About Time

Aristotle said that time is all about movement and change; without movement and change there would be no time. Newton, however, wrote in his Principia "Absolute, true, and mathematical time, of itself, and from its own nature, flows equably without relation to anything external..." They also differed in their views on the concept of "now", which was elegantly explored by Augustine of Hippo. 

People have tried to keep track of time for thousands of years; living by the sun, the sundial was probably one of the earliest instruments. To keep the hours through the night they used a ghati in India, and a klepsydra in Greece. Water clocks were used for hundreds of years, until Galileo hit on the pendulum, and pendulum clocks remained the best until the 20th century. Meanwhile various calendars have been developed (and built) around the world to track the seasons. 

People have always lived by the Sun, and developed circadian rhythms, which naturally seem to run closer to 25 hours than 24, but the Moon also has surprising influences on people, animals, and plants. 

Do things really happen in slow motion during emergencies? What can sting you in less than a microsecond? Time travel to the future is definitely possible, but can we go back to the past? These are some of the questions I shall be discussing. 



 About Prof. Adam Hart-Davis : 

Adam Hart-Davis is a freelance writer, photographer, and science communicator, based in the UK. He has authored several books, most recently "The book of Time".