Around 1917, Albert Einstein added a term to the expansion-contraction equation of the universe. Subsequently, he called this term his “greatest blunder.” Instead, I propose that his abandonment of the aether was his greatest mistake. Ironically, the aether offers the physical basis for Einstein’s Special Relativity; namely, every large, massive object, such as a planet, is surrounded by an aether atmosphere because of gravitational attraction, similar to the earth’s air atmosphere. Special Relativity has it that the velocity of light everywhere is 3 X 10^{8} m/s, regardless of the velocity of the object with respect to the earth observer. This is exactly what one should expect if the object carries its own aether atmosphere.The Michelson-Morley (MM) experiment, in1887, showed that the aether, if it exists, was carried along by the earth. But it was not possible to detect the aether “background” in interplanetary space. A ray of light apparently does not bend, in traversing an aether motion discontinuity, because the transmission of transverse electromagnetic waves is fundamentally different from that of longitudinal sound waves. Nevertheless, with sensitive MM equipment mounted in a space station, it should be possible to measure the aether “background.”

The phenomena associated with a planet that is very rapidly receding from us is reviewed because, if it is carrying an aether atmosphere, light on the planet travels at 3 X 10^{8} m/s. Regarding the earth and receding planet as non-accelerating platforms, an observer on earth sees their clocks running more slowly than ours, they age more slowly than we do, and there is a shortening of length in a direction away from us. These effects also occur if they are approaching very rapidly.

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**Introduction**

Nowadays it is common knowledge that the universe is expanding. But around 1917, Albert Einstein (and other astrophysicists) were convinced that the universe was “flat,” not expanding or contracting. Accordingly, Einstein added a term to stabilize the expansion-contraction equation. In 1929, however, Edwin Hubble revealed that the universe was, in fact, expanding. Einstein’s comment, with regard to the term he had added to the equation, was that this was his “greatest blunder” [1].

But this was not really a serious mistake, because the expansion of the universe is an ongoing topic in cosmology; a major change was introduced as recently as 1998. (Einstein died in 1955 at the age of 76.)

In the present paper it is claimed that Einstein committed a far greater transgression– he created all of the conditions that necessitated an all-pervading aether, and then he abandoned it!

The propagation of sound requires a material medium – atoms or molecules. Without a carrier, sound cannot pass through a vacuum. Analogously, the aether was “invented” by James Clerk Maxwell and his contemporaries, around 1864, because the electromagnetic field (EMF) has to have a carrier in order to travel through “empty space.”

An EMF (radio wave, light ray, X-ray, gamma ray, and so forth) consists of minuscule photons. Each photon is a tiny oscillation at a frequency corresponding to its color (if it is visible light). Each photon has an electric field oscillating at right angels to a magnetic field; the direction of propagation is at right angles to the electric and magnetic fields. A photon carries energy, proportional to its frequency, that is surrendered when the photon is absorbed by a material object. The important point here, however, is that an aether carrier is required for the transmission of electromagnetic waves.

It is easy enough to detect a sound-wave carrier: Place a buzzer inside a jar and start to pump out the air. The loudness of the buzzer gradually diminishes until, with sufficient vacuum, it is no longer heard. Another important property is that the speed of sound does not depend on the frequency it is carrying; it only depends on two characteristics – the elasticity and density (weight) of the medium.

Unfortunately, it is not possible to pump the aether out of a jar. It is assumed here that the aether consists of aether particles—EPs—that are the same size or smaller than an electron, and that occupy the “empty space” inside and between atomic structures. Paraphrasing the above, the velocity of an EMF does not depend on the frequency (color) it is carrying; it only depends on two characteristics—the permeability and permittivity of the medium. In a “perfect vacuum,” the velocity of an EMF is 2.998 X 10^{8} m/s; in the present paper, however, it is much more convenient to use the approximate value c = 3 X 10^{8} m/s. (From here on, let’s assume that the medium is a “vacuum,” and not a material substance such as glass.)

**The Search for the Aether**

Following Maxwell’s EMF revelations, valiant efforts were made to detect the putative aether. The most famous experiment was carried out by Albert A. Michelson and Edward W. Morley in 1887 [2]. It was generally believed that the aether drifts through space without much regard for material objects, such as air, that happen to occupy that space. It was known that the speed of earth around the sun is 3 X 10^{4} m/s. Therefore, the velocity of light should be c = 3 X 10^{8} + 3 X 10^{4} m/s (an increase by a factor of 0.0001) if the ray of light is moving “downstream,” and decreased by a factor of 0.0001 if the light is moving “upstream.” Well, Michelson–Morley were not able to detect any difference!

