How gravitational constant can be constant in expanding space?

[1x0]

Can gravitational constant point that the overall energy and mass of the Universe increase?

Edited May 26, 2015 by 1x0

[Strange]

 

How gravitational constant can be constant in expanding space?

 

Why not?

 

Can gravitational constant point that the overall energy and mass of the Universe thrive?

 

I have no idea what that means.

[1x0]

 

Why not?

 

 

I have no idea what that means.

Because with bigger distances gravitational attractive force decreases.

 

I mean that the constant can be constant because as space expands the overall amount of energy and matter and so mass increases in the system maintaining a stabil gravitational constant.

Edited May 26, 2015 by 1x0

[ajb]

An expanding or contracting Universe does not directly mean that Newton's constant G changes. I assume this is what you mean by the gravitational constant?

[1x0]

An expanding or contracting Universe does not directly mean that Newton's constant G changes. I assume this is what you mean by the gravitational constant?

Yes. Why that does not change if the amount of energy and matter is constant in the system? Does the amount of energy, matter, mass has to be constant in the Universe?

[ajb]

So far all indications are that there is no need for G to change and that general relativity is a good theory where it is expected to be so. However, people from at least the 1960's have thought about different theories of gravity that allow a variable gravitational constant, Dirac himself thought about this.

[Strange]

Yes. Why that does not change if the amount of energy and matter is constant in the system?

 

Why should it change? It is a constant because it doesn't depend on the amount of mass (or energy) involved.

 

Does the amount of energy, matter, mass has to be constant in the Universe?

 

No. There is evidence that the amount of dark energy may be increasing. Apart from that, there is no requirement for mass-energy to be conserved in GR.

[1x0]

 

Why should it change? It is a constant because it doesn't depend on the amount of mass (or energy) involved.

 

 

No. There is evidence that the amount of dark energy may be increasing. Apart from that, there is no requirement for mass-energy to be conserved in GR.

Because the gravitational constant is a result of something. Maybe the overall mass of the universe in absolute space? We know that space expands than why mass would not increase?

[Strange]

Because the gravitational constant is a result of something. Maybe the overall mass of the universe in absolute space?

 

There is no evidence that G depends on the total mass in the universe.

 

We know that space expands than why mass would not increase?

 

There is no evidence that mass increases as space expands.

[swansont]

Because the gravitational constant is a result of something. Maybe the overall mass of the universe in absolute space? We know that space expands than why mass would not increase?

 

Are there any other constants of nature that behave like this? Does Boltzmann's constant depend on how much of a material you have? Coulomb's constant?

[Delta1212]

 

Are there any other constants of nature that behave like this? Does Boltzmann's constant depend on how much of a material you have? Coulomb's constant?

Perhaps there are several constants that change like this and no one has realized it yet because we've mistaken them for variables.

[Strange]

Perhaps there are several constants that change like this and no one has realized it yet because we've mistaken them for variables.

 

Surely, if they changed in this way then they would be variables, not constants?

[Delta1212]

 

Surely, if they changed in this way then they would be variables, not constants?

To quote Rainier Wolfcastle, "That's the joke."

[swansont]

Perhaps there are several constants that change like this and no one has realized it yet because we've mistaken them for variables.

 

 

If the discussion is about things we think are constants but are actually changing, we check for things like that. Dimensionless constants, like the fine structure constant, because other terms are byproducts of the unit system we choose.

[1x0]

 

 

If the discussion is about things we think are constants but are actually changing, we check for things like that. Dimensionless constants, like the fine structure constant, because other terms are byproducts of the unit system we choose.

The question is does expanding space at one hand and increasing overall mass and energy on the other hand are the reason for the observed and determined constants? In other words they balance eachother. Can be that those constants are "evolving/increasing" too just the changing currently almost zero as the system what we inspect them in is enormous? Do we have any evidence that those constants changing?

 

If changing of the constants would be possible could we determine how much that would be at the beginning of the system?

 

If they do not change can be that those constants are the same since the beginning of the system?

 

Can we apply those constants together with Einsteins theories at the first moment of the system where Einstein´s equations determining the rate of evolution of the system? In other words how big space has to be that a certain amount of energy and mass(positive subatomic particles) are present? Can be that expanding space is the cause for the appearance of energy and mass?

Could c2 stand for the expansion rate of space in low energy circumstances (first moment) where the presented energy "limit" the expansion rate of "almost free" space in c2?

