Why Relativity Exists

Why Relativity Exists


This paper provides the reason for the existence of relativity that Einstein himself never realised. In the theory of relativity, time and space distort depending on our state of motion, while the speed of light always remains constant. Einstein considered the constancy of the speed of light as a postulate that cannot be explained.

This so-called postulate, however, is actually not a fundamental law of nature because there is an underlying explanation for it: We perceive the speed of light to be constant because the physiological functioning of our body (including our brain) depends on the speed of electromagnetic transmission (which is the speed of light), and we have defined our time according to how we physiologically experience it. We have thus effectively used the speed of light as the standard for defining our time, and that is why the speed of light is always constant according to our time.

This also reveals that relativity exists because our science is actually a science of what we experience, and not a science of a universe independent of us as observers. If scientists ignore this fact, we would be like the prisoners in Plato’s Cave, who have no idea that they are trapped by their perceptual limitations. Thus, in science, we need to take into account our crucial role as conscious observers.

(See also the related articles: Relativity Proves that Time and Space are Empty of Inherent Existence and A Direct Experiential Interpretation of Quantum Mechanics. For an easier introduction to the key concepts on Relativity and Quantum Mechanics presented by the author, see the talk on “why this is not a materialistic universe” given by the author on YouTube.)



The Michelson-Morley Experiment
Explaining the Michelson-Morley Experiment
Einstein’s Postulates
Distortions in Time and Space
The Physiological Basis of Relativity
Why the Speed of Light is Constant
Relativity and Plato’s Cave



An enduring mystery in modern physics has been the reason for the existence of the famous theory of relativity. The story goes that the great physicist, Werner Heisenberg, on his deathbed, stated that he wanted to ask God two things—why relativity and why turbulence? While the problem of turbulence belongs to another field of physics (and beyond our scope here), this paper aims to address Heisenberg’s first question—why relativity?

That relativity should be one of the puzzling phenomena foremost in Heisenberg’s mind is hardly surprising. The brain-child of Einstein, relativity invokes extremely bizarre concepts—time slowing down, space contracting, curvatures in space-time, and so on. While the mathematical formulation of relativity has, over the last century, been found to be consistent and sound, the question nonetheless remains: Why do these contortions of time and space occur?

Often physicists get around the lack of intuitive understanding by claiming that “we understand if we can compute,” thus brushing aside the fact that we may not actually know why the mathematics employed in a particular situation work. In other words, we often employ a mathematical camouflage for our ignorance.

This paper addresses this problem by providing an intuitive understanding of special relativity and explains why these distortions of time and space occur—an explanation that Einstein himself had not realized. This explanation also reveals something of critical importance in the very nature of science itself.

The Michelson-Morley Experiment

Our story begins in 1887, the year of the famous Michelson-Morley experiment. This experiment was a defining moment in the history of physics because it was the first crack in the wall of this grand monument called classical physics.

Prior to that fateful event, the classical physics of Newton and Maxwell appeared to be reaching a state of total fulfilment. Everything had fallen into place and this grand edifice of classical physics appeared almost complete, with only some subtle final touches needed to round off an apparently perfect structure.

Ironically, it was Albert Michelson who casually remarked, at that time, that all that remained undone in physics was to fill in the sixth decimal place (meaning to say that physicists only had to fine-tune the established classical laws). Yet, in 1887, together with Edward Morley, Michelson himself lit the fuse for a scientific explosion that shattered a very fundamental premise of classical physics. Their experiment ushered in the era of what came to be called modern physics, a new scientific understanding whose theoretical framework rests entirely upon the wonderfully strange world of relativity and quantum theory.

The Michelson-Morley experiment helped destroy the classical idea of an absolute space and time, and it did this by first undermining the concept of the ether. The ether was the hypothetical medium considered necessary for light to travel in. It was thought, at that time, that every wave required a medium, and light was an electromagnetic wave. So, just as ocean waves required water, and sound waves required air, it was felt that light waves required the ether as the medium to travel in.

What the ether actually was, however, proved to be a puzzle since it appeared to be totally undetectable. It had zero density, perfect transparency, and no measurable properties whatsoever. Little wonder then that it had been impossible to determine exactly how the ether travelled in relation to the Earth.

Nonetheless, what Michelson and Morley set out to do, in 1887, was to measure the effect of the Earth moving in relation to this hypothetical ether. The scientific reasoning at that time was as follows:

Since the Earth rotates around the Sun, and if—as was widely thought—the ether was stationary relative to the Sun, the Earth would then be flying through the ether at its orbital speed of about 30 km per second. We, on the Earth, would thus find this “ether wind” moving past us at this same speed (the same way we would feel the air whizzing past us in an open car).

Also, it was noted that, in orbiting the Sun, the Earth travels in opposite directions every six months. So, even if the ether was not stationary relative to the Sun, it cannot remain stationary to the Earth throughout the year. We should generally be feeling the ether wind traveling past us.

The Michelson-Morley experiment was designed to measure the effect of this ether wind, and the key instrument employed was the Michelson interferometer. This ingenious device splits a light ray into two parts and sends them traveling to-and-fro along different directions perpendicular to each other. The two light rays meet again at the end of their different paths and interact with each other to form an interference pattern. The difference in the time required by the two light rays to complete their respective journeys affects this interference pattern.