The experiment has been repeated many times since 1887. Two possible explanations were offered to account for the results:

(a) There is no aether. Somehow, photons can propagate for billions of years, through the vastness of the universe, without a carrier, at a velocity independent of photon frequency, and without an iota of attenuation.

(b) There is an aether that permeates all of space, but its local component is stationary relative to the earth. Perhaps it is gravitationally attracted to the earth, like the earth’s atmosphere of air. This viewpoint is depicted in Fig. 1(a). The earth is labeled “US,” and is pictured as being a “stationary” platform. This is not quite true; there are small centrifugal accelerations because of the earth’s rotation around the sun plus its daily rotation around its axis. For the purpose of the present paper, however, we can ignore these accelerations and regard the earth as a non-accelerating platform.

The aether “atmosphere” is shown as a finite layer with a sharp motion discontinuity; that is, inside the “atmosphere,” the EPs are moving with the earth; outside, they move with the aether “background.” Actually, the layer must attenuate exponentially in some fashion similar to that of the air atmosphere. Tentatively, however, it is convenient to draw, as well as to think about, a layer of aether atmosphere that has a sharp discontinuity.

Far off to the right, in Fig. 1(a), is another planet, labeled “THEM,” which, for convenience in drawing, is the same size as the earth. It is speeding away, relative to US, with a velocity v. It is also a non-accelerating platform, and it is carrying, of course, its own aether atmosphere.

Between US and THEM is interplanetary space, with its own aether particles moving or drifting, say, in a northerly direction at some unspecified velocity relative to US. Herein resides a strong argument, however, against the model of Fig. 1(a). If a laser beam (the photon path) leaves US and is directed to THEM, it has to bend when it encounters the motion discontinuity. First it bends in an upward direction as it leaves the earth’s aether atmosphere; then it bends downward when it enters the distant planet’s aether atmosphere. These effects have not been observed. The aberration of starlight, when photons from a distant star enter the earth’s atmosphere, shows that no bending occurs [3]. (The aberration is caused by the earth’s motion around the sun, which results in telescopic changes by an angle of arctan 0.0001, which is based on the velocity of the earth relative to the velocity of light.)To summarize: The Michelson-Morley results can be explained if EPs are gravitationally attracted to every large, massive body, but the bending when a light beam leaves or enters the earth’s aether atmosphere has not been observed.

This can be explained, however, by a simple conjecture: The only fact we know about the EPs is that they transmit EMF waves at a velocity of c = 3 X 10^{8} m/s. Although the characteristics of a sound wave offer some helpful hints, they are completely different from EMF transmission in one important respect: A sound wave is longitudinal; that is, the molecules oscillate in the same direction as the propagation. An EMF, however, is transverse; the electric and magnetic fields oscillate at right angles to the direction of propagation. The notion that bending should occur, in Fig. 1(a), is a throwback to sound-wave ideology. Aether particles undoubtedly transmit in a completely different way – perhaps they spin, and the spin is somehow transmitted. We have no idea as to how electric and magnetic fields are transmitted from one aether particle to the next. The direction and speed of spin rotation could be the physical embodiment of an electric and magnetic field.

My conjecture is that a light ray does not bend when it reaches an aether motion discontinuity. This is depicted in Fig. 1(b). The “photon path” follows its original direction, continuing on at c = 3 X 10^{8} m/s, ignoring motion discontinuities.

If Fig. 1(b) is correct, it explains why it has not been possible to detect the aether. Also, if the aether does not do anything, it explains why Einstein avoided it. As Peter Galison wrote in his fascinating and informative book, Einstein’s Clocks, Poincaré’s Maps: “Earth’s motion through the aether could not be detected … and,therefore, so the argument went, Einstein concluded that the aether was ‘superfluous’ ” [4]. Apparently, Albert Einstein was happy that his spacetime equations were correct; he had more interesting and important projects on his agenda than trying to figure out how an EMF propagates, so he abandoned the aether. Nevertheless, Henri Poincaré and many other scientists did not regard the aether as “superfluous.” Without a reasonable explanation for how an EMF can propagate in a vacuum, the aether hypothesis could never be laid to rest.

