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.

The possibility that there might be many parallel worlds has just become a little more likely.

Mathematical models predict how fast a rumour will spread and how many people it's likely to reach.

A model of the interaction between predators and prey explains why sometimes frogs appear to eat snakes.

What would happen if the Sun suddenly exploded? Einstein wondered the same thing, and completely changed our understanding of the Universe.

A model of backward causation in which the future affects the past could help unite quantum mechanics and general relativity – and satisfy a challenge thrown down almost a century ago by Arthur Eddington.

Mapping the ancestral history of spacetime in an effort to unite quantum mechanics and general relativity.

A new model argues the forces between particles in the early universe loosed time’s arrow, creating temporal order from chaos.

This problem about an infinite sum has a surprising answer.

This surprising result about 3D shapes tells us something deep about the nature of space.

Euler may not have cracked this problem completely, but it led to a lot of important work, including on what we today know as sudoku.

Can you move a knight on a chessboard so that it visits every square exactly once? Euler was one of the first to analyse this problem systematically, but some questions about it are still open today.