If one light ray travels along the line of motion of the ether wind and the other perpendicular to the motion of this same ether wind, the two light rays should require different times to complete the journey. In effect, it is like comparing the different times taken for an athlete to run to and fro along a track when there are different wind directions. In one scenario, the wind is first blowing directly against him and then directly behind him (when he turns around). In the other scenario, the wind is first blowing at him from his left and then from his right (when he turns around). Because the wind’s direction affects the runner’s speed, it can be shown that the runner would require more time to complete the journey under the conditions of the first scenario.

In the interferometer, the different times required by the two light rays (for their respective journeys) affect the interference pattern they form when they meet at the end. Now, if we rotate the interferometer so that the direction of the ether wind relative to the paths of the two light rays are changed, we would expect this time difference to be altered. This, in turn, should then cause a change in the interference pattern.

To the surprise of the scientific community, however, Michelson discovered no change in the interference pattern no matter how he rotated the interferometer. The ether wind appeared not to be there at all!

Because this result was so surprising, similar experiments were repeated many times (by Michelson and others) under different conditions. Michelson and Morley even conducted the experiment on a mountaintop in case that somehow made a difference. In the end, however, it was found that the varying conditions made no difference whatsoever. All these other experiments consistently produced a null result, i.e. no change in the interference pattern. So where was the ether wind?

Explaining the Michelson-Morley Experiment

The null result of the Michelson-Morley experiment baffled the physics community. Why was the ether wind undetectable? A number of attempts were made to explain this unexpected finding.

One proposed explanation that received serious attention was the “ether drag” hypothesis, which suggested that the Earth dragged the ether along with it when it moved. This explanation, however, was found to be invalid because it contradicted the findings of other experiments. Notably, the “stellar aberration” observed by British astronomer James Bradley in 1728 demonstrated that there really was no ether drag.

What Bradley observed was that the position of the stars appears to rotate in a circular motion over the period of a year. This meant that the direction of the light rays from the stars were affected by the motion of the Earth around the Sun. Just as raindrops appear slanted towards us when we run forward, the light rays from stars appear slanted because of the motion of the Earth. If the Earth dragged along the ether, this stellar aberration would not occur.

So the question remained. If the Earth did not drag along the ether, why was the ether wind not detected by the Michelson-Morley experiment? H. A. Lorentz and G. F. FitzGerald, working independently of each other, came up with another possible explanation. They suggested that the length of objects contracted in the direction of the ether wind and remain unchanged in the other directions perpendicular to this wind, an effect now known as the Lorentz-FitzGerald contraction.

This would mean that the two perpendicular arms of the Michelson interferometer (along which the light rays travelled) would have different lengths depending on how the interferometer was orientated in relation to the ether wind. Their lengths would vary in just such a way that compensated for the effect of the ether wind on the light rays, the end result being that both light rays would take the same amount of time to traverse the different paths. Hence the null result of the Michelson-Morley experiment.

Technically, the Lorentz-FitzGerald contraction did provide a solution to the Michelson-Morley experiment. The problem with the theory, however, was that it missed the big picture. While it explained why the ether wind could not be detected, the theory nonetheless accepted the presence of an ether wind.

It was finally left to a young patent clerk, in 1905, to make the bold suggestion that the Michelson-Morley experiment was actually a vital clue to the very nature of time and space itself. The visionary difference here was the realization that there was no ether at all!

Einstein’s Postulates

In 1905, while working as a patent clerk, the 26-year-old Albert Einstein published three scientific papers in one issue of the Annalen der Physik. This issue of the physics journal has since become a unique collector’s item because any one of those three papers, alone, would have won Einstein the Nobel Prize in physics.

Ironically, of the three papers, Einstein was awarded the Nobel Prize in 1921 for his paper on the photoelectric effect, and not for the one on the theory of relativity, the theory synonymous with his name. Relativity—Einstein’s main work—was apparently still being disputed in 1921. This was hardly surprising given the bizarre nature of relativity. Effects like time dilation, length contraction, and distortions in space-time, were not exactly your everyday intuitive events. How then did Einstein reason his way to such apparently fantastical scientific conclusions?

In his 1905 paper “On the Electrodynamics of Moving Bodies”, Einstein introduces the two postulates that form the starting point for his theory of relativity. The first of these postulates, which Einstein calls the “Principle of Relativity” gives his whole theory its name.

The Principle of Relativity abolishes the idea of an absolute state of rest. All observers moving at constant velocity relative to each other thus have equal status; no observer can claim to be the “special one” at rest. For example, a man standing on a train station may claim that he is stationary while his friend on the train is moving. His friend, however, may claim, instead, that he is the one actually at rest while the man on the platform is moving. Both are equally correct. According to Einstein, all velocities are relative. Hence, an object’s designated velocity conveys little meaning unless we also know which frame of reference we are viewing this velocity from.

While this first postulate may be revolutionary, it is nonetheless reasonably intuitive, i.e. it feels logical in a “common sense” way. Einstein’s next postulate, however, is extremely counter-intuitive, and weird consequences arise from it. Unlike the first postulate, this one defies common sense. The second postulate states that the speed of light is constant relative to all frames of reference.

Why this is so weird? If we observe a flash of light while standing on Earth, we will find it travelling from us at 300,000 km per second. Another observer, travelling in the same direction as this light ray, should then measure its speed, relative to himself, to be slower. He is, after all, chasing after it. Einstein’s second postulate, however, states that this simply does not happen.

Let us look at an analogous situation. If we are in a police car chasing after a getaway car, we would expect the getaway car to move away from us at a slower speed (relative to us). If the police car manages to move at the same speed as the getaway car, the getaway car would not even be moving away from us at all. Its velocity relative to us would then be zero, since we are keeping up with it. This would be common sense.

