Tag: quantum-field-theory

Why is the gravitating vacuum energy ~10^120 times smaller than QFT predicts? (The cosmological constant problem)

The problem In general relativity, vacuum energy gravitates like a cosmological constant: a Lorentz-invariant vacuum has $\langle T_{\mu\nu}\rangle = -\rho_{\rm vac}\, g_{\mu\nu}$, contributing to the effective … Observations (CMB,…