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Posted

I. More on Gravity

 

If gravity is bent space rather than being a force (as everybody seems to agree), then it ought not to be thought of as a force (except in newtonian realms). With gravity as a force an ever increasing mass would seem to logically reach a point of singularity as a result. But as the bending of space, which is caused by that very matter, it is not at all clear how such should be the result.

 

In a physical discrete space the basic unit would be the limiting factor, preventing things from going divergent. A space could only "be" within the limits of its design. It would have, perhaps knowable, maximum whatevers regarding what it could "do".

 

Here is where geometry would weigh in, were a real discrete space to be fully embraced. If it exists, it exists. It couldn't make its own self go away. A quantum source of existence could not produce such a state that could have itself cease to exist. States come and go. Physics stays.

 

Stars would collapse because their component particles never stop moving and the space in which they move is bent that way. But, there ought to be limits, and so matter would reach a point of "incompressibility". In a real, physical discrete space "compression" would result in reducing the number of unoccupied spaces between the occupied ones, and the limit would conceivably be a black hole which would contain no unoccupied spaces. A black hole would be a region of space wherein every single discrete-space was manifesting a rest mass.

Posted (edited)

The term bending of spacetime is misleading. It does not mean spacetime is a material or fabric. It is in fact a mathematical descriptive of the geometric influence if spacetime. Space being simply volume filled with the energy matter contents of the universe. The term spacetime is in fact a mathematical term whose meaning us "any metric that adds the time component to space"

 

The images you see with bending sheets etc are merely visualization aids.

When you use the critical density formula you can calculate the average energy mass density to volume. Thus will give a value of roughly 1 photon per cubic meter. Including dark energy and virtual particle production. So indeed there is a whole lot of empty volume we call space. The warping twisting stretching space terms are all misleading and one if the most common mistakes is thinking that space itself is a fabric or substance. GR does not teach this it tells us that the sphere of influence that gravity has on particles is in a bent curvature

 

for that matter only fermions make up matter the force carriers bosons such as the hypothetical graviton is not a form of matter this is where the real question of whether gravity is a force comes into play we cannotvas of yet detect the graviton however we do detect the other 3 force carriers. However this doesntvmeancthe graviton does not exist. We simply cannot produce high enough energy in particle accelerators to create gravitons.

Edited by Mordred
Posted

In a physical discrete space the basic unit would be the limiting factor, preventing things from going divergent.

People do think about discrete models of gravity, there are several theories here. Do you have some particular description in mind here?

Posted

The term bending of spacetime is misleading. It does not mean spacetime is a material or fabric. It is in fact a mathematical descriptive of the geometric influence if spacetime. Space being simply volume filled with the energy matter contents of the universe. The term spacetime is in fact a mathematical term whose meaning us "any metric that adds the time component to space"

 

The images you see with bending sheets etc are merely visualization aids.

When you use the critical density formula you can calculate the average energy mass density to volume. Thus will give a value of roughly 1 photon per cubic meter. Including dark energy and virtual particle production. So indeed there is a whole lot of empty volume we call space. The warping twisting stretching space terms are all misleading and one if the most common mistakes is thinking that space itself is a fabric or substance. GR does not teach this it tells us that the sphere of influence that gravity has on particles is in a bent curvature

 

for that matter only fermions make up matter the force carriers bosons such as the hypothetical graviton is not a form of matter this is where the real question of whether gravity is a force comes into play we cannotvas of yet detect the graviton however we do detect the other 3 force carriers. However this doesntvmeancthe graviton does not exist. We simply cannot produce high enough energy in particle accelerators to create gravitons.

1 photon?

Are photons used to determine average mass density?

Posted (edited)

roughly 6.62*10-10 joules per m3 roughly if you prefer different articles gives similar values there is some minor discrepancies depending on what value you use for Ho

actually I miscalculated it will be closer to 5 protons per m3

Edited by Mordred
  • 2 years later...
Posted

People do think about discrete models of gravity, there are several theories here. Do you have some particular description in mind here?

Any good model will do as long as cell size/radius is never zero.

  • 4 weeks later...
Posted

The term bending of spacetime is misleading. It does not mean spacetime is a material or fabric. It is in fact a mathematical descriptive of the geometric influence if spacetime. Space being simply volume filled with the energy matter contents of the universe. The term spacetime is in fact a mathematical term whose meaning us "any metric that adds the time component to space"

 

The images you see with bending sheets etc are merely visualization aids.

When you use the critical density formula you can calculate the average energy mass density to volume. Thus will give a value of roughly 1 photon per cubic meter. Including dark energy and virtual particle production. So indeed there is a whole lot of empty volume we call space. The warping twisting stretching space terms are all misleading and one if the most common mistakes is thinking that space itself is a fabric or substance. GR does not teach this it tells us that the sphere of influence that gravity has on particles is in a bent curvature

 

for that matter only fermions make up matter the force carriers bosons such as the hypothetical graviton is not a form of matter this is where the real question of whether gravity is a force comes into play we cannotvas of yet detect the graviton however we do detect the other 3 force carriers. However this doesntvmeancthe graviton does not exist. We simply cannot produce high enough energy in particle accelerators to create gravitons.

 

Thanks, I never meant that bent space is anything more than a model. Math, of course, is the best model.

 

"The [GR] mathematical result Einstein found underlies the figures [images of warping] and is embodied in what are called the Einstein field equations. As the name indicates, Einstein viewed the warping of spacetime as the manifestation -- the geometrical embodiment -- of a gravitational field." (Brian Green, The Fabric of the Cosmos, p.70)

 

The warped space model comes from that math. Gravity as a force model comes from Newton.

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