general relativity

Has the future already already been written? Is time just an illusion? Take a step outside of spacetime with cosmologist Marina Cortês to discover the block universe.

Fundamental physics says time is symmetric - so why does time move forwards for us in a block universe?

Is time real? Are we just puppets living out a future already written? Marina Cortês explains why she thinks time is fundamental and that we don't live in a block universe.

Marina Cortês is one of a growing number of physicists who believe time is fundamental. We ask her about the alternatives theories to the block universe, where time comes first.

Physics tells us that we live in a block universe, containing all of the past and all of the future. What does this perspective mean for our understanding of time, events, and free will?

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.