8.5   FIZEAU EXPERIMENT

Light has in a dense medium a velocity W slower than its velocity in vacuum c due to the successive interactions of the photons with the atoms. The photons are slowed down in a little interval of time and in a small distance near the atoms. Between the atoms they recover its vacuum velocity. W is the average velocity.

The Fizeau experiment measure the light velocity in a liquid medium that travels at velocity u. Fizeau determined that if the velocity of light in the medium at rest is W₀ then the absolute velocity of light (relative to a frame at rest) is:

ç = W₀ + u(1 – W₀²/c²)

where c is the light velocity in vacuum.

It is proposed here that two phenomena should be taken into account in the experiment:

a)      The medium is moving with velocity u then u should appear as a source component of the final absolute velocity.

b)        The velocity of light relative to the medium is dependent on the velocity of the medium: W = W(u)

With the Emission Theory the absolute velocity is:

ç = u + W(u)

Then Fizeau experiment gives us the function of the relation of W with u.

If we take the Fizeau expression and reorganize terms we have:

ç = u + W₀ (1 – uW₀/c²)

Then:

 NOTE:

It’s important to note that the analogy between the equivalence between the formulas of the addition of velocities in Relativity Theory and that obtained by Fizeau in his experiment is valid only under a questionable approximation.

The formula of Relativity for the experiment described above gives us:

ç = (u + W₀)/(1 + u W₀/c²)