Time, Light, and Relativity: Photons from the Past

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

Discussion Overview

The discussion revolves around the nature of time as it relates to photons and the implications of relativity. Participants explore the concept of time for light and photons, questioning how time behaves at the speed of light and the relationship between time and the existence of photons from distant sources.

Discussion Character

  • Debate/contested

Main Points Raised

  • One participant asserts that if relativity is true, then photons from a billion light years away would not exist in the present unless they stopped for a billion years after reaching Earth.
  • Another participant counters that time does not apply to photons, stating that since no clock can travel at the speed of light, the concept of time stopping at that speed is meaningless.
  • A different viewpoint suggests that photons do experience time, arguing that if spacetime exists, anything moving through space would experience time, and questioning the nature of time if all clocks were destroyed.
  • One participant raises a question about the relationship between photons as time-variant electric and magnetic fields and the claim that they do not experience time, indicating confusion over this concept.

Areas of Agreement / Disagreement

Participants express conflicting views on whether photons experience time, with no consensus reached. Some argue that photons do not experience time, while others believe they do, leading to an unresolved debate.

Contextual Notes

There are limitations in the discussion regarding the definitions of time and spacetime, as well as the implications of relativity on the nature of photons. The assumptions underlying these claims remain unresolved.

dtyarbrough
Messages
6
Reaction score
0
Relativity states that as anything approaches the speed of light, time slows down. At the speed of light, time stops. If this is true then photons from 1 billions light years away would not exist in the present unless they stopped and remained stationary for 1 billion years after reaching earth. What am I missing?
 
Physics news on Phys.org
Time does not slow down to a stop at the speed of light, in spite of what you may have heard or read. Time does not apply to light or photons. Einstein said that time is what a clock measures and since no clock can travel at the speed of light, there is no meaning to the concept that a clock stops and thus time stops at the speed of light. Photons don't experience time.
 
Photons experience time as all inanimate objects do. They change over time. If there is a spacetime, which I doubt, anything moving through space would experience time. If we destroy all the clocks, will time stop?
If time slowed down at all, my point is made. It does not have to stop.
 
Last edited:
Maxwell showed that photons are time-variant electric fields giving rise to time-variant magnetic fields and vice versa right? So how is this if photons don't experience time? I have not been able to understand this one.
 

Similar threads

  • · Replies 4 ·
Replies
4
Views
1K
  • · Replies 23 ·
Replies
23
Views
935
  • · Replies 50 ·
2
Replies
50
Views
3K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 51 ·
2
Replies
51
Views
5K
  • · Replies 20 ·
Replies
20
Views
3K
  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 7 ·
Replies
7
Views
3K
  • · Replies 55 ·
2
Replies
55
Views
4K
  • · Replies 4 ·
Replies
4
Views
2K