 |
 |
Gravity and Photons
Name: Unknown
Status: N/A
Age: N/A
Location: N/A
Country: N/A
Date: Around 1993
Question:
When gravity acts to bend light, is it because a photon does have
mass when it has velocity, or does gravity act on the energy of the photon,
which I understand has no rest mass?
Replies:
Well, gravity acts on everything since it really acts on space
itself! Yes, a photon has no rest mass, and that means that it is always
traveling at the speed of light. The energy of a photon is actually
proportional to its frequency, y, which does not really have much to do with
the way gravity acts on it. However, since bending involves a change of
momentum, the force that gravity exerts on the photon is proportional to its
momentum (which is in turn proportional to its energy). And in fact, it is
generally the total energy (rest energy plus kinetic energy etc.) that is
important for gravity, whether the particle in question has a rest mass or
not.
Arthur Smith
Click here to return to the Physics Archives
| |
Update: June 2012
|
|
