsight?
Nov
6
comment Why do covalent bonds form?
@KirkWoll: If you bring two classical polarizable atoms close, they don't attract. When you bring two quantum atoms close, they do, because the electrons can tunnel to the other atomic volume, reducing their energy. That's it. When they are really close, you get repulsion between the nuclei.
Nov
4
comment Is Stephen Wolfram's NKS, an attempt to explain the universe with cellular automata, in conflict with Bell's Theorem?
@agemO: I see. I'll write up something coherent. I never wrote it, because John Mattick has compiled the evidence well in 2001 (you can google Mattick RNA), and thinks similar things, although not with the computational point of view. The evidence is actually overwhelming by now, it's pretty much the only point of the enormous ENCODE project, to give this thesis scholarly weight.
Nov
4
awarded  Nice Answer
Nov
4
comment Is Stephen Wolfram's NKS, an attempt to explain the universe with cellular automata, in conflict with Bell's Theorem?
... I don't give references for anything except for priority, as I don't know and don't care about authority. I noticed this myself. I might have been first, I doubt it. There is a Leslie Valient who says similar things, but is confused on how RNA works. Most people who notice that the random mutation models fails are religious, and use it to say "God did it supernaturally", so I can't cite them with a straight face, as they generally would reject RNA rewrites just as vehemently, as RNA is not Biblical either. But RNA rewriting is required. I really am not sure about acceptance, nor do I care.
Nov
4
comment Is Stephen Wolfram's NKS, an attempt to explain the universe with cellular automata, in conflict with Bell's Theorem?
@agemO: It works (badly) as a method of parameter optimization not as a method of evolution. Better parameter optimization is gotten through simulated annealing, or steepest descent, or both, depending on the details of the cost function. Evolution is not a simple optimization process, rather evolution in a computing system involves writing new code, making existing code more complex. It has been unfortunately thought of as a version of parameter optimization. Random mutation just isn't the natural process in a computing system, rather large scale coherent rewriting.
Nov
3
comment Is Stephen Wolfram's NKS, an attempt to explain the universe with cellular automata, in conflict with Bell's Theorem?
@agemO: It does not give any results either. The local protein mutations which change fitness can be counted on one hand--- moth color and sickle-cell anemia, that's about it. Those are exceptions, not the rule, but they are put as the rule in the books. The picture is simply wrong, because it is a non-computing picture, and it is also deliberately wrong, because it fits with an atheistic idea that natural computations don't exist. This type of no-computation-in-nature atheism is falsifiable and falsified. You had the impression because it is dogma, it's what everyone says, wrongly.
Nov
3
comment Is Stephen Wolfram's NKS, an attempt to explain the universe with cellular automata, in conflict with Bell's Theorem?
@agemO: It only superficially seems to work to the naive intuition, it doesn't really work, and this is what many critics of modern synthesis evolution have been pointing out for decades. It gets impossible to mutate-evolve past a certain complexity without co-evolving the mutation mechanism along with the system. The reason is that the distance between roughly equal fitness maxima generically grows with complexity, so that the steps you make must be larger. The current model is simply not correct. But the correct mechanism to fix this is also obvious today--- RNA editing of DNA.
Nov
2
comment Is Stephen Wolfram's NKS, an attempt to explain the universe with cellular automata, in conflict with Bell's Theorem?
@agemO: The ridiculous part is that the mutation mechanism is brainless and non-computing. There is no evidence for this. It is true that SNP type mutations in proteins are random, but they are also generally pointless, they make clock-like neutral evolution. The interesting aspects of evolution is the effect on non-coding DNA, and these changes are extremely complicated, and certainly regulated by RNA networks making a sophisticated computation. These mutations bear no relation to the models in population genetics, they look more like intelligent design, with RNA being the designer, not God.