Destroying the universe: How hard can it be?

In quantum field theory, the vacuum state refers to the lowest energy state in a system. Particles are excitations above this state and carry energy, hence the term "vacuum" to refer to the state with no particles. Nothing requires this state to be unique. There may be many different field configurations that are local energy minima, and hence stable against small perturbations. A local minimum that does not globally minimize energy is called a false vacuum. While locally it looks like a stable vacuum, it is unstable and will decay to the deeper, true vacuum. If the energy barrier between the false and true vacuum is high, however, then the decay rate is exponentially suppressed and the false vacuum may be very long-lived. Analogous behavior is common in other physical systems. Open a carbonated drink and the CO₂, more stable as a gas once the pressure is released, comes out as bubbles. But the bubbles take a moment to appear, and they form on the sides of the bottle rather than throughout the liquid. A bubble has to pay an energy cost to create its surface—the boundary between gas and liquid—and small bubbles have a larger surface-to-volume ratio. The energy gained by moving CO₂ into the gas grows with the bubble's volume, while the cost of its surface grows only with its area; so below a critical radius the cost wins and the bubble redissolves, and above it the gain wins and the bubble grows. Reaching that critical size takes a large enough chance fluctuation, which is why…