Now imagine the scenario if the getaway car behaves like Einstein’s light ray. What happens then is this. The getaway car continues to pull away from the police car at the same speed, no matter how fast the police car chases after it. It’s the ideal getaway car. It runs away from us at exactly the same speed no matter how we race after it.

The really strange thing is this. A man standing on the pavement also sees this same getaway car pulling away from him at the same speed as we do in the police car. In other words, the speed of the getaway car relative to the man on the pavement, and relative to us in the police car chasing after it, is exactly the same! For example, if the getaway car is pulling away from the man on the pavement at 100 km per hour, it is also pulling away from us in the police car at 100 km per hour, even though we are tearing after it as fast as we can. How can this be? Surely this defies common sense.

This weird behaviour of the getaway car is, nonetheless, what Einstein is proposing for the light ray. The same light ray travels away from all observers at the same speed of 300,000 km per second, regardless of whether the observer is stationary or moving. The velocity of the observer makes no difference whatsoever. The speed of light is constant relative to all frames of reference. This then is Einstein’s second postulate. It sounds positively crazy!

Nonetheless, this second postulate of relativity has passed the test of time. It has survived a whole century of close scientific scrutiny, and has become a fundamental cornerstone of all modern physics. How do we explain this phenomenon?

Actually, Einstein never gave an explanation for his second postulate. That, in fact, is why it is called a postulate. A postulate is a principle simply assumed to be true, and then used as the basis for further derivations and conclusions. For some reason, Einstein’s second postulate works. But why does it work? And why is nature so strange? That was the question Heisenberg, on his deathbed, was purportedly still puzzling over. Why—Heisenberg was essentially asking—does relativity exist at all?

Distortions in Time and Space

How is it possible for the speed of light to remain constant to all frames of reference? Surely, observers moving at different velocities should see the same light ray travelling at different speeds relative to themselves. How is it that this does not happen?

There is one possible solution to this conundrum. Perhaps time and space actually distort when we travel, and they distort in just such a way that all observers still measure the speed of light as the same. Strange as it may sound, this was exactly the solution Einstein implemented in his theory of relativity, and incredibly, it worked!

We can almost sense the knowing smile appearing on the lips of all lovers of conspiracy theories. Here, surely, must be the ultimate conspiracy theory! Even time and space conspire to contort themselves in exactly the correct way needed to fool us into measuring the speed of light as constant.

These contortions in time and space are no mean feat either. They are extremely complicated, and require time to slow down, space to contract, and simultaneity to become an observer-dependent phenomenon.

This last distortion on simultaneity means that while one observer may consider two events to be occurring at the same time, another observer may not. Simultaneity is relative. This means, also, that while one observer may perceive Event A to occur before Event B, another observer may, instead, perceive Event B to occur before Event A. The temporal sequence of events may be different for different observers.

While all these distortions in space-time appear extremely complicated, there is nonetheless a method in their madness. All the distortions appear precisely engineered so that we always end up measuring the speed of light as constant. We can never measure the speed of light in vacuum as anything other than 300,000 km per second, no matter how fast, or in which direction, we move. Time and space consistently modify themselves so that we never measure the speed of light as anything else. It is really like an elaborate conspiracy.

Yet, why would nature behave this way? Could we be missing something? If we step back and reexamine the situation without preconceived bias, one thing does seem evident. If the speed of light is always constant, while time and space so readily transform, is it not more logical to consider the speed of light—rather than time and space—as the fundamental entity?

Perhaps, by considering time and space to be fundamental, we have been placing the cart before the horse all this while. The reverse, in fact, may be true. Perhaps time and space are actually entities derived from the more fundamental phenomenon, which is the speed of light. A closer examination will reveal that this is actually the case, a realization that will also highlight a crucial quality we need to recognize about the very nature of science itself.

The Physiological Basis of Relativity

Einstein and the physicists of his day never grasped why relativity occurs. Their poor understanding of human physiology probably accounted for that. Apart from their lack of training in that area, the very science of physiology itself was insufficiently advanced in the early twentieth century.

This reason for Einstein’s failure to explain why relativity occurs may come as a surprise. What has physiology to do with relativity? Startling as it may sound, human physiology has everything to do with relativity. The theory of relativity would not even exist if not for the way our human body functions!

How do we come to such a staggering conclusion? First, we need to raise the question that has, for centuries, been left unaddressed. Actually, the question has never even been asked, let alone addressed. This question, nonetheless, has been lurking in the shadow of this long and grand exhibition of human scientific achievements ever since its misty beginnings centuries ago.

The question is simply this: Are our scientific theories actual theories of phenomena that are independent of man, or are they merely theories of how man experiences the universe? In other words, is our science a study of the universe that is independent of us, i.e., one that would be equally valid even if we were not around? Or—as we are now asking—are our scientific theories actually only theories of how our mind and senses perceive and interpret the universe?

While scientific theories are based on data obtained from scientific experiments, the key point is this: We need to observe these experiments. Even the use of scientific measuring apparatus does not obviate this requirement; ultimately we have to retrieve the data from the scientific equipment, and this means observation by humans. This is the crucial point. Sooner or later, our human sensory apparatus and our consciousness come into play. It is unavoidable.

