112,055 reputation
7164327
bio website motls.blogspot.com
location Czech Republic
age 41
visits member for 4 years, 4 months
seen 6 hours ago

Hi, I am a string theorist and a publicist.


Mar
26
comment Why does large curvature of spacetime imply high temperature?
Dr Bollinger's answer is on the right track but I believe that because he rejects the key concept of tidal forces, someone who is confident that the right buzzword is the "tidal forces" should post a full-fledged answer here (David?). The canonical example is the observer approaching a black hole singularity. He's torn apart by the tidal forces which are really the nonrelativistic equivalent of the spacetime curvature. Tidal forces rip him apart, big force, big temperature.
Mar
26
comment Entanglement and relativity
Dear Dr Neumaier, the measurement in QFT isn't "poorly researched". It's exactly as well researched and understood as measurement in any other quantum mechanical theory because all QM theories share the same postulates and foundations so the explanations are completely universal and hold for all QFTs as well. They only differ in the list of quantities that can be measure, not in the logic how it's measured and what it means. Also, it's a matter of a few lines – known since 1930 or so when QFT was born as a framework – to prove the Lorentz invariance (and thus locality) of quantum field theory.
Mar
25
comment Entanglement and relativity
Dear Giulio, the correlation is unambiguously and quantitatively predicted by quantum mechanics, in agreement with the experiment, and the quantum calculation makes it self-evident that the reason for the correlation is the contact of the two subsystems in the past (the initial state) and not anything that happens during the measurements. It's nearly guaranteed, both in classical and quantum physics, that two subsystems in contact remain correlated with each other. None of the things provides a glimpse of a rational evidence for MWI, "real collapse", or any of these unphysical superconstructs.
Mar
25
answered Entanglement and relativity
Mar
24
comment Spectrum of Free Strings
Good answer, +1. I still think that one may expand and/or re-emphasize some points. When one determines masses, they're not just "defined". The mass spectrum of particles contains much of the information about the theory and it has to be calculated; of course that this calculation depends on the background. The massless spectrum depends on the background in field theory, too. It's not a "disadvantage" in any sense; it's a tautology. We're just saying that the most important feature of the dynamical laws, the spectrum, depends on the dynamical laws governing individual particles/strings.
Mar
24
answered What is the connection between extra dimensions in Kaluza-Klein type theories and those in string theories?
Mar
23
comment What experiment would disprove string theory?
Third, it is absolutely irrational and unjustifiable to treat ST differently than QFT. Both of them are falsifiable frameworks and, as far as the doable experiments go, they make the same predictions. So it is nonsensical to pick one of them as being the right one and the other one as being the one that you can eliminate. Whether something was discovered before or later may be interesting for historians of science but it has nothing whatsoever to do with the validity of the theories.
Mar
23
comment What experiment would disprove string theory?
Nope, Anixx, none of your propositions is right. First of all, concerning 1st sentence, falsification of a hypothesis has absolutely nothing to do with other hypotheses; they have nothing to do with the process of falsification of a given hypothesis. Second, it is absolutely not true that string theory brings nothing new. It brings everything new - among other virtues, it's the only theory that is consistent in the quantum gravity regime for which it predicts what happens.
Mar
23
comment Spinor integration
Hi! It may be done by some straightforward algebra but it's also good to notice that both sides have the same support - they're integrals over the future light-cone - and in both cases, the delta-function imposing the support to the light cone combined with the Lorentz invariance uniquely determines the measure up to the normalization (the spinor products are Lorentz invariant much like delta of $l^2$) so they have to be equal up to the normalization one has to check (or believe). The normalization may be checked either by boring algebra or by integrating a particular example function.
Mar
23
revised Does this Zeilinger group result provide experimental proof of backward-in-time causation?
added 1 characters in body
Mar
23
revised Does this Zeilinger group result provide experimental proof of backward-in-time causation?
added 1727 characters in body
Mar
23
answered Does this Zeilinger group result provide experimental proof of backward-in-time causation?
Mar
21
answered Spinor integration
Mar
18
awarded  Nice Answer
Mar
17
answered Interacting classical strings?
Mar
16
answered CP Violation of the CKM Matrix
Mar
16
revised What experiment would disprove string theory?
deleted 14 characters in body
Mar
15
comment Energy Measurements in a Two Fermion Double Well System
Dear Marty, the OP's question makes it absolutely clear that twistor59 is asking about the textbook example of spinless electrons so your discussion of the spins has nothing to do with the original question. In the real world, this "spinless electron" system is embedded in such a way that all the electrons we consider must be e.g. spin-up. In your spin-ful language, one only picks the two-electron states with $s_z=+1$ which really means the unique state from the triplet. Allowing different spins creates more states, and therefore the Pauli's principle becomes even less constraining.
Mar
13
comment Does the Pauli exclusion principle instantaneously affect distant electrons?
I think that Jim Parsons would still win in this respect, Phil. He has more physically accurate writers of the script, too.
Mar
13
revised Energy Measurements in a Two Fermion Double Well System
added 134 characters in body