Why Do Physicists Postulate the Existence of a Graviton?

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Discussion Overview

The discussion revolves around the question of why physicists postulate the existence of a graviton, particularly in the context of gravity being described as the bending of spacetime in Einstein's theory of relativity, rather than as a force. The scope includes theoretical considerations, quantum mechanics, and the interplay between general relativity and quantum theories.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Exploratory

Main Points Raised

  • Some participants note that while there are force-carrying particles for other fundamental forces, gravity is described differently in general relativity, leading to confusion about the necessity of a graviton.
  • It is mentioned that the current theories of gravity and quantum mechanics do not align well, indicating an ongoing area of research.
  • One participant argues that there is no requirement for a graviton, as general relativity is not a quantum theory and gravitons have not been observed.
  • Another participant suggests that the prediction of gravitational waves in general relativity implies a need for quantization, which supports the argument for the existence of gravitons.
  • A later reply reiterates the argument for gravitons based on the quantization of waves, while also expressing appreciation for the clarity of the previous response.
  • There is a question raised about the reasoning behind postulating a heavy particle for gravity, given its long-range effects.

Areas of Agreement / Disagreement

Participants express differing views on the necessity and existence of gravitons, with no consensus reached on the topic. Some argue for the likelihood of gravitons based on theoretical grounds, while others challenge the need for such a particle.

Contextual Notes

The discussion highlights the unresolved nature of integrating quantum mechanics with general relativity, as well as the lack of empirical evidence for gravitons.

Psyguy22
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We know that there are force carrying particles for the strong and weak nuclear force, and the electromagnetism force. But in Einsteins theory of relativity, he states that gravity is the bending of space time, not a force. So if there is no force, why do we say there must be a graviton?
Ps I'm just an undergrad student that has a interest in particle physics. I just don't understand most of it!
 
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This is an open question in physics that many people are working on. The "classical" or general relativistic theory of gravity and the way we look at things from a quantum perspective (like in particle physics) do not mesh as they are now.
 
There doesn't have to be a graviton. It's just that current quantum theories use the concept of "force mediators" in the form of bosons to explain how different particles interact with each other. However, General Relativity is not a quantum theory. We have yet to develop a quantum theory of gravity nor have we observed gravitons, so we cannot claim that gravitons exist.
 
Even though gravity isn't a real force, GR predicts the existence of gravitational waves and according to QM all waves without exception must be quantized hence the need for the graviton. While the above argument isn't really a "proof", it is definitely a strong argument making the existence of gravitons highly likely.
 
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dauto said:
Even though gravity isn't a real force, GR predicts the existence of gravitational waves and according to QM all waves without exception must be quantized hence the need for the graviton. While the above argument isn't really a "proof", it is definitely a strong argument making the existence of gravitons highly likely.

This is the first EVER answer to this question, in over a decade of asking and searching, that I can accept as actually addressing the issue. Brilliant. Lots of like!

So is this why quantum physicists postulate a heavy particle rather than an essentially weightless one, as the infinitely long range of gravity would seem to require?
 
TerribleTadpole said:
So is this why quantum physicists postulate a heavy particle rather than an essentially weightless one, as the infinitely long range of gravity would seem to require?

Who does this?
 

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