Time, death and the universe

[MMI]

Best thread in a long time! I was gonna give up and take up an interest in bdsm or something ... but, hey, this brings me back.

So many questions, and not a single answer (except that homeopathy is bunkum). Not that anyone can really expect any, but we do, Ian, get the chance to air our views and to pick up ideas from others.

I don't have much to contribute at this stage other than to offer a few observations.

While there is no reason in physics why time cannot run in any direction, I suggest that once it starts, it can only run in one, and cannot change. But that's just an idea. It might help explain why things never grow younger, or why coffee goes cold, but does not heat up.

The ice block falling back up into the glacier ... surely gravity trumps time here? (As I make this glib suggestion, I am struck by the thought that, in order to reverse time, maybe we have to reverse physics entirely!)

The arrow of time tends towards entropy (chaos, waste). Does it? Throughout all of elapsed time so far, it seems to me the universe has evolved, not disintegrated. Maybe that will change, but will it affect the direction of time?

"Death" (and "life") is frequently, and I believe was in Brian Cox's programme, used as a metaphor for the stages of a star's existence, or that of the universe: while active, the star was passing through its lifetime, and after it ceased to exist, or became a brown dwarf/pulsar/black hole or whatever, it had "died". We all know that stars do not live, and only living things can die. On that assumption, I believe it is a mistake to link the end of life too closely with physical disintegration. It is taking the comparison (which is useful) too far.

The cause of the Big Bang/Nature abhors a vacuum: Nature is part of the physical universe and there is nothing to suggest it "predated" the Big Bang. Whatever caused the universe to come into being is/was not bound by the laws of physics - and as such is/was not prevented from being an uncaused cause, nor is/was it bound to leave demonstrable evidence of its precise nature behind in its new creation. (I say this as an atheist.)

Nothing escapes a black hole: Thorne suggests gravity can. I also seem to think that black holes can be identified by the material they eject back into space in their polar streams.

Will the universe dissipate into (virtual) cold nothingness, or can it be brought back into being somehow (e.g., by another Big Bang?). I think the current theory is that it will spread out so far that it will almost cease to exist. As I understand space and time (which might be not at all well) both would continue to expand (or elapse) indefinitely. If there were to be a second Big Bang in the space created by the first one, would there now be two times running? Would they both be bound to run in the same direction.

Will I live again? I think not. Maybe some of the atoms making up my body at the moment will be incorporated into another living being sometime, but I suspect the chances are small. If it will happen, then it will most likely happen here on Earth before our sun goes supernova (will it do that?). After that, those atoms are most likely to become part of some other star, and then another, and so on. The likelihood of any of them becoming part of another living creature is too remote to contemplate.

Why do we ask these questions? For the same reason we asked that one!

[ksst]

At dinner tonight Master postulated a new theory, new to me at least. The universe actually gets created tomorrow, and all of this stuff that we think happened will be implanted as false memories then. It's a good thing I was drinking sake or my head would hurt.


I also heard someone say that eventually the universe will start to contract again and it will all end in a Big Crunch. And not Nestles either.

[Thorne]

At dinner tonight Master postulated a new theory, new to me at least. The universe actually gets created tomorrow, and all of this stuff that we think happened will be implanted as false memories then. It's a good thing I was drinking sake or my head would hurt.

Sounds a lot like Last Thursdayism

I also heard someone say that eventually the universe will start to contract again and it will all end in a Big Crunch. And not Nestles either.

There was some speculation about that during the early days of the Big Bang Theory, but current measurements show that the speed at which the universe is expanding is actually increasing, which would indicate that there will be no Big Crunch.

[Thorne]

Best thread in a long time!

I have to agree with you there.

It might help explain why things never grow younger, or why coffee goes cold, but does not heat up.

But coffee does heat up! You just have to add energy to it. Perhaps time can be reversed by the proper application of energy?

The ice block falling back up into the glacier ... surely gravity trumps time here?

Same problem as the coffee. If you apply enough energy, at the right time, you can push that ice block back onto the glacier.

The arrow of time tends towards entropy (chaos, waste). Does it? Throughout all of elapsed time so far, it seems to me the universe has evolved, not disintegrated. Maybe that will change, but will it affect the direction of time?

The law of entropy only applies in a closed system. The universe as a whole is a closed system, since it contains everything in existence. Parts of the universe temporarily reverse entropy, which is why we have life on Earth, for example, but overall, entropy rules.

Whatever caused the universe to come into being is/was not bound by the laws of physics

We don't know that, though. There could be (and probably are) physical properties which we have yet to unravel. There are many cosmologists who are speculating about how the universe could have formed, using what we know about the current universe. One, or more, of these speculations could prove to be right.

Nothing escapes a black hole: Thorne suggests gravity can. I also seem to think that black holes can be identified by the material they eject back into space in their polar streams.

That material is taken from the accretion disk of material whirling around the black hole, not from the black hole itself. But Hawking hypothesized that the black hole would give off radiation on it's own, and I believe this radiation has been detected. This is what would cause the black hole to evaporate.

Will I live again? I think not. Maybe some of the atoms making up my body at the moment will be incorporated into another living being sometime, but I suspect the chances are small.

Actually, the chances are quite large. Most of the decay of your body will be caused by the organisms both inside of you and in the ground in which you are buried. If you go the cremation route, some of your molecules will be distributed into the atmosphere, and be breathed in by many creatures. All of your waste products eventually wind up in the gut of some form of bacterial life. One thing life is good at is recycling.

If it will happen, then it will most likely happen here on Earth before our sun goes supernova (will it do that?).

No, it won't. It will eventually expand into a red giant, probably encompassing the Earth itself, before collapsing down into a white dwarf.