To you. There is no such thing as absolute speed. You say cosmic rays are crashing into the earth at 99% the speed of light. The cosmic ray says it is sitting still and you (and the Earth) are approaching it at 99% the speed of light. Some other particle moving at 70% relative to you will give a different speed for the cosmic ray. All of you are right.
To you. There is no such thing as absolute speed. You say cosmic rays are crashing into the earth at 99% the speed of light. The cosmic ray says it is sitting still and you (and the Earth) are approaching it at 99% the speed of light. Some other particle moving at 70% relative to you will give a different speed for the cosmic ray. All of you are right.