Post Closed as "duplicate" by tpg2114, Emilio Pisanty, Qmechanic of
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I know that the speed of light, the universal constant of gravitation and the Plank'sPlanck's constant are considered to be the three fundamental constants of the universe. But, why is speed of light considered as a fundamental constant? The speed of light changes from medium to medium for satisfying Fermat's principle then, how can it be a constant?

I know that the speed of light, the universal constant of gravitation and the Plank's constant are considered to be the three fundamental constants of the universe. But, why is speed of light considered as a fundamental constant? The speed of light changes from medium to medium for satisfying Fermat's principle then, how can it be a constant?

I know that the speed of light, the universal constant of gravitation and the Planck's constant are considered to be the three fundamental constants of the universe. But, why is speed of light considered as a fundamental constant? The speed of light changes from medium to medium for satisfying Fermat's principle then, how can it be a constant?

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I know that the speed of light, the universal constant of gravitation and the Plank's constant are considered to be the three fundamental constants of the universe.But But, why is speed of light considered as a fundamental constant? The speed of light changes from medium to medium for satisfying Fermat's principle then, how can it be a constant?

I know that the speed of light, the universal constant of gravitation and the Plank's constant are considered to be the three fundamental constants of the universe.But, why is speed of light considered as a fundamental constant? The speed of light changes from medium to medium for satisfying Fermat's principle then, how can it be a constant?

I know that the speed of light, the universal constant of gravitation and the Plank's constant are considered to be the three fundamental constants of the universe. But, why is speed of light considered as a fundamental constant? The speed of light changes from medium to medium for satisfying Fermat's principle then, how can it be a constant?

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Why is the speed of light considered as a fundamental constant if its speed changes with medium resulting in refraction?

I know that the speed of light, the universal constant of gravitation and the Plank's constant are considered to be the three fundamental constants of the universe.But, why is speed of light considered as a fundamental constant? The speed of light changes from medium to medium for satisfying Fermat's principle then, how can it be a constant?