Physics Forums FAQ

ZapperZ

This forum contains simple responses to the most frequently-asked questions in the Physics sub-forums. It is a continually evolving thread, and more FAQ's will be added.

For more in-depth coverage of Physics FAQ's, refer to

http://math.ucr.edu/home/baez/physics/

Please PM me all questions, comments, corrections, etc.

Zz.

.

List of questions covered in this FAQ:

.

Light, Photons, and Relativity

Is light a wave or a particle?

Do Photons Move Slower in a Solid Medium?

Do photons have mass?
(Includes: But photons have energy. By E = mc², doesn't this mean that they have a mass?)

If photons don't have mass, why do their paths "bend" in a gravitational field?

I've read that in relativity the concept of the rest frame of a photon doesn't make sense. Why is that?

.

Quantum Physics (Excluding Light and Photons)

Why don't electrons crash into the nucleus in atoms?

Does the Heisenberg Uncertainty Principle imply energy nonconservation?

.

Thermodynamics

What is Heat?
(Includes definitions of internal energy, work, and heat)

.

Classical (or Newtonian) Mechanics

Why is acceleration due to gravity a constant?