[Epona]

Time, interesting subject Yorick.

There are many different ways to view the subject.

Einstein's Theory of General Relativity states that time does not move at a constant rate. A moving clock will tick slower than a stationary one (works with digital too, so not just motion acting on the gears of a clockwork device - and I've seen it demonstrated by means of a pushed trolley and groups of people with digital stop-watches). This is called time dilation. Spacetime is curved, imagine a rubber sheet suspended at the corners with a bowling ball in the middle. Rolling a marble onto the sheet demonstrates the effects of gravity not just on matter, but also on time. Hans von Baeyer described spacetime as 'an invisible stream flowing ever onward, bending in response to objects in its path, carrying everything in the univers along its twists and turns'.

Of course the effect of gravity on time is miniscule at low velocity - it is when you approach the speed of light that its effect is greatest (gravity being equivalent to motion - the gravitational pull of the earth is the same as no gravity but instead travelling upward in a lift at the rate of 32 feet per second.) Travel at the speed of light would distort time as would a black hole - from which the escape velocity is greater than the speed of light, which is why it is 'black'. Spacetime is curved by both events.

An observer far from a black hole would observe time passing extremely slowly for an astronaut falling through the hole's boundary (event horizon). The observer would never see the victim fall in, time would appear to stand still from the observers viewpoint. The same can be said of travel at the speed of light - the traveller would not age relative to stationary observers. This is true of travel at *any speed* but of course at low velocity the difference in the flow of time is unnoticeable.

Then there is the measurement and perception of time. To the hunter-gatherer time was largely unimportant, other than the passage of summer into winter for which he or she must stockpile food to some extent. Agriculture increased the importance of seasonal variation, with attention being paid to sowing time, harvest time, ploughing time. Although measuring the passage of time was an interesting study for pre-industrial societies, its function was mostly one of philosophical ponderance rather than a need to know what the time was. It is with early industrialisation and the Enclosures Act (in England) that the need to know time becomes most important - people moving away from agriculture and being forced into industrial labour - where the industry owner is dependent upon a workforce turning up at the same time and working for a certain number of hours. Since then the measurement of time has become more and more accurate, with people more fixated upon minutes and seconds, and will I be late for my meeting.

Hope that's the sort of comment you wanted Yorick! Sorry it's so long, I find the subject utterly fascinating.