Understanding the Age of Observed Light: A Scientific Perspective

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Discussion Overview

The discussion revolves around the concept of the "age" of light observed from astronomical objects, specifically the Triangulum Galaxy. Participants explore the implications of relativity on the perception of time for light and whether it is meaningful to discuss the age of light in this context.

Discussion Character

  • Debate/contested, Conceptual clarification, Exploratory

Main Points Raised

  • One participant suggests that the light from the Triangulum Galaxy is about 2.7 million years old.
  • Another participant questions the validity of asking for the age of light, indicating that it may not make sense.
  • A different viewpoint argues that while light does not experience time, it is valid to ask when a photon was emitted relative to our reference frame.
  • Some participants assert that there is no meaningful way to discuss what light "experiences" due to the lack of a frame of reference in which light is at rest.
  • One participant acknowledges that the typical definition of time does not apply to light but suggests that conceptualizing it using Minkowski diagrams can be useful.

Areas of Agreement / Disagreement

Participants express differing views on whether it is meaningful to discuss the age of light, with some arguing against it based on relativity, while others find value in the question when framed appropriately.

Contextual Notes

The discussion includes assumptions about the nature of time in relation to light and the implications of special relativity, which remain unresolved among participants.

FrankC
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Not to get off subject but, when I gaze at the Triangulum Galaxy how “Old” is the light I’m observing?
 
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About 2.7 million years old.
 
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Does it make sense to ask for the age of light?
 
DrStupid said:
Does it make sense to ask for the age of light?
Kind of.
 
DrStupid said:
Does it make sense to ask for the age of light?
If you know Relativity no as anything traveling at the speed of light does not experience "time". However you can validly ask "when was a photon of light emitted relative to our reference frame". For someone lacking an understanding of special or general relativity and used to our largely nonreletavistic everyday experiences where Galilean transformations produce close enough approximations to reality that those rules were only valid for speeds much less than the speed of light wouldn't be realized until Michelson and Morley's famous experiment showed the speed of light is a constant of nature and that no "Aether" exists.
 
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Dragrath said:
no as anything traveling at the speed of light does not experience "time".

That is a pop-science nonsense. There is no frame of reference in which light is at rest, so there is no meaningfull way to talk about what light "experiences".
 
weirdoguy said:
That is a pop-science nonsense. There is no frame of reference in which light is at rest, so there is no meaningful way to talk about what light "experiences".
True that typical definition of time doesn't apply, hence why I said "time" not time, but it is a useful way to conceptualize a minkowski diagram as it will fall entierly along the spatial axes so it helps get the point across.
 
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