8 replies to this topic

[shifter]

Just random thoughts

Everything in the universe is being pulled away from each other further and further as the universe expands. Currently, we can still see many galaxies out there. IF mankind is still out there billions of years from now (or if we only developed to our present level billions of years from now), What would we see out there? Perhaps we would think ourselves inside a void of nothingness? What could we have seen if we were around 5 billion years earlier?


And if the universe is held together by energy and fabric, perhaps the more it expands, the weaker it becomes. What if in a few billion years, the fabric holding everything together is stretched so far it tears. Perhaps the universe will start splitting apart and look like an archipelago. Each part a rougue universe in itself but inhabitants inside unable to see or travel to the other break aways (different end to the 'big crunch' theory).

Also as a general rule, energy cant be created from nothing. So when the big bang started, there was a set amount of energy. So lets imagine in another 15 billion years what the universe will look like. Every (or almost all) stars we see and know out there today will have run out of fuel and be gone. (lifeless dwarf stars, black holes, etc) But energy cant be 'destroyed' right? So what will happen to it all? Will all the galaxies have their lights out and the universe nothing but an lifeless place with rocks and dust? Or can the energy find another way to keep the 'lights on'.

This sub forum seems a little inactive so I thought I would try and stimulate peoples imagination What are your thoughts?

[PWAIN]

Everything in the universe is being pulled away from each other further and further as the universe expands. Currently, we can still see many galaxies out there. IF mankind is still out there billions of years from now (or if we only developed to our present level billions of years from now), What would we see out there? Perhaps we would think ourselves inside a void of nothingness? What could we have seen if we were around 5 billion years earlier?

And if the universe is held together by energy and fabric, perhaps the more it expands, the weaker it becomes. What if in a few billion years, the fabric holding everything together is stretched so far it tears. Perhaps the universe will start splitting apart and look like an archipelago. Each part a rougue universe in itself but inhabitants inside unable to see or travel to the other break aways (different end to the 'big crunch' theory).

What if the space is not expanding as currently taught, but rather the matter inside is shrinking. This works perfectly with an apparently expanding universe and means that tears in the fabric of space are unlikely. It seems more logical to me that energy reduces rather than space (emptiness) getting bigger. Eventually all the galaxies are likely to be too far away for us to see any more but at least initially, our super cluster will keep relatively close and our own galaxy will stick around until all the stars start to die out.

Also as a general rule, energy cant be created from nothing. So when the big bang started, there was a set amount of energy. So lets imagine in another 15 billion years what the universe will look like. Every (or almost all) stars we see and know out there today will have run out of fuel and be gone. (lifeless dwarf stars, black holes, etc) But energy cant be 'destroyed' right? So what will happen to it all? Will all the galaxies have their lights out and the universe nothing but an lifeless place with rocks and dust? Or can the energy find another way to keep the 'lights on'.

What will eventually happen is that all the particles/waves will become incredibly diffuse and too far apart to accumulate via gravity. Proton decay may or may not happen. All this will probably take a lot longer than 15 billion years. Read "The five ages of the universe" where the authors discuss what will happen to the universe up until 10 to the power of 100 years. The universe is still a tiny baby.

This sub forum seems a little inactive so I thought I would try and stimulate peoples imagination What are your thoughts?

Yeah, I am surprised by the lack of activity in this sub forum.

[Not A Naked Ape]

I am not an educated physicist, but I have thought about similar problems, too.

What if the space is not expanding as currently taught, but rather the matter inside is shrinking. This works perfectly with an apparently expanding universe and means that tears in the fabric of space are unlikely. It seems more logical to me that energy reduces rather than space (emptiness) getting bigger. Eventually all the galaxies are likely to be too far away for us to see any more but at least initially, our super cluster will keep relatively close and our own galaxy will stick around until all the stars start to die out.

The hypotheses

(A) The universe expands and the size of all objects remains the same.

(B) The universe is static but all objects shrink.

seem to be equivalent. But: One Billion years ago, a light beam needed the same time as today to travel from the sun to the earth. Therefore, the two hypotheses are in fact:

(A) The universe expands, the size of all objects remains the same and the speed of light is constant.

