What 'Does the inertia of a body depend upon its energy content?' concluded — mass and energy are interchangeable

What the equivalence principle says — being in a gravitational field is locally indistinguishable from acceleration

Equivalence Principle: Gravity mimics acceleration, indistinguishable locally

What the Einstein field equations relate — the curvature of spacetime (Gμν) to the energy-momentum tensor (Tμν)

Einstein's field equations: Gμν = 8πTμν, relating spacetime curvature to energy-momentum

Why time translation symmetry gives energy conservation — if physics doesn't change with time, energy is conserved

Time translation symmetry implies unchanging physics, thus conserving energy

What the Boltzmann distribution describes — probability of a state with energy E is proportional to e^(-E/kT)

Boltzmann distribution: Probability of state E ∝ e^(-E/kT)

Why nothing with mass can reach the speed of light — the Lorentz factor γ diverges as v approaches c

As velocity v approaches c, Lorentz factor γ increases, preventing massive objects from reaching light speed

Why neutrino oscillations proved neutrinos have mass — contradicting the original Standard Model

Neutrino oscillations imply mass differences, violating Standard Model's massless neutrino assumption