It’s the ultimate nightmare scenario: A bubble in spacetime that grows at the speed of light and eventually destroys the universe. That’s vacuum decay.
Try to imagine somewhere in the universe, a tiny subatomic bubble formed. A bubble inside which all physics as we know it ceases to exist. Particles don’t form into atoms, atoms can’t turn into molecules, all the fundamental forces cease to have any meaning.
And then that bubble expands outward at the speed of light, obliterating everything it touches. Asteroids, comets, planets, stars, whole galaxies just dissipate immediately, their constituent particles flung apart like ashes in the wind. Until eventually the entire universe ceases to exist.
This is a real thing that could happen, spontaneously at any time and at any point in the universe. In fact, it could have already happened, and we’d have no way of knowing it. Because it travels at the speed of light, the first sign we’d get that it happened would be us and everything we know blinking out of existence in a fraction of a second.
This is vacuum decay. And to understand how this could happen, there are three concepts we need to understand.
The first is the standard model of particle physics.
I did a whole video on the standard model that I’ll share right here, so I won’t go too in the weeds about this but a quick overview is that all atoms are made up of fundamental particles that fall into 3 categories, leptons, quarks, and bosons.
Leptons are our electrons and neutrinos in their various flavors, quarks make up protons and neutrons, and bosons are force carrier particles, they make the four fundamental forces possible.
But the final piece of the standard model that we know of so far anyway was the famed Higgs boson.
But the Higgs boson is actually just a tiny chunk of the Higgs Field. Which brings us to the second concept we need to understand… Quantum field theory.
So I’ve never really done a video on Quantum field theory, so that’s long overdue, but the basic gist of it is that all of the particles I just mentioned are actually just excitations in a corresponding field.
In other words, reality as we know it is made up of layers of fields of different energy levels. You’ve got quark fields, electron fields, neutrino fields, boson fields, and most important for this discussion, the Higgs field.
When the Higgs field was predicted, by the illustrious Peter Higgs, it was calculated at a very specific energy level. Any higher or lower and physics as we know it ceases to exist.
126 GeV is a tiny amount of energy to us, but as particles and fields go, it’s pretty high. Scientists began to wonder if this was really as low as it could go.
And with a little fancy math, scientists at CERN in 2013 were able to prove that there is, theoretically, a lower energy level that the Higgs field could exist in. An ultra-dense Higgs field.
This means that the Higgs field that keeps the entire universe together is not a stable true vacuum, it’s a metastable false vacuum.
Which means that if at any place in the universe a tiny part of the Higgs field slipped down into this energy level, entropy would take over and the entire Higgs field would collapse into the ultra-dense state.