QUOTE (stranger@mirror @ Jul 21 2008, 12:42 PM)

Exactly. If there was no time "before" the big bang, then i think its clear that nothing can be "before" that as there isn't any before if there is no concept of time.
But i still can't understand it...how can there be a situation/place where there is no time?? How exactly..?? Can't even think it properly..having a headache properly...just imagine a place/situation where there is no concept of time. How exactly is it possible?? Time has to exist...or i ...its not possible there to be no time...its all so confusing...
Thats why it is always said that Time is the most complicated thing ever...
Time is part of the universe; its part of spacetime. No universe = no time. The thing to realize is that there was never a time when there was no time. The universe has existed for all time because time is the universe. The concept that the universe didn't exist, was created, then existed is a meaningless concept because those are time relationships.
You can consider the universe to be 4D (at least) object that either exists or doesn't exist. Time and our perception of flowing time, past, present, and future is simply how we (as part of the universe) perceive relationships in spacetime with other parts of the universe. The same is true of 'space'.
However, the big bang isn't necessarily the 'start' of time ('start' is actually incorrect, but I'll use it for now for simplicity). Its possible that the big bang is simply another event in a bigger universe (multiverse) or that the universe expands / contracts and there *could* be a time before the big bang.
But for arguments sake, let's say the big bang is the 'start' of it all. The thing about the big bang is that the big bang is simply a 'perceived' start point. Spacetime has no start point, its just a series of 4D (at least) relationships. The big bang is a convergence of those spacetime relationships. We perceive it as a start point because our memories are governed by causality and the big bang is where every event in the universe relates to every other event. In all likelyhood, if we could truly understand all the physics and go beyond our inate bias on the nature of space/time, we'd see that at the big bang, every spacetime event converges to a single event. Space and time would lose their seperate meaning and it would make perfect sense that there is no time before the big bang. It'd be no different than understanding that there is no north of the north pole.
Its helps if you try to envision the universe as spacetime, and not a big chunk of expanding matter.
A concept of string theory or quantum gravity (or whatever particular theory that is trying to describe the nature of existence), is that 'nothing' truly exists except relationships. Matter and energy are illusions. Both are simply relationships in spacetime. Your desk is just a bunch of molecules. Those molecules are just atoms. Those atoms are just protons and neutrons. Those protons and neutrons are just quarks. The quarks are just collection 'strings' or whatever unit you chose to describe them in. There is no base 'solid' unit of matter. There is not packet of glowing energy. The strings of string theory is just a unit of information that describes a relationship with another unit (they're called strings simply because its a handy way to understand the relationships, you could equally call it the 'apple' theory with a few tweaks). Create a big enough network of these relationships and you weave spacetime, and all the larger-order relationships that we perceive as matter, energy, space, and the flow time.
edit: all sorts of typos.