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In the string theory landscape, the set of particles we observe, their masses and interaction strengths originate from one of many different possible compactifications. What fundamental physical reality/principles/laws is the same in all string theory compactifications/universes in the landscape?

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    $\begingroup$ Assuming that string theory is a quantum field theory, the laws of quantum mechanics would hold. $\endgroup$ – CuriousOne Jun 3 '15 at 21:42
  • $\begingroup$ Would all compactificatiosn preserve at least some part of the Poincare group? (just as our universe presumably preserves 4d Poincare) $\endgroup$ – innisfree Jun 3 '15 at 21:57
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    $\begingroup$ String theory is not a quantum field theory, they are structurally different ncatlab.org/nlab/show/… and it is relativistic, so quantum mechanics would not apply. We can not say much more than that all (viable) string theories reduce to standard model and general relativity in appropriate limits, other than that they can accomodate pretty much anything. $\endgroup$ – Conifold Jun 4 '15 at 1:47
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    $\begingroup$ This question should not be closed. $\endgroup$ – Mitchell Porter Jun 4 '15 at 4:28
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    $\begingroup$ Agree with @MitchellPorter - this question should be left open. Fine, it's research level, but it isn't too unclear in my opinion. I may answer myself if I get a moment this afternoon! $\endgroup$ – Edward Hughes Jun 4 '15 at 9:52
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One answer to your question, which laws of physics should be reproduced in any string compactification, could be the following: If the Weak Gravity Conjecture, see http://arxiv.org/abs/hep-th/0601001, holds true, then gravity should come out as the weakest force in any string compactification. (Notice that there are - as far as I know - only arguments for the WGC coming from generic considerations of a theory of Quantum Gravity.)

Moreover, one can hope to find constraints on certain SM or cosmological parameters from string compactifications. For instance, the energy scale of inflation must not be too high, b/c otherwise one risks destabilisation of the extra dimensions. This translates into upper bounds on the field range of the inflaton. (By the way: If the WGC is true, then certain scenarios of natural inflation cannot be realised.)

psm

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  • $\begingroup$ Is this related to the so-called swampland? en.wikipedia.org/wiki/Swampland_%28physics%29 $\endgroup$ – innisfree Jun 5 '15 at 9:49
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    $\begingroup$ If the WGC is correct and if in an effective field theory gravity is not the weakest force, then this EFT sits in the so-called swampland but is not part of the string theory landscape. $\endgroup$ – psm Jun 5 '15 at 11:30
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these fundamental properties are unexplained and the same in all compactifications: totalitarian principle. speed of light. space has quantum jitters. space can expand. space can create particles. particles experience up to 4 forces at low energy, 1 of them know about all particles, 3 of them know about only some particles

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  • $\begingroup$ somewhere pertinent but it's efficient. Please let's know some links, preferably well signed. $\endgroup$ – user46925 Jun 4 '15 at 22:46

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