# Vacuum decay

## Main Question or Discussion Point

It's been hypothesized that, at a high enough energy density (say, in a collision of particles), a bubble of true vacuum could be formed, which would then grow at the speed of light and envelop our universe, which is currently in a false vacuum, thus making all matter disintegrate. Is this possible?

Related High Energy, Nuclear, Particle Physics News on Phys.org
Pythagorean
Gold Member
I'm in now ways an expert on the subject, but a quick search revealed:

One scenario is that, rather than quantum tunnelling, a Particle accelerator, which produces very high energies in a very small area, could create sufficiently high energy density as to penetrate the barrier and stimulate the decay of the false vacuum to the lower energy vacuum. Hut and Rees,[9] however, have determined that because we had observed cosmic ray collisions at much higher energies than those produced in terrestrial particle accelerators, that these experiments will not, at least for the foreseeable future, pose a threat to our vacuum. Particle accelerations have reached energies of only approximately four thousand billion electron volts (4 ×103 GeV). Cosmic ray collisions have been observed at and beyond energies of 1011 GeV, the so-called Greisen-Zatsepin-Kuzmin limit. John Leslie has argued[10] that if present trends continue, particle accelerators will exceed the energy given off in cosmic ray collisions by the year 2150.
from http://en.wikipedia.org/wiki/False_vacuum#Particle_accelerator

as always, of course, be wary of Wikipedia.

ZapperZ
Staff Emeritus
2018 Award
It's been hypothesized that, at a high enough energy density (say, in a collision of particles), a bubble of true vacuum could be formed, which would then grow at the speed of light and envelop our universe, which is currently in a false vacuum, thus making all matter disintegrate. Is this possible?
If this is true, then wouldn't you think that it would have happened already after so many billion of years and so many particles with such high energies in existence?

Note that when you are citing some "hypothesis", especially when it isn't something standard or well-known, please make a full citation to the source. This is something we strongly encourage here on PF, that the source be clearly identified.

Zz.

samalkhaiat
It's been hypothesized that, at a high enough energy density (say, in a collision of particles), a bubble of true vacuum could be formed, which would then grow at the speed of light and envelop our universe, which is currently in a false vacuum, thus making all matter disintegrate. Is this possible?

Yes, it is! Breathtaking, is it not? S. Coleman called it a "cancer of space".
The quantitative features of the decay of the false vacuum require a good knowledge of instantons physics and of symmetry bracking. However, it is easy to understand the qualitative features of the hypothesis by looking at the nucleation processes of statistical mechanics, for example, the boiling of superheated fluid. The superheated fluid phase corresponds to the false vacuum and the vapor phase to the true vacuum. We know that thermodynamic fluctuations cause bubbles of vapor to materialize in the fluid. Small bubbles shrink to nothing, as the gain in volume energy is compensated for by the loss in surfase energy. However, once a large enough bubble is formed, there is no need to worry about fluctuations anymore; it is energetically favorable for the bubble to expand converting the available fluid to vapor or coalesces with another bubble.
Now, you can picture the decay of the false vacuum if you replace thermodynamic fluctuations by quantum ones.

The hypothesis can be traced back to E. Gliner (from Leningrad) at the end of the 1960's. But Gliner was trying to understand the secret behind the birth of the universe. In 1972, A. Linde and D. Kirzhnits showed that a state of giant negative pressure can indeed arise in the expanding universe.

The key (technical) papers on this subject are;

M B Voloshin, Sov. J. Nucl. phys. 20, 644(1975).
S Coleman, phys. rev. D15,2929(1977).
M Stone, phys. rev. D14,3568(1976).
A Linde, phys. Lett. 70B,306(1977).
A Linde, Rept.prog.phys. 42, 389(1979).

See also the work of A. Sakharov and Y. Zeldovich on the same subject.

regards

sam

samalkhaiat
If this is true, then wouldn't you think that it would have happened already after so many billion of years and so many particles with such high energies in existence?
S. Coleman, aspects of symmetry, Cambridge press,1985.

From Page 329;

"The relevant parameter for cosmology is that cosmic time for which the product of $\Gamma / V$ and the volume of the past light cone is of order unity. If this time is on the order of microseconds, the universe is still hot when the false vacuum decays, ... . If this time is on the order of years, the decay of the false vacuum will lead to a sort of secondary big bang, .... . If this time on the order of billions of years, we have occasion for anxiety."

regards

sam

ZapperZ
Staff Emeritus
2018 Award
S. Coleman, aspects of symmetry, Cambridge press,1985.

From Page 329;

"The relevant parameter for cosmology is that cosmic time for which the product of $\Gamma / V$ and the volume of the past light cone is of order unity. If this time is on the order of microseconds, the universe is still hot when the false vacuum decays, ... . If this time is on the order of years, the decay of the false vacuum will lead to a sort of secondary big bang, .... . If this time on the order of billions of years, we have occasion for anxiety."

regards

sam
So this whole thing is just one big IF?

Zz.

