The waves of the electromagnetic spectrum (including light) travel at a speed of approximately 300,000 kilometres (186,000 miles) per second. In our present state of knowledge that seems to be the universe’s speed ceiling. By considering the ways in which that very high speed can be measured, we may arrive at theories of ways in which an instanton of time can be measured — if it exists.
During the early seventeenth century, the few scientists who were around didn’t accept the idea that light had a speed. Their practical, common-sense experience of life told them that light didn’t travel anywhere at any speed: it was just there. It was instantaneous. It could cover any distance in zero time. Galileo (1564-1642) — often called the father of physics, the father of astronomy, and the father of science — didn’t feel happy about the instantaneous light hypothesis and undertook an experiment to measure the speed of light. He stood on one hilltop while his assistant went to another summit a mile away. Both men carried lanterns with shutters. The idea was that Galileo would open his lantern shutter, and as soon as his assistant saw Galileo’s light, he would open his shut-ter. Galileo intended to repeat the experiment once or twice to confirm their findings and their expected measurement of the time required for the light to travel a mile.
There was nothing wrong with the broad outline of his methodology — Galileo failed simply because light was far, far too fast to be measured using any instruments available in his time.
(It was a prime era for pioneering scientists: Galileo’s great contemporary Johannes Kepler, the first modern astrophysicist, lived from 1571 to 1630.)
An approximate time for light to cover one mile would be 0.000005 of a second. In order to get any sort of figure from such an experiment, it would be necessary to use a much greater distance than the one Galileo and his assistant used.
The man who did that was Ole Roemer (1644-1710), a Danish astronomer who was studying lo, one of Jupiter’s many moons, in 1675.
He noticed that lo’s orbit could vary by as much as twenty minutes — which was a significant observation considering that lo completed an orbit in only one day and eighteen and a half hours. Roemer worked out that these twenty-minute differences he had observed were due to the speed of light.
When the observer on Earth was farther away from Jupiter, the apparent increase in the orbit time was simply because the light took longer to travel from lo to Earth. When Jupiter and Earth were closer, the time difference went the other way. Roemer’s calculations gave him a figure of 225,000 kilometres per second (against the modern 299,792, which is conveniently rounded up to 300,000 kilome-tres per second).
Time-scientists are understandably interested in the speed of light because of Einstein’s work on time dilation, which will be examined in detail in Chapter 2. This is a curious phenomenon that indicates to a sta-tionary observer that the rate at which time passes in objects that are moving relative to his stationary situation is slower. His stationary clock, for example, is recording two seconds, while an identical moving clock is recording only one second. In Einstein’s theory of special relativity, clocks that are moving relative to an inertial system (the motionless observer) run more slowly.
In Einstein’s theory of general relativity, it is gravity, not movement, that makes clocks run more slowly. Clocks that are close to a massive body that has a strong gravitational field will run slower than clocks that are not influenced by the same gravitational strength.
The intriguingly named gravitational redshift is the phenomenon of light apparently losing energy as it moves away from a massive body, so that spectral lines shift towards the red end of the spectrum.
The gravitational blueshift reverses the process: light coming from a zone of weaker gravity undergoes a shift of spectral lines towards the blue end of the spectrum.
The speed of light is, therefore, of primary importance to the scientist examining the phenomenon of time and the effect that movement has on it. If lightspeed is the absolute velocity limit in the known universe, what happens to time when lightspeed is reached?
Scientists and philosophers find it difficult to agree on the ontological differences — if any — separating the past, the present, and the future. What exactly do they mean when they discuss the ontology of time? Our modern word ontology is derived from the Greek ontos, meaning “to be,” and logos, meaning “study.” Ontology is often regard-ed, therefore, as the most important component of metaphysics, as well as being inseparable from time-science and from the philosophy of time. Ontology may be defined as the fundamental study of being, of existence. Ontology asks whether there are different levels and degrees of being, and whether one thing’s being can actually exceed the being of another. Mass can vary, energy can vary, time can vary in the circumstances that induce time dilation — but can being itself vary? Are we here confronted by an absolute? We assume a thing either exists or it doesn’t — but could there be infinite gradations along the ontological spectrum? This is curiously reminiscent of the time argument concerning instantons. Is there an incredibly small and indivisible unit of teleological duration? Or is time infinitely divisible, so that no such thing as an instanton can exist? All studies of ontology — from whatever meta-physical, philosophical, or scientific perspective they evolve — are confronted by the same inescapable fundamental question: What exists?
It is impossible to define time by using any other quantity — simply because in our present state of knowledge there is nothing more fundamental than time.
Mass and space are also regarded as fundamental quantities because it is possible to measure them — just as it’s possible to measure time — but it is not possible to break them down into anything more fundamental within the boundaries of our twenty-first-century science. In short, fundamental quantities can be measured but cannot be analyzed, explained, or defined in terms of anything more elemental.
Following this idea of time as a fundamental quantity, it is interesting to note the types of measurements and measuring devices that have been employed over the centuries to try to improve the accuracy of the measurement of time. Returning again to the controversy over the existence of the instanton, vast improvements have been made in the various horological devices with which we measure time with increasing precision. Sundials were among the earliest measurement devices, first appearing around 3500 B.C.
Some two millennia later the earliest known water clocks, the clepsydra, were built in Egypt. Most were designed with two cylinders of water at different heights. As water from the higher cylinder came steadily down a tube into the lower one, the rising and falling of the water levels could be read off against time marks on the cylinders.
