Why Does Gravity Pull Objects Together?

[bill alsept]

There have been description that explain gravity. I'm not sure why they have not been studied more considering they are all that have been offered.

http://en.wikipedia.org/wiki/Le_Sage's_theory_of_gravitation

 

[OnlyMe]

There have been description that explain gravity. I'm not sure why they have not been studied more considering they are all that have been offered.

http://en.wikipedia.org/wiki/Le_Sage's_theory_of_gravitation

The Le Sage model of gravity has been examined and re-examined repeatedly since its first introduction in 1690. The Wiki article in the above link does a fair job of outlining the timeline and near its conclusion mentions Feynman's 1965 resurrection, even if only for reasons of example...

These kinetic gravity models, do a decent job of explaining the Newtonian concept of gravity. They fall short in some other respects, better explained by general relativity. However, there are, at least two significant flaws. The first is that to explain even the Newtonian model of gravitation, requires superluminal force carriers, which is not consistent with experience or experiment, in particle physics. The other involves the disipation of the kinetic energy required to effectively simulate gravitational forces. As I believe Feynmen pointed out, and I am paraphrasing, the kinetic energy would rapidly result in the vaporization of the atom and thus the universe as we know it.

 

[Delta2]

Well to try to answer this in a different manner, we can try to think what would happen if gravity didnt exist. Then some crucial macroscopic large scale phenomena of this universe wouldn't happen like the formation of stars and planets. Imagine a universe without stars! Gravity is the major player in the macroworld in cosmological scale.

 

[bill alsept]

[/QUOTE]These kinetic gravity models, do a decent job of explaining the Newtonian concept of gravity. They fall short in some other respects, better explained by general relativity.[/QUOTE]

In what way does it fall short? Could you be more specific? I would say GR falls short considering it never even attempted to explain how gravity works.


[/QUOTE]However, there are, at least two significant flaws. The first is that to explain even the Newtonian model of gravitation, requires superluminal force carriers, which is not consistent with experience or experiment, in particle physics.[/QUOTE]


Yes to explain the standard models of gravity one would need to come up with some unexplainable force like that. That is why models like or similar to Lasage's (I think it needs a few changes) should be looked at again. Kinetic models are the only models to even try to mechanically explain gravity. Kinetic energy needs no special or undetectable force carriers.



[/QUOTE]The other involves the disipation of the kinetic energy required to effectively simulate gravitational forces. As I believe Feynmen pointed out, and I am paraphrasing, the kinetic energy would rapidly result in the vaporization of the atom and thus the universe as we know it. [/QUOTE]

How?

This is what interests me about this subject. Everyone is willing to except gravity without physical explanation but dismiss kinetic gravity without specific or better explained reasons.

 

[bill alsept]

Well to try to answer this in a different manner, we can try to think what would happen if gravity didnt exist. Then some crucial macroscopic large scale phenomena of this universe wouldn't happen like the formation of stars and planets. Imagine a universe without stars! Gravity is the major player in the macroworld in cosmological scale.

There would still be the effect of gravity. Kinetics offer something to work with, an explanation that no one else has.

 

[cbConnect]

I believe that this is a rather interesting question. While it definitely does have its connections with philosophy, as i remember someone stating (and starting a mini-flamewar), the physics of gravity is a part of science i believe not to be fully understood. There is a lot of debate on the existence of gravitrons, which is quite the example of discord in the science community. I may be saying nothing new here, but i believe that while we do know how gravity works, we don't actually know why.

Though the reverse gravity concept Delta stated seems fun to imagine.

 

[OnlyMe]

These kinetic gravity models, do a decent job of explaining the Newtonian concept of gravity. They fall short in some other respects, better explained by general relativity.

In what way does it fall short? Could you be more specific? I would say GR falls short considering it never even attempted to explain how gravity works.

Newtonian gravity required gravity to function instantaneously between bodies. For a kinetic model as they have been presented to do this the force carriers have to have velocities many orders of magnitude greater than c. This was also noted below.

