The famous “Michelson-Morley” experiment was made in order to determine the change of the speed of light due to the motion of the Earth in its orbit around the Sun. On the base of the known speed of the Earth (approximately 30 km/s), the Michelson’s expectations were that the displacement of the interference fringes will be different at night and during the day (when the direction of the еther wind is opposite), and will correspond to the calculations made. However, the result was unexpected – no displacement was fixed. The problem has two reasons. The first is that the speed of light in vacuum remains always the same during the travel of the Earth around the
The theories of light at that time.
Historically, in the seventeenth century, two rival theories of the nature of light were proposed – the wave theory and the corpuscular theory.
The Dutch astronomer Huygens proposed the wave theory of light – the first mathematical theory of light. The known mechanical waves propagate through a material medium (solid, liquid, or gas) at a wave speed which depends on the elastic and inertial properties of that medium. Two basic types of wave motion for mechanical waves were known: transverse waves and longitudinal waves. For Huygens, the light was a longitudinal wave (like sound waves in air) and propagates through a medium called “ether”, or “aether”. The ether must fill all space and be weightless and invisible (in fact, as the space itself).
In 1690 Newton proposed the corpuscular theory of light. For him, the light was emitted from a source in small particles, and this view was accepted for over a hundred years.
The quantum theory put forward by Max Planck in 1900 combined the wave theory and the particle theory, and showed that light can sometimes behave like a particle and sometimes like a wave.
After the development of Maxwell’s theory of electromagnetism, the questions about the speed of light and what medium supports the transmission of electromagnetic waves arose again. For James Clerk Maxwell and other scientists of that time, the answer was based on the supposition of Christiaan Huygens that light travels in a hypothetical medium called “luminiferous aether” – the space-filling substance, thought to be necessary as a transmission medium for spreading of the electromagnetic radiation.
Vector (Euclidean vector) in physics, is a quantity that has both magnitude (size, length) and direction. It is represented as an arrow, whose length is proportional to the quantity’s magnitude. However, the vector has no position. It means that the vector is not altered if it moves parallel to itself.
Scalar is a quantity that has a magnitude but not a direction.
For example, velocity and acceleration (with magnitude and direction) are vector quantities, while speed (the magnitude of velocity), time, temperature, length, and mass are scalars.
Vector projection of a vector “A” on (or onto) a nonzero veсtor “B” (also known as the veсtor component or veсtor resolution of “A” in the direction of “B”) is the orthogonal projection of “A” onto a straight line parallel to “B”. It is a veсtor parallel to “B”.
Scalar projection of a vector on a coordinate axis (or on another vector), is a scalar, equal to the length of the orthogonal projection of the veсtor on the axis, and with a negative sign if the projection has an opposite direction with respect to the axis (or vесtor) direction.
In other words, some of the scalars in physics have two directions, that correspond to the signs “plus” and “minus”, while a vector can have infinite directions. The scalar projection of the vector on another vеctor can be recorded as
where θ is the angle between the two vectors.
Note: In order to be more precise, we will use the term “velocity”, when we mean the vector (with its direction); and we will use the term “speed”, when we mean the scаlar magnitude |V| of the vector.
7.1. About the velocity of light. Experiments – expectations and results
The Earth rotates around its axis, moves in its orbit around the Sun, and together with the Solar System moves around the center of our galaxy Milky Way.
The expectations of the scientists at the end of the 19th century.
