No it can't be infinitely old if it began with a big bang.http://cmb.physics.wisc.edu/tutorial/bigbang.html

The answer has to be yes, because if a Big Bang took place,something had to be there in order to create the explosion. It is eternity...something way beyond our heads....

Something must have existed before the big bang, but that something is not our universe. Our universe contains just that space and time in which we exist. It does not contain anything that may be outside of these four dimensions with which we are familiar (various grand unification theories not withstanding). So, before the big bang, nothing in our universe existed, no space, no time, no mass, no energy, nothing. As I said there may have been something out side of what became our universe out of which our universe formed. However our understanding of physics does not really allow to see what that something was because it is not part of our universe. So, based on the big bang theory, estimates place the universe at about 14 billion years old.

No, No, And Maybe. In that order... The answer for the conventional Big Bang picture is No. The standard Big Bang theory has spacetime appearing spontaneously from nowhere, and growing from there. There is nothing before the big bang. ... er, no, I'll rephrase that... There isn't even *nothing* before the big bang. How can that be? Here's an analogy: Imagine we were one dimensional beings, living in one-dimensional space. Imagine that one dimensional space is really a horizontal circle lying on the surface a sphere like a line of latitude. Imagine that increasing time corresponds to a decrease in the height of the circle - like stretching the the circle down over the sphere. The latitude decreasing towards the equator. Start at the top of the sphere. The space and time of the one dimensional circle universe is created simultaneously and the space suddenly expands (at the north pole of the sphere) and continues to expand as the latitude approaches the equator, just like the old fashioned conventional Big Bang. But what's outside this "sphere". You noticed there are possible heights higher than the top of the sphere, and space inside and outside the sphere. My "circle universe" appears to have an "outside", and time coordinates before the beginning of the "big bang" seem to make sense in my "circle universe". But only because I "embedded" it in our 3D space in order that we could visualize it. Mathematically the structure itself need not have an outside at all, it might be all there is, with no "outside" other than the one I made up. The modern inflation theory started as an extra big expansion part (inflation) inserted at the beginning of the conventional Big Bang. For this theory the answer is No too. The circle universe picture is not very different. But some theorists belive that since we can only so far deduce what happens from the end of inflation, and as far as we know the universe is infinite, it could have been expanding for ever as far as we know before that. Hence: Maybe.

Of course not. If the universe were infinitely old, then how could it ever be "created" with a big bang? It simply would have always existed.

I've heard that there were big bangs throughout time. The universe keeps expanding and contracting.