I have seen no kinetic model that explains either precession (a limitation of Newton's model also) or gravitational lensing.

However, there are, at least two significant flaws. The first is that to explain even the Newtonian model of gravitation, requires superluminal force carriers, which is not consistent with experience or experiment, in particle physics.

Yes to explain the standard models of gravity one would need to come up with some unexplainable force like that. That is why models like or similar to Lasage's (I think it needs a few changes) should be looked at again. Kinetic models are the only models to even try to mechanically explain gravity. Kinetic energy needs no special or undetectable force carriers.

Kinetic energy does in fact require a force carrier, either in the form of a super luminal particle as most LeSage style kinetic models involve or in the form of an ether like substance in space that transfers the kinetic energy as would a "liquid". The particle problem is covered below. The ether model has its own problems. There have been some ether models of GR proposed. I am unaware of any that have been successful in duplicating the success of GR. If an ether model were found that was consistent with GR, it might provide some basis for a kinetic model of gravity, of some sort.

The other involves the dissipation of the kinetic energy required to effectively simulate gravitational forces. As I believe Feynmen pointed out, and I am paraphrasing, the kinetic energy would rapidly result in the vaporization of the atom and thus the universe as we know it.

How?

When using a kinetic model for gravity that involves a particle as a force carrier, some portion of the kinetic energy exchange winds up as heat. There is a heat build up that exceeds any reasonable rate of dissipation, which results in the vaporization of atomic structures.

This is what interests me about this subject. Everyone is willing to except gravity without physical explanation but dismiss kinetic gravity without specific or better explained reasons.

I think that the kinetic models that have been proposed have been dismissed, because they have not duplicated the predictive success that GR has and in each case there have been some fatal flaw(s), as mentioned above.

Personally, I like the idea of a kinetic model, though I have not seen or come up with one that stands up to the issues raised above. Still, it seems that a kinetic model would provide a better opportunity to reconcile some of the problems that stand between GR and QM. That does not change the fact that there is a great deal of current experience and experimental evidence that does not seem explainable from within a kinetic model. In some sense quantum gravity and loop quantum gravity do begin to approach some of those issues from what could be described as involving a kinetic model. They also have not yet been entirely successful.

 

[DaveC426913]

QUOTE=OnlyMe-I have seen no kinetic model that explains either precession (a limitation of Newton's model also) or gravitational lensing. END QUOTE
yadda yadda

Unable to parse.

Is there something wrong that you can't use the existing quote feature?

 

[bill alsept]

Unable to parse.

Is there something wrong that you can't use the existing quote feature?

Yes, I am ignorant to how the function works for some reason when I use the multi quote I mess it up. Sorry

 

[DaveC426913]

Yes, I am ignorant to how the function works for some reason when I use the multi quote I mess it up. Sorry

Even if you can't get the Quote or Multi-quote buttons to work (and we can fix that), the advanced editor has a quote feature - and you can always manually add [ QUOTE ][ /QUOTE ] tags.

 

[bill alsept]

Thanks

 

[bill alsept]

Newtonian gravity required gravity to function instantaneously between bodies. For a kinetic model as they have been presented to do this the force carriers have to have velocities many orders of magnitude greater than c. This was also noted below.

I don't think Kinetic gravity is presented that way and it wouldn't need force carriers. The physics behind kinetic gravity are just as simple as two billard balls hitting each other or fields passing through each other causing drag. GR and Newtonian models on the other hand may need some kind of instantaneous and mystical force that can reach infinantly across the universe and grab hold of something and then pull it back.

I have seen no kinetic model that explains either precession (a limitation of Newton's model also) or gravitational lensing.

Why should it? Could you explain?

Kinetic energy does in fact require a force carrier, either in the form of a super luminal particle as most LeSage style kinetic models involve or in the form of an ether like substance in space that transfers the kinetic energy as would a "liquid". The particle problem is covered below. The ether model has its own problems. There have been some ether models of GR proposed. I am unaware of any that have been successful in duplicating the success of GR. If an ether model were found that was consistent with GR, it might provide some basis for a kinetic model of gravity, of some sort.

