How probable is the big bounce

[wolram]

https://en.wikipedia.org/wiki/Big_Bounce

I may be wrong but my reasoning to think the bouncing universe is true is because dark energy can not be infinite and gravity will eventual over come it

 

[phinds]

https://en.wikipedia.org/wiki/Big_Bounce

I may be wrong but my reasoning to think the bouncing universe is true is because dark energy can not be infinite and gravity will eventual over come it

? If, as seems to be the case (but is not known for sure) the universe is infinite, then the amount of dark energy is already infinite. In any case, "dark energy cannot be infinite" does NOT imply a big bounce. Think about it.

 

[wolram]

I do not know what you mean Phinds, I do not believe the universe is infinite, if you mean a torus or some other topology that is not infinite to my way of thinking.
Would you agree that every unit of space has the same amount of dark energy no matter how many units there are?

 

[jbriggs444]

https://en.wikipedia.org/wiki/Big_Bounce
I may be wrong but my reasoning to think the bouncing universe is true is because dark energy can not be infinite and gravity will eventual over come it

That reasoning seems flawed. Escape velocity is finite in a Newtonian universe, but gravity cannot overcome that.

 

[phinds]

Would you agree that every unit of space has the same amount of dark energy no matter how many units there are?

Yes, and there is no reason why this would ever be overcome by gravity, thus no bounce.

 

[wolram]

This is what I mean Dark energy is supposed to be infinite yet for every unit of expansion there must be more dark energy to fill it, now for every way of producing power I know there is a limit, from a petrol engine to a star or a supernova so where is this energy coming from in regards to dark energy?

 

[phinds]

... so where is this energy coming from in regards to dark energy?

Figure that out and you'll get a Nobel in physics.

 

[phinds]

I do not believe the universe is infinite

I"m not too sure about it either but the universe really doesn't care what we think so that's a non-arguement

 

[PeterDonis]

where is this energy coming from in regards to dark energy?

It doesn't have to come from anywhere. The intuitive notion of "energy conservation" you are using does not apply to a universe with dark energy.

 

[wolram]

Why is that Peter, If we have an expanding universe and it is infinite where is this infinite power plus coming from ?

 

[PeterDonis]

f we have an expanding universe and it is infinite where is this infinite power plus coming from ?

Read my previous post again. I've already answered this question.

 

[wolram]

Peter you are not saying any thing ineligible to me

 

[Ibix]

Why is that Peter, If we have an expanding universe and it is infinite where is this infinite power plus coming from ?

Expressed in Lagrangian terms, energy conservation turns out to boil down to a statement that "today is broadly the same as yesterday". Today is not the same as yesterday in cosmology - space is expanding. So naive notions of energy conservation do not apply.

 

[phinds]

Peter you are not saying any thing ineligible to me

I think your type-ahead speller got the better of you.

 

[wolram]

Expressed in Lagrangian terms, energy conservation turns out to boil down to a statement that "today is broadly the same as yesterday". Today is not the same as yesterday in cosmology - space is expanding. So naive notions of energy conservation do not apply.

This to me is just gobbledegook, To me expanding space, means more units of space are being added constantly so we need more dark energy to fill it, where is my reasoning wrong?

 

[PeterDonis]

This to me is just gobbledegook

Then the issue is with your understanding, not the model.

To me expanding space, means more units of space are being added constantly

Then you have an incorrect understanding of the actual model of the universe used in cosmology. There is no such concept of "expanding space" in the actual model.

where is my reasoning wrong?

It starts from an incorrect premise. See above.

 

[Ibix]

This to me is just gobbledegook, To me expanding space, means more units of space are being added constantly so we need more dark energy to fill it, where is my reasoning wrong?

It may not be (I'm not making a statement one way or the other). But it doesn't matter since energy (in the way you are using it) is not expected to be conserved in this situation.

 

[PeterDonis]

Today is not the same as yesterday in cosmology - space is expanding.

