"That string theory unites general relativity and quantum mechanics is a profound success," I wonder if this is really true, or whether it reflects a fundamental misunderstanding of Einstein's general relativity by almost all the string theorists. They all consider gravity as a "force" from the exchange of virtual spin 2 gravitons in a flat Minkowski spacetime. This is a perturbation theory and is very limited. They also point to non-perturbative ADS/CFT duality that fits Susskind's "world is a hologram" - we live in The Matrix etc. That is attractive I admit. However, Einstein showed that gravity is not a real force, it is frame-dependent fictitious pseudo-force just like centrifugal and Coriolis et-al fictitious forces that are artifacts of local non-inertial-frames (LNIFs). In fact, gravity determines the timeline geodesic pattern of real force-free motion of massive test particles in addition to the pattern of null geodesic light cones whose relative tilt is curvature (e.g. Roger Penrose, The Road to Reality). Therefore, it may well be a delusion, that finding that closed strings are massless spin 2 gravitons, is enough to claim the unification of gravity and quantum theory. That really is a leap of faith. Are string theorists fooling themselves violating Feynman's golden rule? Maybe not, I am just asking the question. Does the Emperor have clothes? That said, I do think Susskind's landscape and his use of the Weak Anthropic Principle is reasonable provided we accept string theory. Different universes on the landscape can be connected by traversable wormholes held open by a strong phase of dark energy. This would make Susskind's proposal Popper falsifiable. There is also the issue of the extra dimensions attacked by Roger Penrose in "The Road to Reality" - allowing tachyons might avoid the need for extra dimensions. Of course, tachyonic quantum fields have unstable ground states and this leads to the spontaneous breakdown of symmetries that we see in the Higgs field, superconductors, ferromagnets and even ordinary crystals. I first introduced the idea of ER = EPR in my 1975 book "Space-Time and Beyond" (E.P. Dutton with Fred Wolf and Bob Toben) mentioned by MIT physics historian David Kaiser in "How the Hippies Saved Physics." Susskind rediscovered the idea more mathematically admittedly recently. However, he assumes that the ER wormholes pinch off - are not traversable. This corresponds to the no-signaling "theorems" of orthodox linear unitary quantum theory. However, we know from Kip Thorne that traversable ER wormholes are conceivable. This would then correspond to a post-quantum theory with what Antony Valentini calls entanglement "signal nonlocality." Such nonlinear non-unitary extensions of orthodox quantum theory have been investigated by Weinberg, Polchinski, Stapp, Josephson and myself, though a lot more work needs to be done. Seth Lloyd at MIT and David Deutsch at Oxford have shown how such traversable ER wormholes may give us very powerful post-quantum computers, more powerful than quantum computers. Indeed, I have reason to think such post-quantum computers have consciousness, the same consciousness we have, because our brain is such a post-quantum computer. See slides 25 and 31 of http://www.tcm.phy.cam.ac.uk/~mdt26/PWT/lectures/bohm8.pdf
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  • Quantum mechanics of time travel - Wikipedia, the free ...

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    Jump to Lloyd's prescription - ... later presented by Seth Lloyd based upon post-selection and ... He assumed it is ill-defined to speak of the actual density state of the CTC ... Now, quantum computers using time machines can only ...
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