Eternity of universe

[Danneskjöld]

I am neither a physicist nor a "full-grown" philosopher, so in case I am wrong in my assumptions and conclusions, just show it and I will adapt my thinking.

Assumptions (which I heard once in high-school and still think to be true):

a) all matter of universe has emerged from a single starting point

matter is spreading away from this point

c) matter is spreading slower today than in the past

My scenario for the future:

As the speed of spreading is decreasing, the forces of gravity will have an increasing impact until matter stops moving away. This system will have a center of gravity which will pull matter back.

As a result, in the far future, when galaxies are banging constantly into this mass in the center, the increasing energy results finally in a "Big Bang", and matter is spreading away again.

That has been my physical explanation of eternity of universe for years.

Thoughts?

Ragnar

[DavidOdden]

That has been my physical explanation of eternity of universe for years.

Before getting to a physical explanation of something, you should sort out what that something is. What is time? The abstract concept "eternity" is defined fundamentally in terms of time, so what is time and what is the relationship of time to the universe (i.e. "the totality of existence").

[Danneskjöld]

Before getting to a physical explanation of something, you should sort out what that something is. What is time? The abstract concept "eternity" is defined fundamentally in terms of time, so what is time and what is the relationship of time to the universe (i.e. "the totality of existence").

I do not see, why the concept of time is relevant, if I try to explain that "the" Big Bang and the "creation" of universe never happend. But that there is instead an endless chain of Big Bangs over and over again.

But if you wish: Time as such does not exist, it is only perceivable through other entities. Through the change of an attribut in entities, to be exact.

So if this physical explanation is correct, there would be endless movements in/of universe, therefore with the universe time itself exists enternally.

[Grames]

a) all matter of universe has emerged from a single starting point

matter is spreading away from this point

c) matter is spreading slower today than in the past

The current version is c) matter is spreading faster today than in the past.

[shadesofgrey]

I do not see, why the concept of time is relevant, if I try to explain that "the" Big Bang and the "creation" of universe never happend. But that there is instead an endless chain of Big Bangs over and over again.

But if you wish: Time as such does not exist, it is only perceivable through other entities. Through the change of an attribut in entities, to be exact.

So if this physical explanation is correct, there would be endless movements in/of universe, therefore with the universe time itself exists enternally.

Well, nothing can actually happen without time. If you have three dimensions of matter, it's just going to sit there unless time exists as a dimension in which it can be acted upon by other things or an outside force. Time exists regardless of whether or not anyone is around to perceive it. Our perception is somewhat irrelevant, because of instances when time is warped, as when an object approaches the speed of light or crosses the event horizon of a black hole. The perception of time changes (even to the same observer) when events like this take place. It becomes RELATIVE. Hence, the Law of Relativity.

I'm not sure if this is the current thinking, but as I understand it, some people think that time itself began with the Big Bang and before that, there was no such thing as matter or time. This presents the paradox of the Prime Mover (i.e. if there was no time or matter, what started it and where did the matter come from?).

Personally, I can't get my head around the notion of a singularity, a point of infinite mass and density, because it seems to me that even that should be quantifiable in some way.

The current version is c) matter is spreading faster today than in the past.

Actually, yeah I remember reading that. Instead of the Big Crunch where everything comes back together, it just keeps spreading out forever until everything reaches absolute zero, resulting in the thermal death of the universe. Cozy thought.

[DavidOdden]

I do not see, why the concept of time is relevant

You have presumes the "eternity of the universe". Explain what "eternity" is, without referring to "time.

Time as such does not exist, it is only perceivable through other entities. Through the change of an attribut in entities, to be exact.

What is "time as such"? If you are simply saying that time is not an entity, then we agree; but not all existents are entities. So time is a relational attribute of entities.

So if this physical explanation is correct, there would be endless movements in/of universe, therefore with the universe time itself exists enternally.

Time does not exist separate from the universe, and logically depends on the universe; "eternal" means "for all times"; so "universe" subsumes "all times", hence "is eternal". We can get to the philsophical conclusion of an eternal universe regardless of the physical explanation.

[Capitalism Forever]

Actually, yeah I remember reading that. Instead of the Big Crunch where everything comes back together, it just keeps spreading out forever until everything reaches absolute zero, resulting in the thermal death of the universe. Cozy thought.

I've heard of another scenario in which things warm up because of increasing entropy, resulting in a thermal death of the Universe. I haven't made my mind up yet as to which of these two is the greater nonsense...

[KurtColville]

I've heard of another scenario in which things warm up because of increasing entropy, resulting in a thermal death of the Universe. I haven't made my mind up yet as to which of these two is the greater nonsense...

Well, there's no physical law that rules out a "Big Crunch". It's just that we observe an acceleration of the most distant objects away from each, with the rate of acceleration increasing with distance. Some force, which physicists mysteriously label "dark energy", appears to be pushing things apart faster than gravity can pull them together. However, there is still a lot of science to be done, principally in the analysis of redshifts, before the verdict is in. Were it to turn out that there is some repulsive, anti-gravitational force that is fundamental to the universe, like gravity is, then we could rule out a Big Crunch. We'll just have to see.

