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Physics/Speed of Light Computation.

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Question
Dear Prof Steve

en.wikipedia.org/wiki/Speed_of_light
www.speed-light.info
galileoandeinstein.physics.virginia.edu/lectures/spedlite.html

The Speed of Light = 299792458 m/s - Universal Physical constant.

1 What is the method used for computing the speed of Light and how this value for the speed of light given above is computed and derived ?.

2 Is there a single method or there can be several methods to calculate
the Speed of Light and derive the above value?.

Thanks & Regards,
Prashant S Akerkar

Answer
The speed of light is a defined constant.  It would be more accurate to ask what is the method to compute the length of one meter in terms of that constant and the international standard for one second.  Basically, though, light is an electromagnetic wave which obeys a wave equation.  Its speed in any medium (including empty space) obeys this wave equation.  In the case of light, it obeys Maxwell's equations.  That's really the only way that the speed of light is calculated, solving the wave equation for the wave speed.  Since the electromagnetic force has never been observed to violate Maxwell's equations (which would lead to many very obvious and strange results), no second method is really necessary.  I'm unaware of another way to calculate it from first principles.

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Dr. Stephen O. Nelson

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I can answer most basic physics questions, physics questions about science fiction and everyday observations of physics, etc. I'm also usually good for science fair advice (I'm the regional science fair director). I do not answer homework problems. I will occasionally point out where a homework solution went wrong, though. I'm usually good at explaining odd observations that seem counterintuitive, energy science, nuclear physics, nuclear astrophysics, and alternative theories of physics are my specialties.

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I was a physics professor at the University of Texas of the Permian Basin, research in nuclear technology and nuclear astrophysics. My travelling science show saw over 20,000 students of all ages. I taught physics, nuclear chemistry, radiation safety, vacuum technology, and answer tons of questions as I tour schools encouraging students to consider careers in science. I moved on to a non-academic job with more research just recently.

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Ph. D. from Duke University in physics, research in nuclear astrophysics reactions, gamma-ray astronomy technology, and advanced nuclear reactors.

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