If you seriously want to get a layman's targeted definition of special relativity, read "Why does E=MC²?, (And why should we care?)" by Brian Cox and Jeff Forshaw. It'll change your life.

Gauge symmetry confuses me. Just can't grasp it for some reason.

>> ^eRadthorpe:

If this is so then why is glasses opacity different from alternate angles?


I think because the surface of the glass comes into play then causeing refraction/reflection etc. If you ignored the polished surface, the inside of the glass wouldn't change in opacity.