Gravity: Alternative Theories & Concepts

[Anonymous]

Has anyone got any thoughts on the alternative theory of gravity which basically goes something like this...

The universe was created in the big bang, this was when the universe basically exploded outwards and began its continuous expanding outwards. The theory is that all matter in the universe is not only explanding outwards but actually phisically explanding as well. Of course we would never know this seeing as our measurement instruments expand as well. If two objects expanded next to each other, say for example, yourself and the Earth then you would both push into each other, hence... Gravity.

I did a quick google but could only find one link which appears to be showing the same theory.

 

[SoundDust]

Scott Adams mentions it in "The DIlbert Future" near the back

 

[rynner2]

I like new theories!

This one, however, only seems to apply to objects in contact with each other - eg, us standing on the earth.

It doesn't explain how the earth's gravity keeps the moon in orbit, or how the sun keeps the planets in their orbits.

Or have I missed something?

 

[Anonymous]

Hmm, sounds crap to me.

 

[Anonymous]

The crap thing was my instinct saying that. I'll give it a bit more thought and come back to why it was crap.

 

[rynner2]

Save your brain capacity for more important things, like whistling the theme tune to 'EastEnders', or rubbing your belly and patting your head at the same time.

Oh Rats, I never could do that.

 

[brianellwood]

The universe is supposed to be expanding at an ever increasing rate according to the latest theory i read, and so its components must be accelerating. If so then the fitzgerald contraction would apply and the individual components would get smaller, if i remember rel. theory correctly. A shot in it's foot?

 

[harlequin2005]

Intersting theory of gravity I saw implied that space time 'pushed inward' into a body equally from all directions in three dimensional space. If you have two bodies, one orbiting the other, effectively the 'push' was blocked by the opposing body, thus pushing them together, the tangent force vector to the orbit keeping the the orbit stable.

The reasoning worked pretty well, predicting the inverse square law, and to a degree universal expansion of space-time, but what this mysterious force was still wasnt defined nor was its source.

I'll see if i can dig out a reference...

8¬)

 

[rynner2]

That sounds like a theory pushed by Tom van Flandern. The pressure comes from hypothetical FTL particles.

I'll dig out a link drekkly....
...'ere'tis!

Sounds plausible, IF there are FTL particles.

 

[NilesCalder]

That sounds like a theory pushed by Tom van Flandern. The pressure comes from hypothetical FTL particles.

I'll dig out a link drekkly....
...'ere'tis!

Sounds plausible, IF there are FTL particles.

Your Honours . Since popular consensus has it that Gravity is an effect based upon the curving of space-time it could be argued that it has no speed as such.

Speed is, it is said, the rate at which something moves, changes or functions. Speed in the context of the above article is the rate that gravity propigates through space time, but since, has I intend to shown, such a concept is meaningless the question "what is the speed of gravity" becomes meaningless itself.

If gravity is a function of the curveture of space-time then it cannot proigate through space in the sense that light can. Instead gravity propigates as space-time. The speed of light presumes that something is moving through space-time and not as it. A comparison would be to lay out a piece of paper, draw to dots upon it and ask what the speed of the paper is between to the dots. The paper does not move.

A comparabel, and more valid, question could be "how fast can space bend" but, with our current understanding of space-time and gravity, impossible to answer.

Niles "making sense?" Calder

 

[harlequin2005]

Bent Space Time works pretty well as a model, but so does the concept of some spooky force permeting all of the universe pushing things together. In the end, theyre both just models which fit *most* of what we see. The spooky force model, to me, falls over since gravitic lensing cannot intuitively occur, as it can with warping the fabric of space time, and which has been an observed phenomena.

One thing that sort of bothers me about the warp theory, is how does the search for quantum gravity fit in there?

BTW if gravity is a warping of space time, then it has to propagate something like a standing wave front. Try flexing the proposed piece of paper to see what I mean.

8¬)

 

[rynner2]

One thing that sort of bothers me about the warp theory, is how does the search for quantum gravity fit in there?

I'm readinga book on string theory at present, so I might have an answer in a few days

- or weeks...

Don't hold your breath!

 

[Mattattattatt]

I reckon that antigravity's just stuff moving in a straight line instead of a circle... A simple case of rebellion!

Or then again there may be more to it than that.

 

[Anonymous]

Hi all. Is it possible that, if space time does got more 'dense' towards the centre of massive (and I suppose ALL) objects. Is there a small, infinitely compressed dot of spacetime at the centre of Earth and other bodies in space? What would be its effect if it did exist?

Would the compression - IF it were real - account for the acceleration of falling objects as they go from 'thinner' to 'thicker' time?

NettiNetti

 

[Anonymous]

If gravity is a function of the curveture of space-time then it cannot proigate through space in the sense that light can. Instead gravity propigates as space-time. The speed of light presumes that something is moving through space-time and not as it. A comparison would be to lay out a piece of paper, draw to dots upon it and ask what the speed of the paper is between to the dots. The paper does not move.

A comparabel, and more valid, question could be "how fast can space bend" but, with our current understanding of space-time and gravity, impossible to answer.

Niles "making sense?" Calder

I think that you will find that the answer to your last question is that the deformations propagate with the speed of light. This is the origin of gravitational waves. (i.e. gravitational fields travel at the speed of light, at least within the confines of GR.)