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bio website motls.blogspot.com
location Czech Republic
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visits member for 3 years, 7 months
seen 12 hours ago

Hi, I am a string theorist and a publicist.


Apr
2
revised Why aren't D-branes and strings independent degrees of freedom?
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Apr
2
answered Why aren't D-branes and strings independent degrees of freedom?
Apr
2
revised Pseudoscalar action in classical field theory
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Apr
2
revised Pseudoscalar action in classical field theory
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Apr
2
revised In quantum mechanics, why do the probabilities of the possible outcomes of a measurement add up to 1?
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Apr
2
comment In quantum mechanics, why do the probabilities of the possible outcomes of a measurement add up to 1?
Thanks, Mark, +1 for the relevant math supplement. ;-)
Apr
2
answered Pseudoscalar action in classical field theory
Apr
2
answered In quantum mechanics, why do the probabilities of the possible outcomes of a measurement add up to 1?
Apr
2
answered How might a resonant antenna and black body radiation interact?
Apr
2
answered Massless charged particles
Apr
1
comment Graviton Emission from D-Branes
Good, +1, but could you please add a comment about the counting of the ghost number of this disk diagram? Of course, the answer could be uninteresting by your saying that you may insert any PCO operators anywhere to cancel it but one should still know why, what the rules are.
Apr
1
comment Why is a classical formalism necessary for quantum mechanics?
"One can be trapped in thinking that something is beyond improvement." - This thinking, whether or not you use it in the same sentence with "traps", is called "rational reasoning". There is no improvement of the fact that 2,3,5,7 are the only primes smaller than ten, whether you like this fact or not. The necessary changes that have to be made as in "mutatis mutandis" form an empty set in the case of one-digit primes much like in the case of decoherence. You (and we...) are spending lots of time talking about things that have been proved not to exist.
Apr
1
answered conformal, Weyl transformations, apparent discrepancies and confusions
Apr
1
revised conformal, Weyl transformations, apparent discrepancies and confusions
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Apr
1
comment Effects on a tree exposed to the vacuum of Space
If you managed to feed it by some nutrients, water, light, and CO2, the weaker gravity would make the tree grow differently. It would probably be less straight, unable to find out where is "up" so easily - because of the weaker gravity field. On the other hand, the tree could ultimately be able to become much longer and larger. Or maybe I am wrong? ;-)
Apr
1
comment Why is a classical formalism necessary for quantum mechanics?
@Peter, I found your "it bugs me" and "skeptical enough" comments utterly irrational. Imagine that a mathematician claims that one-digit (smaller than 10) primes are fully known, and they're 2,3,5,7. You start to protest because you don't find the list big enough. Instead, you apparently want thousands of books to be written about one-digit primes, and to create millions of new jobs so that people may be productive discussing one-digit prime. When someone explains to you that there are no other one-digit primes, you find him "insufficiently skeptical". Huh!? Isn't it better to follow evidence?
Apr
1
comment Why is a classical formalism necessary for quantum mechanics?
Dear @Peter Morgan, I am not sure what it means to require decoherence to be "productive" and why a sensible person would want something like that. Decoherence is, first of all, true which is what primarily matters in physics. Indeed, it doesn't tell us anything "shocking and new" because it just confirms something we - and the Copenhagen school physicists - have always known or assumed, namely that "large" objects behave classically. Decoherence just shows that it follows from the universal laws of quantum mechanics; the Copenhagen school treated it as an independent assumption.
Apr
1
comment Why is a classical formalism necessary for quantum mechanics?
@Koantum: the comments I wrote have nothing to do with MWI which is just a psychological crutch to "visualize" something. I don't think that MWI is a part of physics, and I don't believe MWI in any sense. My preferred interpretation is in terms of the Consistent Histories, but I view it just as a modern formalism that doesn't really change anything substantial about the canonical/Copenhagen interpretation of quantum mechanics. Probabilities of outcomes are everything that physics may predict and QM gives totally clear rules how to do it; everything else is philosophical flapdoodle.
Apr
1
comment Why is a classical formalism necessary for quantum mechanics?
Dear @Koantum, there is no sharp, meaningful separation of "macroscopic" and "microscopic" in physics. The only qualitative difference between the behavior of these two classes is about the presence of the quantum interference, and decoherence fully explains at what level this occurs or ceases to exist. The idea that "something else is needed" for QM to deal with nearly classical, macroscopic objects is a misunderstanding, a misconception. See pages 9-16 for decoherence and interpretations of QM, karlin.mff.cuni.cz/~motl/entan-interpret.pdf
Apr
1
answered Angular momentum in string theory