I will adapt the Goldstone theorem to spontaneously broken boosts, and show that, while still predicting gapless Goldstone states, it is quite forgiving regarding the nature of such states. In particular, I will show that while for solids and superfluids the role of the boost Goldstone states is played by phonon single-particle states, for a Fermi liquid such a role is played by the particle-hole continuum, that is, by two-particle states.