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Physics, Astronomy & Cosmology / Re: Light's interaction with matter

« on: 01/10/2005 17:49:11 »

Is it important to remember that a photon doesn't experience time according to relativity, or does one dismiss relativity whilst thinking in QM terms?  

A photon does have mass, just no rest mass.

For any other object, its kinetic energy is a function of its rest mass, yet a photon has no rest mass.  It is precisely for this reason that nothing other than a photon can reach light speed.

As a massive body approaches light speed, more and more of its net mass is made of Kinetic Energy, analogous to photonic mass.

Sorry, just thinking aloud:)

42

Physics, Astronomy & Cosmology / Is Relativity Wrong?

« on: 01/10/2005 15:23:15 »

I think the generally accepted interpretation of relativity says that when you go faster your time slows down.  So, for example, the astronauts who went to the moon and back are slightly younger than other peeps who were born at the same time but stayed on Earth.

I was thinking, if a ship and some light left a planet then the ship came back, having aged less than the people on the planet, wouldn't the distance the light had travelled have to be different as well?  Either that or it would have to have travelled at a different velocity for those on the planet and those on the ship, right?

Am I making some kind of basic error here?