The photon does have a lifespan?

  • Thread starter Thread starter artevolved
  • Start date Start date
  • Tags Tags
    Photon
Click For Summary

Discussion Overview

The discussion revolves around the concept of a photon's lifespan, exploring whether photons have a finite existence or if they can be considered eternal. Participants examine theoretical implications, observational evidence, and the nature of photon interactions with matter.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants propose that a photon is 'born' and 'dies' upon interaction with particles like electrons or positrons, suggesting a cyclical nature of existence.
  • Others argue that the oldest photons observed have traveled for billions of years and appear identical to newly generated photons, implying no limited lifespan.
  • A participant suggests that a photon could be considered 'dead' if it becomes redshifted beyond the observable universe's radius, though they note this has not yet occurred.
  • It is mentioned that, from a photon's perspective, no time elapses during its travel, despite the billions of years observed from an external viewpoint.
  • One participant clarifies that the absorption of a photon relates to energy rather than wavelength, questioning the relevance of the universe's size in this context.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the lifespan of photons, with no consensus reached on whether photons have a finite existence or are eternal.

Contextual Notes

Discussions involve assumptions about the nature of time from a photon's perspective, the implications of redshift, and the relationship between energy and wavelength in photon absorption. These aspects remain unresolved.

artevolved
Messages
3
Reaction score
0
it is born.
 
Science news on Phys.org
artevolved said:
it is born.

It 'lives' until it runs into an electron or a positron, then it 'dies', to be 'reborn' again when the electron (or positron) falls back to a lower energy level and 'gives birth' to the photon.
 
The "oldest" photons we measure have come to us from the most distant edge of the "observable universe". They have traveled for billions of years. (google "observable universe") So far as we can tell those photons are identical to newly generated photons. So, the observational evidence is that there seems to be no limited lifespan of a photon.
 
Bobbywhy said:
The "oldest" photons we measure have come to us from the most distant edge of the "observable universe". They have traveled for billions of years. (google "observable universe") So far as we can tell those photons are identical to newly generated photons. So, the observational evidence is that there seems to be no limited lifespan of a photon.

I'd think a photon could be considered "dead" when it has red shifted to the point that its wavelength is greater then the radius of the observable universe. At that point we could never receive the entire wave. Granted that the universe is not old enough for that to have happened yet.
 
'As far as the photon is concerned', no time has elapsed, despite the fact that we see it as having traveled for billions of years.
 
Absorption of a photon is a question of energy, not wavelength. The two are related, of course, but I don't see how the size of the universe matters
 

Similar threads

High School Lifespan of a Photon: Debunking the Myth of Time Travel
  • · Replies 33 ·
2
Replies
33
Views
3K
Undergrad Coherent two-photon lidar...does this mean lidar range is greater?
  • · Replies 1 ·
Replies
1
Views
2K
Undergrad Stimulated Emission & Emitted photon direction
  • · Replies 1 ·
Replies
1
Views
2K
Graduate Uncovering the Mysteries of Photons: Energy, Illumination, and Mass - FAQs
  • · Replies 12 ·
Replies
12
Views
3K
High School What Keeps Photons Traveling Across the Galaxy?
  • · Replies 13 ·
Replies
13
Views
2K
High School Do Photons Have Mass?
  • · Replies 1 ·
Replies
1
Views
7K
High School A cone of photons from one (of many seen objects) hits the retina....
  • · Replies 25 ·
Replies
25
Views
3K
Undergrad What is the lifetime of a photon in a medium?
  • · Replies 3 ·
Replies
3
Views
2K
Undergrad Are there inherent limits to Interferometer size?
  • · Replies 5 ·
Replies
5
Views
2K
Graduate Photon Polarization: Questions & Answers
  • · Replies 23 ·
Replies
23
Views
10K