This podcast featuring Paul Davies, a theoretical physicist and cosmologist at Arizona State University and Director of BEYOND: Centre for Fundamental Concepts in Science, explores this difficult question and accompanies our What is time article.

Over the last few decades physicists have been developing a curious idea. Perhaps the world we inhabit is a hologram, lacking a crucial feature of the world as we perceive it: the third dimension.

To mark international cat day, here's a quick look at the most famous cat in the history of science: Schrödinger's cat.

Are you fascinated by the double slit experiment? Then hold on to your hat for Wheeler's delayed choice experiment.

Could there be more than three?

A possible way of resolving the greatest problem of physics.

Explore the biggest problem in modern physics.

One of the most famous experiments in physics demonstrates the strange nature of the quantum world.

Untangling how the human perception of cause-and-effect might arise from quantum physics may help us understand the limits and potential of AI.

Researchers are exploring if quantum mechanics could make machine learning more powerful and shed light on evolution.