Is Gravity a Force or Curvature?

  • #1
jazamm
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The Wikipedia article on Quantum Gravity reads: "The observation that all fundamental forces except gravity have one or more known messenger particles leads researchers to believe that at least one must exist for gravity. This hypothetical particle is known as the graviton"

To which... yikes. Is this true? If so, why on earth?? Should it not instead read "the observation that gravity is a curvature and not a force leads researchers to believe that messenger particles are unlikely to be related to gravity as they are to the three forces."

Is the attempt to unify the theories really happening by just eschewing the relativistic concept of gravity and forging ahead treating it as if it were indeed a "force," and Einstein's model is just wrong?

I can't imagine anyone would do that, (although I guess the old adage "to a man with a hammer, everything looks like a nail" is possible).

Please let me know if there is any other quantum paradigm with which this is being approached, that maintains gravity is the shape of space and time, and is not a force, therefore very unlikely to be mediated by any particle. (Even if ultimately it can be modeled as such through considerable extra acrobatics).

Sorry if I seem a little incredulous, not at you folks but at the Wikipedia article and its potential for misinformation.

Please let me know what I'm misunderstanding, thanks so much in advance for your help.
 
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The very short (and very layperson's) answer is that General Relativity and Quantum Mechanics are mutually incompatible theories. When we try to apply them both to the same scenario, we are inundated with infinities arising from the continuous field nature of the former and the discrete particle nature of the latter. Heisenberg's Uncertainty Principle raises its ugly head (If it's a field, then you have can two events immeasurably close to each other, which results in energy transfers that go off-the-charts).

So, our current understanding of the compatibility of the very large with the very small has to be incomplete.
 
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  • #4
jazamm said:
The Wikipedia article on Quantum Gravity reads: "The observation that all fundamental forces except gravity have one or more known messenger particles leads researchers to believe that at least one must exist for gravity. This hypothetical particle is known as the graviton"

To which... yikes. Is this true? If so, why on earth?? Should it not instead read "the observation that gravity is a curvature and not a force leads researchers to believe that messenger particles are unlikely to be related to gravity as they are to the three forces."

Is the attempt to unify the theories really happening by just eschewing the relativistic concept of gravity and forging ahead treating it as if it were indeed a "force," and Einstein's model is just wrong?

I can't imagine anyone would do that, (although I guess the old adage "to a man with a hammer, everything looks like a nail" is possible).

Please let me know if there is any other quantum paradigm with which this is being approached, that maintains gravity is the shape of space and time, and is not a force, therefore very unlikely to be mediated by any particle. (Even if ultimately it can be modeled as such through considerable extra acrobatics).

Sorry if I seem a little incredulous, not at you folks but at the Wikipedia article and its potential for misinformation.

Please let me know what I'm misunderstanding, thanks so much in advance for your help.
Newton's theory of gravity gave accurate predictions for the solar system. But, it relied on instantaneous action at a distance. Newton himself was critical of his own theory in that respect. GR was a major update to Newton's theory and, although it removed action at a distance, it included no explanation of how elementary particles create spacetime curvature. GR needs an upgrade in this respect. It doesn't mean GR is wrong, just that it cannot be the whole story.

I don't believe all potential theories of quantum gravity entail gravitons. In any case, QG is proving a tough nut to crack.
 
  • #5

FAQ: Is Gravity a Force or Curvature?

Is gravity a force according to Newtonian physics?

In Newtonian physics, gravity is considered a force. It is described by Newton's law of universal gravitation, which states that every mass attracts every other mass with a force that is proportional to the product of their masses and inversely proportional to the square of the distance between their centers.

How does Einstein's theory of General Relativity describe gravity?

Einstein's theory of General Relativity describes gravity not as a force, but as the curvature of spacetime. Massive objects cause spacetime to curve, and this curvature affects the motion of objects, making it appear as though they are experiencing a force. Objects move along the paths determined by this curvature, which are called geodesics.

What is the main difference between Newtonian gravity and Einstein's gravity?

The main difference is that Newtonian gravity views gravity as a force acting at a distance, while Einstein's General Relativity views gravity as the effect of curved spacetime on the motion of objects. Newton's theory works well for most everyday situations, but General Relativity provides a more accurate description, especially in the presence of very massive objects or at very high speeds.

Can both perspectives on gravity be correct?

Both perspectives can be considered correct within their respective domains of applicability. Newtonian gravity is an excellent approximation for most practical purposes involving relatively low masses and velocities. However, for extreme conditions, such as near massive stars or black holes, General Relativity provides a more accurate description of gravitational phenomena.

Why is it important to understand gravity as curvature in modern physics?

Understanding gravity as curvature is crucial in modern physics because it allows for more accurate predictions and explanations of astronomical and cosmological phenomena. This perspective is essential for understanding the behavior of black holes, the expansion of the universe, and the bending of light around massive objects, known as gravitational lensing. It also plays a critical role in the search for a unified theory of quantum gravity.

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