I was merely informing you all of what conclusion I have reached based on my logic. It is quite possible that I am completely wrong.
I hope you’ll excuse my last post. I quoted the wrong post. I meant to quote the one just above it.
I don’t think of the universe as a thing that has a beginning or ending. I think of it as this place full of things that have a beginning and ending. Look at your computer. It did not always sit where it is now, but the place where it sits existed before before the computer was there, and it will be there after the computer is gone.
The universe(aka all the space there is) sometimes has a bunch of stuff in it, and sometimes it has a lot of energy in it, sometimes there is a mix of stuff and energy. But the space where all this happens will always exist.
The hole is always there, whether the donut is there or not.
We’re going on logical proofs and metaphors here. Can’t we jsut admit that without an experiment (with a control universe) to observe, no one really has a clue if/whythe universe began?
Err…no, not exactly. First, there has to be some sort of electromagnetic radiation and there has to be some potential well. (In plainspeak: there has to be a source of energy and something to motivate the energy to change states.) Then, the phenomena of pair production occurs with the EM radiation converting into a matter/anitmatter pair.
Something else:
Albert Einstein and his Special Relativity threw the “arrow of time” concept out the window. By General Relativity, space-time itself is not rigid but malleable.
Yes, I’m a physics person. I’ll go hide my head now.
nahtanoj
nahtanoj wrote:
However, there is still the notion of irreversible changes, i.e. the total Entropy of a closed system (such as the universe) can never decrease but will often increase. Hawking still uses the term “arrow of time” in this sense.
Now we’re back to a question I asked earlier. Why wouldn’t an infinitely old universe have a uniform temperature?
I dunno Lib… Would an infinitely old ocean have a uniform temperature? Don’t stars and other sources of heat account for local variations in temperature?
Yes, tulley, but stars eventually burn out. Even their stellar “corpses” eventually lose energy.
My point:
- There is a finite amount of energy in the Universe.
- Energy is always moving from places of high energy to places of low energy.
- Given an infinite amount of time, the Universe will reach equilibrium.
This means that either the Universe is not infinitely old, or that there’s some process or something that can keep the energy density unbalanced throughout all time.
I would agree. I would concern my argument with the things currently within the emptiness.
The question regards the universe as a closed system. There are no other sources of heat.
Libertarian:
I’ve been thinking about this since you first posted it above.
OK, if we posit that the universe has been here forever, it would indeed seem to follow that it would have entropy’d down to uniform temp.
OTOH, if we posit that the universe has not been here forever, we need to explain the origins of the finite universe and its temperature differentials. The chain of prior causation leads to recursive questions about what caused the causal situation to exist, and so on, until we either posit a non-caused event such as the Big Bang’s singularity (massive quantum vaccuum fluctuation or items such that the term “before” has no meaning, whatever, an end to the ability to say “but what caused THAT?”). Which is fine as far as it goes, but having obtained such an answer with regards to the universe of finite duration, mightn’t we borrow such an answer and apply it or a similar / parallel answer to the hypothetical universe that has been here forever? e.g.,
a) The infinitely old universe does not currently have the appearance of a uniform surface temperature because of the ongoing status of large events that tend to occur as spontaneous fluctuations, and while the net sum is zero the local attribute of space-time is somewhat otherwise;
or
b) The infinitely old universe does not currently have a uniform surface temperature because it is in an ongoing state of coming into existence, i.e., in the larger sense of the word it is constantly and continuously the immediate after-splitsecond of a virtual singularity not truly intersected by time itself (because of Hawking time curvature). Just as there was no actual “Big Bang” singularity, there is also no origin in time or space from which it can be said to be “coming” – it has always been here and it has always maintained a temperature differential which has always been subject to entropy which will always be approaching but will never attain a temp diff of 0.
(or something like that).
I agree with the previous post by AHunter3 to a great extent, but it could be argued that actually both (a) and (b) case are really one in the same.
We should also be very careful about what we define as the universe. Practically, the universe is anything that is observable. However, there are generally a nontrivial number of philosophers and others who will argue that the universe is something more than that. Sure, we can speculate on embeddings and what’s beyond event horizons, but that doesn’t really get us anywhere other than massive head-trip headaches.
If we take the observable universe, it is very easy to conceive of a scenario of infinite existence with cyclic assymetries popping up at different periods of time. Being infinite says nothing about the actual character of the universe.
Indeed, entropy can increase in strange ways given an infinite amount of time. Thermodynamics is not the be-all and end-all of existence… especially when considering how in the hell it is able to be talked about in any Grand Unified Theory sense.
There is another thread concerning this topic in GQ. Basically, what I said in there was that the very sentence “beginning of the universe” is meaningless
Hunter
Does what you’re saying boil down to an assertion that the universe is not a closed system? If so, what evidence exists?
Shalmanese
From that thread:
Inasmuch as time is one of the universe’s coordinate dimensions, if there was no time before the Big Bang (assuming there was a Big Bang), then there was no space either, and the Big Bang is the beginning of the universe. If that’s the case, then the universe cannot be infinitely old — not if it’s a closed system.
Princeton
I don’t understand the relevance of your point. Thermodynamics need not be the be-all and end-all in order to apply where appropriate, as in closed systems, does it?
In my opinion, it is something less than that. The universe is nothing more than a probability field.
(Incidentally, it is strange that such a thread is in General Questions.)
The point I was trying to make, Libertarian, was that since the argument of a homogeneous universe comes from the second law of thermodynamics, there are temporal considerations. Absolutely, one must apply this law where appropriate… and it’s a question of what appropriate means in this sense.
When dealing with infinities, to some extent the laws of thermodyamics break down (specifically the second law) which appeal to the number “zero” being something that is so unlikely as to not be able to occur in a reasonable period of time. Obviously a reasonable period of time is not infinite. We have no idea what laws come into play given an infinite amount of time (or even if it’s practical to speak in such terms), so there really is no way to say that, even given a closed system, thermodynamics can be adequately applied. Thus, there’s no good argument from thermodynamics that a universe infinitely extended in time should be homogeneous.
I’m sorry to be so dense, Princeton, but I still don’t understand. Isn’t entropy merely a ratio of heat and absolute temperature (joules per degree) — T[symbol]D[/symbol]s = [symbol]D[/symbol]u - P[symbol]D[/symbol]v, where T is temperature, s is entropy, u is available energy, and v is volume?
I thought the universe did have a remarkably uniform temperature, minus these pesky stars and galaxies here and there.
What is the life expectancy of a star?