Hi, Physics Forums! This is my first post here and I know just about zero physics, so I apologize in advance if the question is a little daft/naïve.(adsbygoogle = window.adsbygoogle || []).push({});

Ok, so here's what I'm wondering: suppose you have a light source that produces EM waves in all directions at some frequency ν, and a camera set up very far away to observe the frequency. If the camera is at rest, the light appears to have an incoming velocity c and frequency v, but if the camera is moving at a constant velocity towards the light source, it appears to have velocity c and the frequency is blueshifted to something greater than v. So the same number of photons pass the moving camera each second, butthey appear to have more energy.Moreover, they should actually have more momentum, and the capacity to do more work on the camera (suppose there's something like a solar sail mounted to it—then the light "pushes the moving camera harder.") How is this extra energy accounted for? I'm clearly missing something big, and it's gone right over my head.

Thanks!

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Does the energy of light depend on the observer's reference frame?

**Physics Forums | Science Articles, Homework Help, Discussion**