"Could you tell me the right time?" asked the woman at the next table in the coffee shop.

Her question posed others. The right time? Did she think that I might deliberately give her the wrong time? Did my watch, in fact, tell the right time? She probably owned a timepiece. Why did she leave home without it? Why does this public place not have a wall clock? For that matter, what is time? Is there an agreed definition?

To avoid using the word 'time' for the nonce, the question came at an interesting juncture.

Just the day previous I had watched the 1960 film version of the H.G. Wells 1895 novella The Time Machine. In the story a Londoner builds a vehicle that can take him into "the fourth dimension". The spatial dimensions are height, length and breadth. The fourth dimension is time.

The film impelled me, if not into the future, at least into reading the original Wells story again. Its hero is not named. He is simply "the Time Traveller". Those to whom he reveals his planned journey into the far future are designated "the doctor", "the psychologist", and "the editor". Each is sceptical, claiming that what one should do is make the best of the time one has without meddling in what is to come.

The ensuing tale raises a question about whether or not they were right. Even if time travel were possible, could one live happily after being transported either into the distant past or future?

When the Time Machine propels its passenger into the unimaginable year 802701, a journey that required only a few Earth minutes, his disorientation there is all but total.

Reading the story, I remembered, for what it is worth, that one year on the planet (?) Pluto, which has a long elliptical orbit, is the equivalent of 248 Earth years.

The Time Traveller comes upon two distinctly evolved types of humanoids. One lives pleasantly but indolently in a utopian world without memory, compassion, philosophy or religion. The other mutants have for aeons dwelt underground where, because their life is more difficult, they have had to us brain and brawn to cope. They prey nocturnally upon the creatures living 'uptop'.

Wells observes (chapter 10) that "intellectual versatility is the compensation for challenge, danger and trouble. Only those animals partake of intelligence that have to meet a variety of needs with initiative".

In the story, 'thinking outside the box' meant thinking beyond each of the four dimensions. For most of us, especially after reading his novella or seeing one of the films made from it, we may be glad we live in the Earth time assigned to us.

The question remains "Is there another dimension in which we have lived, do live or could live?". Is time, as the poet Irving Layton, said "the small change of eternity"?

"The fundamental things apply as time goes by," said the song in Casablanca. Does time actually go by or is it we who do so?

Woody Allen said that his problem with the idea of eternity is "When would it ever end?". Will time? Perhaps it might do so in the black hole of an imploding star but does it go on for ever elsewhere? And what would happen, if anything, if it stopped?

That kind of question defies the human mind. We may think that nothing is more important than having enough time to do what we wish to do. Does that imply that 'nothing' does indeed have meaning or value? If so, as with time, how could we calculate it. We know the importance of a zero placed after any other digit or set of digits. What, then, of the zero that may follow what Macbeth called "the last syllable of recorded time"?

If time is what clocks measure, has it some intrinsic reality or is it simply the interval between two happenings. But it is a daily experience that "slow comes the hour; its passing speed how great". Does time, then, move at varying speeds under different circumstances and in different places?

Sir Isaac Newton (1642- 1727) posited (mistakenly, it now seems) that time had an absolute existence if its own, something like water that flows independently of the vessels on its surface or of the banks between which it moves.

It was Albert Einstein (1879- 1955) who distinguished between absolute and relative time by theorising about the 'relativity' between time and space, mass and energy, motion and inertia. While time can be measured in relation to things that happen in relation to it, it remains a mystery in itself. Perhaps an equal mystery is the fact that the human mind can contemplate both time and eternity and ask questions about them - or it.

In 1895 the Time Traveller foresaw the definition of time as the fourth dimension. The problem is that it is the one that cannot be seen. We can define an object's position by its length, height and breadth, how far it is to the right or left of us or how close to either the floor or the ceiling. But 'timewise' it could have been somewhere far away just yesterday and may be in quite another place tomorrow.

Neither space nor time is an absolute. Both are relative to the observer and the thing observed. Time is always interconnected with the three dimensions of space in something that could be designated as 'space/time'. The Time Traveller told his guests "London was at the bottom of the sea ten thousand years ago".

A year before his death in 1944, Sir Arthur Eddington, the noted astronomer, was asked if it were true that only three people in the world understood Einstein's theory of relativity. Pausing, he said, "I am trying to remember who the third person is". The rest of us, able to fathom neither the relativity nor the quantum theories, may never understand what time is other than, like the sand in an hour glass, it is always in flux.

One would like to put 'a wrap' - or should that be a 'warp'? - on this fascinating topic but, perhaps fortunately, neither time nor space permits that here.