Text: Time rules our life

Adam: Have you ever counted how many times you look at a clock in one day?
Brenda: No, I haven't.
Adam: Just test yourself: If you have to catch the morning bus, if school lessons get boring, if you meet friends - every time you look at a clock.
Brenda: Or a watch - I prefer my mobile phone.
Adam: Me too. But thousands of years ago people could only measure time in days and nights. Days and nights were easy to see and count.
Brenda: True, and they also measured it in months, by watching the phases of the moon and in years, by watching the cycle of the seasons.
Adam: And later the date was fixed by the calendar: 12 months with a total of 365 days.

Brenda: But remember: Every fourth year is a so called leap year which has one extra day, February 29th.
Adam: As far as I know, Marina, my girlfriend, was born on February 29th. She's "five" now.
Brenda: So she would be twenty if she were born on the February 28th, right?
Adam: Right. You are quite good at maths, aren't you? By the way, do you know when leap years are?
Brenda: Yes, every year that can be divided by four, for example 2000, 2004, 2008 and 2012. But why are such leap years necessary?
Adam: Well, the Earth takes slightly longer than 365 days to go once around the sun.

Brenda: Have you heard people say we could change the time?
Adam: No, that's impossible. Every one knows that behind us in time lies the past which we know or remember. Ahead lies the future, which we cannot know. We cannot change time. It always flows in the same direction.
Brenda: We can only measure the time.

Adam: I've read that people in former times used sundials or even candles with marks on to measure the time.
Brenda: Incredible. Today many clocks and watches are electronic and rely on the regular vibration of a quartz crystal to keep time accurately.
Adam: I've heard that there were many time zones in Great Britain?
Brenda: (laughing) Yes, in the olden days. Almost every town or village had its "own" time. But when the first trains went from one place to the other they needed the same timetable for every town. Today the United Kingdom is all under one time zone. During the winter months the time is the same as Greenwich Mean Time, but in the summer the clocks are put forward one hour. Generally the U.K and Ireland are one hour "behind" continental Europe.

Adam: Thanks for all this information. One last fact that I heard at school: I think it was Albert Einstein, a German physicist, who once said that time is not constant but would pass more slowly if you could travel very fast - near the speed of light or in strong fields of gravity.
Brenda: Would that mean that you grew older on Earth while I travelled to remote galaxies?
Adam: Well, I don't know. But I think that's what Einstein said.