Consider calculations reproducing the original calculations of Michelson and Morley:

Richard Feynman: "First, let us calculate the time required for the light to go from B to E and back. Let us say that the time for light to go from plate B to mirror E is t_1, and the time for the return is t_2. Now, while the light is on its way from B to the mirror, the apparatus moves a distance ut_1, so the light must traverse a distance L + ut_1, at the speed c." http://www.feynmanlectures.caltech.edu/I_15.html

Feynman's last words,

"at the speed c",

obey the light postulate of special relativity:

"The speed of light is independent of the speed of the source".

If, instead of "at the speed c", we have a new assumption,

"at the speed c + u",

in accordance with Newton's theory, the calculation (based on the new assumption) will give a new prediction,

t_1 + t_2 = 2t_3 = 2L/c,

which exactly matches the null result of the Michelson-Morley experiment.

Below John Norton exposes theoretical physicists ("later writers") as deliberate liars. They use the Michelson-Morley experiment "as support for the light postulate of special relativity", knowing that this experiment is "fully compatible with an emission theory of light that contradicts the light postulate":

John Norton: "In addition to his work as editor of the Einstein papers in finding source material, Stachel assembled the many small clues that reveal Einstein's serious consideration of an emission theory of light; and he gave us the crucial insight that Einstein regarded the Michelson-Morley experiment as evidence for the principle of relativity, whereas later writers almost universally use it as support for the light postulate of special relativity. Even today, this point needs emphasis. The Michelson-Morley experiment is fully compatible with an emission theory of light that contradicts the light postulate." http://philsci-archive.pitt.edu/1743/2/Norton.pdf

"Emission theory, also called emitter theory or ballistic theory of light, was a competing theory for the special theory of relativity, explaining the results of the Michelson–Morley experiment of 1887...The name most often associated with emission theory is Isaac Newton. In his corpuscular theory Newton visualized light "corpuscles" being thrown off from hot bodies at a nominal speed of c with respect to the emitting object, and obeying the usual laws of Newtonian mechanics, and we then expect light to be moving towards us with a speed that is offset by the speed of the distant emitter (c ± v)." https://en.wikipedia.org/wiki/Emission_theory

Banesh Hoffmann, Einstein's co-author, admits that, originally ("without recourse to contracting lengths, local time, or Lorentz transformations"), the Michelson-Morley experiment was compatible with Newton's variable speed of light, c'=c±v, and incompatible with the constant speed of light, c'=c:

"Moreover, if light consists of particles, as Einstein had suggested in his paper submitted just thirteen weeks before this one, the second principle seems absurd: A stone thrown from a speeding train can do far more damage than one thrown from a train at rest; the speed of the particle is not independent of the motion of the object emitting it. And if we take light to consist of particles and assume that these particles obey Newton's laws, they will conform to Newtonian relativity and thus automatically account for the null result of the Michelson-Morley experiment without recourse to contracting lengths, local time, or Lorentz transformations. Yet, as we have seen, Einstein resisted the temptation to account for the null result in terms of particles of light and simple, familiar Newtonian ideas, and introduced as his second postulate something that was more or less obvious when thought of in terms of waves in an ether." Banesh Hoffmann, Relativity and Its Roots, p.92 https://www.amazon.com/Relativity-Its-Roots-Banesh-Hoffmann/dp/0486406768

The deliberate lie:

"The conclusion of the Michelson-Morley experiment was that the speed of light was a constant c in any inertial frame. Why is this result so surprising? First, it invalidates the Galilean coordinate transformation. Note that with the frames as defined in the previous section, if light is travelling in the x' direction in frame O' with velocity c, then its speed in the O frame is, by the Galilean transform, c+v, not c as measured. This invalidates two thousand years of understanding of the nature of time and space. The only comparable discovery is the discovery that the earth isn't flat! The Michelson Morley experiment has inevitably brought about a profound change in our understanding of the world." http://www.berkeleyscience.com/relativity.htm

Joao Magueijo, Faster Than the Speed of Light: "A missile fired from a plane moves faster than one fired from the ground because the plane's speed adds to the missile's speed. If I throw something forward on a moving train, its speed with respect to the platform is the speed of that object plus that of the train. You might think that the same should happen to light: Light flashed from a train should travel faster. However, what the Michelson-Morley experiments showed was that this was not the case: Light always moves stubbornly at the same speed. This means that if I take a light ray and ask several observers moving with respect to each other to measure the speed of this light ray, they will all agree on the same apparent speed!" https://www.amazon.com/Faster-Than-Speed-Light-Speculation/dp/0738205257

