Physics and time
Physics and persistence
Humans are conditioned by experience to think that the world around them is stable and subject only to gradual change. In fact that is a dangerous illusion based on persistence, the apparent endurance in geometrical shape of vast patterns of atoms. This is due to the relatively enormous differences in various scales of time: we do not live long enough to see mountains rise or church window glass slowly creep downwards under gravity. Our natural perceptions such as vision are based on physical processes that take tiny fractions of a second to register in our brains, so that processes that take days or longer can appear to be static. The point was well put by the physicist Chew:
There is, nevertheless, a possibly unavoidable reason for a difference in status between electromagnetic and strong interactions. Electromagnetism provides the tools that make feasible the measurements on which physics is based. For example, the existence of solid (or pseudosolid) matter, which can maintain a shape in which different components are distinguishable, is essential to the concept of measurement. It is difficult to see how solids could exist without two key features of electromagnetism:
(1) the zero (or very small) photon mass, which gives long range forces; and (2) the small fine-structure constant, which allows the size of the atom to be much larger than that of the nucleus, while adding very little mass.20 Purely nuclear matter, even if unrestricted by electromagnetism, seems unlikely to develop the characteristics of a solid.21 If such a view is correct, the photon mass and the fine-structure constant are closely interlocked with the problem of measurement, perhaps even with the meaning of macroscopic space-time . . . [Chew, 1966]
The relative persistence of patterns in our environment not only conditions us to think of those environments as relatively stable but makes the concept of a system under observation (SUO) a practical and economical way of dealing
- 20 Assuming that the small mass of the electron is associated with the smallness of the fine-structure constant.
- 21 Pulsars, or rotating stars consisting of tightly compressed neutrons with a mass density comparable to purely nuclear matter, were first observed in 1967 [Hewish et al., 1968].
Images of Time. First Edition. George Jaroszkiewicz.
© George Jaroszkiewicz 2016. Published in 2016 by Oxford University Press.
with the vicissitudes of life. The illusions of permanence that we create in our minds guide us so well that we easily forget how fragile those illusions are, until an earthquake reminds that nothing endures forever.
These illusions have had an enormous influence on the development of science: Aristotelians believed that the Earth was fixed and that everything else moved relative to it. It took two thousand years to break this conditioning, and the effects still linger. We like to reminisce about our old school or our old home town, and imagine that we might return one day to relive past glories. It is sobering to realize that none of that things ‘exist’ exactly as they were. They will have changed, just as we have: we are not quite the same people we were then. The Earth will have rotated thousands of times on its axis since then, moved around the Sun many times since then, and travelled with it on its huge orbit around the centre of the galaxy many millions of miles since the old days. Since then, the old school may have been torn down and replaced by a supermarket, or as in the author’s case, entire streets razed and communities relocated. When our past is no longer there, when only our memories remain, there comes the most frightening thought of all: when we too have passed and all our civilization with it, there might be left no trace in the universe that we ever existed. Not even persistence is permanent. There is only one fundamental law of time: everything changes, nothing endures forever.
-  The Sun moves around the galactic centre at a speed over half a million miles per hour, taking240 million years to complete one orbit as defined by line of sight with the distant stars.