This introduces us to a very ironic situation, because Einstein’s Special Relativity is based on the aether! This thesis is explored in the remainder of the present paper.

**Special Relativity**

Let’s turn the clock back some 100 years, to 1905, when Einstein was 26 years old. Maxwell’s aether implied that the universe was filled with the aether “background” of Fig, 1, with the aether drifting about relatively slowly (compared to the speed of light) through turbulence created by the stars, planets, and moons. Measurements indicated, whenever they could be made, that the local velocity of light is, always, c = 3 X 10^{8}m/s. Einstein adopted this as a guiding principle, never to be violated.

Next, in Fig. 1, suppose that the planet at the right was retreating from US at one-third the speed of light, or at 1 X 10^{8} m/s. Here is how Einstein would describe a beam of light [the photon path in Fig. 1(b)] sent from US to THEM:

“The beam leaves the earth traveling at c = 3 X 10^{8} m/s. When it encounters the interplanetary space, it continues in a straight line, at c = 3 X 10^{8} m/s. Eventually, the beam catches up with the 1 X 10^{8} m/s receding planet’s atmosphere. The beam somehow speeds up to 4 X 10^{8} m/s relative to US, which is 3 X 10^{8} m/srelative to THEM. The beam thus lands at proper speed.”

Einstein would continue: “Relative to THEM, the interplanetary space and the earth (US) are retreating to the left at a velocity of 1 X 10^{8} m/s. Therefore, if the THEM people send a light beam to US, it would at first travel to the left at 3 X 10^{8} m/s relative to THEM. When the beam reaches interplanetary space, it would speed up to 4 X 10^{8} m/s relative to THEM, which is 3 X 10^{8} m/s relative to US. This time the beam lands on earth at proper speed.”

Today, because the universe is expanding, we know that there really are planets receding from us at a velocity of 1 X 10^{8} m/s. Suppose, now, that a 100 Hz “light” signal originates at this planet and is directed to US. When the signal reaches the equivalent of the above interplanetary space, and its velocity increases to 4 X 10^{8} m/s relative to the planet, the frequency of the signal decreases to 75 Hz. This is the “Red Shift” (the ratio is 1.33, or red shift z = 0.33).

To Einstein’s imagined assessment of the photon path of Fig. 1(b), I would only add “Restore the aether” [5]. This would provide the physical basis for a light velocity of c = 3 X 10^{8} m/s in the earth’s “aether atmosphere,” and the same value at a planet receding from US at a velocity of 1 X 10^{8} m/s. Furthermore, my conjecture is that sufficiently sensitive Michelson-Morley type apparatus, carried aboard a space vehicle, could detect the movement of the aether “background.” At the very least, it should detect the movement relative to the space vehicle. Equipment that can detect motion in three mutually perpendicular directions would be useful.

In reality, the sharp motion discontinuities of Fig. 1 must be rounded off, so that all of the changes discussed above are gradual, with one exception: The velocity of light relative to US and to THEM is, always,c = 3 X 10^{8} m/s.

All of this hopping back-and-forth between 4 X 10^{8} m/s relative to US and 3 X 10^{8} m/s relative to THEM, and vice versa, hides an astonishing fact that Einstein recognized in 1905: The perception of time (and, subsequently, space) to US has to be different from what it is to THEM! The proof is simple (and here I am borrowing heavily from “Space and Time in Special Relativity,” by N. David Mermin) [6]:

Shown in Fig. 2(a) is a clock constructed by attaching a mirror to the end of a stick that is ℓ meters long. At t_{0} = 0 we launch a pulse of light; it strikes the mirror and is reflected back to a detector, reaching it at t_{1}seconds. From RT = D, we get

_{1}= 2ℓ. (1)

Fig. 2- A clock that demonstrates slower time, relative to US, on a rapidly receding planet THEM. (a) The clock consists of a light-pulse generator at t_{0}, a mirror, and a detector at t_{1}. (b) An identical clock, as it is seen through a telescope by an observer on earth. The three views show, respectively, the light-pulse starting off, arriving at the mirror, and arriving at the detector.Now, THEM people have the identical timepiece, so they also get ct_{1} = 2ℓ. But to US, looking through telescopes, the THEM clock is seen as depicted in Fig. 2(b). Three views are shown:

