An explanation of Michelson Morley experiment

From Tesla, Maxwell, and many others we all have learned that light moves through a medium called ether.

A wave that requires a dense medium to propagate is called “elastic” or “mechanic”, because it moves through an elastic or mechanic medium.

I will, in the future, analyze some experiments scientists have performed on light: they all prove the Earth is not moving in the universe. To understand them you have to know something more about waves behavior. The experiments I want to consider are the following:

  • Michelson-Morley experiment;
  • Michelson-Gale experiment;
  • Sagnac experiment;
  • Airy experiment.

The major parts of them are light interference experiments. In this article I will consider The Michelson Morley experiment; I will explain it and we will see how the formulas behind this experiment can be explained in a very simple way when we consider the Earth being immovable.

Interference happens when two waves sum up forming a resultant wave that can have a greater, lower or the same amplitude.

A wave that moves along the x axis is described by an expression that satisfies the wave equation (D’Alembert equation):

Where f is the wave function, v is the wave speed  and t is  time.

A possible solution of the wave equation is the harmonic wave described by the following:

Where A is the amplitude of the wave, k is the wave factor, w is the pulsation and φ0 is the initial phase.

Let’s consider 2 waves and sum them up (interference) :  f=f1+f2.

The interference is called constructive when      

In this case the amplitude is:

The interference is called destructive when

In this case the amplitude is:

With specific instruments (for example Fresnel mirrors)  it is possible to visualize interference between two coherent waves that manifest with fringes that are illuminated zones alternated with obscure zones.

Michelson’s interferometer.

The instrument represented in the picture is Michelson’s interferometer. A ray of light coming out from the source S is partly reflected in the movable mirror M1 and  partly transmitted to the fixed mirror M2. The return light rays from M1 and M2 hit first against the beam splitter and then are cast against the detector that is the focus of the splitter lens. The detector receives two coherent rays of light that are conveyed from the same source. (Coherent means that these rays have the same phase). These rays, one from M1 and another from M2, interfere or superpose reinforcing or weakening each other, depending on the optical path that comes from the AM1 and AM2 distances.

By suitably cha
nging the distance AM1, it is possible to produce in O (the detector) interference fringes with a maximum or minimum of intensity.

By varying the distance AM1 of λ/4 ( being λ the wave length of the casted beam of light) you can pass from a minimum to a maximum. A compensating lens is used to produce exactly the same optical path in the two rays.

The Michelson Morley experiment.

In 1881 Michelson and Morley made an experiment to examine if , in  the same way sound requires an elastic medium (such as air of water ) to propagate , similarly  light to spread out would need a mechanical medium, called ether . Ether should be present all over in the intermediate space, to allow light to reach Earth from the stars. This implies that space is not empty:  vacuum is only a vacuum of air but not an absolute vacuum.

Call  c  the speed of light in the ether. When you move towards the light ray inside of a fixed ether with a speed v you shall measure a total speed of light c+v, but you shall measure c-v when you move in the same verse of the light ray. This expression has much to do with the Galilean relativity.

Michelson and Morley thought that this principle could be used to check if the ether does exist. They thought that an interferometer could be used to evaluate the variation of the interference fringe due to the speed of the Earth. Their idea was the following: when you put one branch of the interferometer in the direction of the speed of the Earth v and the other branch  perpendicular to the first you obtain a well precise drawing of interference fringes. Then, by rotating the interferometer of 90 degrees you can invert the two interferometer  branches. Since the optical path changes also the fringes should change.

Let’s see the calculation. The two branches of the interferometer AM1 and AM2 have the same length. The AM2 branch is rotated in the direction of the motion of the laboratory and relatively to the cosmic ether. When we consider the ether as motionless, fixed to the stars, the direction and the entity of the Earth speed v should depend on the hour of the day and on the day of the year.

For the law S=vxt of the rectilinear uniform motion  the ray of light going from A to M2 takes a time t=l/(c-v). To return from M2 to A it takes a time t=l/(c+v). The total time for the branch AM2 is

Time t1 of the other branch (AM1) has a different value. For this case we have to remember that during the time t1 the Earth keeps moving. Thus the total trajectory of the ray is triangular.

. While the ray of light moves from A to M1 the mirror A moves in the direction of the speed of the Earth. This distance AA’ can be calculated taking in consideration the speed v and the time t1 necessary for the light to reach M1 and to return to A’. So we have AA’=vt1. The ray of light has thus to travel the distance AM1A’=2AM1 with a speed c. The  needed time will be:

The result will be:

These two coherent rays superpose in the O point  in a way that depends on  t1 and t2. Then, when you  rotate the interferometer in order to range the branch AM1 in the direction of the speed of the laboratory in respect of the ether, t1 and t2 change, so there should be a difference of phase in the two rays in O with a consequent change of the interference fringes.

Every time this experiment has been repeated, at  different hours of the day and on different days of the year,  it has always given  the same result: no change in the fringes.

Obviously , when the  physicians tried to explain this result, no one supposed the Earth to be motionless, so Einstein solved the problem with his famous statement on which he later based his theory of relativity: light moves with equal speed c in all directions and in all different reference systems.

Many researchers have proved the Einstein’s relativity to be wrong, And here I want to quote an interesting idea taken from the site

True, light moves  on a straight line through the air at a speed of 299700Km/s (299792,458 Km/s in the vacuum) but the particles of light on monochromatic waves in the meanwhile happen to travel on a sin wave, in this way covering  during  an equal unit of time a longer path .

Since there are matter particles definitely able to travel at such a speed, the only possible explanation for the Michelson Morley experiment is that the Earth doesn’t move. In this case v=0 and you will notice that t1 and t2 become equal: t1=t2=l/c (no change in the interference fringes). This is the main idea: formulas behind this experiment become incredibly simple if we consider the Earth immovable.

So, here we have another astonishing proof that the Earth doesn’t move.

An image from

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