 

Could "almost free space" in high gravity exist? (as a center of a spherical Universe where we could observe matter free space in high gravity - the high gravity is the overall gravitational attraction of the absolute mass of the system - could the observed "black holes" be a result of such a structure? ) Could we measure the axis of the galactic centers in proportion to the galactic appearance and theirs possible alignments towards an Universal center? Have there been any observation in this direction?

[swansont]

Do we have any evidence that those constants changing?

 

No, nothing solid.

[Strange]

Do we have any evidence that those constants changing?

 

No. There have been attempts to test this. As far as I am aware, all observations show the constants to be constant. G is difficult though: it is hard to measure accurately so it is difficult to rule out the possibility that it might chnage (over time, or even in different places).

 

Also, some researchers claim to have found evidence that alpha (the fine structure constant) has changed in the past and in space.

http://en.wikipedia.org/wiki/Fine-structure_constant#Is_the_fine-structure_constant_actually_constant.3F

 

 

If changing of the constants would be possible could we determine how much that would be at the beginning of the system?

 

Maybe. It depends if we could produce a model explaining why they changed (if they did).

 

 

If they do not change can be that those constants are the same since the beginning of the system?

 

Maybe. Or they may have changed very early on and then "froze" to their current values at some point.

 

 

Can be that expanding space is the cause for the appearance of energy and mass?

 

There is no evidence for that. Apart from the fact that dark energy seems to increase as space expands.

 

 

Could c2 stand for the expansion rate of space in low energy circumstances (first moment)

 

No. The expansion of the universe is measured as 1/t, not d²/t².

 

And the early universe had a much higher energy density, so I'm not sure why you refer to it as "low energy".

 

 

Could "almost free space" in high gravity exist?

 

What does "almost free space" mean?

 

 

Could we measure the axis of the galactic centers in proportion to the galactic appearance and theirs possible alignments towards an Universal center? Have there been any observation in this direction?

 

There was one study that appeared to show a small bias in the orientation of galaxies. But I don't know if it has been confirmed or not.

Edited May 26, 2015 by Strange

[Delta1212]

 

 

If the discussion is about things we think are constants but are actually changing, we check for things like that. Dimensionless constants, like the fine structure constant, because other terms are byproducts of the unit system we choose.

 

I know. I was (apparently unsuccessfully) making a joke about constants that change being variables.

[J.C.MacSwell]

 

I know. I was (apparently unsuccessfully) making a joke about constants that change being variables.

It's OK to make jokes about variables, they are flexible enough to hold there own (you don't fix variables, they fix you), but no one here is going to laugh while you pick on constants.

[Mordred]

Oh we can joke about Hubbles constant as its only constant in space, not in time.

[MigL]

But G is a measured proportionality constant. It relates the force to the masses involved and the separation between them. It is certainly not a derived ( from first principles ) constant.

 

I assume everyone is familiar with 'Newton's bucket', and the implications which Ernest Mach derived from the thought experiment.

What if inertial mass is a result of the interaction with all the far-flung masses of the universe ?

Then as the universe expands, mass moves out of the observable universe, which itself, becomes larger and larger, with the effect that mass is reduced and separation increased. This would decrease the strength of the interaction with a local test mass, i.e. its inertial mass would be reduced.

And since we have no way of ( experimentally or theoretically ) separating inertial mass from gravitational mass, we must conclude that gravitational mass is also decreasing as the universe expands.

 

Now we are certainly not going to assume that mass changes over time, so when we perform the experiment to relate the force of gravity to the masses involved and their separation, we measure the proportionality constant, or G, to be increasing over time.

 

I post this just for discussion, as it makes for an interesting thought experiment ( and maybe what the OP was getting at ).

[imatfaal]

...

And since we have no way of ( experimentally or theoretically ) separating inertial mass from gravitational mass, we must conclude that gravitational mass is also decreasing as the universe expands.

...

 

If you mean on a wide scale then yes - but on a discrete system then no. Observations are underway on three body pulsar systems which aim to measure and test the strong equivalence. If understand correctly these tests will seek to ascertain if the massive (pun intended) gravitational binding energy causes breaches of the sep or not; the higly extreme conditions of the high spin millisecond pulsar orbitted by a white dwarf and a large planetary obbject mean that small differences may be discernable

 

S. M. Ransom, et al, A millisecond pulsar in a stellar triple system

Nature 505, 520–524 (23 January 2014)

[MigL]

I agree with you imatfaal, and I don't put much faith in a changing G.

 

However I'm not naïve enough to dismiss it outright, or ridicule the OP (not that anyone has ).