Comment on “the ultimate limits of the relativistic rocket equation. The Planck photon rocket”

Abstract

We disprove the claim that was published in a recent paper [1] about an absolute maximum velocity related to the value of the Planck mass for a photon-propelled rocket in vacuum. This claim is based on incorrect hypotheses and is incompatible with the theory of relativity. We also review the relative bound that can actually be derived for the velocity of such an ideal rocket, as measured in the inertial frame in which it was at rest at a given initial time