Alexander Vilenkin spontaneous creation

[momo666]

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 ?

 

[jim mcnamara]

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.

 

[PeterDonis]

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.

 

[Haelfix]

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).

 

[bapowell]

The universe is *close* to flat, but may still be closed.

 

[momo666]

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.