A

#### adharr

##### Guest

My definition derives from the fact that within the limits of our understanding in this universe, it is impossible to achieve a temperature of absolute zero. In other words, a physical state for matter of absolutely zero energy. Expanding on that fact, this seems to apply and is true to the best of my knowledge, that there is nowhere in our universe where a temperature of absolute zero exists. Theoretically, although we can get extremely close to achieving absolute zero, we cannot get there. So, every incremental step in that direction simply leads to it being infinitely unachievable.

So, if absolute zero cannot exist within our universe, I think we can say that it could theoretically only exist OUTSIDE of our universe. Therefore, that would seem to me to imply a clearly definable "theoretical" boundary for ascribing the limits of our universe. In other words, a place beyond where any matter or energy as we know it exists.

Now, if that is the case, then just as our attempts to achieve absolute zero here on earth find the goal to be infinitely far away, then that would also seem to hold true at the boundaries of the universe. In other words, there can be no finite boundary and the universe can only be said to be infinite.

Now, if the universe can only be infinite, then it cannot be possible to determine a finite size, age or origin of the universe. After all, where do you start and where do you end? How can we define the origin as a "big bang" when we can never really establish a starting point for the oldest matter and/or energy in the universe?