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Richard Nirui asked the Naked Scientists:I)How can astronomers tell how far the light from a star had to travel to reach us? In other words how do they determine how far a star is from us? And how accurate is this measurement,a few light years or thousands of light years?What do you think?
I dont see any reasonable natural reasons why speeds is constant.
"I dont see any reasonable natural reasons why speeds is constant."Because you can calculate it from Maxwell's equations. http://en.wikipedia.org/wiki/Speed_of_light_in_vacuum [nofollow]The two factors in the equation are the permittivity of a vacuum and the permeabillity of a vacuum.Now, for the speed of light to be different in different places the value for one or other of these properties of the vacuum would need to change.How does a vacuum know where it is so it can have the right value for these two quantities?