To the extent that they need to be observed, all scientific data are thus observer dependent. The real question, however, is this: Is the actual content of the data we observe also affected by this observer dependence? In other words, does this need to be observed show up in the very data itself? There is, naturally, an inherent problem with answering this question. We simply cannot compare observed data with unobserved data. No observation means no data; so we do not have any “unobserved data” to compare with. How then do we address this question?

All we can do, really, is to look for clues suggesting this observer dependence in the observed scientific data itself. So, are there these clues that indicate our observed data is intrinsically tied in to our physiological sensory apparatus and/or to our consciousness (i.e. the things that enable us to be observers)? The answer that leaps back at us is glaringly clear: it is, in fact, a resounding “Yes”!

The very foundation of all modern physics—both relativity and quantum theory—point to the fact that our scientific data are actually observer dependent. Without the observer, much of quantum physics and relativity would not even make sense (see “A Direct Experiential Interpretation of Quantum Mechanics”). This strongly suggests that our scientific theories are actually theories of how we experience the universe, as opposed to being theories of a universe that is independent of us as observers.

Let us return our focus now back onto the theory of relativity. Relativity essentially deals with time and space, so the crucial question here is this: Are time and space inherent properties of the universe (independent of man) or are they only entities that reflect our human experience?

According to the theory of relativity, time and space vary according to the frame of reference of the observer. These entities, therefore, vary depending on the observer’s experience. If they are entities independent of man, why should our vantage point matter?

This strongly suggests that what we define as time and space are, in fact, not inherent properties of the universe. They are simply our time and space, i.e., what is experienced by us. Thus, time and space, as defined by our science, are actually only properties pertaining to how our senses interpret the universe.

There is a further critical clue from the theory of relativity. And that is Einstein’s second postulate: the speed of light is constant to all frames of reference. The idea that time and space invariably modify themselves just so that we always measure the speed of light as constant almost suggests a conspiracy by nature. Actually, there is no such conspiracy. The speed of light happens to be constant to all human observers simply because the speed of light (which is the speed of electromagnetic transmission) plays an intrinsic role in how our body and our perceptual apparatus function. The speed of electromagnetic transmission directly affects how we experience the universe because electromagnetism plays a crucial role in the functioning of our biological sensory apparatus.

The transmission of light is essentially the transmission of a disturbance in the electric and magnetic fields. This disturbance is not immediately felt by another charged particle at a distance. This is akin to how a sudden shaking at one end of a long rope is not felt immediately at the other end of the rope. First, the disturbance has to be conveyed along the rope to the other end. Likewise, a disturbance in the electric and magnetic fields needs to be transmitted first in order to be felt at a distance, and the rate of this transmission is exactly the speed of light, since light is an electromagnetic wave.

A similar transmission of electrical disturbance has to occur in the functioning of the human body. For example, an electrical signal in a nerve cell has to be transmitted along the axon of the nerve cell before it can be felt by another nerve cell at the other end. The rate of this transmission is dependent on the general rate of transmission of any electrical disturbance, which is the speed of light.*

Herein lies the physiological basis of relativity. And herein lies the concrete evidence that our science is actually a science of how we experience the universe, and not a science of a universe independent of us as observers. Let us look more closely at this critical clue provided by Einstein’s second postulate.

Why the Speed of Light is Constant

The physiological basis of relativity stems from the fact that all our biological mechanisms function via electromagnetic interactions. Every single organ—as well as every single cell—in our body functions via electromagnetism.

Muscular force is actually electromagnetic force. We are able to move only because our muscular contractions are mediated by electromagnetism. We literally move and breathe via electromagnetic interactions. All our sensory apparatus also rely on electromagnetic interactions. Even our nerves transmit information via electromagnetism; hence our brain functions via electromagnetism. This is the crucial point. It all means that our sensory experience of the universe is mediated by electromagnetism.

Since the speed of light is the speed of electromagnetic transmission, the reason for its constancy now becomes evident. It is constant because of a limitation in our perceptual ability. We are simply unable to experience the speed of light varying because both our perceptual apparatus and our brain function via electromagnetic transmission. In other words, we cannot experience the speed of light to be anything other than constant because the very rate at which we ourselves function depends on the speed of light!

We are essentially trapped inside the system, like the characters inside a video movie. If someone slows down the video, all the characters inside the video—as well as everything else there—slows down equally. The characters’ movements, and even their rate of thinking, slow down exactly in line with everything else. How then would these characters inside the video notice any difference in the speed of the video itself? They would, in fact, not notice any change at all, simply because they cannot escape the system to view it from the outside.

As another example, suppose we want to measure the expansion of an iron rod being heated inside an oven. If we use an iron ruler inside the oven to make the measurement, we detect no expansion. This is because the iron ruler expands by the same proportion as the rod. This iron ruler is incapable of detecting a change because it is also inside the system and equally affected by it.

Likewise, we cannot measure any change in the speed of light because we are also “trapped inside the system.” If the speed of electromagnetic transmission slows down, we ourselves—our actions and our thoughts—slow down by the same amount, so we cannot detect any change. That is the reason for Einstein’s second postulate.

Let us now look at a more elaborate analogy that even more closely parallels the case regarding the speed of light. Suppose we wish to measure the speed of a river flow, and we follow this procedure: We place a buoy on the river as a marker and determine the distance the buoy travels. We then divide this distance by the elapsed time to obtain the speed.