In the first view, the pulse of light is just starting off. Because the clock is moving to the right with velocity v (as seen by US), the light beam takes a slanting path to the right. In view 2 it strikes the mirror. In view 3 it is reflected back to the detector. As seen by US, the velocity of the light beam is c = 3 X 10^{8} m/s, but its path is the hypotenuse d of two identical right triangles: their height is ℓ and their base is vt_{2}/2, so that

^{2}+ (vt

_{2}/2)

^{2}]

^{1/2}= ct

_{2}/2. (2)

Eliminating ℓ in Eqs. (1) and (2), we easily get

_{2}/t

_{1}= 1/[1 – (v/c)

^{2}]

^{1/2}. (3)

_{2}is always greater than t

_{1}, so we perceive that the THEM clock is slow. Some numerical values are presented in Table 1. In the previous example, where v = c/3, we get t

_{2}= 1.061t

_{1}, or the THEM clock runs slow by a factor of 0.943.

Table 1- Perception by US of how slow THEM clocks are as a function of velocity, v.

Since v is squared in Eq. (3), THEM clocks also run slow if the planet is approaching US, in which case v is negative [reverse the arrows in Fig. 2(b)]. Therefore, on any planet that is receding from or approaching US, the clocks run slow relative to planet US clocks. Most amazing is that all biological and time processes run slow, synchronized with the slow clocks, so that people age more slowly relative to US.And vice versa. Relative to THEM, planet US is receding with velocity v. Therefore, while their clocks keep perfect time, they perceive that the clocks on planet US run slow.

If a space ship departs from US, and subsequently returns to US, will the people aboard the space ship return younger than US? Here, “vice versa” is not valid because, in order to return, the space ship has to undergo a tremendous midcourse deceleration and re-acceleration. To properly answer such questions, one should plot a Minkowski diagram, such as that of Fig. 3.

^{8}m/s for 5 years (3 years for THEM) followed by their return at a speed of 0.8c. The space-ship passengers disembark 4 years younger than US inmates. Planet US is stationary (distance = 0) along the vertical axis. With the scales shown, the speed of light is represented by a 45° line.

Figure 3 is the plot for a space ship (THEM) that travels away from US at a velocity of 2.4 X 10^{8} m/s (that is, at 0.8 times the speed of light). After 3 years of THEM time, the ship turns around and heads for US, again at a velocity of 0.8c. The diagram is a plot of time versus distance, but time is given in years and distance in light-years. With the scales shown, the speed of light is represented by a 45° line. The THEM locus starts out at an angle of arctan 0.8 (38.7°). According to Table 1, t_{2}/t_{1} = 1.667, so 3 years on THEM shows up as the same time (vertical scale) as 5 years on US. The voyage ends with 6 years on THEM equal to 10 years on US; that is, the space ship people arrive 4 years younger than the inmates of US (this could be a problem for the IRS), but they had to survive that terrible midcourse reversal of direction.The Minkowski diagram can reveal much more. Figure 4 is a plot of the above voyage with light pulses broadcast from US at I-year intervals (solid lines) while THEM are sending similar light pulses (dashed lines) . The light pulses from US are 45° lines with a positive slope; the first pulse, sent at t = 1 year, arrives at THEM at their 3-year point. Subsequent pulses from US arrive during the THEM return trip, 3 times a year. The light pulses from THEM are 45° lines with a negative slope. The first pulse, sent at t = 1 year, arrives at US at our 3-year point. Their 3-year pulse arrives at our 9-year point. Subsequent pulses arrive 4 months apart.

Fig. 4- The diagram of Fig. 3 if we transmit a light-beam pulse every year (solid lines) to THEM while they, likewise, transmit a light-beam pulse to US every year (dashed lines). The lines from THEM have a -45° slope.All of the above discussion about a space ship zooming along at 2.4 X 10^{8} m/s is academic because of the tremendous amount of energy required to accelerate a vehicle to this velocity. The space ship has to carry its own fuel, of course. Einstein’s Special Relativity has been verified using the atomic equivalents of “space flight.”

Finally, consider how relative velocity causes a perceived change in space (actually, a reduction in length). This is drawn to scale, in Fig. 5, if the velocity of planet THEM is 0.6c = 1.8 X 10^{8} m/s.

