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Relativity/Invariance of c


Is the (observed) constancy of c in vacuo in all reference frames a result of first principles, or is it assumed to be true and not-true leads to a logical or observation contradiction?

In layman's terms, what does Newton's Bucket say about rotational, noninertial or inertial reference frames? Since stars at a suitable distance have relative angular velocities > c, why don't they disappear from this universe? I know why the meniscus is parabolic in Newtonian physics; would it still curve if the bucket and water were the only mass in the universe? Without external mass, can the system even be said to be rotating? Does relativity account for friction being caused by electrical forces?

Thank you, Dave, for the interesting question.

Galileo gave us relativity for mechanics, but it was the theory of electromagnetics by Maxwell that raised the question for light.  The constant c in Maxwell's equations suggested that the value of c is the same in all inertial frames of reference. Experiments have since confirmed this hypothesis.

Your question about rotational motion was the subject of a speculation by Ernst Mach that the distant stars were important in the way that you suggest.  We cannot do that experiment, but our best theories today do not support Mach's idea.

You cannot compare linear velocities with angular velocities.  They are different things.
Is 10 meters per second greater or less than 10 degrees per second. It doesn't make sense.

Uncle Ben


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Uncle Ben


I can answer questions regarding Einstein's Theory of Relativity, particularly in Special Relativity. I will not answer homework questions or mathematical problems that require special symbols.


I have taught physics at the college level, undergraduate and graduate, for many years including Special Relativity. I have taught at Johns Hopkins, Case-Western, and MIT. I have also served as a staff member of the Commission on College Physics, which was supported by the National Science Foundation to recommend improvements in the curriculum of college physics departments in the US. I am also the author of a textbook titled Vector Calculus, which was used at MIT in the teaching of electromagnetic theory and relativity. My research interests were mainly in solid state physics, especially the properties of metals at low temperatures. I am listed in the publication known as American Men of Science.

I have dozens of papers published in the Physical Review and in the American Journal of Physics.

I hold a Ph.D. degree in physics from the Johns Hopkins University.

Past/Present Clients
Johns Hopkins University, Case-Western Reserve University, Massachusetts Institute of Technology, Empire State College, Georgetown University, Commission on College Physics, and UNESCO.

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