I know I’m a dumass but… Ok, is the universe still considered by physics to heading towards temperature equilibrium? Wouldn’t this imply a finite quantity of energy in the universe?
If the universe is infinite, can the amount of energy it contains be finite?
If the energy is not finite, how did one occurrence, the Big Bang, produce an infinite amount of energy?
Are these even valid questions to ask of physics?
Anyone wanna help a junior high drop-out think above his level? I ain’t so good with equations, but metaphor and similies I can handle if ya dont mind.
Yes, the Universe’s energy supply is finite. Yes, we are heading for temperature equalibrium (what physicists call the ‘heat death’ of the Universe). Is the Universe finite? Probably. But it might not be finite in three dimensions. Think of it this way: Imagine an ant or flea living on a slowly expanding balloon. The ant can only see or imagine two dimensions: Forwards and backwards, plus left and right. The insect knows that its universe is expanding. Its walk to work is getting longer every day. But expanding how it cannot imagine. The balloon is expanding into the third dimension, which the insect cannot even think of. The ant knows that it can walk completely around its universe without falling off or hitting a wall. But its universe is finite, because the balloon only has a finite volume and finite amount of rubber. You would find a wall if you were a fly and you hit the balloon.
Okay, let’s tie this in to the real world. This Universe probably exists in more than three spatial dimensions, just like the ant’s balloon exists in more than two spatial dimensions. It has no edges in the three dimensions we live, like the ant’s balloon has no edges in the two dimensions the ant knows. And it is expanding into the other dimensions we, as three-dimensional beings, cannot directly know of, like the ant’s balloon expanding into the thrid dimension. We could send up a space craft, wait a few trillion years, and it might come around here again, having taken the long way around. We are currently studying these questions with the information we get from satellites like the MAP (Magnetic Anisotropy Probe).
That is a religious belief, not a fact. It all depends on which cosmology you believe in. The Steady State cosmology still has its proponents (including me) and in this system, the Universe’s energy supply is constantly increasing.
Chas, I do not hold any beliefs. What I think of as fact I can support by finding evidence. There is plenty of evidence, in fact, that the Universe is expanding and that there is no magic matter-making machine in the center, preventing the mass-energy of the Universe from reaching equalibrium. Do not accuse me of religion and I will not accuse you of idiocy.
Would you mind citing the theory, or theories, from which you draw these conclusions? While, as I implied earlier, my math is weak, I am a guy who, as a kid, stuck my tongue to cold metal on more than one winter day. I carry that tenacity (idiocy?) still, and like to get as deep as I can into things which fascinate me.
I have to say this sounds like you’re telling me that it’s turtles all the way up, as well as all the way down.
I’m not saying that there are any turtles. I’m saying that we, as three-dimensional beings, cannot directly percieve the whole Universe. We cannot ‘step outside’ it and view it growing directly. We see redshift, however, and we see that things in all directions are redshifted equally. So we conclude that we are like a raisin in a loaf of raisin bread that is rising: Distant galaxies are raisins, and all the raisins are moving away from each other as the bread expands (visualize for a second and you’ll get my meaning). So we hold the theory that the Universe is expanding. Of course, we would not hold that theory if it wasn’t supported. We end up like the ant: We can meaningfully say that the Universe is expanding and we can point to evidence that supports that statment and measure the expansion, but we cannot directly see enough of our Universe to actually see it happening.
Is the Universe a closed system, G? Or is it infinite? Can an infinite system be closed? (I know my mind can be closed, it often is – which is how I know it’s not infinite.)
the universe is etimated to be about 12 billion years old, and to have originated from a “big bang”. If this is true, the universe must be finite. Otherwise, at what moment in time after originating from a single point, did it turn into something infinite?
Sorry pal, your BELIEF is religious in nature, you are taking it on faith. You have evidence, but no proof. There are just as many holes in the Big Bang theory as Steady State (or variants like QSSC) and neither system is conclusively proven or disproven.
Ever since the discovery of the cosmic background radiation, physicists have been trumpeting the “proof” of the Big Bang, but all they have proven is that the cosmic background radiation exists. Current SS theories can easily account for this. The only “fact” is that the background radiation exists, all else is interpretation of facts. And nothing changes quite so rapidly as our interpretation of “facts.”
You imagine SS to involve some “magic matter-making machine in the center” but please tell me, where is the center of the universe? That’s another cosmological assumption you’re making, depending on your view of the topology of the universe. Current SS theories I’ve read propose energy being constantly created in infinitesimal amounts, at widely spread points throughout the entire universe, at the quantum level. This easily accounts for the expanding universe, since matter is “injected” into space at essentially EVERY point in the universe. A steady state universe can be unbounded and expanding.