Since a "thermal death" of the universe, as you have described, would necessitate a violation of the conservation of energy (and no small violation at that), I'd vote for that scenario as being the greater nonsense.

[shadesofgrey]

Since a "thermal death" of the universe, as you have described, would necessitate a violation of the conservation of energy (and no small violation at that), I'd vote for that scenario as being the greater nonsense.

Wouldn't the eternal dissapation of all matter and energy in the universe constitute thermal death if there's nothing to reverse it? I would think that even if the span of time were infinite, the entire universe wouldn't reach absolute zero because there would always BE energy as you've stated. Still, it'd be pretty darn close.

[Steve D'Ippolito]

I believe Kurt is referring to Capitalism Forever's allusion to someone who thought the universe would warm up.

[KurtColville]

I believe Kurt is referring to Capitalism Forever's allusion to someone who thought the universe would warm up.

Yep.

[Danneskjöld]

The current version is c) matter is spreading faster today than in the past.

Ok, if this is the case, my scenario is wrong anyway. Then I have to get rid of my thoughts and figure out, what to think.

Well, nothing can actually happen without time. If you have three dimensions of matter, it's just going to sit there unless time exists as a dimension in which it can be acted upon by other things or an outside force. Time exists regardless of whether or not anyone is around to perceive it. Our perception is somewhat irrelevant, because of instances when time is warped, as when an object approaches the speed of light or crosses the event horizon of a black hole. The perception of time changes (even to the same observer) when events like this take place. It becomes RELATIVE. Hence, the Law of Relativity.

I'm not sure if this is the current thinking, but as I understand it, some people think that time itself began with the Big Bang and before that, there was no such thing as matter or time. This presents the paradox of the Prime Mover (i.e. if there was no time or matter, what started it and where did the matter come from?).

[...]

Obviously you are right, time exists anyway, there does not need to be a perceiver. But as matter exists and is moving, time does exist with all its attributes (such as its changing with speed). My conclusion here was, when matter exists eternally, then so does time.

But as it seems, universe is expanding faster than in the past, so I have to rethink the whole issue. I cannot believe, that all of it startet out of nothing and is going into nothing...

[...]

We can get to the philsophical conclusion of an eternal universe regardless of the physical explanation.

But still you cannot detach your conclusions from reality. If you are claiming, that universe is eternal, there HAS TO BE prove of it in reality, i.e. a physical explanation. I just made this bridge by my conclusions. It seems though that I am wrong, so there must be another explanation.

Well, there's no physical law that rules out a "Big Crunch". It's just that we observe an acceleration of the most distant objects away from each, with the rate of acceleration increasing with distance. Some force, which physicists mysteriously label "dark energy", appears to be pushing things apart faster than gravity can pull them together. However, there is still a lot of science to be done, principally in the analysis of redshifts, before the verdict is in. Were it to turn out that there is some repulsive, anti-gravitational force that is fundamental to the universe, like gravity is, then we could rule out a Big Crunch. We'll just have to see.

Since a "thermal death" of the universe, as you have described, would necessitate a violation of the conservation of energy (and no small violation at that), I'd vote for that scenario as being the greater nonsense.

Hm. All in all we still do have a big mess explaining the fundamentals of universe. I guess my physical explanations will have to wait.

Thanx for the inputs, I will think it all over...

[KurtColville]

But still you cannot detach your conclusions from reality. If you are claiming, that universe is eternal, there HAS TO BE prove of it in reality, i.e. a physical explanation. I just made this bridge by my conclusions. It seems though that I am wrong, so there must be another explanation.

There is a physical explanation for the universe being eternal: the fact that the concept "eternal" refers to something outside of time, or to which time is inapplicable, and the fact that the universe (being everything that exists) does not exist in time, but vice-versa -- time exists in the universe. Physical reality is where we go to get those determining facts.

It's an understandably difficult idea to grasp. But it will help to recognize that time presupposes two measuring points: a starting event and a final event. To apply time to the universe, to ask how old it is, we need to know the universe's starting point. But that's the problem: there is no starting point to existence. There is nothing to refer to to use as your starting point that precedes the existence of something. There is nothing that you can refer to and say, "Okay, here is when nothing existed, and that's when I'm starting my measurement of elapsed time in the universe." (This, by the way, is exactly the line of thinking that cosmologists do use in addressing the age of the universe... unfortunately.) The question requires non-existence to contrast with existence, so that you can tell when existence starts. But how do you identify non-existence? How do you place a nothing in time or place?

Hm. All in all we still do have a big mess explaining the fundamentals of universe. I guess my physical explanations will have to wait.

We will indeed have to wait, and we'll need less rationalism in physics to get the answers. The good news is that with each advancement in telescopy, some long-held rationalizations get thrown in the garbage in light of conclusive new data, bringing us a little bit closer to the answers all the time.

Good questions, though, and I hope this helps. And a hearty "Hopp Schwyz!" from a former resident of Zurich and passionate fan of Switzerland.