Eli5: If a laser is shined into space will it continue to infinity (if it doesn’t hit a solid object)?

Question

Seems like a gargantuan, if not infinite amount of energy would be required for this to occur

In: 10

Answer 1

A laser beam consist of photons. Space is almost empty but not completely empty. There are a few atoms per cubic meter in interstellar and intergalactic space. So your beam gets eroded when your photons collide with some atoms. Eventually photon count on your beam reaches to zero and you have no longer have a laser beam.