Suppose, unconventionally, we now decide to measure time by the number of turns of a waterwheel placed on the same river, i.e., we define one unit of time by one turn of the waterwheel. If the rate at which the buoy travels and the rate at which the waterwheel turns are both proportional to the rate of the river flow, we will now always measure the speed of the river flow as constant. The reason for this is that the waterwheel turns correspondingly faster whenever the river flows faster, so we cannot detect the change if we keep to our unconventional way of defining time.

The curious point in this analogy is, of course, our unconventional way of measuring time with the waterwheel, a procedure that makes our measured time dependent on the river flow itself. What we need to check, then, is whether or not we are doing something similar in our actual determination of time. So what determines our human experience of time?

Since the rate of all our bodily functions, including our rate of thinking, depend on the rate of electromagnetic transmission, it can be seen that we have arbitrarily defined time as the rate of electromagnetic transmission in our perceived space. This means that we have been trying to determine the speed of light—a form of electromagnetic transmission—by using a measure of time that also depends on the speed of light! We are thus in a similar situation to that in the river flow analogy. Little wonder, then, that we always measure the speed of light as constant.

But do all our clocks actually measure time this way? Electrical clocks and mechanical clocks not utilizing gravity clearly employ the rate of electromagnetic phenomena to measure time. But are there not other types of time-measuring devices, ones that make use of other phenomena—for example, the rate of radioactive decay, the rate at which the Earth moves around the Sun, and so on? These other time-measuring methods do indeed exist, but that actually does not alter the underlying logic why the speed of light is constant.

To see this, let us return to our analogy: Suppose, now, we want to check whether we can use an anemometer—an instrument that rotates depending on wind flow—instead of the waterwheel, to measure time. If we find that the anemometer rates do not agree with that of the waterwheel, we will have to conclude that we actually cannot use the anemometer instead. This is because we have already defined our time as the rate of water flow. Only if, for some reason, the rate of wind flow happens to be proportional to the water flow in this part of the world, can we utilize the anemometer as a time-measuring instrument.

That is the key point. Our definition of time remains unchanged even if we employ other methods to measure it. These other methods of measuring time will simply have to conform to the definition of time that we already have. Hence, if we have already defined our time according to how we experience it, this time will be proportional to the rate of electromagnetic transmission.

It does not matter, then, what type of clock we use to measure the time we have already defined in this way. We may use other phenomena—like the rate of radioactive decay—to measure time only because we have already determined that they run at proportional rates to electromagnetic phenomena. Obviously, then, it will make no difference to our measurement of the speed of light. By our definition of time according to how we experience it, we have, in fact, also arbitrarily defined the speed of light to be constant.

In this sense, then, the speed of light is the more fundamental entity compared to our time and space. Effectively, we have defined our time and space based on the speed of light because our sensory apparatus functions via electromagnetic transmission. That explains why the speed of light is always constant, while time and space vary depending on the vantage point of the observer. By considering time and space to be fundamental entities—while regarding the speed of light as secondary—we had truly been placing the cart before the horse all this while!

Furthermore, since the speed of light is the more fundamental entity only because our sensory apparatus rely on electromagnetism, it would be hard to escape the conclusion that the very foundation of our science is actually our physiological experience, and not any phenomenon that is independent of us as conscious observers. The theory of relativity demonstrates that even time and space are only secondary entities derived from our conscious experience.

Relativity and Plato’s Cave

We now have an answer to Heisenberg’s question: Why does relativity exist, with all its complicated distortions of time and space? It turns out that relativity exists because our science is actually a science of what we experience, and not a science of a universe “out there” that is independent of us as observers. The philosophical implications of what relativity reveals about this nature of science are staggering. Have we in our long scientific endeavour, all this while, been watching a shadow play, like the characters in Plato’s Allegory of the Cave?

In this famous allegory from Plato’s Republic, Plato describes the strange plight of beings who, since childhood, have only been allowed to stare at shadows on a cave wall. Plato presents this allegory in the form of a dialogue between Socrates and one of his students:

         And now, I said, let me show in a figure how far our nature is enlightened and unenlightened: Behold! Human beings living in an underground den, which has a mouth open towards the light and reaching all along the den; here they have been from their childhood, and have their legs and necks chained so that they cannot move, and can only see before them, being prevented by the chains from turning round their heads. Above and behind them a fire is blazing at the distance, and between the fire and the prisoners there is a raised way; and you will see if you look, a low wall built along the way like the screen which marionette players have in front of them, over which they show the puppets.

I see.

And do you see, I said, men passing along the wall carrying all sorts of vessels, and statues and figures of animals made of wood and stone and various materials, which appear over the wall? Some of them are talking, others silent.

You have shown me a strange image, and they are strange prisoners.

Like ourselves, I replied; and they see only their own shadows, or the shadows of one another, which the fire throws on the opposite wall of the cave?

True, he said; how could they see anything but the shadows if they were never allowed to move their heads?

And of the objects which are being carried in like manner they would only see the shadows?

Yes, he said.

And if they were able to converse with one another, would they not suppose that they were naming what was actually before them?

Very true.

And suppose further that the prison had an echo which came from the other side, would they not be sure to fancy when one of the passers-by spoke that the voice which they heard came from the passing shadow?

No question, he replied.

To them, I said, the truth would be literally nothing but the shadows of the images.

That is certain.

How would the prisoners know or even suspect that what they perceive are only shadows and not the reality? And if they developed a science of what they can perceive and experience, how would they know that their science is severely constrained by their perceptual limitations? In particular, how would they know that their science is only a science of their experience and not a science of a reality that is independent of themselves as observers?

