My first Apramada article on Buddhism and Physics ended by mentioning the contradiction between the Buddhist doctrine of śunyata and Isaac Newton’s belief in phenomena having ‘absolute’ quantities. This belief is implicit within the classical physics that stems from Newton’s ‘laws of motion’. Thus, there is a contradiction between classical physics and Buddhist doctrine. This article explores how, in contrast, the new physics that emerged in the twentieth century has interesting parallels with Buddhist doctrine.
The doctrine of śunyata means that no phenomenon has an intrinsic or ‘absolute’ existence, unrelated to anything else. So fundamental particles, and the atoms and molecules made from them, do not have any separate, intrinsic existence. Similarly, any physical quantity, such as the distance between two things in space, or the time between two events, cannot be given absolute values. In contrast, Newton believed that there are phenomena such as absolute distances, absolute positions in space, absolute velocities, and absolute times.
At the beginning of the twentieth century, two vital theories of modern physics emerged. They both contradict Newton and, in doing so, very much parallel the doctrine of śunyata. The first is the theory of relativity, which will be explored here. The second is quantum mechanics, the subject of a future article.
Just over two hundred years after Newton’s Principia was published, a young physicist wrote a paper entitled ‘On the Electrodynamics of Moving Bodies’.1 The physicist, Albert Einstein, overturned Newtonian ideas about ‘absolute’ quantities and, in doing so, led a revolution in physics.
Einstein developed what became known as the ‘special theory of relativity’ after pondering the implications of the nineteenth-century formulae for electromagnetism, named Maxwell’s equations. Amongst other things, these equations give an understanding of how electromagnetic waves, including light waves, propagate through space.
A light wave is made up of interconnected, pulsating electric and magnetic fields. Importantly, Maxwell’s equations show that, at any specific point in space, at a specific time, the strength of either field depends on the rate of change, with respect to time, of the strength of the other field at that same point in space. Thus, the existence of a non-zero electric field at that given point depends upon the existence of a non-zero rate of change in the magnetic field at that point, and vice-versa.2
But is there such a thing as a specific, or absolute, point in space? Related to this question is the speculated existence of ‘absolute rest’ – can an object in space ever be considered to have zero ‘absolute speed’; stopped at the same absolute point in space? Moreover, is there an ‘absolute’ speed of an object’s movement through space, such as the movement of the Earth? Or can one only ever measure the ‘relative motion’ of an object – its velocity relative to a specific ‘reference frame’ made of other physical objects?
Maxwell’s equations seem to rely on the notions of absolute points in space, and absolute speeds. Einstein’s paper begins by pointing out that, in contrast to this implicit dependence upon absolute quantities, it is relative motion that is important. The example Einstein uses is the interaction between a metal conductor (i.e. a metal through which electricity can flow) and a magnet. He notes that if the magnet is considered to be moving, and the conductor at rest, then Maxwell’s equations imply one process, but if the conductor is moving and the magnet at rest, a different process is implied. Thus, there is an asymmetry. Yet the final result of each process, predicted by those equations, is exactly the same – the production of an electric current in the conductor. Einstein points out that it is only the relative motion between conductor and magnet that is important.
Such examples led Einstein to conjecture that “not only the phenomena of mechanics but also those of electrodynamics have no properties that correspond to the concept of absolute rest”. He continued: “Rather, the same laws of electrodynamics and optics will be valid for all coordinate systems in which the equations of mechanics hold… We shall raise this conjecture (whose content will hereafter be called ‘the principle of relativity’) to the status of a postulate…”.
Einstein then went on to explore what it means to consider two events to be happening at the same time. He understood that to talk about the ‘same time’ in two different places is not straightforward. How does one tell the time? A nearby clock is needed, together with the ability to read the time on it. This depends upon looking at the clock, with light coming from the clock face to one’s eyes. But how does one know what is exactly the same time somewhere else?
Suppose there is a clock in another place. How does one know that that clock tells the same time, or even ticks at the same rate, as the clock next to one? In pondering these questions, Einstein discovered that to talk about the ‘same time’ in different places involves making assumptions about the constancy of the speed of light. After all, one has to be able to see both clocks; in other words, light has to come from both of them to wherever one is. Einstein thought about this and worked on it mathematically. He discovered that one has to make a specific assumption about light taking the same time to travel in opposite directions between the two places, to be able to consider that the clocks are synchronous. This led to his second postulate. Thus: “…light always propagates in empty space with a definite velocity V that is independent of the state of motion of the emitting body.”
