Since the detection of gravitational waves we know for sure that black holes do exist. To understand what really goes on inside them we need a new theory.

The fuzziness of the quantum realm could arise from mathematical restrictions on what can ever be known.

A new framework for the laws underlying reality could explain why nature obeys quantum rules, the origin of time’s arrow, and the power of quantum computing.

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.

A bizarre set of of 8-dimensional numbers could explain how to handle string-theory's extra dimensions, why elementary particles come in families of three... and maybe even how spacetime emerges in four dimensions.

Quantum mechanics and general relativity are incompatible — and this has led to a decades-long search for a theory of quantum gravity that could combine the two. But the particle physicist Richard Woodard thinks that the mismatch between the two could be nothing more than an illusion, created by the complicated maths techniques used in attempts to unite them.