Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: sprain on 11/01/2022 18:29:45

Title: can gravity be a push instead of a pull?
Post by: sprain on 11/01/2022 18:29:45
the way gravity is commonly represented is as a fundamental force that bends spacetime, and the bend in spacetime is what causes all matter to attract towards each other. this is a good abstraction to visualize how gravity works in the universe, but only in terms of time and space.

theory:
is it physically sound to represent gravity as a force that pushes some unknown limitless particle or wave out of all matter, and that split propels the matter towards the source of gravity? for example, a star and all its matter emits gravity outwards in every direction, which naturally loses concentration in quantity over distance. every time gravity interacts with matter, like a nearby planet, it knocks out some elementary particle with the same force as gravity and in the direction it was first hit. then, newtons first law works out and all the matter in the planet, now separated from this hypothetical particle, moves with the same force as gravity but in the opposite direction of the gravity, which would bring it towards the sun. the hypothetical particle that's ejected could be what we detect as gravitational waves.

metaphysically it seems appropriate, no matter now physically inappropriate it seems. gravity itself has a constant force, and each incoming gravity particle or wave would impart the same amount of force on matter. what makes gravity 'stronger' or 'weaker' at certain distances is the idea that more of these particles are hitting the matter at any given span of time, each collision producing its own outgoing gravitational wave. the real question is determining how gravity itself navigates space and time, and whether it shoots out in random directions or all directions at once.

this is mostly just an abstract concept, but im interested to hear how the actual math of physics could contradict this or if any other theories for gravity may be similar.
Title: Re: can gravity be a push instead of a pull?
Post by: Origin on 11/01/2022 19:04:05
theory:
is it physically sound to represent gravity as a force that pushes some unknown limitless particle or wave out of all matter, and that split propels the matter towards the source of gravity? for example, a star and all its matter emits gravity outwards in every direction, which naturally loses concentration in quantity over distance. every time gravity interacts with matter, like a nearby planet, it knocks out some elementary particle with the same force as gravity and in the direction it was first hit. then, newtons first law works out and all the matter in the planet, now separated from this hypothetical particle, moves with the same force as gravity but in the opposite direction of the gravity, which would bring it towards the sun. the hypothetical particle that's ejected could be what we detect as gravitational waves.
It sounds pretty vague.  The biggest problem I see is that for particles to accelerate the mass you would have to have most of the mass be converted to the hypothesized particles.  Someone on the surface of the earth would continuously loose weight in your scenario.  This doesn't look like a workable idea.
Title: Re: can gravity be a push instead of a pull?
Post by: evan_au on 11/01/2022 19:54:05
Quote from: OP
unknown limitless particle or wave out of all matter ...for example, a star and all its matter emits gravity outwards in every direction, which naturally loses concentration in quantity over distance
Yes, there is such an unknown particle with unlimited range, and it has been given a name: Graviton.
https://en.wikipedia.org/wiki/Graviton

Most physicists think that the Graviton exists, but the energy of a single Graviton is so low that we have no chance of detecting a single graviton with current technologies. The best we can do is to detect large numbers of coherent gravitons acting as a wave; these are emitted from high-energy events like colliding black holes.
https://en.wikipedia.org/wiki/LIGO

We have a good theory about how gravitons work in our solar system, but there are some problems with the theory in the extreme environment close to the event horizon of a black hole.
Title: Re: can gravity be a push instead of a pull?
Post by: Eternal Student on 11/01/2022 22:59:48
Hi.

     I would mostly agree with Origin.   However, the ejected particles could be massless but still carry some momentum (similar to photons).  So there doesn't have to be a loss of mass from the gravity receiving object.   This does really tie down the properties of these hypothetical ejected particles quite a bit:   They would need to be light speed particles,  so it would seem that they would carry an amount of energy  = p.c    (with p = their momentum).   So the gravity receiving object is still going to be losing energy.   

    Now, I suppose you could compensate by arguing that it would actually absorb the gravity "wave or particle" that first hit it, rather than just let that gravity thing pass on by.  So, this assumes the gravity "thing" which first hit it is some sort of particle carrying much the same amount of energy that will soon be ejected etc.  This gravity "thing" is looking a lot like a graviton.

