If the Universe were to undergo a vacuum decay event, where we transitioned from a false vacuum to a true vacuum state, the fundamental laws and properties of the Universe would change, destroying all forms of matter thant we know. A bubble of destruction would move outward at the speed of light, and if we were located within 18 billion light-years of such an event, it would destroy us, too. (Credit: public domain/pxfuel)

Ask Ethan: What if the Universe lives in a false vacuum state?

There’s a big difference between the notions of ‘false vacuum’ and ‘true vacuum’ states. Here’s why we don’t want to live in the former.

One of the great existential worries that plagues the minds of theoretical physicists is that the vacuum of space might not be in its true vacuum state, but could instead reside in a false vacuum instead. If you were to remove everything you could imagine from a large region of space, including:

• matter,
• radiation,
• neutrinos,
• external electric and magnetic fields,
• and any gravitational sources or spacetime curvature,

you’d be left with purely empty space, or as close as we can come to a physical definition of “nothing.” You might expect that if you were to draw an imaginary box around this region of “nothing” and measured the total amount of energy inside, you’d find that it was precisely zero. But that’s not what we find; we find that there actually is a positive, non-zero amount of energy inherent to space itself, even if we remove all the identifiable quantum and classical sources of matter and energy. What does this mean for the nature of the quantum vacuum…