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False Vacuum Definition


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#1 Enjgine

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Posted 12 August 2012 - 10:17 AM

I simply need help understanding, what is a false vacuum. I understand it to be a section of space which is not at its lowest energy state, but why is it so dangerous, and why can't it just (worst use of the word ever) become a lower energy state, why don't the atoms just move to the lowest state.

Any help will be appreciated. Thanks.

#2 CraigD

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Posted 12 August 2012 - 11:48 AM

Welcome to hypography, Enjgine! :) Please feel free to start a topic in the introductions forum to tell us something about yourself – like what your user name means? :)

I simply need help understanding, what is a false vacuum.

First, an explanation of what a vacuum is, in quantum mechanical terms:
The quantum vacuum consists of particles that are virtual, rather than actual, meaning that they can be shown to exist using quantum mechanical calculations, but these calculation show that, except in extraordinary situations (such as Casimir effect measuring experiment), they can never be detected.

Next, what a false quantum vacuum is:
If these QM calculations show that these virtual particles can change state from one of higher to lower energy, they’re called a false vacuum. Such a transition is called a vacuum perturbation.

I understand it to be a section of space which is not at its lowest energy state, but why is it so dangerous ...

Though theories abound, there’s no one clearly supported by experimental evidence that gives a definitive answer to how true or false the quantum vacuum in our vicinity, or the universe a whole, is, or what a transition from a higher energy false vacuum to a lower, or lowest energy true vacuum, would be like.

Some theories hypothesize that the transition would be nearly undetectable, and/or is happening right now. Others hypothesize that it would be a universe-as-we-know-it ending catastrophe. Both of these kinds also hypothesize that the universe-as-we-know-it is the result of an ancient (likely about 13 billion years ago) vacuum perturbation.

This is all very speculative, and the mathematical physics involved, hard, much harder than I can manage. IMHO, good hard SF is as useful for imagining a catastrophic vacuum perturbation. My favorite is Greg Egan’s 2002 novel Schild's Ladder.

... and why can't it just (worst use of the word ever) become a lower energy state, why don't the atoms just move to the lowest state.

The quantum false vacuum, like the classical vacuum known to physicists since the 17th century, is empty of actual particles. There are no atoms in it.

#3 Enjgine

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Posted 12 August 2012 - 07:21 PM

Ok, thanks. Thats probably why I could never find one real answer, but I get the basic concept now.
Thanks.