Taken from the 25th anniversary issue of Physics World, this article examines one of the five biggest unanswered questions in physics as selected by the magazine’s editors Scientists and philosophers ...

Few ideas in modern science have reshaped our understanding of reality more profoundly than space-time—the interwoven fabric ...

Physicist Max Tegmark says that time is still one of the biggest mysteries in physics.

Physics What is time? The mysterious essence of the fourth dimension The true nature of time continues to elude us. But whether it is a fundamental part of the cosmos or an illusion made in our ...

But it is boring in comparison to the larger questions about space and time. Discussing what space and time are and where they came from is now within the realm of particle physics.

Spacetime may emerge from a more fundamental reality. Figuring out how could unlock the most urgent goal in physics—a quantum theory of gravity ...

Learn about physics, a science that introduces you to the underlying laws and mechanisms for how the universe works, why you should study physics.