Stephen Hawking, A Brief History of Time, Chapter 2: "The special theory of relativity was very successful in explaining that the speed of light appears the same to all observers (as shown by the Michelson-Morley experiment)..." http://www.amazon.com/Brief-History-Time-Stephen-Hawking/dp/0553380168

Brian Cox, p. 91: "...Maxwell's brilliant synthesis of the experimental results of Faraday and others strongly suggested that the speed of light should be the same for all observers. This conclusion was supported by the experimental result of Michelson and Morley, and taken at face value by Einstein." http://www.amazon.com/Why-Does-mc2-Should-Care/dp/0306817586

Ethan Siegel: "The speed of light doesn't change when you boost your light source. Imagine throwing a ball as fast as you can. Depending on what sport you're playing, you might get all the way up to 100 miles per hour (~45 meters/second) using your hand-and-arm alone. Now, imagine you're on a train (or in a plane) moving incredibly quickly: 300 miles per hour (~134 m/s). If you throw the ball from the train, moving in the same direction, how fast does the ball move? You simply add the speeds up: 400 miles per hour, and that's your answer. Now, imagine that instead of throwing a ball, you emit a beam of light instead. Add the speed of the light to the speed of the train... and you get an answer that's completely wrong. Really, you do! This was the central idea of Einstein's theory of special relativity, but it wasn't Einstein who made this experimental discovery; it was Albert Michelson, who's pioneering work in the 1880s demonstrated that this was the case." https://www.forbes.com/sites/startswithabang/2017/10/27/five-discoveries-in-fundamental-physics-that-came-as-total-surprises/

Joe Wolfe: "At this stage, many of my students say things like "The invariance of the speed of light among observers is impossible" or "I can't understand it". Well, it's not impossible. It's even more than possible, it is true. This is something that has been extensively measured, and many refinements to the Michelson and Morley experiment, and complementary experiments have confirmed this invariance to very great precision. As to understanding it, there isn't really much to understand. However surprising and weird it may be, it is the case. It's the law in our universe. The fact of the invariance of c doesn't take much understanding." https://newt.phys.unsw.edu.au/einsteinlight/jw/module3_weird_logic.htm

Neil deGrasse Tyson: "Beginning in 1905, investigations into the behavior of light got positively spooky. That year, Einstein published his special theory of relativity, in which he ratcheted up M & M's null result to an audacious level. The speed of light in empty space, he declared, is a universal constant, no matter the speed of the light-emitting source or the speed of the person doing the measuring." https://www.amazon.fr/Death-Black-Hole-Cosmic-Quandaries/dp/039335038X

Edward Witten on modern physics

*View: https://youtu.be/fnzLpyDsn3M?t=77*

Understandably, Norton and Stachel, high priests in the Einstein cult, are trying to exculpate Einstein. Actually, Einstein was the original liar - in 1921 he informed the gullible world that the Michelson-Morley experiment had proved constant speed of light:

The New York Times, April 19, 1921: "The special relativity arose from the question of whether light had an invariable velocity in free space, he [Einstein] said. The velocity of light could only be measured relative to a body or a co-ordinate system. He sketched a co-ordinate system K to which light had a velocity C. Whether the system was in motion or not was the fundamental principle. This has been developed through the researches of Maxwell and Lorentz, the principle of the constancy of the velocity of light having been based on many of their experiments. But did it hold for only one system? he asked. He gave the example of a street and a vehicle moving on that street. If the velocity of light was C for the street was it also C for the vehicle? If a second co-ordinate system K was introduced, moving with the velocity V, did light have the velocity of C here? When the light traveled the system moved with it, so it would appear that light moved slower and the principle apparently did not hold. Many famous experiments had been made on this point. Michelson showed that relative to the moving co-ordinate system K1, the light traveled with the same velocity as relative to K, which is contrary to the above observation. How could this be reconciled? Professor Einstein asked." https://ebay.com/itm/ALBERT-EINSTEIN-Lecture-on-SPEED-OF-LIGHT-Time-1st-Visit-to-US-1921-Newspaper/373400655156