Gravity and massless particles

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Discussion Overview

The discussion centers around the interaction of gravity with massless particles, particularly photons, and the implications of gravitational lensing. Participants explore the nature of gravity as a curvature of spacetime and how this relates to massless particles in the context of general relativity.

Discussion Character

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

Main Points Raised

  • One participant seeks clarification on how gravity, a function of mass, interacts with massless particles like photons, questioning if the explanation is straightforward.
  • Another participant affirms that gravity as local curvature of spacetime allows photons to be affected by it, suggesting a simple understanding.
  • Questions arise about whether massless particles can create gravity or attract each other while moving through spacetime.
  • It is proposed that massless particles can indeed contribute to gravitational effects, referencing the stress-energy tensor in general relativity, which includes energy and momentum as sources of gravity.
  • Energy-mass equivalence is mentioned, indicating that gravity can be described as a function of energy rather than just mass.

Areas of Agreement / Disagreement

Participants express varying degrees of understanding and agreement on the nature of gravity's interaction with massless particles, with some affirming the connection while others question the implications of massless particles creating gravity. The discussion remains unresolved regarding the extent of these interactions.

Contextual Notes

There are limitations in the discussion regarding the assumptions about the nature of gravity and massless particles, as well as the dependence on definitions of energy and mass in the context of general relativity.

Who May Find This Useful

This discussion may be of interest to those exploring concepts in general relativity, the nature of gravity, and the behavior of massless particles in physics.

dschwie
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Just finished reading Sean Carroll's "The Higgs Boson and Beyond". I would be grateful if someone could explain how gravity, which I understand to be a function of mass, can interact with massless particles as evidenced by the phenomenon of gravitational lensing. I understand that gravity is a local curvature of spacetime and photons move through spacetime so that makes sense. Is the explanation as simple as that?

Thanks and regards.
 
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Yes but would massless particles like photons moving through space make gravity.
So in effect could massless particles moving through space time attract each other.
 
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Buckleymanor said:
would massless particles like photons moving through space make gravity.
Yes. In general relativity, the "source" of gravity is the stress-energy tensor, whose components contain the energy and momentum of an object. Mass is only one form of energy.
 
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Energy mass equivalence, gravity can also therefore be described as a function of energy.
 
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