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My question is the title of a 1991 paper by Richard Gott and Li-Xin Li: http://arxiv.org/abs/astro-ph/9712344 and is also a subject of his popular book, "Time Travel in Einstein's Universe" Ultimately with cosmology, the chicken and egg question reduces to "How can something come from nothing?" Gott and Li use the concept of a "jinn" (or djinn-genie)---that is something that loops back in time in a closed timelike curve--In the movie, "Somewhere in Time", an elderly Jane Seymour places a pocket watch in young Christopher Reeve's jacket and tells him to come back to her Later, he travels back in time and gives her the watch. The watch is a djinn. Where did it come from? Gott argues that in say the first Planck time, the universe could have pulled a closed timeline curve and created itself. Other than the immense fun value of this thought, is using the concept of CLC in this way valid if it is done in less than the Planck time without violating causality?

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Can you make a more specific question than "what do others think"? This isn't the place to poll people's opinions. –  David Z Feb 1 '11 at 7:38
    
The question is also rather speculative, and suffers from the usual language problem in these matters. To whit: if "the universe" means everything that exists, is there really any other possibility; and if not what does it mean and why shouldn't we push the question back to the universe plus whatever lies outside it to give creation from another source a meaning? The best you can hope for at the highest level is to show self consistency. –  dmckee Feb 1 '11 at 14:35
    
As far as I'm concerned, this is philosophy and not physics. Anyone else tempted to close? –  Noldorin Feb 1 '11 at 15:17
    
OK how about is Gott's use of CTC a violation of causality in this case if it occurs within a Planck time? –  Gordon Feb 1 '11 at 15:35
    
@Noldorin--The paper is physics, was published in Phys.Rev.D and produced a stir at the time at least in the media. Gott took it seriously as physics. Besides, it also resulted in an episode of Star Trek having Spock cite Gott in one of his faux papers :) What are all the questions about interpretation of QM other than philosophy? –  Gordon Feb 1 '11 at 15:37

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up vote -1 down vote accepted

I hope I understand this question properly. The text appears to focus on time loops, or closed timelike curves (CTCs), while the title of the question concerns the creation of a universe from nothing.

The holographic principle of black holes tells us the field theoretic information of strings on the event horizon is completely equivalent to field theoretic information in the spacetime one dimension larger outside. This physics is observed on a frame stationary with respect to the black hole. The question naturally arises; what physics is accessed by the observer falling through the event horizon on an inertial frame? This question is important for the black hole small enough to exhibit fluctuations comparable to its scale. A sufficiently small quantum black hole will be composed of strings in a superposition of interior and exterior configurations or states.

The motion of a string onto a black hole approximates the dynamics of a string in a Rindler wedge. The Rindler wedge is defined by the frame of an accelerated observer, which is equivalent to the frame of a stationary observer near a black hole event horizon. The observer witnesses the final emission of radiation by the string just above the event horizon, where upon the string becomes frozen eternally on the particle horizon. Of course in the Rindler wedge case the string proceeds onwards on its geodesic or string world sheet with no apparent change due to this observed state of affairs. This is approximated as well with the black hole, where the string passes through the event horizon unaffected so long as the radius of curvature is much smaller than the string length. This picture persists until the string approaches the center or singularity of the black hole. At this point the Rindler wedge model departs from reality.

The interior perspective or the physics of a string as measured by an observer falling with the string, is outside the domain of the holographic principle. Once the string passes through the event horizon it evolves on a domain of causal support not included in the data set accessible to an observer on an accelerated frame stationary with respect to the black hole. The observer that falls through the event horizon observes the further evolution of the string beyond the frozen state the stationary observer finds as its final state. Further, the string evolves into a different state as it approaches the singularity. There the string will begin to experience a rapidly growing Weyl curvature. The stationary observer measures transverse modes of the string on the black hole horizon, while longitudinal coordinates are compressed to near the Planck length. The observer falling in with the string will witness the string distended by the growing Weyl curvature in the direction of motion. Consequently, this observer witnesses the extension of longitudinal extension of the string. The frozen state of the string measured by the exterior observer is cancelled by Hawking radiation which escapes later. The string is entangled with the black hole, and there is a superposition of configuration spaces for the string; the exterior and interior configuration variables.

This may put a new twist on the holographic result that events in spacetime do not have the a realism as understood classically. Quantum mechanics removes a measure of reality with the existence of incompatible measurements of observables which exist in incommensurate commuting sets of operators. The invariant interval, or event, is left as something which has an ontology or “realism.” However, this indicates that a realism to any event is not supportable on fundamental grounds. Further, superposition of exterior and interior states of a black hole prevents a sharp distinction between pre-selected and post-selected states. This means that cosmic censorship, chronology protection are aspects of “classical reality,” where underneath the ontology of ordered events or their invariant meaning is lost.

The creation of the universe from nothing might involves something called the biverse. The de Sitter spacetime is a solution of the scale factor $a(t)~=~\sqrt{\frac{3}{\Lambda}}cosh(t\sqrt{\frac{\Lambda}{3}})$, which has this strange backwards part of the hyperboloid. Hawking and others have considered the idea of a universe connected at this minimal scale factor as two universes which are time reversed. It is possible that this is an elementary model for how a “blob” of vacuum energy in a spacetime cosmology quantum tunnels across a potential barrier to form a nascent spacetime cosmology. The blog of vacuum energy is annihilated at one side of the potential by its “opposite” (other half of the biverse), where the “opposite” is annihilated at the other side of the potential by the occurrence of the vacuum blob. This is similar to the tunneling of an electron across a barrier, where we can think of it as annihilated by a positron traveling backwards in time, which in turn is connected to an electron on the other side of the potential barrier.

At the end of the day one might question what are the role of the Hawking-Penrose energy conditions, such as the averaged weak energy condition $T^{00}~\ge~0$. It makes sense that the gravitational states are the Hartle-Hawking states which are degenerate and zero. So ultimately the physical states of the universe globally are zero, or in other words the net total of everything is zero.

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Too many strange ideas for my brain to process, Lawrence, but thanks for the effort. –  Gordon Feb 1 '11 at 16:20
    
Not much interest, I see, so I will give it to you. –  Gordon Feb 5 '11 at 17:50

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