Can we make sense of dissipation without causality?

Understand

Relativity opens the door to a counter-intuitive fact: a state can be stable to perturbations in one frame of reference, and unstable in another one.

• For this reason, the job of testing the stability of states that are not Lorentz-invariant can be very cumbersome.
• We show that two observers can disagree on whether a state is stable or unstable only if the perturbations can exit the light-cone.
• Furthermore, we show that, if a perturbation exits the light-cone, and its intensity changes with time, due to dissipation, then there are always two observers that disagree on the stability of the state.