His mathematics then led to answers that contradict Newton’s ideas about absolute time and space. Thus, Einstein discovered that the rate at which time passes depends upon the ‘reference frame’ one is using. People using different reference frames will experience the flow of time differently. He also discovered that the distance between two places also depends upon the frame of reference one uses, and that the same is true of other physical quantities, such as the velocity of an object.
For example, imagine a group of astronauts travelling into space away from the Earth at a speed of nine-tenths the speed of light. Imagine that the astronauts on the spaceship have a clock with them, and that members of mission control, here on Earth, also have a clock, and that there is a video link between mission control and the astronauts.
The astronauts are going away from mission control at nine-tenths the speed of light. Members of mission control look and see what is going on in the spacecraft, and what they see is that the astronauts all seem to be talking, and walking, and doing things somewhat slower than those on Earth. And they see that the astronauts’ clock is going slower than mission control’s clock.
Meanwhile, the astronauts in the spacecraft are doing exactly the same, looking over the video link at mission control’s clock. Now one might think that because mission control are seeing the astronauts’ clock going slower, then the astronauts must look at mission control and see that its clock is going faster.
But that is not the case. The astronauts look at mission control’s clock and see that it is going slower than theirs, and that the people at mission control are slowed down.
This seems strange, if not completely contradictory. Is this result merely an apparent or illusory effect? Are the real rates of the clocks different from those observed? Einstein’s equations and theory give an unequivocal ‘no’ to these questions – it is not an apparent effect, nor some sort of illusion. It is real. For those in mission control, in the frame of reference here on Earth, the astronauts’ clock is really going slower. In the astronauts’ frame of reference, clocks on Earth are really going slower. The implication is that there is no absolute time, and no absolute rate of flow of time. The rate at which time passes depends upon one’s frame of reference.
The Special Theory of Relativity also entails that the mathematical patterns of conditionality (patterns of pratitya samutpada) between physical objects are different from those that stem from Newton’s ‘laws of motion’. They are still expressed in mathematical equations that include the quantities measured in a given reference frame. But those equations, and the algebraic patterns the quantities collectively possess, are different to those of classical Newtonian physics.
In the Special Theory of Relativity, Einstein was looking at frames of reference that travel at constant velocities in relation to each other. These are called ‘inertial frames’. If people are located in different inertial frames, and they measure something, then they will obtain different results, and everybody will be correct. All those results differ because there are no absolute values to the quantities of space and time, velocity, or physical quantities that derive from them.
In other words, phenomena such as time, distance, and velocity have no intrinsic existence, or independent self-nature, to use Buddhist terminology. Their existence depends upon the relationship between the reference frame of the person measuring them and those physical things they are trying to measure. We do not usually think about the nature of physical reality in this way. However, interestingly, the lack of ‘absolute’ quantities is a close parallel with the Buddhist concept of the lack of inherent fixed existence.
Einstein also went on to develop the General Theory of Relativity, in which it became even more clear that in different frames of reference (not just inertial frames), the values of what one measures are different. (The General Theory also included other fascinating concepts that I will not explore in this article, as that would take us away from the present subject.)
It is important to understand that the ‘frame dependence’ of the values of quantities – i.e. that quantities are actually different for different frames of reference – is logically related to what Einstein called the ‘principle of relativity’. This principle is that ‘physical laws’ are the same for everybody. So, the mathematics of how one writes down the physical laws applies to everybody. This means that there is the same general physical truth in different frames of reference. However, the measurements everyone gets are different, and everybody is correct. Actually, the ‘principle of relativity’ is somewhat misleadingly named, as it is a theory that there are general truths, namely truths that are the same for everyone, as expressed in mathematical equations about the motion of objects. These general truths go along with the ‘frame dependence’ of the quantities measured, quantities whose inter-relationships are expressed in those generally true mathematical formulae.
This tends to defy our usual way of thinking about the world; that there must be a specific distance between two things, for example, that the distance between you and a nearby object is two metres. Well, that may be true in your frame of reference here on Earth, but if someone was travelling in that spaceship at about nine-tenths the speed of light, they would measure that distance and find it was somewhat less than two metres. If they were travelling even faster than that, even nearer the speed of light, they might find that distance to be a centimetre, and that would be equally true.
Thus, there is no inherent value to the quantity that is ‘the’ distance between two objects. According to the Theory of Relativity, this is true of any physical quantities. One could say that, in the appropriate rest frame, quantities have specific values, but that is in the rest frame. In other frames of reference, the values of those quantities are not the same. These are real differences, not just apparent ones.
Our usual way of thinking about the world is that phenomena have an intrinsic existence – that a chair, for example, has an inherent existence, whether or not we are observing or measuring it, no matter what speed we are going at. Moreover, that intrinsic existence implies it has intrinsic attributes that are there as aspects of the chair, and as this is a physical object, we can measure them, and specify its intrinsic length and intrinsic height, and so on. But relativity theory tells us that this is not the case.
It is hard to grasp the implications of this. What is interesting about studying modern physics is that people can do the mathematics, or at least some people can do the mathematics. But even the people who can do that do not necessarily understand the philosophical implications of the mathematics they are using.3 Consequently, it is interesting to consider, with regard to relativity, the implications for one’s ordinary assumptions. An assumption might be that there is a specific distance between oneself and a nearby window, or that one has a specific height. Relativity theory shows it is not as simple as that.
It is also necessary to emphasise that, in a given reference frame, there do exist specific values of quantities. In other words, it is objectively true that, in a given reference frame, an object actually does have a specific length, for example. This quantity is not just a belief that people have. It is not simply a matter of opinion nor an illusion. People could also measure it incorrectly, and if they were to assert that it has a different length (in that reference frame), they would be wrong. Thus it is essential, for example, that engineers do make measurements correctly; otherwise their structures and machines could malfunction and fail.
Nevertheless, that value of the length is only correct in that reference frame. In other reference frames, it is true that it has different lengths. There is no intrinsic length, unrelated to any reference frame.
In relativity theory, however, there are still assumptions. Those assumptions are that in any specific frame of reference, a quantity still exists, whether you are measuring it or not. For example, such an assumption would be that I am six feet in height, and if no-one is looking at me, or measuring me, I am still six feet high in my frame of reference. (I might be three feet high in another frame of reference.) This assumption seems very reasonable.
So, there is still an assumption in relativity theory that the values of quantities exist, even when one is not measuring them, and that they somehow have some independence from the process of measurement. Now is that true of the physical world in general? Is it true, for example, with respect to the ‘fundamental particles’ that make up our bodies and the world around us – the electrons, protons and such like? Do those things have attributes to which one can find specific values? Do they exist without measuring them?
Consider an electron. If one is not looking at it, not measuring it in some way, does it have a specific location in space, at least in one’s own frame of reference? Does it have a specific velocity? Classical physics would say most definitely yes, and even relativity theory implies that, in a given frame of reference, it definitely has specific quantities and definitely exists in a specific place at a given time, with a definite velocity.
The interesting thing is that another branch of modern physics, Quantum Mechanics, makes it quite clear that particles such as electrons do not have such intrinsic existence when one is not measuring them (or at least when they are not interacting with other particles).
I will explore this in my next article on Buddhism and physics.
- A. Einstein; ‘On the Electrodynamics of Moving Bodies’; 1905, translated in ‘Einstein’s Miraculous Year’; J. Stachel, editor; Princeton, 1998
- Maxwell’s equations imply that light waves cannot be ‘standing waves’, i.e. waves which at any given point in space remain the same. If there is no rate of change of either field at any given point, as in a ‘standing wave, then the value of each field is zero. So, if one were travelling along at light speed beside the light wave’, then in one’s frame of reference, it would appear to be a standing wave. But then that would mean it does not exist.
- R. Feynman; ‘QED, The Strange Story of Light and Matter’; Penguin, 1985, p9: ‘Why are you going to sit here all this time, when you won’t be able to understand what I am going to say? It is my task to convince you not to turn away because you don’t understand it. You see, my physics students don’t understand it either. That is because I don’t understand it.