Using Newtonian physics to try to describe light is not okay and neither is mixing James' correct relativistic formula with Newtonian physics so the problems are all with your incompetent application of physics.You can look at my paper, I just use classic physics for analysis. Now James gives a formula for calculating speed. I just apply this formula to the calculation of classical physics. Isn't that okay?

Of course but you have to use it correctly. You are mixing it with Newtonian physics and then trying to pretend it's surprising that the result is nonsense.Can't James' speed be used for things on earth?

It really is.It seems that it is not me who get nonsense.

You are mixing Newtonian and relativistic formulas as I have already said which is not a problem with either theory but a case of you applying them incompetently.If the speed formula given by James is not suitable for simple classical physics calculations, please explain.

Try not to be disingenuous and call it "my" SR theory as if it were some piece of nonsense I'd dreamed up instead of a thoroughly tested and coherent theory that underlies all of modern physics.Please use your SR theory to calculate the elapsed time of light in different directions in Morley's experiment.

You still haven't said which frame you are working in so I am going to choose to work in the local rest frame of the Earth where the apparatus and medium are at rest which means that the total path length along each arm is 20m and the speed of light is isotropic and hence that the answer to both your questions is \(20/(3\times 10^8)\)s. If you want an answer in any other frame you'll have to specify which one you want.