Vacuum decay is a hypothetical event that could occur if the universe is in a false vacuum state, which is a metastable state that is not in the most stable state possible. In this state, the universe could last for a very long time, but it could eventually decay to the more stable one, an event known as false vacuum decay. The Higgs field, which permeates our universe, determines whether the universe is in a true vacuum or a false vacuum state. A true vacuum is the stable, lowest-energy state, while a false vacuum is a metastable state that is not actively decaying but is not exactly stable either. If the universe is in a false vacuum state, it could decay through quantum processes at any time, but the lifetime of a metastable universe is predicted to be much longer than the current age of the universe. However, if the vacuum did decay, it could result in the destruction of the universe. The possibility of vacuum decay has come up a lot lately because measurements of the mass of the Higgs boson seem to indicate the vacuum is metastable.