B What Determines the Speed of Light Limit?

Thread starter thetexan
Start date Dec 17, 2015
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The speed of light, measured at approximately 186,282 miles per second, is often perceived as arbitrary, leading to questions about why it has this specific value rather than another. The discussion highlights that the speed of light is fundamentally linked to the properties of space and time, as well as the electromagnetic constants of vacuum permittivity and permeability. It emphasizes that the numerical value of light's speed is largely dependent on the choice of measurement units, suggesting that if different units were used, the speed would appear as a different number. Ultimately, while the speed of light is a constant of nature, its specific value is not derived from a deeper physical principle but rather from the conventions of measurement. The conversation reflects a broader curiosity about the nature of constants in physics and their implications for understanding the universe.

Dec 21, 2015

Dale

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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.

Last edited: Dec 21, 2015