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Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: geordief on 09/10/2021 15:54:40

Title: Could mass be considered as an excitation of the gravitational field?
Post by: geordief on 09/10/2021 15:54:40
Perhaps I am just regurgitating scientific jargon ,but might it be another way of looking at the relationship between mass and the gravitational field(which I think I may have told is not to be viewed as a physical object and rather a set a of measurements)

Anyway ,does my question have any merit?

Also,however defined , can we imagine the gravitational field to have been established in its initial form  after the BB and to be metamorphosing (changing shape) ever since

I think Einstein  may have used the "mollusk" description about it.

https://www.physicsforums.com/threads/what-einstein-meant-when-he-termed-something-a-mollusc.391139/
Title: Re: Could mass be considered as an excitation of the gravitational field?
Post by: Halc on 09/10/2021 16:47:44
way of looking at the relationship between mass and the gravitational field
You'll have to describe what gravitational field you're speaking of. There is a gravitational potential field, which is a relative (not absolute) scalar at any point, and there is the gravitational strength field, which is the derrivative of the potential field. This is not relative, and is a vector at any given point.

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Anyway ,does my question have any merit?
I think so. Mass certainly effects both, but expressing it that way differs in some ways from the typical 'excitation of field' description. Most importantly, excitations imply positive energy relative to the non-excited state, but it is negative energy with mass present. Empty space with no mass in it has more (zero) energy than does the negative energy of the same space with an object in it.

The 'excitation' doesn't move, but changes to the distribution of it is something that travels at light speed, hence gravitons and gravitational waves, which very much are excitations and fields. So there is a field, but excitations of it move at lightspeed, and gravity doesn't do that any more than gravitons are responsible for the attractions between planets.

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Also,however defined it, can we imagine the gravitational field to have been established in its initial form  after the BB and to be metamorphosing (changing shape) ever since
Sounds good. The potential has been going up ever since the initial maximum negative value of the big bang. The strength on the other hand has been increasing as the energy distribution changed from completely uniform to today's very localized concentrations of mass/energy.

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I think Einstein  may have used the "mollusk" description about it.
Einstein seemed to use the word to describe arbitrary (abstract) coordinate systems (ones that are not inertial or not in Minkowskian spacetime) and not about physical fields, gravitational or otherwise. That's how I read it at least.
Title: Re: Could mass be considered as an excitation of the gravitational field?
Post by: Black hole on 15/10/2021 18:57:09
Perhaps I am just regurgitating scientific jargon ,but might it be another way of looking at the relationship between mass and the gravitational field(which I think I may have told is not to be viewed as a physical object and rather a set a of measurements)

Anyway ,does my question have any merit?

Also,however defined , can we imagine the gravitational field to have been established in its initial form  after the BB and to be metamorphosing (changing shape) ever since

I think Einstein  may have used the "mollusk" description about it.



The simple answer is no ,because gravitational fields are an extension of mass !
Title: Re: Could mass be considered as an excitation of the gravitational field?
Post by: yor_on on 29/10/2021 07:15:45
" Could mass be considered as an excitation of the gravitational field?  "

Maybe? There are different definitions and they go back to a question if SpaceTime is a continus or a discrete expression. I've seen both definitions, f.ex gravity as something 'discrete', meaning that there should be some smallest 'part' of it, or as a continuum in where you can magnify however much you like without finding any 'parts'. SpaceTime relies on the concept of 'energy' and energy is very ill-defined if you want to quantize it. As JP called it, a 'coin of exchange'' not a 'substance' containing parts.