well first of all, nobody can claim we know for sure that there CAN'T not be a beginning. every single thing in our world, including ourselves, has had a beginning and we therfor would not be able to comprehend otherwise.


anyway, quantum mechanics has some great theories on this. if you really understand the nature of reality it begins to make more sense. all mater is made of atoms, all atoms are made of subatomic particles, those particles are made of pure energy, and the line between that pure energy and utter non-existence is a very fine one. a big reason this all becomes so confusing is because our brains distinguish so clearly between existence and non existence, when in reality neither are one in it's own.

on an interesting note, quantum physics have actually been found as a more scientific means of explaning what the Buddha was trying to tell us.