Do photons have mass experiment?

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SUMMARY

The discussion centers on the nature of photons and their mass, specifically addressing the misconception that photons must have mass due to their behavior in gravitational fields. Participants clarify that photons possess zero rest mass but can exhibit momentum, which leads to bending paths in gravitational fields. The conversation also touches on the concept of invariant mass in systems of photons and the implications of relativistic mass. Key points include the distinction between rest mass and momentum, as well as the behavior of photons in different reference frames.

PREREQUISITES
  • Understanding of special relativity and the concept of mass-energy equivalence.
  • Familiarity with the principles of momentum and its relation to mass.
  • Knowledge of gravitational effects on light and the bending of light paths.
  • Basic comprehension of invariant mass and reference frames in physics.
NEXT STEPS
  • Explore the implications of Einstein's theory of relativity on mass and energy.
  • Study the concept of invariant mass in particle physics.
  • Investigate the behavior of light in gravitational fields and its effects on trajectory.
  • Learn about the properties of photons in superconductors and their effective mass.
USEFUL FOR

Physicists, students of physics, and anyone interested in the fundamental properties of light and its interaction with gravity and mass.

  • #31
RobertsMrtn said:
Another question is - can they be said to have kinetic energy? The standard formula for kinetic energy being 1/2mv^2 which of course becomes 1/2mc^2

In Special Relativity, the kinetic energy of a particle is defined as KE=mc2-m0c2 where m0 is the rest mass. That is zero for a photon, so its KE equal to its energy, KE=mc2=hf.

ehild
 
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  • #32
RobertsMrtn said:
Correct me if I am wrong but I don't think that there is such a thing as a photon which is at rest.
Indeed. In order to define an object "at rest" in special relativity, we must first construct an inertial frame and then define an object "at rest" simply as one whose velocity relative to this frame vanishes. As a consequence of one of the fundamental postulates of special relativity, there exists no inertial frame in which light has vanishing speed hence the notion of "at rest" in the above sense does not apply to light.
 

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