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.

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.

Why there is a limit to how much better computer chips can get and what it's got to do with black holes.

In 2004 Stephen Hawking famously conceded that black holes do not devour all information when they swallow matter — seemingly resolving the black hole information paradox that had perplexed physicists for decades. But some argue that the paradox remains open and we must abandon our simple picture of spacetime to unravel it.

Is the Universe finite or infinite? Is there infinity inside a black hole? Is space infinitely divisible or is there a shortest length? We talk to philosophers and physicists to find out.

Is the Universe finite or infinite? Is there infinity inside a black hole? Is space infinitely divisible or is there a shortest length? Can infinity occur at all in the cosmos or is it a mathematical construct? Find out more in our podcast with Anthony Aguirre, John D. Barrow and George Ellis.

Space is the stage on which physics happens. It's unaffected by what happens in it and it would still be there if everything in it disappeared. This is how we learn to think about space at school. But the idea is as novel as it is out-dated.

In the latest poll of our Science fiction, science fact project you told us that you wanted to know if infinity exists. In this interview the cosmologist John D. Barrow gives us an overview on the question, from Aristotle's ideas to Cantor's never-ending tower of mathematical infinities, and from shock waves to black holes.

John Barrow gives us an overview, from Aristotle's ideas to Cantor's never-ending tower of mathematical infinities, and from shock waves to black holes.