.... im interested to hear how the actual math of physics could contradict this or if any other theories for gravity may be similar....
    I've got to agree with Evan-au,  your proposed theory does sound like it has a lot of overlap with theories for force carrying particles called gravitons.

    Next, there is the concern about what happens beyond or "in the shadow" of the gravity receiving object.  If it really did absorb all the gravity particles from the gravitational source then there is effectively a shadow, a region behind the gravity receiving object where the original gravitational source can no longer be felt.   This isn't how gravity behaves:   For example, you can't screen yourself from the gravitational pull of the earth just by laying down some wooden planks between yourself and the earth,  otherwise we'd all end up floating around our houses rather than being pulled to the floor as usual.
   So, I suppose you could make sure that there isn't any sort of "shadow" behind the gravity receiving object by insisting that the hypothetical ejected particles will actually also be gravity causing particles themselves.  So, this is suggesting that the hypothetical ejected particles might also be gravitons.  So the gravity receiving object might absorb a graviton at the front end and kick out a new but perfectly equivalent graviton out of the back end of the object.   Sadly, now we would have defeated the original attempt to make sure the ejected particles would have some momentum to carry away - since if they do then the incoming graviton at the front end was just the same and it's momentum had to be added to the gravity receiving object.

    Hmmm...   well, it's not my theory and maybe you would suggest other things.   

Best Wishes.
Title: Re: can gravity be a push instead of a pull?
Post by: alancalverd on 12/01/2022 17:16:39
The problem with the pushing particles is that they have to know where to go, so the massive body has to radiate some signal telling the pusher (a) where it is and (b) the shortest vector to the next massive body, so that pushing particles moving in the opposite direction don't get in the way.

My name for the radiating signal is "gravity". But I still don't know why it sucks.
Title: Re: can gravity be a push instead of a pull?
Post by: Petrochemicals on 14/01/2022 06:48:42
If the particles are travelling in all directions I do not see why not providing that they are blocked by matter, the net sum would be weight. As one particle arrives another arrives.

If relativity is dense space, that is to say a different spacetime distance for different areas of an optically identical area, both travelling in fact the same distance, it does give rise to the theory of pushing or pulling due to space time. How would space time curvature become curved?
Title: Re: can gravity be a push instead of a pull?
Post by: alancalverd on 14/01/2022 18:19:10
Let's simplify the model by having two spherical lumps of the same material, immersed in a field of pushons moving in all directions.
Put the smaller lump on the left. It shields the larger lump from a few pushons, so the larger lump experiences a small net force to the left.
The larger lump shields the smaller one from more pushons, so it experiences a large net force to the right.
So far, so good, but do we get a 1/r2 effect?
And where do the pushons come from?
Title: Re: can gravity be a push instead of a pull?
Post by: Petrochemicals on 14/01/2022 19:08:49
So far, so good, but do we get a 1/r2 effect?
And where do the pushons come from?
Probably Alan. But that would need to understand the mechanics of pushons, would a 45 degree strike mean a 50% energy? Would it be like billiards or photon absorbtion? Etc etc.
Title: Re: can gravity be a push instead of a pull?
Post by: Eternal Student on 14/01/2022 22:19:45
Hi.

That's an interesting idea, Alancalverd, let's have a look at that.

So far, so good, but do we get a 1/r2 effect?
    We really want an  M   on the top   and also the   r2 on the bottom.  Let's get it all if we can.

    You've talked about shielding effects.   So I'm imagining something like the pushons traveling in straight lines....
So the shielding would actually depend on the size of the object,  where "size" is measured in the usual way by  the amount of space it occupies and thus how much space it can block out from the the other object and stop it receiving pushons.....
   That's not what we want, it should depend on the mass, M, not the physical size....
   So I guess you'll be wanting to re-imagine what density is..... density could be a measure of the objects "block-ability" - it's ability to block pushons passing through it.    Then   (density) x (space occupied)    does get us back to  mass, M.  So far, so good.

