Imagine a region in space where the force of gravity is so strong that nothing—not even light—can escape. A region with physical conditions so extreme that they have not yet been reproduced in any terrestrial laboratory. A region so dense that an object as tiny as a walnut would have the same mass as our entire planet.
The programme looks at the latest understanding of black holes, featuring an interview with Stephen Hawking. Black holes are one of the greatest mysteries in the universe. They behave in a way that is contrary to laws of physics and one has never actually been seen. However, the recent detection of gravitational waves, as predicted by Einstein, proves that black holes exist and provides a way to investigate their remarkable behaviour and properties.