According to the hypothesis of the existence of a “stationary luminiferous ether”, there is an invisible substance filling the space, which was thought to be the necessary medium for propagation of electromagnetic radiation (light). The expectations of the scientists have been that if the hypothesis is correct, the velocity vector of the created “ether wind” at the Earth’s motion at any time, must be equal to the sum (vector addition), but in the opposite direction), of the following three vectors:
1) the velocity vector of motion of the entire Solar System as it whirls around the center of our Galaxy at about 220 km/s (if we measure the speed by means of the units of time and length defined on the Earth’s surface); plus
2) the velocity vector of the Earth’s motion in its orbit around the Sun (which is approximately 30 km/s); plus
3) the vector of the linear velocity of the Earth’s surface at the location of the experiment (due to the Earth’s rotation around its axis). We know that the linear speed of the Earth’s surface of any point at the equatorial line is approximately 0.46 km/s, but it is equal to zero at the points of intersection of the axis of rotation with the Earth’s surface, which coincides with the north and south poles.
Fig. 7.1 is an illustration of the expected “ether wind”, at the motion of the Earth through the hypothetical medium called luminiferous ether. The figure depicts the Sun, the Earth and the Earth’s orbit. The three types of dotted lines depict the three components of the supposed “ether wind”, which have opposite directions to the aforementioned three vectors. The figure does not correspond to a scale (the radius of the Sun is about 109 times larger than the radius of the Earth, and the difference between the speeds of motion of the Earth and of the Solar System is much greater.
The expectations of the scientists have been that the “ether wind” will affect the speed of a light beam (will increase or decrease the speed of light):
• On the one hand, if the experiment is carried out at a fixed location on the surface of the rotating Earth, then the “ether wind”, created by the movement of the Earth on its orbit around the Sun, should have varying size and direction over time (e.g. at night and during the day).
• On the other hand, the experimenter may direct the light beam in different directions. In this way, the influence of the “ether wind” on light beam velocity, will be different.
Therefore, according to the expectations, the resulting speed of the light would be different, depending on the direction of the light beam, and would be different at night and during the day, when the direction of the “ether headwind”, caused by the movement of the Earth in its orbit around the Sun, is opposite. The difference of the speed of light for different seasons of the year (at various points of the trajectory of the Earth in its orbit around the Sun), was expected to be an indication of the velocity of motion of the Solar System in the stationary luminiferous ether.
So, if the hypothesis of the existence of “stationary ether” is true, the created “ether wind” by the Earth’s motion through the stationary ether should increase or decrease the speed of the light beam (depending on the direction and magnitude of the “ether headwind”).
But now let us reveal the “defect” of the fatal for the physics of the twentieth century Michelson-Morley experiment, which experiment continues to be maintained by modern physics.
7.2. The First Michelson’s Experiment
Albert Michelson designed an experimental construction (later known “Michelson interferometer”, and made his first experiment in 1881, in order to determine the change of the speed of light due to the motion of the Earth in its orbit around the Sun through the “stationary luminiferous ether” (see Fig. 7.1 ).
Michelson’s expectations were also that if the “stationary luminiferous ether” exists, the motion of the Earth through the ether would result in an effect of the “ether wind” on the speed of a light beam. Above, we have called the projection of the three-component“ether wind” on the direction of the light beam: “ether headwind” (see Fig. 7.2 ).
In other words, Michelson also expected that the speed of the light beam to be different:
• firstly depending on the direction of the light beam;
• secondly, the speed of the light beam (in the case of a fixed direction in relation to the Earth’s surface) was expected to be different at night and during the day, when the direction of the “ether headwind”, caused by the Earth’s motion in its orbit around the Sun is opposite in relation to the direction of the fixed light beam (see below Fig. 7.3 ).
On this basis, Michelson made his first experiment in 1881 with an interferometer constructed by him – see the scheme of the interferometer below in Fig. 7.4. Michelson used a monochromatic light beam, split (in order the two coherent light beams to be perfectly the same), into two mutually perpendicular directions. The two light beams propagate along two mutually perpendicular arms, each beam reflected in the opposite direction by a mirror. After reuniting of the two reflected beams at the place of splitting, the Michelson expected:
displacement of interference lines which is consistent with the expected difference in the speeds of the two light beams, caused by the “ether wind” due to the movement of the Earth in its orbit around the Sun.