(B) The universe is static but all objects shrink and the speed of light decreases.

Since the natural laws should stay the same, A is in my opinion a better explanation as B.

Also as a general rule, energy cant be created from nothing. So when the big bang started, there was a set amount of energy. So lets imagine in another 15 billion years what the universe will look like. Every (or almost all) stars we see and know out there today will have run out of fuel and be gone. (lifeless dwarf stars, black holes, etc) But energy cant be 'destroyed' right? So what will happen to it all? Will all the galaxies have their lights out and the universe nothing but an lifeless place with rocks and dust? Or can the energy find another way to keep the 'lights on'.

It is indeed difficult to tell how cosmology and the conservation of energy fit together. In fact, energy is not conserved in general relativity. If the universe grows by the factor 2, the amount of dark energy is multiplied by 8. The reason for this is that the volume grows by the factor 8 and the density of the dark energy is a constant. On the other hand, the amount of matter stays the same and the energy of the radiation declines, since all wave lengths are stretched by the factor 2. Here is a link with a more detailed explanation:


http://motls.blogspo...nserved-in.html

I hope this is not too technical.

[cathological]

If any of us live that long we would be damn lucky.

[Not A Naked Ape]

By the way: The dark energy may be the reason why life cannot continue forever. The most natural explanation for the dark energy is a cosmological constant that is added to Einstein's equation. As the universe expands, the density of matter will become smaller. Therefore, gravity cannot hold back the galaxies and the dark energy will become more and more dominant. In the far future, all galaxies that are more distant as 7 billion light years will move so fast that its light will never reach us.

No matter how much technology advances, only a finite amount of energy will ever be available - namely all energy within a sphere of radius of 7 billion light years. The physicist Freeman Dyson has shown that a living being can have an infinite number of thoughts without using infinitely much energy. The idea is that the living being cools down its body temperature more and more and the next thought will consume less energy than the previous one.

However, this works only if you can come arbitrarily close to 0 degree Kelvin. If the universe has a "horizon" at a finite distance, the vacuum will have a non-zero temperature due to the uncertainty relation. Its something like 10^-30 degree Kelvin. Although this is not much, you cannot cool down forever, and life has to come to an end.

In my opinion, the only way out is to create a baby universe and emigrate. I don't know if this is really possible and I don't think anybody else knows. Of course, I hope that life does not need to end, but without more research you cannot answer that question.

[7YearsStrong]

If any of us live that long we would be damn lucky.

Luck has nothing to do with it.

[Brendo]

if everything in the universe was shrinking then there would still be no way to test weather its shrinking since all our measurements would be shrinking as well thus everything would still be relativistic and the speed of light would still be the same wouldnt it??

so it wouldnt make a difference anyway.. and in this sense the universe is actually expanding (both hypothesis seem equivelent).

[Mind]

I am partial to the philosophically "tight" theory that the universe is infinite in time and space. Similarly, I am partial to Hoyle's theory of constant creation as this fits with cyclical/eternal theories as well.

What does this mean? (to me anyway). There is no "end point" of the universe". Everything that could happen has already happened. My life has already been lived (infinite times over) in the exact same manner as it is currently happening. So what really matters in this scenario/theory? That my subjective experience in this instance is "happy" or "pleasurable" or "meaningful" or whatever positive term you want to apply.

[xEva]

The expanding universe hypothesis is based entirely on the redshift. If there is another explanation to the redshift --and some people claim that there are a few, "tired light" being one of them-- then the whole idea collapses.

The thing is, we do not know what space is. We take the 3D that we observe and experience for granted and treat it as given. But the question no one can answer satisfactory is, what exactly is expanding? How? If vacuum is imbued with energy, where all the energy necessary to support its expansion is coming from? The other question is, why is space expanding in between galaxies but not within our own solar system, i.e. the Sun is not getting any farther from the Earth.

IMO, the expanding post-big-bang universe is a half-baked theory based on insufficient data.