If they are unable to perceive any more than the shadows before them, they certainly cannot gain direct confirmation of the severe limitations of their perceptual ability and hence of the limitations of their science. Nonetheless, if they are alert enough, they may recognize clues that such is indeed the real state of affairs.

One such clue may be that the shadows directly in front of them appear broader than those at the extreme sides of their visual field. This occurs because, at the extreme left and right, they are viewing the wall from an acute angle. The reason for this phenomenon is the same reason why we prefer not to have the extreme left or right seats in the front row of a movie theatre. From those seats, our view of the movie will be distorted because we will be watching the screen from an extreme angle. Thus, Plato’s cave prisoners may well notice that the same shadows, when they appear at their extreme left or right always appear narrower than when they are directly ahead of them.

Now, should these prisoners communicate with one another, they may come to realize that the part of the wall where the shadows appear the broadest depends on where each of them is sitting. The shadows are always broadest when they appear directly in front of the observer; and this part of the wall is different for different observers. In other words, it is an observer-dependent phenomenon!

Upon reflection, this clue should suggest to them that their information of the world is only a reflection of what they are able to experience of it and hence is constrained by their perceptual limitations. This, in turn, should also lead them to the conclusion that their science is really a science of their conscious experience and not a science of a reality that is independent of themselves as observers.

Now, are we not in a similar position? Both relativity and quantum physics inform us that the scientific data we receive are actually observer-dependent phenomena. And observer-dependence in the very foundations of its structure must suggest that our science is actually a science of our experience, and not a science of a universe that is independent of us as observers. In other words, our science, even at a foundational level, is only an investigation of what we humans experience.

And what we experience, like that of the characters in Plato’s cave, must necessarily be constrained by our perceptual limitations. Why is it so important for us to acknowledge this truth about our science? Here is one compelling reason. Until we acknowledge that our science is merely a science of our experience, we will not even know to look at our own perceptual abilities and at our own mind as a possible means to get beyond the confines that shackle us. As a result, the doors to new avenues of research and new methods of probing the universe may well remain closed to us.

Acknowledgement of our limitations, on the other hand, will spur us to search for the means to overcome these limitations. If the prisoners in Plato’s cave remain unaware of their limitations, they will have no incentive to find ways to break free from them, but will remain blissfully content watching shadows on the wall, and fooling themselves that that is all there is. It is crucial, therefore, that we acknowledge the limitations of our science and where these limitations lie—for this will provide the incentive needed to push our horizons beyond the current confines that are keeping us in the dark.

We thus have to acknowledge that the observer plays a critical role in our science, and that all the scientific data used to formulate our scientific theories come through the observer. In fact, we do not even know whether the perceived entities and the perceiver can be separated. From relativity, we know that how time and space manifest depends on the observer; and from quantum physics, we know that how particles manifest also depends on the observer (see “A Direct Experiential Interpretation of Quantum Mechanics”).

So can the perceived entities and the perceiver even be separated? We actually have no scientific evidence that the perceived entities can be treated as separate independently-existing entities. What we do know is that, even if they can be treated as such, we have no idea what these entities would be like without the observer. We have no access to a universe that exists independent of the observer. To deny the role of the observer in our science is thus to deny the truth, and that is both illogical and unscientific.

Acknowledging the role of the observer, however, means that we need to study closely the mind and the attributes of the observer through which all our scientific information is obtained. And that means taking into consideration, our human physiology, our human perceptual abilities and limitations, and, particularly, one aspect of the human observer that is poorly understood in scientific terms but which plays an overarching role in our experience of the universe: our consciousness.

A science that ignores consciousness, or artificially relegates the conscious mind to that of a secondary—and hence, unimportant—phenomenon, is actually an incomplete science. All our scientific data relies on the conscious mind as a necessary component. Both relativity and quantum physics tell us that we cannot blindly assume that the conscious mind—that experiences what constitutes our scientific data—has no effect on the nature of the data itself. So, a discipline that willfully chooses to ignore the conscious mind as a vital component of our reality, must be viewed, at best, as an artificially restricted discipline, or, at worst, as a distortion of the truth.


This paper is based on two earlier works of the author: “Why the Speed of Light is Constant” (published in the Mensa International Journal, No. 339, Sep 1990), and “Time and Space” (published in the ISPE anthology “Thinking on the Edge” Agamemnon Press 1993; released as preprint 1988)

In addition to how we define our time, the paper “Time and Space” also explains how we define our space through the use of solid-state matter. The paper shows how the Lorentz Transformation Equations (the mathematical foundation of Einstein’s Special Theory of Relativity) can be derived purely from an understanding of the observer-dependent nature of our science. It also explains mathematically how the Twin Paradox (which was not fully explained at the time) can be resolved because of this observer dependence.

[The paper “Time and Space” was approved for publication in “Thinking on the Edge” by the physics consultant for the book, Professor Kip S Thorne (Feynman Professor of Theoretical Physics, Emeritus, California Institute of Technology). Professor Thorne is a world authority on General Relativity, and co-authored the widely-used textbook “Gravitation” with Charles Misner and John Wheeler. Professor Thorne has now been awarded the 2017 Nobel Prize for Physics.]

See also “Relativity Proves that Time and Space are Empty of Inherent Existence” and “A Direct Experiential Interpretation of Quantum Mechanics”


Additional notes on text:

[*Note, here, that I am not saying that the electrical signal along the axon of the nerve cell travels at the speed of light. I am only saying that the physiological mechanism for this electrical nerve signal depends on the speed of light. (back)]

Copyright © 2016 by Kenneth K C Chan. All Rights Reserved.


