So, I was talking with a good friend of mine yesterday and we started to get into a conversation about God, eternity, and afterlife. As most of you know, I do not believe in any of those three things, but my friend does. Kind of. Her beliefs are kind of hard to define and hardly relevant to the point, so there is no need to discuss them here. Anyways, we were talking about this, and all of a sudden she snapped up and said, "Oh my God, eternity is impossible!" She then explained to me why, and it took a while, but I eventually figured it out. I will now attempt to convey to you what she said to me:
Basically, eternity is never-ending. Not only that, but it also has no beginning. Of course, this already makes it somewhat infeasible to the human mind, but not necessarily an impossibility. However, let us think about what eternity means on a time line. Let's say that time is represented by a line, and the moment that we are now in is represented by a point on that line. However, a point is only useful if there is something else to refernce it to. For example, another point. So, let's say we place that point 200 years away from the original point. 200 years is significant because it has both a beginning and an end, which are represented by the two points on the line. But, compared to eternity, 200 is literally zero. 200 years quite literally is zero when compared to forever. Thus, that 200 year time period could be represented by the same point on an eternal time line, which would have to mean that everything within that 200 years happened all at once in that point.
Well, since eternity goes on forever in both direction, you could take any amount of time that you wanted and say that relative to eternity, it equals zero. You could go so far out as a billion years, and that still is zero compared to eternity. Thus, if eternity exists (we were actually talking about eternity in heaven at this point, but it is applicable to any kind of eternity you could imagine), everything that ever happened within eternity would happen at once, but because eternity goes on forever, that's not possible. But neither is it possible for eternity to just keep going, because even a billion billion years happens in one instant. So basically what you end up with is everything that ever happened is happening and will happen is condensed into a single point that ends at the same time it begins, thus making eternity itself zero, but according to the very definition of eternity going on forever, it isn't possible to cram everything into one point. Thus, eternity is a paradox, making it a complete impossibility.
Now, I hope I have explained my position adequately enough that even if you do not agree with it, you at least understand it. So... discuss.