Later models developed by Greek craftsmen connected the float in the lower water chamber to a vertical rod containing gearwheel-type teeth. This in turn was connected to a cogwheel that rotated the pointer on the face of the clepsydra. Water clocks had an advantage over sundials in that they worked independently of the weather and they also functioned at night.
Another elementary timing device was the hourglass, through which a quantity of sand trickled in approximately one hour.
From approximately 500 to 1300 A.D. there was very little change in methods of time measurement. The aesthetic design and general appearance of sundials altered, but their scientific principles did not.
Then, during the fourteenth century, one or two big mechanical clocks in towers were constructed in leading Italian cities. They worked on what horologists call the verge and foliot control mechanism. This is made from a shaft (known as the verge) and a crossbar (the foliot) with a weight at each end. The weights are adjustable, and can be placed at different points along the crossbar. This makes use of the principle of moments of force, which are derived from the force-applied multiplied by the distance-from-the-pivot calculations.
At the start of the sixteenth century, Peter Henlein of Nuremberg invented spring-powered clocks and watches, which became known as Nuremberg Eggs. Their weakness was a tendency to slow down as the mainspring gradually unwound.
Christian Huygens, a Dutch scientist, was responsible for significant improvements in time measurement in 1656, when he made a pendulum clock with a natural period of oscillation. Huygens’s new clock was reliable to within 1 minute in 24 hours, an impressive degree of accuracy (1 part in 1,440). Not satisfied with his first achievements, however, Huygens refined and improved the mechanism until he had achieved an even more impressive degree of accuracy: 10 seconds in 24 hours (1 part in 8,640).
The study of electromagnetic waves — of which light is a prime example — led Max Planck in 1900 to describe the energy in such waves as small packets that he called quanta. (In Latin, the term quantum means “how much.”)
Einstein used Planck’s concepts to demonstrate that wave energy could also be understood in terms of a particle (such as a photon) with a fixed amount of energy related to its frequency. From this came the theory known as wave-particle duality: the idea that wave-particles were neither waves nor particles but had some properties that were applicable to both!
Einstein’s second theory was relativity. Strictly speaking, there were two theories of relativity: general relativity and special relativity. The famous Michelson-Morley experiments revealed that the velocity of light was absolute. It didn’t make any difference whether the speed of light was measured with equipment moving quickly towards the light source or equally quickly away from the light source: the velocity of light remained constant at 300,000 kilometres per second (186,000 miles per second).
One of the curious enigmas of relativity is that two observers who are moving relative to each other will experience both time differences and length differences. If each observer has a clock and a yardstick, each will experience the other’s calibrated rule as shorter than her own, and the observers’s clock will be going faster than the observed clock!
Einstein realized that quantum theory and relativity were not necessarily contradictory, but neither did they seem capable of being fused into one unified theory, which was what Einstein wanted — in very much the same way that Newton had wanted a simplified, absolute time that would make his laws of mechanics easier to understand and easier to handle.
As recently as 1954, Einstein said that physics had no general, theoretical basis, no logical foundation. He went on to argue that if what might be called the axiomatic basis of physics cannot be extracted from experience and observation, and we have to try to invent it, might it ever be possible to find the objective truth behind everything — if such a truth indeed exists?
Always a positive, optimistic character, Einstein expressed his confident opinion that there was such an objective truth behind the universe, and that the human mind would be capable of finding it eventually. He believed fervently that pure thought was capable of grasping reality.
For Newton time was absolute. For Einstein it was relative, and capable of dilation in certain circumstances.
The next brilliant thinker to examine the intriguing question of time was the outstanding relativistic cosmologist and mathematician Stephen Hawking.
Newton’s theories worked satisfactorily in weak gravity. Einstein said that warped time and curved space enabled gravity to be described: his ideas — unlike Newton’s – worked well in strong gravitational fields. But Einstein’s relativity yields to quantum mechanics when we consider singularities like the Big Bang and the curious things that happen in black holes.
It is Hawking’s genius that is capable of welding quantum mechanics and relativity into a genuine unified field theory.
It is important for an understanding of Hawking’s work and its relevance for time-science to remember that as far as is known to contemporary science there are four forces in the universe. First comes gravitational force, which is responsible for planets, stars, galaxies, and nebulae.
Second is the electromagnetic force, which is the foundation of all chemical reactions and which can be thought of as the force that keeps atoms together.
Third is the strong nuclear force, which holds protons and neutrons inside the nucleus of an atom and which is an integral part of nuclear fusion and nuclear fission.
Fourth is the weak nuclear force, responsible for the radioactive decay that occurs when alpha and beta particles “leak” out of an atomic nucleus spontaneously. Cosmologists like Hawking believe that these four mysterious forces became distinct from one another in the earliest moments of the universe’s existence.
Was time there before them, or did it come into being with them?
The recent work of Hawking and other daringly gifted relativistic cosmologists has pointed to the different cosmological models that relativity can encompass. Some of these models are able to start from a singularity, expand to a given size, and then contract again.
If time is operating within such a model, does it start to run backwards as the model contracts? A second type of cosmological model expands at different rates in different directions. A third type expands forever — there is no destructive return to a singularity for them, they simply go on reaching one magnitude after another. All these very different models are nevertheless compatible with Einstein’s relativity equations.
How many precognitive dream experiences do we need to support Dunne’s intriguing theory? As well as his dream forecast of the Mount Pelée volcanic eruption, Dunne had a vivid precognitive dream of a railway crash involving an embankment before the Flying Scotsman crashed near the Forth Bridge.
The biblical Joseph not only experienced dreams of his own future greatness, he also interpreted the dreams of others: but there are curious little inaccuracies and anomalies in his dreams. In his dream that
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