Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Speed of light measured in/by a parallel frame moving at c

  1. Mar 11, 2013 #1
    Scenario:

    Alice is "sitting" on photon A
    Bob is "sitting" on photon B

    both are moving in same direction, their paths are parallel to each other.

    Per relativity the speed of light is constant

    So Alice will measure Bob's speed to be c
    and Bob will measure Alice's speed to be c

    yet they are both moving at constant velocity c

    how is this (paradox?) resolved?
     
  2. jcsd
  3. Mar 11, 2013 #2

    Doc Al

    User Avatar

    Staff: Mentor

  4. Mar 11, 2013 #3
    If Alice accelerates, trying to catch up with photon A, she finds that it still eludes her, traveling at c.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook