Alexander Vilenkin spontaneous creation

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Discussion Overview

The discussion revolves around Alexander Vilenkin's paper on spontaneous creation in the context of cosmology, particularly focusing on the concept of "nothing" and its implications for the universe's flatness. Participants explore theoretical aspects of inflationary cosmology, quantum fluctuations, and the nature of vacuum states, while also referencing related works and concepts.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested
  • Historical

Main Points Raised

  • Some participants question whether the "nothing" in Vilenkin's paper refers to a philosophical nothing or a material cause, suggesting it indicates a spontaneous creation without an efficient cause.
  • There is uncertainty about how Vilenkin's ideas reconcile with observational data indicating a flat universe, with some participants suggesting this may challenge the paper's conclusions.
  • One participant notes that the inflationary model presented in the paper may not represent the best current models, implying it is of historical interest rather than a leading theory.
  • Another participant describes Vilenkin's paper as significant in the context of quantum cosmology, comparing it to Hawking's no boundary proposal and noting its speculative nature while acknowledging its serious consideration by physicists.
  • There is discussion about the meaning of terms like "small true vacuum bubble" and "metastable false vacuum," with questions raised about their existence in spacetime and the implications for the creation of spacetime itself.
  • Participants express confusion over the concept of "spontaneous" creation, debating whether quantum fluctuations are truly uncaused or if they arise from underlying mechanisms like wave-function collapse or hidden variables.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the interpretations of Vilenkin's work, the nature of "nothing," or the implications of flatness in the universe. Multiple competing views and uncertainties remain throughout the discussion.

Contextual Notes

Limitations include the lack of clarity on specific definitions of vacuum states and the dependence on interpretations of quantum mechanics. The discussion also highlights unresolved mathematical and conceptual steps in understanding the implications of the paper.

momo666
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Recently I've come across Alexander Vilenkin paper . I can't seem to find the 1988 version so if you can help me with that I would appreciate it.

I have 2 basic questions:

1)Am I right in saying that the "nothing" in this paper is not the "philosophical nothing" as in no thing at all ? From my perspective, the paper says the Universe had a material cause (the stuff out of which something is made) but not an efficient cause since it was spontaneous.

2)How does this fit in with the observational data that says the Universe is flat ? Doesn't that refute the paper ? Surely Alexander Vilenkin knows this trivial fact so how does one reconcile his paper with a flat Universe ?
 
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Vilenkin is still at Tufts University I believe. Google for 'Alexander Vilenkin'. Links to talks will come up. This is not an area I know anything about.
 
momo666 said:
Am I right in saying that the "nothing" in this paper is not the "philosophical nothing" as in no thing at all ?

I've read through the paper a couple of times, and I am still not sure exactly what in the mathematical model the term "literally nothing" in the abstract is supposed to refer to.

More generally, there has been a lot of work done on inflationary cosmology since 1982 (or 1988), and I don't think the inflationary model described in this paper is representative of the best current inflationary models. So this paper is probably more of historical interest than anything else.
 
That happens to be a very famous paper that describes a mechanism coming from pure quantum cosmology. Along with the no boundary proposal of Hawking, its one of the very few entirely semiclassical ideas about the initial quantum state in cosmology. Further, its frequently discussed in textbooks and is important to understand when you discuss mini superspace solutions for the Wheeler De Witt equation, and things of that nature. It's very speculative of course, but it is not entirely without merit, and very good physicists study it quite seriously.

Note that the mechanism described in that paper has been utilized in hundreds of different models as well, so its famous for that as well.

Of course the phrase 'creation from nothing' is whimsical and is nothing of the sort. Its completely analogus to nonrelativistic barrier penetration, and the initial state is simply vacuum (eg a closed universe with zero energy possessing a solitary scalar field as matter content and scale factor radius approaching zero).
 
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The universe is *close* to flat, but may still be closed.
 
I hope this does not go against the rules but I have another paper that seems to be similar. Namely, this one: https://arxiv.org/abs/1404.1207

My questions are as following:
1) What is a "small true vacuum bubble" and "metastable false vacuum" ? I am having a hard time finding out and the closest I've came is that they are sectors of space. Does this mean they exist in spacetime or they require spacetime to exist ?

2) What is created exactly in this paper ? Is spacetime created ? That is to say, the paper stars from a system of no space and no time and ends up with a system that has spacetime ? The paper states that "once a small true vacuum bubble is created by quantum fluctuations of the metastable false vacuum" but if the false vacuum is a sector of space that means space (and time ?) already exists in this paper.

3) What is meant by "spontaneous" ? Are the quantum fluctuations really not caused ? I have heard someone say that either wave-function collapse (in collapse theories) or some hidden variable (in non-collapse theories) produces these fluctuations. The only thing there is debate about is whether the causation is deterministic or not.
 

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