Since this language appears to be confusing the OP, let me restate it in terms which do not require any notion of "space expanding": The notion of "energy conservation" the OP is using requires a stationary spacetime, i.e., a spacetime that has a timelike Killing vector field. The spacetime we use to model the universe as a whole in cosmology is not stationary. So there is no notion of "energy conservation" for the universe as a whole that would support the OP's reasoning.

It may not be

No need to temporize; the OP's reasoning is wrong. See above and my previous posts.

 

[wolram]

Peter I am not talking about energy conservation I m talking about an energy field that is increasing with no stated fact as to how, I have looked on the net but I can not find this reason as to how the energy field is increasing in an expanding universe.
It just seems the model is accepted for no other reason that scientists get hot under the colour if it is questioned.
Now if you told me that dark energy is not filling every new unit of space as the universe expands I would understand but that is not what the literature says
Sorry for my ignorance.

 

[kimbyd]

This to me is just gobbledegook, To me expanding space, means more units of space are being added constantly so we need more dark energy to fill it, where is my reasoning wrong?

To reiterate what others have stated, there is no reservoir from which the expansion is drawing. You seem to have a concept that as the universe expands, the change in energy of the universe must draw from something outside the universe. This is incorrect: there is no "outside" to draw from*. The behavior of our observable universe is wholly and completely determined by the properties of the observable universe, not by anything else.

*Caveat: it is possible that there are other things besides our observable universe, but our observable universe does not interact with those other things in such a way that would allow this kind of thing to occur.

 

[Ibix]

Peter I am not talking about energy conservation I

Yes you are - because this:

I m talking about an energy field that is increasing with no stated fact as to how,

You only need a source if energy must be conserved. If it's not conserved then more appearing is not problematic.

 

[wolram]

Yes you are - because this:
You only need a source if energy must be conserved. If it's not conserved then more appearing is not problematic.

I am sorry but I do not understand, all energy must have a source.

 

[Ibix]

I am sorry but I do not understand, all energy must have a source.

Why?

 

[wolram]

The only sources of energy are the weak force, the strong force , gravity etc they all have an origin can you tell me what the force carrier of dark energy is?
Is it negative gravity as predicted by the big bounce model?

 

[Ibix]

The only sources of energy are the weak force, the strong force , gravity

These are not sources of energy. I suppose one could argue that they are ways of moving energy around, but that's all.

So my question stands: why do you think all energy must have a source?

 

[PeterDonis]

I am not talking about energy conservation I m talking about an energy field that is increasing

There is no concept of "energy field" either in the actual cosmological model. You are reasoning from incorrect concepts. That is why you are getting incorrect conclusions. The fact that the term "dark energy" happens to be used does not mean it is an "energy field" in the sense you are using the term.

if you told me that dark energy is not filling every new unit of space as the universe expands I would understand but that is not what the literature says

Please give a reference (textbook or peer-reviewed paper) to support this claim. I am not aware of any valid reference that claims that dark energy is "filling every new unit of space as the universe expands".

 

[wolram]

These are not sources of energy. I suppose one could argue that they are ways of moving energy around, but that's all.

So my question stands: why do you think all energy must have a source?

Let me turn this around , other than dark energy is there any other energy you can name that does not have an origin?

 

[PeterDonis]

Let me turn this around

Sorry, it doesn't work that way. You are the one making positive claims. You need to support them with valid references. Either do that or this thread will be closed.

 

[wolram]

There is no concept of "energy field" either in the actual cosmological model. You are reasoning from incorrect concepts. That is why you are getting incorrect conclusions. The fact that the term "dark energy" happens to be used does not mean it is an "energy field" in the sense you are using the term.
Please give a reference (textbook or peer-reviewed paper) to support this claim. I am not aware of any valid reference that claims that dark energy is "filling every new unit of space as the universe expands".

I may be wrong but that is what I come to believe.

 

[PeterDonis]

that is what I come to believe

In other words, you don't have a valid reference. Then this thread is closed. The responses you have already received are valid (i.e., your belief is wrong), and there is no more to be said.