I just realised that because of the conservation of energy law (energy cannot be created or destroyed), the cooling of the universe must translate into something.
When things in our day to day life go through the process of cooling, it’s different. In those cases the heat energy is passed from one place to the next.
Matter is energy, and energy is matter. The universe is all that is, and all places that are. Because the universe is the “mother” system, energy cannot be passed to “another place”. Because of this, the very fact that the universe is cooling would have to lead to the spontaneous creation of matter in some way, because the energy has nowhere else to go.
(I may be missing something here. If so please correct me :))
Personally my mind can’t grasp the whole “edge of the universe” thing.
I can understand that the universe is only as big as X at this exact moment. And then in another moment, it will be x+1 and on and on.
Until we reach that point in time where we find out if the Universe expands forever and eventually just becomes dead and lifeless islands of mass, or it starts contracting and folds back up on itself.
If it does fold back up on it’s self, I would guess that you would see the temperature start to rise again.
But my mental image of all that happening sort of pre-supposes that it happens WITHIN some huge void that exists either independently of our universe, or as something that our universe is just a part of.
You had it right up until this statment. There no reason to suppose that the universe is contained in a higher dimensional space, except to aid visualization. The higher dimensional space has no real existance.
Ummm, no. . . However, there is no reason to suppose it exists. While we cannot prove that sumething that has no effect on the universe has no existence, such things are not the relm of science. Science is only concerned with that which can be observed in some fashion. Since we are contained in this space, we can’t even look outside it and unless there is some supposed way in which the higher space affects us, we can say as far as science is concerned, it does not exist.
And if the universe is going to expand forever, hopefully it will bounce off the walls and contract when it gets to the edge of the big place we are in.
Seriously though…
It seems to me that we have to be SOMEWHERE. If you could fly out to the farthest edges of the galaxy, what defines the actual edge? Since there is a void in front of you, and a void behind you, what’s the difference?
It seems to me that the mass in the universe is a seperate thing than the actual space in the universe.
Yes by the basic definition of the universe this can’t be true. The universe is the sum of all energy and mass so if there were something out side of the known universe then is would in essence still be the universe.
I’m going to assume you meant universe when you said galaxy. (Please correct me if I’m wrong here.) You cannot reach the edge of the universe, there is no edge. The universe is either finite or infinite. If it is infinite, then it certainly has no edge. If finite, it curves back on itself.
Empty space has extent that can potentially be measured and so yes empty space has volume. If you mean can there be a universe without mass or energy, then no. A totally empty universe would have no way of measuring extent or time. We can only measure distance or time by observing something. If there is no mass-energy, there can be no clocks or rulers. Time (or distance) is an interval between two events. How could you even distinguish two events in an empty void?
The circle is a line that curves back on itself as the surface of a sphere is a plane that curves back on itself. A model for a finite closed universe is the surface of a hyper-sphere. Why do I get the feeling we’ve just come full circle?
Yeah. . . There is only one universe by definition.
The problem is, I can envision a line going perpendicular to the circle or the sphere.
What the heck is a hyper-sphere?
…and…
As you get to the edge of the universe, does time slow so that you can not expand faster than the universe? (with the understanding that you are part of the universe)
I don’t see why there is only one universe by definition. The definitions I’ve seen don’t exclude multiple or parallel universes. Webster’s defin: “U"ni*verse n. [L. universum, from universus universal; unus one + vertere, versum, to turn, that is, turned into one, combined into one whole; cf. F. univers. See One, and Verse.] All created things viewed as constituting one system or whole; the whole body of things, or of phenomena; the mundus of the Latins; the world; creation.”
So where in that defn is more than one system precluded? Or more than one “world”?
From what I’ve read the forces of nature become simplified in higher dimensions. Gravity becomes space-time in four, light is vibrations in the fifth, and at the higher dimensions the other forces become the same force. The whole idea behind superstring theory, no?
Are you suggesting that four is enough, or that the models which successfully unify forces via higher dimensions are just mathematical “tricks”?
You know much of these things, just wondering your opinion. I agree that they are not testable…yet.
