Warning: This is a very abstract question.
Can anything ever, truly last forever? They say “diamonds are forever,” but in 6 billion years when the sun goes boom, I’m betting otherwise. So, just to prevent confusion, I’m talking forever - the REAL unlimited warranty. Even the universe: can some things, or physical properties, last forever?
This one’s even more abstract. Bend your mind.
Can something never happen? Are the rules of physics so “universal” that certain things can never, ever happen?
Basically what I’m asking is: Can the mathematical properties of physics ever shift or vary over billions of years, or is the “present system” set in stone?
Can anything last forever? No.
Are there some things that can never happen? Yes. I could never grow wings and fly like a bird. I could never breathe in space or under water without special apparatus of some sort. I could never become a Bible-thumping fundamentalist. 
I have spent many an hour pondering these questions. i have reached these conclusions:
The only thing that can truly last forever is nothingness.
This thought is hard to put in words… The only event that can never happen is for everything to no longer be extant and for nothingness to become the only reality.
I find nothing, everything, forever, never, existance, and nonexistance to be amazing concepts. You can have a lot of stimulating thoughts by combining them.
Wood Thrush said:
Sorry, nope.
Elementary particles are constantly popping in and out of existence in “nothing,” which means there really is something there – which means nothingness doesn’t last forever.
so every given amount of space is always completely filled?
Not completely filled, no. But nor is it “nothingness.”
If the universe is indeed flat then it will last forever.
What’s to prevent a single hydrogen atom from existing interminably in the depths of intergalactic space?
Dick Clark is clearly an indestructible immortal.
In a very technical sense, everything lasts forever- matter cannot be destroyed…well, I suppose were one to get some anti matter and pure energy…
Here’s my dumb ass rich white suburban kid response: What are the practical applications of this question?
More importantly, if my head explodes while I ponder these questions, will anyone care? Will SDMB pay a bereavment fare?
so if its not completely filled there are empty spaces that can be considered nothingness? are the spaces infinitesimal or something?
OK, here goes.
As far as anyone knows, energy cannot be created or destroyed - the famous conservation of energy. It can, however, change from energy to matter and back. That’s where you get the particles appearing out of nothing in empty space.
Is empty space really empty? Well, depends on how you look at it. Even if you found a chunck with no matter in it at all, you would still be able to measure electrical and magnetic fields. Do those count? I dunno. But you could zoom in and say that those fields are due to tiny massless particles flying around, and the space in between them in empty. One problem with this is that particles of this size are equally as well represented by waves, which screws things up. Another is that Heisenberg’s uncertainty principle means that we can never pin down exactly where they are, making it hard to find where they aren’t.
There’s also gravity to deal with. Again, you would be able to measure a gravitational field in “empty” space. And so far, science has been unable to find the particle that transmits it. That doesn’t mean it’s not there, though. They’re still looking hard. But that messes things up, too.
Hope that made some sort of sense.
Would anyone disagree that change is forever?
And what is outside of the universe? Is it empty space? As I understand, there is no “outside” the universe, unless there is another one. Outside the universe, is not nothing–there isn’t even that. You could think of the universe as existing in a giant box and wonder what was outside the universe. As it turns out, though, the universe is the box and there is no “outside” to be empty.
As for forever, what I got out of reading Hawking was that time cannot exist outside of change. If the universe fizzles and everything goes cold–total entropy–then, eventually, there is no further change. At this point, forever becomes a meaningless concept as there is no time without some sort or change to measure it by. It’s sort of like that nonexistent place outside the box.
On the other hand, all I can say for sure is that it gives me a massive headache.
-VM
btw, Slythe, as I understand it, the answer to this is the reason why scientists are so interested in whether the universe will eventually collapse. If not, then eventually there will be no further change and time will cease to have meaning.
-VM
But if entropy is indeed a basic law in the universe, perhaps when pure nothingness is finally achieved(in effect stopping entropy), another “big bang” is created to continue the process. From what little we know, nothingness existed before, and that didn’t last, did it? 
slythe:
If the universe does not collapse, I wasn’t referring to a state of complete emptiness. IIRC, there is a lot of nothing, evenly dispersed with low-level radiation. As no more “complicated” states exist, it is no longer possible for things to change by increasing entropy. Therefore, no change occurs. Without the changes that are a result of increasing entropy, time is no longer a meaningful concept.
However, if it shrinks back, it could collapse into a new egg and have another big bang and start all over. It could have been doing this forever. It could continue doing this forever.
How did it get started, in either scenario? I didn’t understand that part at all. (I understood all the words…)
-VM