Q: What is the âFalse Vacuumâ and are we living in it?
Physicist: The False Vacuum is just another item on the long list of things to worry about, that are not worth worrying about, and that nobody can do anything about. If you have any other worries, worry about those first.
In any physical system youâll find that thereâs an energy âground stateâ that the system tries to approach. For example, if you pour water into a bathtub there are a lot of ways that the water could arrange itself, but it will rapidly try to assume the ground state: being as low and still as possible.
In any physical system thereâs a lowest energy state called the âground stateâ. If you allow the energy to drain out of a system, then it will approach its ground state.
Gravitational potential (the energy that something on a high shelf has more of, and thatâs released when things fall) is the easiest example of an energetic system to picture. Being on the ground is the lowest gravitational potential a thing can have (without digging); thus the name.
But in the tub example, the water in the tub doesnât âknowâ about the drain or the area around the tub. Given the chance the water would flow out of the tub and into a new, lower, ground state. In fancy-math-speak, youâd say that the water in a tub is in a âlocal energy minimumâ. Within the tub, water definitely assumes the only ground state it can find. However, if it jumped out of the tub, or somebody pulled the plug, then it would try to find a new, lower ground state and would find that it gained a bunch of new energy in the process (what with the flowing and splashing and whatnot).
Thereâs no good way to find out if youâre in a local âfalseâ ground state or a true ground state.
The idea of energy levels, and ground states, and all that, applies to pretty much everything. That includes electromagnetic fields and even particle fields. A âparticle fieldâ is the quantum mechanical way of describing particles (all smeared out, instead of being all in one point), and each field has a pretty reasonable set of energy levels. Every new particle elevates the energy level by one step, and the ground level is exactly what youâd expect: zero particles.
The vacuum is the most absolute ground state: no waves, no particles, nothing at all to elevate the energy above zero. So, the idea behind a false vacuum is that what we consider the ground state of the universe isnât really the ground state, and it may be possible to drop into an even lower-energy state (drain the tub, so to speak). What we think is the ground state, the vacuum, may not be the true ground state. Â
The âdangerâ of living in a false vacuum is that, under the proper circumstances the false vacuum can drop into the true vacuum. The cause is usually described as a sufficient burst of energy to get the appropriate fields âover the humpâ (picture above). If the difference in energy between the false vacuum and true vacuum is large enough, then the surrounding space can likewise be tipped into the lower state. In theory, a âfalse vacuum collapseâ would expand at light speed (or about light speed) from the originating event, and destroy the heck out of everything in the affected, and ever-expanding, region.Â
Via Ask a Mathematician / Physicist