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.

From the perspective of physics, time is just as troublesome, but for different reasons. Time is employed pretty much everywhere but in physics, it's not obvious why it has a particular direction.

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

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 ...

Physicist Carlo Rovelli talks about his new book, "The Order of Time," the nature of time, the second law of thermodynamics and whether time travel is possible.

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.

The ability to jump forward and backwards in time has long fascinated science fiction writers and physicists alike. So is it really possible to travel into the past and the future?

Classical physics describes the fabric of space-time as a four-dimensional structure, with three dimensions of space and one of time.