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 ...

What Is The Time? The concept of time feels so natural that we often forget just how peculiar it is. What actually is time? Figuring it out remains one of the trickiest problems in physics.

Time is all around us: in the language we use, in the memories we revisit and in our predictions of the future. But what exactly is it? The physicist and Nobel laureate Frank Wilczek joins Steve ...

What is time? Sten Odenwald explains how recent theories about the quantum nature of gravity provide some unique and fantastic answers.

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

What does it mean to be to space-time? The seemingly simple question gets to the essence of twentieth-century physics and has ...

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

Neils Bohr once said “Physics concerns what we can say about Nature." Neils Bohr said, “It is wrong to think that the task of physics is to find out how Nature is. Physics concerns what we can ...