Do Photons Decay? Cosmic Event Horizons Explained

  • Context: Graduate 
  • Thread starter Thread starter dst
  • Start date Start date
  • Tags Tags
    Decay Photons
Click For Summary

Discussion Overview

The discussion centers on the concept of photon decay and its implications for cosmic event horizons. Participants explore whether photons can decay similarly to protons and the potential consequences of such decay on our understanding of light propagation and cosmic boundaries.

Discussion Character

  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants propose that photons might decay, questioning the implications of such decay on cosmic event horizons.
  • Others argue that photons cannot decay, suggesting that even if a decay mechanism existed, it would not be observable due to time dilation effects.
  • One participant raises concerns about the conservation of momentum and energy if photons were to decay into massive particles.
  • There is mention of theories regarding proton decay, with some participants noting the lack of experimental evidence for such decay and discussing the estimated lower boundary for the proton's half-life.
  • Another participant confirms the lower boundary for proton decay as approximately 10^35 years, referencing literature on the topic.

Areas of Agreement / Disagreement

Participants generally disagree on the possibility of photon decay, with some asserting it cannot happen while others explore the hypothetical implications if it could. The discussion remains unresolved regarding the nature of photon decay and its consequences.

Contextual Notes

Participants express uncertainty about the assumptions underlying photon decay and proton decay theories. The discussion highlights the lack of experimental evidence for proton decay and the implications of conservation laws in the context of photon decay.

dst
Messages
379
Reaction score
0
From what I gather, even the proton has a probability to break apart after however long.

Is this valid for photons as well? Supposing they did decay, then would there be a second "cosmic event horizon" by which light from a certain distance can't reach us regardless of time?
 
Science news on Phys.org
No, as far as I know photons cannot decay. But as you say, even if there was some mechanism by which a photon could decay, due to time dilation the decay would never be observed in any reference frame.
 
Bleurgh!

So what constraints do we have on our information apart from this event horizon? Anything time-independent?
 
If a photon would decay into massive particles, then it would violate momentum or energy conservation: a massless particle always has more momentum than an equal energy massive particle.
 
dst said:
From what I gather, even the proton has a probability to break apart after however long.

although this was not the main part of your question, I would like to provide a clarification to this point.

there exist some theories that the proton might decay, but until now there is no experimental evidence for this. the guys at the super-kamiokande detector herded quite a lot of protons together, watched them, and - nothing happened !

so all we can say at the moment is, that there is a lower boundary for the half-life of the proton (I think its 10^35 years, could anybody confirm / correct this number ?). but it might very well be that the half-life is in fact infinite, i.e. the proton might not decay at all.
 
Yeah I've read (I believe in a book by Martin Rees) that the lower bound is somewhere around 10^35 years for decay of a proton.
 

Similar threads

  • · Replies 5 ·
Replies
5
Views
4K
  • · Replies 9 ·
Replies
9
Views
4K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 7 ·
Replies
7
Views
1K
  • · Replies 22 ·
Replies
22
Views
4K
  • · Replies 25 ·
Replies
25
Views
5K
  • · Replies 12 ·
Replies
12
Views
4K
  • · Replies 1 ·
Replies
1
Views
4K
  • · Replies 3 ·
Replies
3
Views
3K
  • · Replies 3 ·
Replies
3
Views
2K