Casimir's Effect

The dynamic Casimir effect arises when a mirror or boundary accelerates at relativistic speeds, causing quantum vacuum fluctuations—normally virtual particles—to convert into real photons.

This phenomenon stems from rapid changes in the electromagnetic field boundary conditions, which alter the mode structure of the vacuum and “squeeze” the zero-point energy, effectively pulling energy out of the vacuum itself.

For instance, in superconducting circuits simulating rapidly oscillating mirrors, modulating the boundary at GHz frequencies leads to detectable microwave photons.

The effect is deeply rooted in quantum field theory, where the vacuum is not empty but teeming with transient particle-antiparticle pairs, and motion changes the field’s Hamiltonian fast enough to generate real radiation from these fluctuations, respecting conservation laws via energy input from the mirror's motion.