Do You Know What Time It Is?

Particle physicist Professor Brian Cox asks, 'What time is it?' It's a simple question and it sounds like it has a simple answer. But do we really know what it is that we're asking? He investigates the concept of time, exploring its origins and its limits, and questioning whether travelling through it will ever be possible. Brian visits the ancient Mayan pyramids in Mexico where the Maya built temples to time. He finds out that a day is never 24 hours and meets Earth's very own Director of Time. He journeys to the beginning of time, and goe...

What on Earth is Wrong With Gravity

That might seem a bizarre statement, coming a century after Einstein showed that gravity is the result of matter warping space and time around it.

Pavlopetri: The City Beneath the Waves

Just off the southern coast of mainland Greece lies the oldest submerged city in the world. It thrived for 2,000 years during the time that saw the birth of western civilisation. An international team of experts is using cutting-edge technology to prise age-old secrets from the complex of streets and stone buildings that lie less than five metres below the surface of the ocean. State-of-the-art CGI helps to raise the city from the seabed, revealing for the first time in 3,500 years how Pavlopetri would once have looked and operated.

Russia's Mystery Files

The Soviet Union was a sinister world. Now the Iron Curtain has fallen, and for the first time we can investigate those rumours.