Subsequently, the construction of the experiment “Michelson-Morley” was improved ‒ the light beams are reflected repeatedly, but the same conception is used again – the usage of two coherent light beams in two directions, from the splitter of the monochromatic beam to the mirrors and backward. The idea was to use two beams (one reflected) on the same arm, which means that each one goes exactly the same distance but in opposite directions ‒ from the monochromatic beam divider to the mirror and back. This, however, means that if the speed of the two opposite light beams, moving in opposite directions changes, the change will be the opposite, and the difference will be completely compensated, because the path of the two beams is perfectly the same!
Thus, on the base of the speed of the Earth in its orbit around the Sun, which is approximately 30 km/s, the results (the expectations of Michelson) were that the displacement of the interference fringes, will be different at night and during the day and will correspond to the calculations made.
Fig. 7.3 is a schematic representation of the opposite directions of the expected “ether wind” at night and during the day due to Earth’s motion along its trajectory around the Sun.
The yellow arrows show the direction of motion of the Earth’s surface, where the interferometer is located. According to the presented image, the direction of surface motion during the day is in the direction of the hypothetical “ether wind”, and at night – in opposite to the “ether wind” direction. The figure depicts a glimpse of the trajectory at which the Earth moves clockwise.
Note: The experiments were carried out in a short interval of time (the “Michelson-Morley experiment” was carried out from July 8 to July 12). This means that the Earth was located in approximately the same place on its trajectory around the Sun. That is why, the difference of speed of light due to the “ether wind” at different points of the Earth’s trajectory around the Sun (which is an indication of the speed of motion of the Solar System in the Milky Way with about 220 km/s – see Fig.7.1), was not calculated by Michelson…
The Michelson’s interferometer
The designed by Michelson experimental construction (the interferometer), illustrated below in Fig. 7.4, uses a two-way light propagation path.
The interferometer consists of a monochromatic light source (with an accurate frequency); semi-silvered mirror separating the monochromatic light beam from the source along the two mutually perpendicular arms; two mirrors (A and B) reflecting the coherent light beams in opposite direction; and a detector depicting the interference fringes after reuniting of the two light beams. They are all located horizontally (at the same gravitational potential).
As stated, the predicted change in the direction of the “ether wind” during the day and at night, in relation to the fixed arms of the interferometer to the Earth’s surface, should have led to a different change between the speeds of the two light beams, that should have been registered as a different displacement of the interference fringes. Using a wavelength of about 600 nm, Michelson expected that there would have been a displacement of the interfering fringes of about 0.04 of the distance between the fringes. The expected difference in displacement of interference fringes during the day and at night, has been sought in different directions of the two perpendicular arms of the interferometer.
However, the expected displacement of the interference fringes was not ascertained.
The results reported by Michelson:
“The small displacements -0.004 and -0.015 are simply errors of experiment.” (Michelson, 1881).
The Michelson’s conclusion was:
“The interpretation of these results is that there is no displacement of the interference bands… The result of the hypothesis of a stationary ether is thus shown to be incorrect, and the necessary conclusion follows that the hypothesis is erroneous.” (Michelson, 1881).
7.3. The well-known Michelson-Morley Experiment
The famous Michelson–Morley experiment was performed in 1887. Albert Michelson, with the collaboration of Edward Morley, constructed a new improved interferometer. As in the first experiment, the improved interferometer used two-way paths of two light beams on two perpendicular arms. But by using multiple mirrors, the light path length of the two light beams was about 10 times longer. The light was repeatedly reflected back and forth along the arms of the interferometer, increasing the light path length to 11 m. Thus, according to the intention, there was more than enough accuracy to detect the ether-hypothetical effect of the Earth’s motion. At the path length of 11 m, the expected displacement should have been about 0.4 of the distance between the fringes. To eliminate thermal and vibration effects, the Michelson and Morley’s interferometric apparatus was assembled on the top of a large block of sandstone, about a foot thick, which was then floated in a pool of mercury.