CarlB
Homework Helper
The concept that we're going to destroy the universe with one of our puny particle experiments is quite hilarious. We can't approach anywhere near the energy of cosmic rays, and that's what impinging on our atmosphere every day. If you want to imagine nature's particle experiments, take a think at what happens when a supernova goes off. The vacuum in particle physics is just a mathematical crutch used to hobble over the fact that theory is clueless about where mass comes from.

When a mathematical theory of physics generates reams of science fiction nonsense, none of which is observed in experiment, this is a sign that the mathematical theory is nonsense. The fact that, in other areas, the theory correctly predicts experiments is a sign that there is some truth to it, but if the theory predicts stuff that isn't observed, that's not a good sign for the theory.

The general theory of relativity does nicely for the weak situations where we can check observations (though it seems to be failing to account precisely for spacecraft motion having to do with the "slingshot" effect and there does seem to be some weirdness going on in the speeds of rotation of galaxies etc.), but we have essentially zero precise tests of it inside of black holes. The mathematics says that spacetime can connect on itself and do various things with wormholes, white holes, etc., but none of this nonsense has ever been observed, and our astronomical data about the insides of black holes ends well outside of the event horizon. To extrapolate GR to the insides of black holes is nonsense, and to fear particle experiments because they might build a black hole that would engulf the earth is silly.

samalkhaiat
So this whole thing is just one big IF?
So? Do you know that the whole of cosmology is built on a very similar "IF"?

By the way, the subject is "standard", "well-known" and (surprise) it comes out from the Higgs sector of the SM! See;

P. Frampton, Phys.Rev.Lett. 37, 1378(1976).

So, my friend, instead of questioning the "IF"s of S. Coleman, grab one of the papers, I mentioned, and gain some knowledge about the subject. Trust me, you wont regret it. It is serious science investigated by very serious physicists.

regards

sam

ZapperZ
Staff Emeritus
2018 Award
So? Do you know that the whole of cosmology is built on a very similar "IF"?
The only difference here being that the "If's" that you described seem to cover ALL the possible basis, meaning there's no way to falsify it, whereas many of the "If's" in cosmology CAN be falsified or shown to be false.

And I'm not sure how you can claim it to be "well-known" when it has such a large "wiggle room" coming out of a sector of the Standard Model that has no verification.

.... or do we no longer care about experimental verification before we call something "well-known"? I still want to see where such catastrophe is considering what I've said already. The recent results from Auger Observatory has clearly shown that we do have very high energy particles that exceeds anything we'll ever get in any conceivable particle collider. Where are these vacuum bubble?

Zz.

Last edited:
samalkhaiat
The only difference here being that the "If's" that you described seem to cover ALL the possible basis, meaning there's no way to falsify it, whereas many of the "If's" in cosmology CAN be falsified or shown to be false.
I see no difference at all. Indeed, you can estimate the decay probability per unit time per unit volume,$\Gamma / V$, once the "critical" density of the universe is determined/measured.
Now, remember the "If's" of cosmology; If $\rho > \rho_{c}$, the universe is closed. If $\rho < \rho_{c}$, the universe is open!

And I'm not sure how you can claim it to be "well-known" when it has such a large "wiggle room" coming out of a sector of the Standard Model that has no verification.
It is "well-known" in the same sense as supersymmetry is "well-known".

.... or do we no longer care about experimental verification before we call something "well-known"?
I am theoretician. Experimental verefication is not my business. However, I believe that the clever people of experimental physics are quite capable of verifying/falsifying my theory. I just have faith in them

I still want to see where such catastrophe is considering what I've said already. The recent results from Auger Observatory has clearly shown that we do have very high energy particles that exceeds anything we'll ever get in any conceivable particle collider. Where are these vacuum bubble?
You (and the OP) seem to confuse INDUCED decay (by high energy particle collisions and so on) with SPONTANEOUS decay (which is a symmetry breaking effect). I am partly responsible for this confusion because I didn't explain the difference between the two decays to the OP.
I have talked about spontaneous decay of the false vacuum which is, as I said, a serious science. INDUCED decay (for example; a non-negligible X-section for the production of a bubble at CERN, Fermilab or somewhere in the space) is, on the other hand, an internet garbage! We can not even decide whether this X-section is negligible or not. We simply don't know where to start!

regards

sam

Last edited:
I am theoretician. Experimental verefication is not my business.
Would you call yourself a physicist or a mathematician ?

Did it occur to you that Coleman's anxiety was not about our actual life, but about the fate of the theory ?

samalkhaiat
Would you call yourself a physicist or a mathematician ?
I call myself sam.

Did it occur to you that Coleman's anxiety was not about our actual life, but about the fate of the theory ?
No, it didn't. "Aspect of Symmetry" is not a collection of ambiguously written political articles. In case that YOU developed such doupt, here is what Coleman writes on page 336;
"Since even $10^{-10}$ sec is considerably less than the response time of a single neuron, there is literally nothing to worry about; if a bubble is coming toward us, we shall never know what hit us."

sam

Newbie here.

I wonder if low temperature experiments at a tiny fraction of a Kelvin could be dangerous.
Could a vacuum decay occur if you lower the temperature of a confined space sufficiently?