In Fig. 5(a) [also called View (1)], we again have a clock constructed by attaching a mirror to the end of a stick that is ℓ_{1} meters long. At t_{0} = 0, we launch a pulse of light; it strikes the mirror and is reflected back to a detector, reaching it at t_{1} seconds. We get

ct_{1} = 2ℓ_{1}. (4)

Fig. 5- The clock of Fig. 2 with orientation changed in order to demonstrate shortening of sticks (length), relative to US, on the rapidly receding planet THEM. The drawing illustrates v = 0.6c = 1.8 X 10^{8} m/s. (a) The clock on the stationary planet, US. (b) An identical clock, as it is seen through a telescope by an observer on earth. Views (2), (3), and (4) demonstrate, respectively, the light pulse starting off, arriving at the mirror, and arriving at the detector. View (4) actually overlaps View (3), so it is drawn below View (3) for the sake of clarity.The THEM people have the identical timepiece, so they also get ct_{1} = 2ℓ_{1}. But to US, looking through telescopes, the THEM clock is seen as depicted in Fig. 5(b). Three views are shown:

In View (2), the pulse of light is just starting off. Because the clock is moving to the right with velocity v (as seen by US), the light beam has to travel a considerable distance before, in View (3), it strikes the mirror. In View (4) it is reflected back to the detector. Because View (4) actually overlaps View (3), it is shown below View (3) for the sake of clarity.

As always, as seen by US, the velocity of the light beam is c = 3 X 10^{8} m/s. Then

_{3}= ℓ

_{2}+ ℓ

_{3}(5)

and

_{3}= ℓ

_{3}, (6)

_{3}is the time between Views (2) and (3),

ℓ

_{2}is the length of the stick perceived by US,

ℓ

_{3}is the distance the mirror moves in t

_{3}seconds.

From Eqs. (5) and (6), eliminating ℓ_{3}, we get

_{3}(c-v) = ℓ

_{2}. (7)

Similarly,

_{4}= ℓ

_{2}-ℓ

_{4 }(8)

_{4}= ℓ

_{4}, (9)

where t_{4} is the time between Views (3) and (4), ℓ_{4} is the distance the mirror moves in t_{4} seconds.

From Eqs. (8) and (9), eliminating ℓ_{4}, we get

_{4}(c + v) = ℓ

_{2}. (10)

The next step is to use the perceived slowing down of THEM clocks, as given by Eq. (3). In Fig. 5, the total perceived time, t_{3} + t_{4}, takes the place of t_{2} in Eq. (3). Then

_{1}/(t

_{3}+ t

_{4}) = [1-(v/c)

^{2}]

^{1/2}. (11)

Finally, we are interested in length rather than time. Substitute for t_{1}, t_{3}, and t_{4} from Eqs. (4), (7), and (10) to get

_{2}/ℓ

_{1}= [1 -(v/c)

^{2}]

^{1/2}. (12)

In this equation, ℓ_{2} is always less than ℓ_{1}, so we perceive that the THEM stick has shortened. The numerical values of Table 1 are again applicable if the last column stands for ℓ_{2}/ℓ_{1}.The numerical values used in drawing Fig. 5 follow: v = 0.6c, ℓ_{1} = 10, ℓ_{2} = 8, ℓ_{3} = 12, ℓ_{4} = 3, t_{1} = 20, t_{3} = 20, and t_{4} = 5.

Since v is squared in Eq. (12), THEM sticks also shorten if the planet is approaching US, in which case v is negative [reverse the arrows in Fig. 5(b)]. Therefore, on any planet that is receding from or approaching US, we see a shortening or flattening of material objects, but only in the direction away from or towards US. In Fig. 3, when the space-ship inmates disembark after 10 US years (or 6 THEM years), will their faces be flattened? Positively not! As the space ship decelerates from v = 0.8c = 2.4 X 10^{8} m/s to zero, the flattening (as seen in our telescopes) will gradually vanish. But they will be 4 years younger than US folks.

**References**

[1] L.M. Krauss and M.S. Turner, “A Cosmic Conundrum,” Sci Am, vol 291, pp 71-77, Sept. 2004.

[2] W.K.H. Panofsky and M. Phillips, “Classical Electricity and Magnetism,” Addison-Wesley, Reading, MA, 1955, pg 176.

[3] op.cit., pg 237.

[4] P. Galison, Einstein’s Clocks, Poincaré’s Maps, Norton, New York, 2003, pg 324.

[5] S. Deutsch, Return of the Ether, SciTech, Mendham, NJ, 1999.

[6] N.D. Mermin, “Space and Time in Special Relativity,” Waveland, Prospect Hts., IL, 1968.