What if light had a rest mass?

How different would the universe be if light had a mass?
would some physical laws be changed?
and how would man be living differently if life was still possible

>>1
How much mass?

>>2
10^-inf

>>1
I don't know about the physical implications of it; you'd have to ask a particle physicist. But from my limited knowledge of cosmology, massive light would drastically change the critical balance of mass during nucleosynthesis, causing very different ratios of hydrogen, helium and deuterium in the universe. So the universe would be a radically different place, even if the physical laws weren't all that different.

Of course if this mass were small enough, it would have very little noticeable effect, just as massive neutrinos have very little noticeable effect (until you start looking at huge cosmological structures like galaxies, dark matter etc).

Hypothetically, the speed light of light through a vacuum would be slower and cease to be constant.  Not to say that the mathematical constant 'c' would necessarily change; light would simply no longer travel at it.  I also imagine it would lose all wave characteristics (diffraction, interference) and behave more like a "pure" particle.

>>5
No, if the mass small enough it would not lose it's wave characteristics, see wave-particle duality.

And besides, if light had enough mass to lose all wave characteristics, the radiation would likely kill us.

>>6 And by all wave characteristics, I mean most wave characteristics.

>>7 And by that, I mean it usually behaves more like a particle than a wave...hell, I am confusing myself.

>>5
I also imagine it would lose all wave characteristics (diffraction, interference) and behave more like a "pure" particle.
Fail. They've actually observed the exact same kind of diffraction and interference patterns with electrons. Ever heard of de Brogli? He proposed that over 80 years ago.

>>8 And by that, I mean I suck cocks.

slow light is slow

I feel the need, the need for weed!

Marijuana MUST be legalized.