Speed of information-carrying radiation

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Discussion Overview

The discussion revolves around the concept of how information-carrying radiation is perceived by observers moving towards a source, particularly focusing on the implications of relative motion on the rate at which information is received. The scope includes theoretical considerations and interpretations of the Doppler effect, as well as the implications of observer motion on the perception of information transmission.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants suggest that an approaching observer can receive information at a higher rate due to their motion towards the source, leading to a perceived difference in the timing of information reception.
  • Others argue that the observed differences in information reception are a result of the Doppler effect, emphasizing that no individual signal travels faster than the speed of light, c.
  • One participant proposes that the information-carrying radiation has a variable velocity relative to different observers, depending on their motion towards the source.
  • Another participant challenges this notion, requesting clarification and emphasizing the need for precise units in the discussion.
  • There is a mention of the density of information in the radiation, with some participants noting that while the speed of light remains constant, the frequency and information content can vary.
  • One participant warns against repeating previously addressed misconceptions regarding the variable velocity of radiation relative to observers.

Areas of Agreement / Disagreement

Participants express disagreement on the interpretation of how information is received by moving observers, with some supporting the idea of variable information velocity and others firmly stating that this is incorrect. The discussion remains unresolved, with competing views on the implications of observer motion and the nature of information transmission.

Contextual Notes

Participants highlight the importance of keeping track of units and the definitions of terms used in the discussion, indicating that some assumptions may not be universally accepted or clearly defined.

Speady
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How can an approaching observer receive the information from a source at a higher rate (as an accelerated recording), while the information-carrying radiation could not?
 
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Speady said:
How can an approaching observer receive the information from a source at a higher rate (as an accelerated recording), while the information-carrying radiation could not?
I'm not sure what you mean. Can you be more specific about the scenario you have in mind?
 
Speady said:
How can an approaching observer receive the information from a source at a higher rate (as an accelerated recording), while the information-carrying radiation could not?
It's not clear what you are asking, but keep this in mind: Although the information-carrying radiation will travel at the constant speed of light, c, the density of information or frequencies in the radiation can change. There can be red or blue shifts and the information content density (rate) can decrease or increase.
 
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2 observers A and B watch the same film that is broadcast from station S. A and B see the first fragment of the film next to each other. A remains at a fixed distance from S and B travels from the beginning of the film at a uniform speed of 30 km/s to S.

After 02:46:55 hours B sees the last fragment of the film. The last fragment has to travel another 299,792.458 km to reach A. One second later A also sees the last fragment. B has seen a film from 02:46:55 hours and A has seen a film from 02:44:56 hours. (B sees the same film as A, but a sped-up recording, with a difference in duration of a whole second).

The same information must have arrived at B at a higher rate than at A. The information had a higher velocity relative to B than relative to A. Ergo: the information-carrying radiation had a higher velocity relative to B than relative to A.

I think the conclusion must be that radiation has a variable velocity relative to an observer, depending on the motion of the observer in the direction of the source. (If time dilation existed, it would be negligibly small in this example.)
 
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This is just the doppler effect. "Information velocity" is not a thing, and no individual signal/packet of data traveled faster than C. Different packets travel different distances so they take different amounts of time to arrive.
 
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@FactChecker: I see what you mean, about the density of information, but notice that both observers received the same total information with a difference in time of one second. To achieve that difference, the information at B must have arrived faster, right?
 
Speady said:
The information had a higher velocity relative to B than relative to A
Why do you say this? It doesn’t seem correct to me. Be sure to show your work and keep track of the units. So far I don’t see anything in your discussion with units of m/s other than c.
 
@russ_watters: Speed of information is just a thing. Doppler effect is also correct. No faster than c applies in any case with respect to the source and with respect to the remotely fixed observer A. Your last sentence is also correct. Only the speed of the information and implicitly the speed of the radiation with respect to B I miss in your answer.
 
@Dale: what exactly are you missing or what is not entirely clear to you in my message #4?
 
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Speady said:
@Dale: what exactly are you missing or what is not entirely clear to you in my message #4?
@Speady you have had multiple previous threads all pushing the same mistaken understanding on your part. Nothing has changed since those previous threads. Your claim here...

Speady said:
I think the conclusion must be that radiation has a variable velocity relative to an observer, depending on the motion of the observer in the direction of the source.
...has already gotten you one misinformation warning. This topic has been discussed more than enough. If you post about it again you will receive another warning which will result in a temporary ban from PF.

Thread closed.
 
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