Stuff happens: Time in a block universe

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When Einstein developed his general theory of relativity he removed the special status of time – it became just one of the dimensions of spacetime, the fundamental fabric of the Universe. As a consequence, physics tells us that we live in a block universe, containing all of the past and all of the future. What does this block time perspective mean for our understanding of time, events, and free will? We explore these questions and the arguments for and against the concept of block time in this package of articles and videos, produced in collaboration with cosmologist Marina Cortês.

These articles and videos are part of our Stuff happens: The physics of events project.


What is a block universe? — 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.

Time in a block universe — It might surprise you, but time is reversible according to the fundamental physics. We talk to Marina Cortês about why our experience of time passing may just be a mathematical artefact of the physics if we live in a block universe.

Why not block time? — Is time real or just an illusion? Are we 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.

The future is time — A small but growing number of physicists are challenging the traditional view that time is an illusion. Marina Cortês gives us a tour of some of the alternative theories in this emerging area of physics.

These articles, videos and podcasts first appeared on the FQXi website.

Is gravity time's archer? — A new model argues the forces between particles in the early universe loosed time’s arrow, creating temporal order from chaos. This article is accompanied by a podcast.

Time to go retro — 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. An accompanying video outlines Eddington's challenge.

The cosmic family tree — Mapping the ancestral history of spacetime in an effort to unite quantum mechanics and general relativity.

The crystallising Universe — According to Einstein, the past present and future all have the same character. So why do we feel that there's a special moment called "now"?

Background information

Einstein's general theory of relativity — What would happen if the Sun suddenly exploded? Einstein wondered the same thing, and completely changed our understanding of the Universe. Find out more in this brief introduction to his general theory of relativity.

What is general relativity? Plus asks David Tong — For a deeper explanation of general relativity, see this video featuring David Tong of the University of Cambridge.

The second law of thermodynamics — A simple introduction to this fundamental law of physics.


In this interview cosmologist Marina Cortês explains how time emerges in a block universe, how the arguments for and against this theory, and alternative explanations where time is fundamental.

You can also watch this interview as a series of shorter clips: