False vacuum
[5][6] The effects could range from complete cessation of existing fundamental forces, elementary particles and structures comprising them, to subtle change in some cosmological parameters, mostly depending on the potential difference between true and false vacuum.
Some false vacuum decay scenarios are compatible with the survival of structures like galaxies, stars,[7][8] and even biological life,[9] while others involve the full destruction of baryonic matter[10] or even immediate gravitational collapse of the universe.
[11] In this more extreme case, the likelihood of a "bubble" forming is very low (i.e. false vacuum decay may be impossible).
[12] A paper by Coleman and De Luccia that attempted to include simple gravitational assumptions into these theories noted that if this was an accurate representation of nature, then the resulting universe "inside the bubble" in such a case would appear to be extremely unstable and would almost immediately collapse: In general, gravitation makes the probability of vacuum decay smaller; in the extreme case of minimal energy-density difference, it can even stabilize the false vacuum, preventing vacuum decay altogether.
In the absence of gravitation, this is no problem, no matter how small the energy-density difference; all one has to do is make the bubble big enough, and the volume/surface ratio will do the job.
Although this space-time is free of singularities, it is unstable under small perturbations, and inevitably suffers gravitational collapse of the same sort as the end state of a contracting Friedmann universe.
This is in contrast to events like risks from impacts, gamma-ray bursts, supernovae and hypernovae, the frequencies of which we have adequate direct measures.
[15]: 218 A future electron-positron collider would be able to provide the precise measurements of the top quark needed for such calculations.
In 2014, researchers at the Chinese Academy of Sciences' Wuhan Institute of Physics and Mathematics gave an actual mathematical demonstration of the already existing idea that the universe could have been spontaneously created from nothing (no space, time, nor matter) by quantum fluctuations of a metastable false vacuum causing an expanding bubble of true vacuum.
[19] The stability criteria for the electroweak interaction was first formulated in 1979[20] as a function of the masses of the theoretical Higgs boson and the heaviest fermion.
Discovery of the top quark in 1995 and the Higgs boson in 2012 have allowed physicists to validate the criteria against experiment, therefore since 2012 the electroweak interaction is considered as the most promising candidate for a metastable fundamental force.
[22][23] The diagrams show the uncertainty ranges of Higgs boson and top quark masses as oval-shaped lines.
Underlying colors indicate if the electroweak vacuum state is likely to be stable, merely long-lived or completely unstable for given combination of masses.
[15]) A definitive answer requires much more precise measurements of the top quark's pole mass,[15] however, although improved measurement precision of Higgs boson and top quark masses further reinforced the claim of physical electroweak vacuum being in the metastable state as of 2018.
[30][31] Reanalysis of 2016 LHC run data in 2022 has yielded a slightly lower top quark mass of 171.77±0.38 GeV, close to vacuum stability line but still in the metastable zone.
(Anti-de Sitter space),[48] while topological defects including cosmic strings[49] and magnetic monopoles may enhance decay probability.
[10] In a study in 2015,[45] it was pointed out that the vacuum decay rate could be vastly increased in the vicinity of black holes, which would serve as a nucleation seed.
[50] According to this study, a potentially catastrophic vacuum decay could be triggered at any time by primordial black holes, should they exist.
The authors note, however, that if primordial black holes cause a false vacuum collapse, then it should have happened long before humans evolved on Earth.
[51] In 2019, it was found that although small non-spinning black holes may increase true vacuum nucleation rate, rapidly spinning black holes will stabilize false vacuums to decay rates lower than expected for flat space-time.
It is likely to be unrealistic, because if such mini black holes can be created in collisions, they would also be created in the much more energetic collisions of cosmic radiation particles with planetary surfaces or during the early life of the universe as tentative primordial black holes.
[54] Hut and Rees[55] note that, because cosmic ray collisions have been observed at much higher energies than those produced in terrestrial particle accelerators, these experiments should not, at least for the foreseeable future, pose a threat to our current vacuum.
John Leslie has argued[56] that if present trends continue, particle accelerators will exceed the energy given off in naturally occurring cosmic ray collisions by the year 2150.
In a 2021 paper by Rostislav Konoplich and others, it was postulated that the area between a pair of large black holes on the verge of colliding could provide the conditions to create bubbles of "true vacuum".
