Vacuum Metastability: Estimating the Lifespan of a False Vacuum”

[physics9c]

I recently learned about the possibility of the universe being in a false vacuum, but it seems really hard to find real information on it. I've looked at academic papers but they're well above my undergrad math.

Does the acceleration of inflation imply that we do exist in a false vacuum?

and if we are in a false vacuum, what are some reasonable estimates for its lifespan?

everywhere i look people seem to say "at least 13billion years" which doesn't seem to be saying much at all.


the thing is I can't find even tentative calculations on how long the universe would be expected to last even IF assumptions are given - like a higgs boson of 115Gev or something.

that makes the vacuum metastable, but why can't we calculate a half life from that?

 

[edgepflow]

Try this paper (especially Section 5.1):

http://arxiv.org/abs/astro-ph/0009491

 

[physics9c]

i appreciate the article, as its one i actually haven't seen yet - and I've looked at about 100.

ill read it more in depth in a bit here but one sore point with me is that it reiterates a point that i don't find reassuring:

"the decay time is at least a Hubble time."

its like discovering a bomb was put in a building on monday, finding it on tuesday and saying - we can at least be assured that the bomb takes at least a day to explode. it says nothing about the future of what the bomb will do.

i like the bit about a rolling vacuum - if i understand it at all which of course i dont. that seems to suggest things are less likely to tunnel out in a bang and more likely to slowly fall into a new vacuum state?

 

[edgepflow]

"the decay time is at least a Hubble time."

I don't know where that number came from either - always wondered about it. Maybe somebody else can explain.

 

[Chronos]

Lawrence Krauss has a paper you may find interesting:

http://arxiv.org/abs/0711.1821
The Late Time Behavior of False Vacuum Decay: Possible Implications for Cosmology and Metastable Inflating States

 

[physics9c]

it doesn't seem to give any good news though.

"If our universe is metastable, the expected survival time
may be not much larger than the current Hubble age."

all the rest is referred to as a "modicum of hope"

 

[bapowell]

This is one of those things that we literally can't know. Given the potential energy function of the field providing the energy density, one can calculate transition rates to the true vacuum. But this function might not exist, and if it does, there's very little guidance from fundamental theory as to its probable form. If I were you, I'd be more nervous about an impending ekpyrotic brane collision wiping out the universe. That or a GRB frying the atmosphere ;)

 

[LithiumHelios]

It may be worth looking at some of the classical papers on vacuum decays and false vacua such as:

http://prd.aps.org/abstract/PRD/v15/i10/p2929_1
http://prd.aps.org/abstract/PRD/v21/i12/p3305_1
http://www.springerlink.com/content/v77280v32825v618/
http://www.springerlink.com/content/tx37504u67jx3g72/

 

[physics9c]

i understand that academic journals need subscriptions to keep alive, but some of those articles are old. have any been released to the public yet?

i can't actually view any of them.

thanks though.

 

[bapowell]

i can't actually view any of them.

Yeah, that's frustrating. You can always try google scholar; you can get the Coleman & De Luccia paper. In case you don't know of it, the arXiv eprint server has most recent stuff (from the 90's or so onwards) for free: "arxiv.org"[/URL]
Bousso's cosmological constant paper isn't available for free, but his TASI lectures on the same subject are available and probably similar in scope:
[PLAIN]http://arxiv.org/abs/0708.4231" .

 

[physics9c]

i still can't seem to gather how likely the event is or even what the regional probabilities are.

i suppose it depends on unknown constants in nature but arent there conjectures based on existing models?

like.. if we assume higgs boson of 115Gev then... a probability of so many years.. etc.?

 

[cansay27]

I've actually been looking into the metastability event myself, but I don't think anyone could truly know. Any experimental evidence to suggest it exists would end the universe in the blink of an eye =P

 

[twofish-quant]

Does the acceleration of inflation imply that we do exist in a false vacuum?

Right now we are still trying to nail down the observations, and it's a bit premature to guess what might be causing the acceleration.

i still can't seem to gather how likely the event is or even what the regional probabilities are.

At some point you get into the realm of philosophy. How do you define the likelihood of an event for which there is no good model for that event? At some point, you just have to say that you can't.

i suppose it depends on unknown constants in nature but arent there conjectures based on existing models?

Not really. Right now the fact that we are here constrains the theory more than the theory constrains the observations. The thing that makes it unlikely that the universe will go poof tomorrow is the fact that it's been around for 13 billion years.

 

[physics9c]

well I've seen in a nature article for example, a quote that said the chances are 1 in 169billion. it seems like that scientist involved must at least have had a model.

after all, there are models for quantum tunneling in other circumstances.

however, now i think the point is moot for another reason.

my understanding is that we almost certainly _are_ in a false vacuum because of accelerating inflation. given that, scientists have written articles about the possibility of triggering vacuum decay in a controlled environment - possibly in an attempt to gain energy - I am not sure why exactly.

in all the universe some civilization somewhere must eventually achieve this and there either will eventually be a mistake, or a religious zealot of some sort - I am sure all civilizations would have them - would detonate the device as an act of supreme faith in god.

which makes me think that it will in fact happen and might have already happened.

 

[twofish-quant]

well I've seen in a nature article for example, a quote that said the chances are 1 in 169billion. it seems like that scientist involved must at least have had a model.

I'd be interested in seeing that article. I suppose you can argue that the chances are X given a certain model, but the big unknown is whether the model is correct or not.

my understanding is that we almost certainly _are_ in a false vacuum because of accelerating inflation.

That's not my understanding. We don't know nearly enough about cosmic acceleration or inflation to make that statement.

 

[physics9c]

Popular Science, February 2002,
"Hey, Who Switched Off The Universe"?