What is it that sets the speed limit of light?

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Discussion Overview

The discussion centers on the question of what sets the speed limit of light, exploring both the numerical value of the speed of light and the underlying reasons for its existence. Participants examine the nature of this limit from theoretical and observational perspectives, without reaching a consensus.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions what causes the speed of light to exist, drawing an analogy to speed limits set by legislation.
  • Another participant asserts that the specific value of 299,792,458 m/s is a defined standard within the SI units, suggesting that it is a matter of definition rather than a derived quantity.
  • It is noted by a participant that there is currently no complete theory that predicts the speed of light from more fundamental concepts, similar to the situation with other fundamental particle properties.
  • A request for observational evidence related to the speed of light is made, indicating a desire for empirical support for the discussion.
  • A suggestion is made to refer to a specific sticky post in the forum that discusses the experimental basis for special relativity, which may provide relevant information.

Areas of Agreement / Disagreement

Participants express differing views on whether the speed of light's value is a defined standard or if it has deeper theoretical implications. The discussion remains unresolved regarding the fundamental reasons for the speed of light's existence.

Contextual Notes

The discussion highlights the lack of a comprehensive theory that explains the speed of light and acknowledges that current understanding is based on observations rather than first principles.

Lino
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There are quite a number of threads (and FAQ's) that discuss why the speed of light is the "number" that it is, but I'm having difficulty finding some information on what is causing, or setting, the limit. So, let me ask and answer a different question as an example of the what I am tryinh to find out here. Q: Why is the speed limit on our national roads the number it is? A: This number is caused by government / legislation that causes the speed limit to exist.

So, without a reference to a measurement or unit, what is it that causes the speed of light to exisit? If anyone can help / direction me to a relevant paper / article on this, it would be greatly appreciated.

Regards,


Noel.
 
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If you're asking about why specifically the 299,792,458 m/s number is what it is, it's because we defined it that way. I'm always sketchy about the history/details, but we define SI units such that that is true.

If you're asking why, without reference to any units or numerical value, it is the way it is, it just is. We have no underlying theory that would predict the speed of light from some more fundamental concept.
 
As noted, we have no complete theory yet Just like we have no theory to predict the mass
nor the charges of any fundamental particles...All that stuff in the standard model is based
on observations rather than first principles.
 
Thanks all.

Naty1, any pointers observational evidence?

Regards,

Noel.
 
Lino said:
any pointers observational evidence?

About the speed of light? See the sticky post at the top of this forum, "Experimental Basis for Special Relativity."
 
Thanks JTbell. Much appreciated. It'll keep me (good) busy for a while!
 

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