Yes, this is a religious debate, not a physics debate. Even Einstein resorted to religious metaphors when describing cosmology. And the SS vs. BB problem is the longest-standing religious debate in the physics world. Perhaps you should reject Physics dogma with all the fervency that you reject religious dogma.
Things get screwy with infinities, but if the universe is “closed” (i.e., finite - - note this cosmological topology is a different kind of “closed” than a thermodynamically “closed system” - - just an unfortunately similarity of words that can be confusing), then energy would be finite. If the universe is “open” or “flat” (which it seems to be), then energy may be infinite, but since an open/flat (infinite) universe is infinite in extent, it’s an infinity spread out over a larger infinity. Or something like that that makes my head spin. Overall, the energy available at a particular point in space is far from being infinite, so eventually, as space expands, and time proceeds, the universe will run down to a heat death.
Derlith’s explanations are also good. The concepts of infinity, like I said are kind of screwy and still being researched. Although I’d note that there currently is no evidence for other dimensions within which our 3D space is expanding. I see the expansion & curvature of space as more of a characteristic of space within the context of the 4th dimension of time. No time, no expansion/curvature of space. Without one, there is no other.
I disagree. Acceptance of the leading theory in the scientific community is not an act of faith. With faith, you do not question. With a scientific theory, you constantly question it and try to improve it with obtaining better evidence. With faith, you believe despite the evidence. Whereas you accept or reject a scientific theory based on the evidence. The vast majority of the scientific community accepts the Big Bang Theory. Theories do not provide Truth, only explanations. 100% proof may not be obtainable.
There are far fewer proponents for SS than for BB. Not that the majority is always right, but the evidence for BB seems to strongly outweigh the evidence for SS.
A finite lifecycles of stars (born-live-die). Dwindling supply of fuel (more hydrogen & helium get used up with each new generation of stars) means that fewer stars will be born. Space keeps expanding & spreading/diluting everything out. And after a mind-boggling amount of time, black holes evaporate, atoms fall apart, etc. There’s obviously more to it, but I hope this helps a little.
The universe is a thermodynamically closed system. It receives no input from “outside”. In fact, as far as is known, there is no “outside”. You may also consider it a closed system by definition…since the universe is defined as containing everything that exists.
Untrue. SS has more holes in it, if it didn’t it would have more acceptance in the scientific community.
There is more evidence for BB than just the cosmic background radiation. Expansion of space, abundance of elements, etc.
This just sounds like the cosmological constant. What type of “energy” is being “injected” and from where? Energy is not a specific thing. And there is certainly no evidence for any kind of metauniverse. SS does have an appealing aspect in that the universe wouldn’t have such a bleak end to it.
Immediately. Right after Time=0 (the single point when such a question has no meaning), the universe started out as infinite (boundless). Consider the balloon analogy. At first, it’s a point. Then it’s a teeny tiny balloon…but if you were on the surface of it, you could walk around it forever and never reach an end.
Sorry for the brief responses, but there’s a lot to talk/think about here. I guess I’ll stop here & see what other responses there are. There probably have been a few in the time that I’ve been typing this! *
As far as the Cosmic Microwave Background goes, the difference between BB ans SS cosmology is that Big Bang cosmology predicted the CMB, whereas SS only explained it. That it to say, the Big Bang theory in its simplest form predicted that the CMB would be detected, before it was actually detected. The Steady State theory did not predict it, so when it was discovered, the theory had to be modified to accomodate it. Now, all theories are modified to fit observations, but a theory cannot be considered to be tested until it makes an accurate predicition. The Steady State model has not done this, whereas the big Bang model has done it time and again.
According to currently-accepted models, if the Universe is infinite, then it has an infinite amount of energy, but only a finite amount of that is available to any given point. If the Universe is finite, then the energy it contains is finite.
thanks a lot for taking the time to explain all that Phobos!
I’m still not clear on the whole “infinite universe” thing. You said that right after the beginning, the universe became infinite in size because you could walk around it and never reach an end. Isn’t this just like painting a circle on the ground and following the line. There’s no end, but it’s not something that’s considered infinite. I read that in the first minute of inflation, the universe’s size increased by a magnitude of 10(60). This would indicate finite size would it not? I mean 10(60) times something finite, is some much larger, but finite number. 10(60) times infinity is just infinity.
You may be able to walk around a balloon forever, but there’s definately a difference between a ballooon with just a little air, and one that’s fully inflated.
