-1

First off I am not a physicist and I do not know how to do the math involved. But I like knowing what the math means.

The speed of light is constant in a vacuum regardless of the motion of the observer or the light source. I find this very confusing. Does this mean that say hypothetically someone is moving at 99% the speed of light and they turn on a flashlight while at the exact some time someone else is moving at say 1% the speed of light turns on a flashlight then 8 seconds later the distance the light travels from both people is measured would that distance be the same?

Thomas
  • 7
  • 2

1 Answers1

0

Does this mean that say hypothetically someone is moving at 99% the speed of light and they turn on a flashlight while at the exact some time someone else is moving at say 1% the speed of light turns on a flashlight then 8 seconds later the distance the light travels from both people is measured would that distance be the same?

Independently, both of these observers measure lightspeed to be $c$ exactly (assuming flat spacetime). So in their own frames, they both measure their own light to have travelled the same distance away from themselves. If they took this measurement and then met up, they'd have the same number.

What they wouldn't agree on is the time for which the other person's light has been travelling. Their coordinate systems are not the same and as such person A will see person B turning off their light after a period of time that is not 8 seconds, and vice versa; since person A still sees the light travelling at $c$, person A will say that person B's light has travelled a different distance, and vice versa.

controlgroup
  • 8,801