Gravity: Particle or Shape of Space?

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Discussion Overview

The discussion revolves around the nature of gravity, specifically whether it is transmitted by a particle (such as a graviton) or if it arises from the curvature of spacetime. Participants explore theoretical implications, comparisons to historical concepts like aether, and the challenges of reconciling different theories of gravity.

Discussion Character

  • Debate/contested
  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants propose that gravity could be due to the shape of space, questioning its similarity to the aether concept.
  • Others argue that quantum theory suggests gravity should be quantized, implying the existence of a particle, but this does not negate spacetime curvature.
  • There is uncertainty about how particles, such as gravitons, would interact with spacetime and whether they would themselves cause curvature.
  • One participant speculates that spacetime curvature might correlate with graviton density at a point in space.
  • Another participant raises the idea that if spacetime is a matrix of gravitons, it resembles an aether-like substance.
  • Different theories interpret gravity in various ways: Newton's instantaneous force, Einstein's curvature of spacetime, and quantum theory's discrete picture with gravitons.
  • There is a suggestion that the relationship between gravity and other fundamental forces remains unclear, and the unification of these theories is a significant challenge.
  • One participant expresses confusion about the inverse square law arising from the distortion of spacetime fabric.

Areas of Agreement / Disagreement

Participants do not reach a consensus, as multiple competing views on the nature of gravity remain. The discussion reflects a range of interpretations and uncertainties regarding the relationship between gravity, spacetime, and quantum mechanics.

Contextual Notes

Participants acknowledge limitations in their understanding of general relativity and quantum theory, and there are unresolved questions about the implications of graviton density and its relation to spacetime curvature.

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Is the force of gravity transmitted by a particle or is gravity due to the shape of space (of some sort).

If gravity is due to the shape of space, why isn't this similar to the aether concept?
 
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Quantum theory indicates that gravity should be quantized, which would mean having an associated particle. This does not, as far as I know, eliminate spacetime curvature.

This is completely different from aether theory. The aether is a postulated substance acting as a universal frame of reference against which everything could be measured. Modern physics has demonstrated that no such frame of reference exists.
 
Quantum theory indicates that gravity should be quantized, which would mean having an associated particle. This does not, as far as I know, eliminate spacetime curvature.

I don't understand why the force of gravity would be transmitted by a particle if gravity is thought of as a curvature. Do the particles curve spacetime?
 
Something I personally have never understood about gravitons. Will they themselves have energy and so cause curvature? I'm not qute sure about how massless particles affect spacetime, my understanding of GR is crude at best (though improving slowly =]).
 
Spacetime curvature might be graviton density at that point in space. (speculation)
 
If spacetime is a matrix of gravitons of differring density, it sort of sounds like an aether like substance.
 
differing density?
 
I might have misunderstood the other poster (speculating that the density of gravitons is what curves spacetime).
 
Pjpic said:
If gravity is due to the shape of space, why isn't this similar to the aether concept?
Because you cannot assign a velocity to curved spacetime.
 
  • #10
Curvature being graviton density (one assumes that means number of gravitons per unit spacetime i guess?) then would this mean that something producing a gravitational field would have to emit gravitons at a constant rate? so as to keep the curvature at a point the same, and thus the force the same?

Gravity confuses me, i need to go read a book.
 
  • #11
Different theories "see" (interpret) gravity differently:

Netwon: an instantaneous force , three dimensions of space, space and time is fixed

Einstein: curvature of space time, not a force, wave field like theory,continuous smooth, cosmic sizes, four dimensions of spacetime with variable space and time

Quantum theory: gravitons are the carrier of gravity, discrete picture, atomic realm


Trying to precisely compare all these is difficult: The first two are quite complementary and Einsteins picture simplifies to Newtons in many cases; Nobody knows how to "unify" the last two..it's been one of the major objectives since the 1920's. Einstein shows that gravity occurs due to mass, energy and pressure.

String theory has a slightly different view from any of the above: It views all particles, gravitons included, as vibrating bits of two dimensional energy...different vibrational patterns cause different particles in 11 dimensional spacetime.

Gravity is also related to the other three forces (strong,weak, electromagnetic) but nobody knows exactly how. And Maybe Higgs bosons (field) are also related to gravity since they theoretically cause mass and mass in turn causes gravity.

In some vague sense you might consider curvature of space and aether "similar" in that both are "something". But curvature of spacetime is far more fundamental and subtle than "aether". Aether was postulated to carry light; it had nothing to do with any other force, such as gravity. gravitational curvature is unnecessary for the other forces; aether has been pretty well proven to be no existent.

"We know a lot, we understand little."
 
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  • #12
quantum theory sees space as consisting of a vast number of quantum oscillators. these can be thought of as tiny masses connected by springs. its easy to imagine how a mass could distort such a fabric. its not so easy to see how one gets an inverse square law out of that distortion.
 
  • #13
"We know a lot, we understand little."[/QUOTE]


Thanks, that gives me the sense of it.
 
  • #14
Pjpic said:
If spacetime is a matrix of gravitons of differring density, it sort of sounds like an aether like substance.

As massless particles, gravitons must move at the speed of light.
 

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