1. Classical momentum is derived using this formula: p=mv. The mass of a photon is zero, so then, how can it have momentum? Does it have some other kind of momentum that differs from classical momentum? 2. Photons are particles, why then do they travel in a wave? I've heard it's because space-time is distorted in a higher spatial dimension, and light being a vibration from this higher dimension, follows a straight line in the higher dimension, but from our limited perspective, appears to be taking a path, which is not the shortest route between two points. But this doesn't make sense to me, why would a vibration, a form of harmonic motion in a higher dimension cause particles(photons) to appear? 3. Does anti-matter only explode upon contact of its matter counterpart, or upon contact with any form of ordinary matter? And why does it explode at all? For example, why would a neutron, and its anti-matter equivalent explode when they came into contact? They both carry no charge. And what exactly is the difference between a matter neutron, and an anti-matter neutron? Are they composed of different point particles, or what? 4. Why is our universe all matter, and no anti-matter? Is there some special property, or was it simply luck which caused our universe to be composed of matter? Obviously both cannot coexist, but surely it was just as probably for the universe to form from anti-matter. 5. Could someone please explain the 'spin' of subatomic particles to me? Apparently it isn't actually rotation of a particle around it's center of mass, but something different from classical rotational momentum.