General Relativity. Can the strength of gravity reduce for dense masses?
New discussion
Is there anything in Einstein’s Field Equations that allows the strength of gravity to reduce for regions of high mass/radius ratio? It could be desirable for two reasons.
Reason 1) From Newtonian considerations. The flatness problem is equivalent to (for each mass m).
mc^2-GMm/R=0 (1)
G=Rc^2/M (2)
Where M and R represent the mass and radius of the rest of the universe up to the Hubble radius. Small numerical constants omitted for simplicity.
For a larger mass, with the self-potential energy term included
mc^2-GMm/R-(Gm^2)/r=0 (3)
r is the radius of mass m , leading to
G_reduced = c^2/(M/R+m/r) = G/(1+Gm/(rc^2 )) (4)
i.e. a reduction in G for masses of high m/r ratio, approaching c^2/G
Reason 2)
It would allow bounces or explosions form galactic centres and avoid a situation of infinite density and pressure. It could account for the ‘foam’ like large scale structure.
It's part of a new cosmology
https://www.researchgate.net/publication/342040580_A_New_Solution_of_the_Friedman_Equations
that predicts an apparent omega(m) of between 0.25 and 0.333 and matches supernovae data without a cosmological constant.
Well gravity will depend on masses rather on density. If two objects are there with same masses and different densities they will have same gravitational field. Though I follow Tesla's dynamic theory of gravity.
Yes, the masses determine gravity, but in extreme cases, but... if G(effective) = G(1 - Gm/rc^2), then there's a good way to avoid singularity problems and explain explosive events such as AGNs, it's insignificant for most masses such as the sun, but significant for galactic centres.
Well I think you are talking about supernova explosions. They are caused due to the gravitational pull by other heavy mass celestial bodies according to recent studies. (ref - https://www.ias.edu/ideas/2013/katz-dong-kushnir-1a-supernovae ). It states that when the gravitational pull of the stars core becomes lesser than the pull exerted by nearby celestial bodies on its outer layer then a supernova explosion can take place. My understanding of gravitation also supports it.
The 'reduction' mechanism might be involved in supernovae explosions - although apparently the physics of supernovae is understood with conventional physics...but at 1.4 solar masses and radius of 10km, the conditions are right for the mass/radius to approach c^2/G. I
t was more to do with AGNs whose mechanism isn't as well understood. Perhaps a future theory of gravity approximating GR, will contain the feature that G reduces when m/r approaches c^2/G - can such a theory be possible?
I think its not and also General Relativity is a theory only and its practical implications are very limited. I think G should stay a constant as it is even if m/r or the density increases. The AGN nuclei is composed of super massive black holes that has very high mass hence gravity. So its field will be very high near it and also that has effects till the outer layers of galaxies. Beyond that its field is almost negligible. But when these black holes had larger radius and were in the form of a star then the range of gravitational field would be different for its surface gravity and for different layers of the star. The field that could be noticed will only be due to its surface gravity. The field reduces with distance while for the other inner layers of the star will also have a gravity the range of whose field will be inside the field of the surface layer. This is why at the places where the field is for both the surface layer and inner layer the net field adds up. These two reasons are why gravity is more near surface and less at a further distances. Now when it forms a black hole its mass is still the same but more than the surface layer of the star because the whole mass acts as single point hence the whole mass can be thought as the surface of the black hole and that corresponds to gravity. For this reason the range of its gravitational field will also be more than that for the surface layer of the star. Also it seems that almost whole of the mass adds its field to the range here specified which increases the intensity of the field. This is why it seems that the gravitational field is more for black holes than stars which do have same mass but different radius. Hope this explains your question.
Our universe with over 100 billions of galaxies, where each galaxy is holding billions of solar system that none of them is the same, but following same principle of planets go around a sun, is not mechanical. The building block of universe is Quantum Mechanics phenomenon, therefore Gravity is Internal NOT External as Mr. Newton or Einstein or big bag fan stating. we are much smarter than hundred years old theory.
Article Gravity is an Internal Force
Article How the Quantum Universe Works
[Software glitch, I can only read first 3 lines of question.] Solving Einstein's Field Equations for extended central mass M embedded in a vacuum yields an exterior gravitational attraction dependent on M but not on density, ie. there is no shielding. If however M is embedded in a constant background density, the central gravitational attraction is dependent on, and decreases with, background density.
Dear Kathleen Rosser
Gravity cannot be create by any mass, but gravity is holding the mass. On other hand Gravity is Internal Not External.
Article Gravity is an Internal Force
Dear Javad Fardaei , (I have a ResearchGate software problem, so I can only read the first 2 lines of what you said, and my own answer can't be more than 5 lines.) How gravity is created, alas, is not addressed by general relativity, and few alternate theories today discuss the topic, despite its critical importance. My answer above was based strictly on general relativistic calculations.
Dear Kathleen Rosser I am rejecting mechanical theory of GTR, and presenting QM universe. including Gravity, as Internal not external, if you go to my file you see, regard,
If anyone knows a way in which gravity can reduce for dense matter that would be useful for avoiding singularity problems. It would have to approximate GR of course.
The only model that allows/predicts a reduction of the strength of gravity on density is the STOE. But then it is not strictly the density that allows the reduction, it is the apparent cross-section of the matter. Hence, the observation of a radial relationship of the Z (atomic number of atoms) in spiral galaxies.
Also, the observation of light bending around stars (direction of travel perpendicular to the radial distance to the star) compared to theoretically NO acceleration of the light from objects (Earth) straight ahead.
Hi John Hunter,
Instead of "reducing gravity", what about "reducing the mass of matter" once neutron degeneracy pressure is exceeded? For example, in a collapsing neutron star, what if the mass of those neutrons were to be reduced during the collapse?
Recall that a neutron is thought to get 99% of its mass from (1) a cloud of virtual gluons, and (2) the momentum of its quarks. Only 1% of the mass of a normal neutron is thought to come from its quarks interacting with a Higgs type field.
Which makes me wonder: if the quarks in each neutron can be "confined" by gravity instead of by gluons, there'd be no need for all that glue (and the associated mc^2). Also, as gravity confines the range for those quarks to move, their momentum might also be reduced (asymptotic freedom).
Which raises the question: in a collapsing neutron star, as all those neutrons become increasingly compressed by gravity, as the mass each neutron gets from gluons and momentum disappears, does this mean that the mass of a collapsing neutron star reduces as it shrinks?
Nigel
Dear John Hunter
The Big Bang , or GTR is not science to have exact way to be calculated, just what ever it comes to your mind is correct.
Our universe with our 100 billions of galaxies ?, where each is carrying billions of solar system like our, mathematic calculation be exhausted anyway.
By the way, what ever Mr. Einstein said is not working for our universe, he made up everything before look up and see how universe is working. We should seek how the universe is working, not how the universe should work.
https://www.academia.edu/38670214/The_Theory_of_Everything
regard.
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