26 thoughts on “Why Relativity Exists

    1. Thank you for your interest, Laverne. I wouldn’t really call myself a professional writer. The last book I completed was more than ten years ago, and that one was actually on Shakespeare’s Hamlet, entitled “Quintessence of Dust: The Mystical Meaning of Hamlet.” I guess I am a bit of a polymath, and it was my knowledge of both medicine and physics that initially led me to this understanding of Einstein’s relativity.


  2. I read your article with great interest. Solving the question of the nature of electromagnetism and the speed of light sure must be important. However, you are completely wrong when you address the speed of light to be some factor linked to the human biology. Our biology is unfortunately linked to very slow electric currents derived from ionic charge differences over membranes; nerve speed 2-300 m/s depending on the fibre type, same for muscles. The speed of light is irrelevant for human biology. The problem seems to be the opposite. Human nature can not grasp this because the speed of light is so different from our biology and experience.

    1. The electrical impulse along the axon of the nerve cell, of course, does not travel at the speed of light. Movement of the sodium and potassium ions, however, causes a disturbance in the surrounding electric field, and it is this disturbance that is transmitted at the speed of light, to other charged particles (and that continues the electrical impulse along the axon by causing further movement of ions). All that is required is the fact that the functioning of the nerve cells does depend on this speed of light.

      The transmission of the disturbance in the electric field, caused by the movement of ions, is necessary for the human body to function. Without this transmission of the electrical disturbance, the movement of ions in one location of a cell cannot influence the movement of ions in an adjacent location. So the transmission of the electrical disturbance is a necessary mechanism in physiology, and since its rate of transmission is essentially the speed of light, the speed of light is definitely involved in human biology.

  3. That is great article written by you sir. Taking the analogy of Plato’s cave and the assumption of ours being trapped in the system of electromagnetic transmission, how far do you think this can leads us toward a stimulation argument, as the example of the video character you mentioned in the article?

    1. Thank you for your comment. The example of the video character is mainly to illustrate the point that our scientific data is dependent on the perceptual characteristics of the observer. This is an unavoidable fact. It is therefore crucial that we acknowledge the conscious observer as an essential component of our reality.

      If scientists refuse to do this, we will be artificially distorting reality and will, in all likelihood, misinterpret our scientific data. Unfortunately, this is largely what is happening in the scientific community, in spite of the fact that there is clear evidence, in both relativity and quantum physics, that our scientific data is observer dependent.

  4. Hi sir
    I read this article. It is a good writing. Sir I have a doubt on this, suppose if there is a digital instrument, which accurately reads and indicates the time interval. Then will it be the correct interval since it is an inanimate material.

    1. All our scientific instruments that measure time are, in fact, inanimate objects. And they do accurately measure “time” as we have defined it. This, however, does not change the fact that the speed of light is constant relative to all frames of reference because our physiological functioning depends on the speed of light itself.

      This is because “time” itself has been defined based on how we experience it. That is the key to the explanation. The explanation resides in how we have defined “time” itself according to our physiological functioning and experience.

      The section of my paper, “Why the Speed of Light is Constant,” explains this more fully. Note this paragraph from that section:

      “It does not matter, then, what type of clock we use to measure the time we have already defined in this way. We may use other phenomena—like the rate of radioactive decay—to measure time only because we have already determined that they run at proportional rates to electromagnetic phenomena. Obviously, then, it will make no difference to our measurement of the speed of light. By our definition of time according to how we experience it, we have, in fact, also arbitrarily defined the speed of light to be constant.”

  5. These are probably very naive comments/questions. Given that now our theories and postulates explaining certain phenomena are linked/dependent on the observer could this mean that our understanding of the universe could be unfounded? In other words what we think about the existence of the universe and its behaviour is just an interpretation and no more than that?

    1. This is actually a very good question, and raises a lot of philosophical issues. In a philosophical sense, I guess our science can be considered as an interpretation by us, human observers. This is because our experience of the universe may not be a definitive experience of the universe, since it is possible that the experience of the universe by, perhaps, an alien being, with different physiology, may be very different.

      However, there is really no reason to think that our understanding of the universe is unfounded in any way. What we need to do in science is to be brutally honest, and admit that the role of the observer is an intrinsic part of our science.

      In science, we aim at understanding reality. So if it is simply the truth that the conscious observer does play a significant role in our science, we need to admit it. Acknowledging the limitations of our science may, in fact, be the first step towards finding possible ways of overcoming these limitations.

      1. A very interesting article, with idea that match my own understanding of our “reality”. Would it not be accurate to say that human understanding of the universe can never be more than a partial understanding, limited to those elements and functions of the universe that our senses are able to perceive? We have instruments now that enable us to perceive elements that our senses cannot access, but as you clearly demonstrate, that perception is always limited by the limits of our human biology.
        As a corollary to your ideas, I have often wondered whether it is possible for human consciousness to ever truly understand itself and its nature. Can an entity truly understand itself, other than within the parameters set by the entity itself? This would seem to bring us back to Plato’s cave.

        1. Hi Ian. Thanks for your comments. At this point in time, there is no scientific equipment that can detect consciousness, let alone measure it. That is why scientists know next to nothing about consciousness. No scientific equipment to measure consciousness means no scientific data. And no scientific data means no actual scientific theory on consciousness.

          Currently, the only way to actually probe our consciousness is through the use of our own mind. That is, in fact, what the advanced meditators are doing, and a lot can be learned from it. But we need to train our mind to do that effectively.