The result of the experiment was entirely unexpected and inexplicable again – the apparent velocity of the Earth around the Sun through the hypothetical ether was practically zero at any time of day or night, at all times of the year in different points of the Earth’s orbit. The reported results were given by Michelson:
“It seems fair to conclude that if there is any displacement due to the relative motion of the earth and the luminiferous ether, this cannot be much greater than 0.01 of the distance between the fringes.” (Michelson & Morley, 1887).
As it turns out (see chapter 4), in the one-way measurement of the speed of light between two points on the same latitude:
• the measured velocity of light in the “West to East” direction in the reference system related to the Earth’s surface is (c-V);
• the measured velocity of light in the “East to West” direction in the reference system related to the Earth’s surface is (c+V);
, where c is the scаlar “speed of light in
The evidence presented in the above-mentioned experiments “One-way measurement of the speed of light” and “Michelson-Gale-Pearson” (in chapters 4 and 6 of the book respectively), clearly ascertain the effect of the Earth’s rotation around its axis on the speed of light, measured on the Earth’s surface. They demonstrate with great accuracy the validity of Galileean transformations (which are a fact in our local physical reality).
In the “Michelson-Morley” experiment, however, no effect on the speed of light can be found, as a result of the Earth’s rotation. The reason lies in the inappropriate conceptual design, embedded in the construction of the interferometer. As justified, when using “two-way measurement of the speed of light”, the change of the speed of the two light beams for the two opposite directions, for each arm of the interferometеr, in the reference system connected to the surface of the Earth, completely compensates! If the resultant speed of the light beam in the direction “from the semi-silvered mirror to the reflecting mirror (either mirror A or mirror B)” is (c+V), then the speed of the light beam in the opposite direction will be exactly (c-V), where c is the speed of light in vacuum and V is the scalar projection of the linear velocity of Earth’s surface on the arm of the interferometer (i.e. on the direction of the light beam propagation). The path of the light beam in both directions for each arm is absolutely equal, and the direction and the length of the arm are irrelevant, because, at any value of V, this speed will be completely compensated. Thus, the resulting speed (measured for the two directions of the light beam in any arm) will always be equal to c :
This means that the interference fringes will never be displaced, because the speed of each light beam for both directions of any arm will always be exactly equal to c, regardless of the length of the arm, regardless of arm’s direction!
So, in the “one-way measurement of light speed experiments” and the “Michelson-Gail-Pearson experiment”, the
change of the speed of light as a result of the Earth’s rotation in the
reference system related to the surface of the Earth can be registered, when
using the inappropriate conceptual design of the construction of the
Michelson’s interferometer – this is impossible!
The conclusion is:
“Actually, if even the “ether wind” exists (caused by the Earth’s movement through the stationary luminiferous ether) – the difference in the speed of light between the two light beams, traveling in two opposite directions on the same arm, will be completely compensated. It is true for any arm in any direction! In other words, if the projection of the velocity of the “ether wind” on the direction of one of the light beams is (+V), then the projection of the velocity of the “ether wind” on the direction of the reflected light beam (traveling in opposite), will be exactly (-V).” (Sharlanov, 2016).
Over the past 100 years, too many variants of the Michelson-Morley experiment were carried out by many scientists from different famous universities and institutes of relativity and cosmology, with increasing sophistication and with increasing accuracy. However, the result cannot be other – the difference in the speed of light between the two light beams, traveling in two opposite directions on the same arm, is completely compensated if the construction of “two-way light beam interferometer” is used.
An example of this continuing and nowadays delusion, is also a publication in “Physical Review
The “Michelson-Morley experiment” is actually the primary root cause for the great delusion that “the speed of light is the same in all inertial frames of reference”, which is the core of the special theory of relativity.
The analysis of the article “On the Electrodynamics of Moving Bodies”, reveals the essence of the special theory of relativity (see the analysis).