general relativity

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.

What would happen if the Sun suddenly exploded? Einstein wondered the same thing, and completely changed our understanding of the Universe.

Astronomers have explained a strange effect observed in the vicinity of black holes.

A closer look at the power of symmetry in physics.

Finally we can be sure — black holes, those gravitational monsters that gobble up everything that gets too close to them, do exist.

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.

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

Small, dark, and very hard to see. This and far more indepth answers to every question you ever wanted to ask about black holes.