When an E.T race becomes capable of utilizing the amount of energy it would take to do interstellar travel in a reasonable amount of time, they can probably, ac

When an E.T race becomes capable of utilizing the amount of energy it would take to do interstellar travel in a reasonable amount of time, they can probably, accidently, or on purpose, use that energy to cause a lot of damage to a planet. For example, an interstellar traffic accident at near light speed of a sufficiently massive object would cause a lot of damage to a planet.