What is time?

Let’s get one thing straight. Whatever you have read or heard,
nobody understands what time really is. There has been so much
written about the nature of time, particularly over the past few
years, that it would be difficult in this book to contribute much
that is original or that has not been discussed elsewhere. But that
is not my intention. I do not feel as though I need to have trawled
through the many excellent books (and some less so) that have
dealt with the subject of time—although I have read a fair few over
the years—and then to try and come up with some new ‘angle’ or
clever argument not used before: my theory of time. Of course
a lot of what has been written about time is utter nonsense, but
there is much that, despite sounding like nonsense the first time you come across it, actually makes some sense provided you are
prepared to give it some thought.
I mentioned at the beginning of the book that the subject of
time had fascinated me as a child, and still does. I amnot alone. In
fact I amprobably in the majority. The sad fact is that I amno closer
today than I was at the age of ten to understanding what time really
means. I understand how many of the laws of physics contain time
in a fundamental way, I have heard many of the philosophical
arguments about the flow of time, the direction of time, whether
time is really ‘out there’ or is just an illusion: a construct of human
imagination. But whether I amany more enlightened is debatable.
One thing is for sure though. Like so much else we have seen
thus far, Einstein’s theories of relativity at the beginning of this
century overthrew the old and cherished notions. I will discuss
the relativity of time in the next chapter. For now I will lead you
through some of the ideas in physics and philosophy about the
nature of time, most of which were around long before Einstein.