What Determines the Speed of Light Limit?

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Discussion Overview

The discussion centers on the question of what determines the speed of light, specifically why it is approximately 186,282 miles per second, and what physical properties or principles might limit or define this speed. Participants explore theoretical, conceptual, and philosophical aspects of this question, avoiding reliance on relativity as an explanation.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested
  • Technical explanation

Main Points Raised

  • Some participants express curiosity about the arbitrary nature of the speed of light and question why it is not a different value, suggesting that it seems odd or arbitrary.
  • Others propose that the speed of light can be seen as a constant of nature, linked to fundamental physical constants such as vacuum permittivity and permeability.
  • A participant discusses the relationship between space and time, suggesting that when measured in consistent units, the speed of light becomes dimensionless and equals one, which raises questions about its significance.
  • Some argue that the speed of light is a result of the structure of space and time, and that understanding its value may require deeper insights into quantum field theory and the nature of the vacuum.
  • There are mentions of Maxwell's equations and how they relate to the constancy of the speed of light, but the underlying reasons for its specific value remain unclear.
  • One participant highlights that while the speed of light is often treated as a constant, it may be more accurately described as a free parameter of current physical theories.
  • Another participant notes that the question of why the speed of light has its specific value often leads to deeper philosophical inquiries that are not easily resolved.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the reasons behind the speed of light's specific value. Multiple competing views and hypotheses are presented, with ongoing debate about the significance of units of measurement and the nature of physical constants.

Contextual Notes

Limitations include the dependence on definitions of units, the unresolved nature of the relationship between the speed of light and other physical constants, and the complexity of the underlying physics that may not be fully understood.

  • #31
Whyndham_UCL said:
c is a fundamental constant.
No, c is not a fundamental constant.

http://math.ucr.edu/home/baez/constants.html

To all: this thread has gotten out of hand and is full of misinformation. Please read the linked article. The value of c is entirely an artifact of your choice of units and has no physical significance; furthermore you cannot logically talk about the value of c independent of the units.

The only quantities which are independent of the units are dimensionless quantities, like the fine structure constant. I don't know why so many people seem resistant to this idea. Also, the dimensionless constants are the ones that contain the physics. See:

https://www.physicsforums.com/showpost.php?p=2011753&postcount=55
https://www.physicsforums.com/showpost.php?p=2015734&postcount=68

Thread closed.
 
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