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Hello, when writing the Principia Mathematica, Isaac Newton declared his hand on most of the big questions in physics.

He outlined the nature of space, explained the motions of the planets and conceive the operation of gravity.

He also laid down the law on time, declaring,

absolute true and mathematical time of itself and from its own nature flows equably without relation to anything external.

For Newton time was absolute and set apart from the universe, but with the theories of

Albert Einstein time became more complicated.

It could be squeezed and distorted and was different in different places.

Time is integral to our experience of things, but we find it very difficult to think about.

It may not even exist and yet seems written into the existence of

absolutely everything.

With me to discuss time and Monica Grady, professor of planetary and space sciences

at the Open University, Ian Stewart, Professor of Mathematics at the University of Warwick,

and Jim Alkalele, Professor of Theoretical Physics and Chair in the Public Engagement Science

at the University of Surrey.

Jim Arkeler, let's start with a clock on the wall with its hour, minutes and seconds.

What time, what sort of time is that marking?

Well it's very interesting.

A lot of people confuse time with clocks and so you know

without clocks would there be any time clocks are just counters they're just

our human invention our way of recording how we perceive time to go by so a clock is

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