Everyone knows what time is. We can practically feel it ticking away, marching on in the same direction with horrifying regularity. Time has enslaved the Western world and become our most precious commodity. Turn it over to the physicists however, and it begins to morph, twist and even crumble away. So what is time exactly?

This podcast featuring Paul Davies, a theoretical physicist and cosmologist at Arizona State University and Director of BEYOND: Centre for Fundamental Concepts in Science, explores this difficult question and accompanies our What is time article.

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A possible way of resolving the greatest problem of physics.

Explore the biggest problem in modern physics.

The impact of GPS on our lives is celebrated with the Queen Elizabeth Prize for Engineering.

We asked cosmologist Pau Figueras everything we’ve ever wanted to know about black holes. In this podcast he explains what black holes are, physically, and how we hope to observe them.

Physicists have finally detected the gravitational waves they have been chasing for nearly 100 years.

A hundred years ago, on 25 November 1915, Einstein first presented his general theory of relativity. We explore this famous theory and what it says about the world we live in.

Pau Figueras explains how Einstein's theories predicted the existence of black holes, and how to describe them mathematically.

We asked cosmologist Pau Figueras everything we’ve ever wanted to know about black holes. In this podcast he explains what black holes are, physically, and how we hope to observe them.

At the heart of modern physics lurks a terrible puzzle: the two main theories that describe the world we live in just won't fit together.