Three Roads To Quantum Gravity

52 THREE ROADS TO QUANTUM GRAVITY
images themselves that are the illusion. The world is never
still ± it is always in motion. The illusion that photography
creates is of a frozen moment of time. It corresponds to
nothing in reality, nor is it itself real, for any photograph is
also a process. In a few years it will fade as a result of
chemical processes which are always going on between the
molecules that make up the apparently still image. So what
happens in a movie is that the real world of motion and
change is recreated from a sequence of illusions, not the
reverse.
We humans seem to be fascinated by our ability to hold
back change for long periods of time. This may be why
painting and sculpture are so fascinating and so valuable, for
they offer the illusion of time stopped. But time cannot be
stopped. A marble sculpture may look the same from day
to day, but it is not: each day the surface becomes a little
different as the marble interacts with the air. As the Florentines
have learned only too well from the damage wrought
to their heritage by pollution, marble is not an inert thing, it is
a process. All the skill of the artist cannot turn a process into a
thing, for there are no things, only processes that appear to
change slowly on our human timescales. Even objects that
seem not to change, like rocks and can openers, have stories.
It is just that the timescale over which they change signi®cantly
is longer than for most other things. Geologists and
cultural historians are very interested in narrating the stories
of rocks and can openers.
So there are not really two categories of things in the world:
objects and processes. There are only relatively fast processes
and relatively slow processes. And whether it is a short story
or a long story, the only kind of explanation of a process that
is truly adequate is a story.
The illusion that the world consists of objects is behind many
of the constructs of classical science. Supposing one wants to
describe a particular elementary particle, say a proton. In the
Newtonian mode of description one would describe what it is
at a particular moment of time: where it is located in space,
what its mass and electric charge are, and so forth. This is
called describing the `state' of the particle. Time is nowhere in