          1. Hi Kenneth, thank you for your reply.
            I understand what you are saying, but even meditation would seem to be an act of observation, and therefore still an anthropocentric process. I do not meditate (find it very hard to silence the torrent of thoughts), so I am unable to know what the meditating mind experiences, but it is hard to see how even the most profound practice can lead to any real understanding of what consciousness is. How basic electromagnetic processes are translated into our thoughts and emotions.
            I am going to read your article on the correlations between quantum mechanics and Buddhist philosophy. Books on the subject – Fritjof Capra, Gary Sukov – were a large part of my reading matter 30-odd years ago.
            Regards, Ian
            PS: I was forwarded your article by Stewart Green, who I went to school with in the 60’s.

          2. Hi Ian. The question we really need to ask first is this: Are electromagnetic processes actually translated into our thoughts and emotions? As I mentioned in my paper on quantum mechanics, there is actually no real scientific evidence that consciousness is purely derived from matter. This is just an assumption made by most scientists. But an assumption, even by many scientists, does not make it science. The scientific evidence from quantum physics actually supports the opposite conclusion: that consciousness cannot be purely derived from matter. I have provided the reasoning for this in my article “A Direct Experiential Interpretation of Quantum Mechanics.”

  6. Sir, I have read your article with curiosity. It solved many doubts of mine. It was really fantastic work done by you, sir. I have one small doubt; you have said that speed of light is always constant with any reference because it relates to the perceptual characteristics of observer. If the speed of the speed of the light is 3,00,000km/sec as per our consious science, then what would be the actual speed of light?

    1. Thank you for your comment, Patnana Naveen. There is no “actual speed of light” that is independent of how we, human observers, define our time and space. We have defined our time and our space in accordance with how we experience the universe. And since this physiological experience is dependent on the rate of electromagnetic transmission (which is the speed of light), we have inadvertently used the speed of light itself to define our time and our space. We are thus effectively caught inside a closed loop. Since we have defined our time and space using the speed of light, we cannot measure the speed of light in vacuum as anything but constant.

  7. That was an amazing article ! Thank you for opening up my eyes, helping me perceive the very issues that limit the way I perceive the world around me.
    To speak more about me, I am a student, much interested by physics in general. Quantum Physics would be my favourite. If you work in that area, kindly get back to me. I have much to learn from geniuses like you.

    Once again, thank you for the eye opening article.

  8. Great piece of paper and from my own knowledge this theory is closely linked to Mahayana Buddhism

  9. Thank you for the insightful article. I was just wondering, does this explain why clocks tick slower at faster speeds as observed by some? Do clocks rely on the speed of light in their mechanisms to keep time?

    1. Yes. It explains why clocks that are travelling faster appear to tick slower according to an observer that is stationary. Electric clocks certainly rely on the speed of light in their mechanisms to keep time.

      The interesting question, however, is this: what about other clocks, like atomic clocks? While these clocks do not directly rely on electromagnetic transmission in their mechanism of keeping time, they have, in fact, been experimentally verified as being consistent with other clocks that do rely on the speed of light to keep time. That is the reason why they can be used as clocks in the first place.

      So what has happened is that man has inadvertently defined time using the speed of light as the standard because that is how man experiences time. With this definition of time, it means that only clocks that agree with this standard can be considered as appropriate time-keeping devices.

  10. This view is very interesting, especially in combination with the observer’s influence on quantum physics experiments. However, twin paradox can be solved because such an experiment – although difficult in practice – is theoretically possible, and would give us a specific result: When the spacecraft returns to Earth and the door opens, a young man or an old man will come out. Perhaps this translates to the fact that there are tools available that allow us to get out of the “system” and perform more objective measurements (?).

    1. Thank you for your comment, George Plousos. The twin paradox is real, but the explanation for the twin paradox is not that we are able to “get out of the system.” It occurs because the observer, in the spacecraft that turns around to return to Earth, experiences a change in the frame of reference. The shift in the frame of reference causes the arbitrary construct of time and space to be altered.

      If the change in the frame of reference is abrupt, there will be a sudden instantaneous jump in time. This occurs because time is an arbitrary construct in the first place based on how we, humans, experience it. Time does not inherently exist “out there” independent of the observer. It is only an arbitrary construct. And that is why an abrupt shift in the frame of reference will result in an abrupt shift in the way we construct our system of time and space.

      A full mathematical explanation of the twin paradox can be found in Part V of my paper “Time and Space” entitled “The Twin Paradox”.

  11. Hello Mr. Chan, Thank you for this wonderful article. I’ve been pondering for some time on why the speed of light is constant. Your reasoning gives me much to think about and I plan to read your other writings. Best regards.

  12. This article is written in a wonderfully easy to understand story – type style, which a person with little knowledge of physics and mathematics can also grasp, more or less. Secondly, It doesn’t directly jump to the main topic of relativity, rather it gives sufficient background of the understanding that existed before it and important developments which led Einstein to it (Michelson Morley experiment is mentioned, although I request you to add more material about other previous discoveries and experiments which are related to it). Truly, I wish science was taught this way – giving reference to how the ideas (of one scientist or experiment) are related to the previous ones. What were the problems with the previous theories which led to new ones. When you just throw the concepts of work, energy etc., on 15 year old students, which are completely disconnected from what they experience in daily life, without giving any perspective as to where these concepts came from in the first place, makes science almost scary to them.

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