Quote:
Originally Posted by JustAsking  David,
The question used to be answered by looking at the total mass of the universe and the velocity of deep space objects. Knowing those things, you can determine whether things are moving at below or above escape velocity. If they are above escape velocity, then the universe would expand forever. If they are below escape velocity, they will eventually slow down to a stop and then fall back towards the center of mass of the universe.
But since that time (the 1970s), there is more evidence that the universe is far more massive than what you get when you add up all the apparent observable mass. The extra unassigned mass is attributed to something called Dark Matter. It is a hot topic in astrophysics right now.
I think at the moment, the question is unanswerable. Your working premise that the chain of causation is infinite and matter can't be created or destroyed is interesting, but I don't think that accounts for "leaks" of energy into or out of the universe. I would have to say that your premise can only be speculative. But it is surely an interesting question. |
That's why I try not to think about it much. I've read that if the universe continues to expand, everything will freeze. Obviously not likely to happen in our lifetimes but not a pleasant thought in general. "The Big Freeze" is what they're calling it, I believe. Aptly named. The only real way to answer the question is to learn what's beyond the expanding blackness. Cosmic radiation is evidence the universe is expanding, which suggests it's expanding into an already existent space. What lies in this space? Is it the source of the dark matter? etc etc.
Personally, I'm of the belief the universe has experienced multiple bangs throughout it's existence. Hah am I speaking about the universe as if it was alive? Perhaps. The current state of things is the result of one bang but whatever existed before was the result of another bang. I think eventually, the universe reaches a point in which everything stops expanding and starts to implode instead. Once the implosion is complete, another Big Bang occurs and the whole mess starts over. In this way, matter isn't being spontaneously created (through the bang) or destroyed but rather compressed and then exploded outward. Like a rubber band that keeps stretching to it's maximum distance and then shooting back inwards when it reaches that point. A perpetual rubber band, as it were. I'm not a physicist, just a theorist. Take my wacky ideas with a grain of salt...and a shot of tequila. No need to waste good salt.