Do All Massless Particles Travel at the Speed of Light?

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Discussion Overview

The discussion revolves around the question of whether all massless particles can travel at the speed of light, specifically focusing on photons and neutrinos, as well as the implications of mass in relation to speed. Participants explore theoretical and conceptual aspects of massless particles, their properties, and the nature of light speed in various contexts.

Discussion Character

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

Main Points Raised

  • Some participants assert that only massless particles, like photons, can travel at the speed of light, while others question whether neutrinos, which may have mass, can also travel at light speed.
  • There is a suggestion that the existence of neutrinos is uncertain, with some arguing they have mass and thus cannot travel at the speed of light.
  • One participant proposes that the definition of mass is crucial to understanding the speed of particles, indicating a need for clarification on what constitutes mass.
  • Some participants mention the Cherenkov effect as evidence of particles exceeding the speed of light in certain media, raising questions about the implications for mass and speed limits.
  • Quantum entanglement is discussed as a phenomenon that may suggest information can be transmitted faster than light, leading to further debate on the nature of speed limits in physics.
  • There are claims that the speed of light is an upper limit for information transfer, but this is contested by references to quantum phenomena.
  • One participant discusses the exponential energy requirements for accelerating mass to light speed, emphasizing the challenges of achieving such speeds with massive particles.

Areas of Agreement / Disagreement

Participants express a range of views, with no consensus on whether neutrinos can travel at the speed of light or if any particles with mass can achieve that speed. The discussion remains unresolved, with competing theories and interpretations presented.

Contextual Notes

Participants reference various theoretical concepts and experimental observations, but there are limitations in definitions and assumptions regarding mass and speed. The discussion includes speculative ideas about faster-than-light particles and the nature of light speed.

  • #31
To my knowledge, gravitation travels at the speed of light.
 
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  • #32
Generalization

One could make the generalization that all massless particles travel at the speed of light. They have no choices, one could argue (correct me if I am wrong), due to the symmetry predicted by special relativity. So, this would include a few force carriers, such as:

EM force carrier: photon
Strong force carrier: gluon
Gravitational force carrier: graviton(?)

Does not include the carriers of the strong force, the W+, W-, and the Z0. They have a NON-ZERO mass.
 

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