Or how the current dark ages in physics have been drawn by the flawed conventional analysis of that infamous experiment
The Michelson-Morley experiment was conducted in 1887 with the definitive scope of detecting the (rather ill-thought) concept of ether wind. But the experiment was more apt at establishing if there are such things as absolute motion and absolute space, in fact. For those with a limited knowledge of the main aspects related to the experiment the paragraphs below may be helpful.
Physics theories of the late 19th century postulated that, just as water waves must have a medium to move across (water), and audible sound waves require a medium to move through (such as air or water), so also light waves require a medium, the "luminiferous aether". Because light can travel through a vacuum, it was assumed that the vacuum must contain the medium of light. Because the speed of light is so great, designing an experiment to detect the presence and properties of this aether took considerable ingenuity.
Earth travels a tremendous distance in its orbit around the sun, at a speed of around 30 km/s or over 108,000 km per hour. The sun itself is travelling about the Galactic Center at even greater speeds, and there are other motions at higher levels of the structure of the universe. Since the Earth is in motion, it was expected that the flow of aether across the Earth should produce a detectable "aether wind". Although it would be possible, in theory, for the Earth's motion to match that of the aether at one moment in time, it was not possible for the Earth to remain at rest with respect to the aether at all times, because of the variation in both the direction and the speed of the motion.
At any given point on the Earth's surface, the magnitude and direction of the wind would vary with time of day and season. By analysing the return speed of light in different directions at various different times, it was thought to be possible to measure the motion of the Earth relative to the aether.
Michelson had a solution to the problem of how to construct a device sufficiently accurate to detect aether flow. The device he designed, later known as an interferometer, sent a single source of white light through a half-silvered mirror that was used to split it into two beams travelling at right angles to one another. After leaving the splitter, the beams travelled out to the ends of long arms where they were reflected back into the middle on small mirrors. They then recombined on the far side of the splitter in an eyepiece, producing a pattern of constructive and destructive interference based on the spent time to transit the arms. If the Earth is traveling through an ether medium, a beam reflecting back and forth parallel to the flow of ether would take longer than a beam reflecting perpendicular to the ether because the time gained from traveling downwind is less than that lost traveling upwind. The result would be a delay in one of the light beams that could be detected when the beams were recombined through interference. Any slight change in the spent time would then be observed as a shift in the positions of the interference fringes.
The paragraphs above are from Wikipedia, where you can also find a detailed conventional analysis of the experiment. In what follows I will also use a conventional analysis of the Michelson-Morley experiment, written by Isaac Asimov. The reason I'm using that particular description is two-fold: Firstly, because Asimov's description is better suited to my purpose (which is looking for absolute space and motion); secondly, because in Asimov's description I found a beautiful “slip of tongue” about how common sense has been stripped of its sense by a silly assumption, a dogmatic view, and a terrible mathematical translation. Before getting to that, however, I want to show you below an animation with a basic image of the interferometer used in the experiment. (My interferometer may look different than Michelson's, but it nevertheless contains all the relevant features of the original interferometer. In the animation below S is the source of light, the two M are the two mirrors, and the two d represent the lengths of the interferometer's arms. The rest of the animation is pretty much self explanatory, so I'll say no more about that.)
In analysing the experiment we shall assess individually the two paths travelled by the beams of light. Thus, in the case where light is sent out in the direction of earth's motion, from the source S to the mirror M over the distance d, the light travels at its velocity c + the velocity of the earth v. This is the first leg of the journey, and mathematically this is expressed thus: d / (c + v). The second leg of this (parallel) journey takes place from the mirror M back to the source S, over the distance d. In this case, however, the light travels at its velocity c minus earth's velocity v. Mathematically this second leg of the journey is expressed thus: d / (c – v). In Asimov's words, from this point on:
The total time for the round trip is:
Combining the terms algebraically, we get:
Now suppose that the light-beam is sent out to a mirror at the same distance in a direction at right angles to the earth's motion through the ether. The beam of light is aimed from S (the source) to M (the mirror) over the distance d. However, during the time it takes the light to reach the mirror, the earth's motion has carried the mirror from M to M ', so that the actual path travelled by the light beam is from S to M '.
This distance we call x, and the distance from M to M ' we call y (see diagram above). While the light is moving the distance x at its velocity c, the mirror is moving the distance y at the velocity of the earth's motion v. Since both the light and the mirror arrive at M ' simultaneously, the distances travelled must be exactly proportional to the respective velocities. Therefore:
Now we can solve for the value of x by use of the Pythagorean theorem... In the right triangle S M M ' then, substituting vx/c for y:
The light is reflected from the mirror at M ' to the source, which meanwhile has travelled on to S '. Since the distance S ' S '' is equal to S S ', the distance M ' S '' is equal to x. The total path travelled by the light beam is therefore:
The time taken by the light beam to cover this distance at its velocity c is:
How does this compare with the time that light takes for the round trip in the direction of the earth's motion? Let us divide the time in the parallel case by the time in the perpendicular case...:
Now any number divided by its square root gives the same square root as a quotient... So the last equation simplifies to:
This expression can be further simplified if we multiply both the numerator and the denominator [like below]:
And there you are. That is the ratio of the time that light should take to travel in the direction of the earth's motion as compared with the time it should take in the direction perpendicular to the earth's motion. For any value of v greater than zero, the [last] expression above is greater than 1. Therefore, if the earth is moving through a motionless ether, it should take longer for light to travel in the direction of the earth's motion than in the perpendicular direction. (In fact, the parallel motion should take the maximum time and the perpendicular motion the minimum time.) Michelson and Morley set up their experiment to try to detect the directional difference in the travel time of light. By trying their beam of light in all directions, and measuring the time of return by their incredibly delicate interferometer, they felt they ought to get differences in apparent velocity...
They found no differences at all in the velocity of light with changing direction! To put it another way, the velocity of light was always equal to c, regardless of the motion of the source—a clear contradiction of the Newtonian laws of motion. In attempting to measure the absolute motion of the earth, Michelson and Morley had thus managed to cast doubt not only on the existence of the ether, but on the whole concept of absolute rest and absolute motion, and upon the very basis of the Newtonian system of the universe. (I. Asimov—Asimov's new guide to science, pp. 811-814)
The results of the experiment generated a subsequent linear reasoning and theoretical development which eventually reached a climax with Einstein's creation of the relativistic philosophy. Thus, following the path opened by the Michelson-Morley experiment, in 1893...
...the Irish physicist George Francis FitzGerald came up with a novel explanation to account for the negative results of the M-M experiment. He suggested that all matter contracts in the direction of its motion and that the amount of contraction increases with the rate of motion. According to this interpretation, the interferometer is always shortened in the direction of the earth's “true” motion by an amount that exactly compensates for the difference in distance that the light beam has to travel. Moreover, all possible measuring devices, including human sense organs, would be “foreshortened” in just the same way, so that the foreshortening could, in no possible way, be measured.
Then:
The Dutch physicist Hendrik Antoon Lorentz soon carried FitzGerald's idea one step further. Thinkink about cathode rays, on which Lorentz was working at the time, he reasoned that if the charge of a charged particle were compressed into a smaller volume, the mass of the particle should increase. Therefore, a flying particle foreshortened in the direction of its travel by the FitzGerald contraction would have to increase in mass.
Until, finally:
Einstein introduced a second important idea in his special theory of relativity: that the speed of light in a vacuum never varies, regardless of the motion of its source. In Newton's view of the universe, a light beam from a source moving toward an observer should seem to travel more quickly than one from a source moving in any other direction. In Einstein's view, this would not seem to happen, and from that assumption he was able to derive the Lorentz-FitzGerald equations. He showed that the increase of mass with velocity, which Lorentz had applied only to charged particles, can be applied to all objects of any sort. Einstein reasoned further that increases in velocity would not only foreshorten length and increase mass but also slow the pace of time; in other words, clocks would slow down along with the shortening of the yardsticks. (I. Asimov—Asimov's new guide to science, pp. 352-357)
And there it is—the theoretical development following the Michelson-Morley experiment. According to the conventional establishment, the road from the Michelson-Morley experiment to the creation of relativity was a natural and sensible progression that culminated with Einstein's vision. The special theory of relativity became one of the most precious jewels in the crown of physics, and as such it has been reigning absolutely now for just over a century. Most conventional physicists, who are die-hard relativists, no longer question the special theory of relativity—in spite of its many apparent vagaries. But, in the last four or five years, a small number of conventional physicists have found the need (and courage) to question the absolute validity of Einstein's first theory of relativity. One of them, Lee Smolin, believes for instance that the special theory of relativity needs to be changed, somehow, (although he doesn't seem to know how exactly that could be done, or what exactly needs to be changed). However, the cold fact is that physicists like Lee Smolin are so very few at this point in time that the special theory of relativity should still enjoy its absolute status for quite a while yet.
The special theory of relativity has been—nevertheless—opposed by many people since its inception, and that reality is still manifest today. The conventional physicists may scream all they want about the “irrefutable” validity of the theory; the fact is that more and more people are no longer fascinated by the bombastic picture painted by relativists. Instead, they are increasingly asking: “What on earth are you saying, Messrs. Physicists?” To which, of course, the relativists of today can only reply with the same arguments and the same mental pictures used by the relativists at the very beginning of the twentieth century. Not much has changed in the relativity saga, with the exception of some new “patching up” being required. For instance, Einstein assumed that the known velocity of light could never be superseded. That assumption had to hold, for otherwise things could be sent backwards in time. But the fact of the matter is that the speed of light has been superseded (and in the worst of all possible scenarios, in the form of an undeniable signal)! So, our relativists had no choice but to “patch up” the theory, somehow. In the end no one is quite sure if that particular hole in the special theory of relativity has been “patched-up”, although you can bet your last dollar that no relativist would accept that the “hole” is still there for all to see! In fact, no one is quite sure how relativists could claim that other “holes” in the special theory of relativity (in the form of the twin and the clock paradoxes) do not exist. I will come back to these issues a little later. Next, however, we'll reassess the Michelson-Morley experiment from the “common sense” perspective.