    Now let's see if we can get the 1/r2  .....    We can consider a solid angle blocked out by an object at a distance d and obviously we're going for spherical everythings....   If you can sketch that yourself, that'll be great....  I'll just mumble and pretend I spent the time to prepare the diagram with a graphics package.....   
   So, looking at the diagram we're considering solid angles and let's have θ be half the angle subtended at the apex of the cone,  then if that's the cone blocked  by an object of  height (diameter) h   at a distance d from the object on the right  then we see the relation  Sin θ = h/d.
   Next, we're going to need the sort of thing Petrochemicals was talking about.... the momentum of an incident pushon resolved along the x-axis for an incoming angle  Ψ  might go like   p. Cos Ψ.....   need to do some integration here ... If you could do that, that'll be great -  I'll mumble and pretend I spent the time to create all the LaTex forumlae...
    Now let ψ vary between 0 (straight along) and θ (the edge of our solid angle or cone shape blocked out) and we can sum all the momentum along the x-axis that is being blocked out.
   Well that's a shame, we seem to be hitting some limits.   
    I could check it again but it seems there would have to be an upper limit on gravity.   I'll tell you what - let's just look at one example instead of the maths.  I'm not sure about you but that integration was a bit tricky and there's no need go over that again....     Instead, just imagine the object on the left is a fixed distance d away from the object on the right but it is massive (in physical size), so  that it blocks out almost 2π steradians from the other object (the gravity receiver).    Well, that's it, that's the maximum push the object on the right is ever going to get, it's getting nothing to push it on the left and there's no more we can take away from the left side of it.   

    However, gravity doesn't seem to have a limit like that, if we keep increasing the mass of the object on the left then the thing on the right should feel more force.

   We're almost stuck.   I suppose it is possible to assume there is an infinfite supply of these pushons found in space, so even though an upper limit for the force of gravity is obtained when the gravity source blocks out half the sky that limit could still be infinity.
   I'm not going to suggest how you could work with these infinities:   It's your suggestion, Alan, you determine how this will be re-normalised.

Best Wishes.
Title: Re: can gravity be a push instead of a pull?
Post by: alancalverd on 15/01/2022 09:45:24
So the shielding would actually depend on the size of the object,  where "size" is measured in the usual way by  the amount of space it occupies and thus how much space it can block out from the the other object and stop it receiving pushons.....
No need for that complicated diversion (even though you end up in the same place!). We are familiar with the absorption of photons and other radiation, which depends on the amount of stuff (electrons or nucleons) in the path of the beam, and hence the mass of the absorbing object.

But I think you have identified a significant problem with pushons: the gravitational field downstream of an object depends on its cross-sectional area as seen from the test point, so a thin cylinder will have a smaller effective mass "end on" than "side on".

Just shows the danger of simplified models - my "spherical lumps" are actually a special case, not a generalisable one!  Which is a pity, because the idea that the observable universe is subject to an overall collapsing force would resolve a lot of questions.
Title: Re: can gravity be a push instead of a pull?
Post by: MrIntelligentDesign on 15/01/2022 21:58:36
YES! Gravity is a pushing force, that is the testable reality, that is how we can test and demonstrate. If Gravity is not a pushing force, then, you cannot detect gravitational wave or bending of light... Even Michio Kaku accept that fact.

This is one of many topics that I had discussed in my Physics book, "[book removed]"...

And the pushing photons? I called it "squeezon".

It is so easy for anybody to demonstrate GRAVITY in a pool of water and balloons

I also discuss the Uncertainty Principle that is not really uncertain... too many interesting topics... see ya!
Title: Re: can gravity be a push instead of a pull?
Post by: Kryptid on 15/01/2022 23:10:04
Please don't use other people's threads to advertise.
Title: Re: can gravity be a push instead of a pull?
Post by: Centra on 27/01/2022 21:34:19
I don't think there are particles being shot out, no, because gravity affects the inside of objects, not just the outer surface, and it can't be shielded, you would be able to shield particles.
 
Title: Re: can gravity be a push instead of a pull?
Post by: Kryptid on 28/01/2022 23:18:44
you would be able to shield particles.

That very much depends on the nature of the particles. Neutrinos are extraordinarily difficult to shield against, as one example.