I am trying to understand in non-mathematical terms the meaning and physical reality posed by Einstein’s law which tells us that the speed of light is the same relative to all observers.(adsbygoogle = window.adsbygoogle || []).push({});

I start with a basic hypothetical: Observer A observes B riding a motorcycle that is traveling at 50 mph past A. There is a brick wall located X number of feet in front of B. B throws a ball in the same direction he and his bike are traveling. We know that by adding the velocities of B and the ball, the ball is traveling at 60 mph relative to A. We also know that A and B will mutually agree that the ball hit the brick wall before B and his bike did.

Assume that A observes B straddling a beam of light. I assume it is correct to say that A is observing B to be traveling at the speed of light. Now, let’s assume that B, while riding on his motorcycle which is itself traveling at the speed of light, takes out a flashlight and aims a beam of light in the same direction he and his bike are traveling.

Question 1: Is it correct to conclude that B is observing the beam moving away from him at the speed of light? If not, then what is B actually observing about the beam of the flashlight? Will he beam from his flashlight enable B to see any objects in front of him?

Question 2. Will B observe the beam from his flashlight hit the brick wall before he and his bike hits the wall? If yes, how is that possible since B ability to make such an observation would mean that the flashlight beam is traveling faster than he and his bike are.

Question 3: What is A seeing? Stated differently, will A see the beam of the flashlight hit the brick wall before B and his bike hits the wall? Or will A see B, the bike and the beam of the flashlight hit the wall at precisely the same time?

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# Who hits the wall first: the light beam or light traveller?

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