It would not be from ether it would be particles, most likely the smallest form of anything as in quanta. GR has never been successful at explaining how gravity works it only helps predict what it will do. GR never even attempts to explain it. As far as I know Kinetics have been the only idea offered to mechanically explain gravity.

When using a kinetic model for gravity that involves a particle as a force carrier, some portion of the kinetic energy exchange winds up as heat. There is a heat build up that exceeds any reasonable rate of dissipation, which results in the vaporization of atomic structures.

If this is the best argument against kinetic gravity then its still doing better than any other theory offered. I don't think the heat dissipation would be a problem besides it could never be as big a problem as the singularity that standard gravity causes and no one has a problem with that. As for heat there seems to be plenty at the center of dense planets.
One idea I never hear anyone speak of is the possibility of quanta being packed so dense at the center that they couldn't move anymore. Without movement there could be no heat and wouldn't that be completely cold? Wouldn't that be the perfect heat sink?

I think that the kinetic models that have been proposed have been dismissed, because they have not duplicated the predictive success that GR has and in each case there have been some fatal flaw(s), as mentioned above.

Kinetic models conform to the standard laws of motion and are completely predictable.

Personally, I like the idea of a kinetic model, though I have not seen or come up with one that stands up to the issues raised above. Still, it seems that a kinetic model would provide a better opportunity to reconcile some of the problems that stand between GR and QM. That does not change the fact that there is a great deal of current experience and experimental evidence that does not seem explainable from within a kinetic model. In some sense quantum gravity and loop quantum gravity do begin to approach some of those issues from what could be described as involving a kinetic model. They also have not yet been entirely successful.

Other than the issue of heat dissipation (which I don't see as a problem) what else is wrong with kinetic gravity?
Standard gravity has at least two problems much greater as in singularities and having to come up with a mystical force that can reach out billions of light years in every direction, grab hold of everything and then pull everything back and still no physical or mechanical description of how it does this.

 

[TGlad]

Kinetic gravity "Although it is not regarded as a viable theory within the mainstream scientific community, there are occasional attempts to re-habilitate the theory outside the mainstream"
:)

So the best explanation so far seems to be that gravity arises from the need for the laws of physics to be invariant under acceleration.
And the need for invariance can often be explained as simply massively bumping up the likelihood of us being in that system. Just as it is massively more likely that you will find yourself in an invariant orbit around a star than heading towards or away from one. Or massively more likely that your will be in a universe that conserves energy.

But that doesn't explain to me why we don't see invariance in higher derivatives of time, why aren't the laws invariant under a frame of reference that is jerking?

 

[bill alsept]

Kinetic gravity "Although it is not regarded as a viable theory within the mainstream scientific community, there are occasional attempts to re-habilitate the theory outside the mainstream"
:)

So the best explanation so far seems to be that gravity arises from the need for the laws of physics to be invariant under acceleration.
And the need for invariance can often be explained as simply massively bumping up the likelihood of us being in that system. Just as it is massively more likely that you will find yourself in an invariant orbit around a star than heading towards or away from one. Or massively more likely that your will be in a universe that conserves energy.

But that doesn't explain to me why we don't see invariance in higher derivatives of time, why aren't the laws invariant under a frame of reference that is jerking?

I'm not sure if your for or against kinetic gravity?

If you were explaining how gravity actually work in some way I didn't get it.

 

[TGlad]

Oh sorry Bill, I am against Kinetic gravity, but my own opinion isn't very important so that was a link to a wikipedia article with citations explaining why it isn't a viable theory.

The rest was referring to https://www.physicsforums.com/showpost.php?p=3441303&postcount=30".

 

[D H]

Yikes! This thread is a mess, particularly the last page or so. Rather than wasting my energy to clean it up, this thread is locked.

Final note: Le Sage's theory of gravitation is and always has been a crackpot theory. Discussions of fringy and crackpot notions are not condoned at this site. PhysicsForums is a site for discussions and questions regarding mainstream science.