Accurate measurement of time is one of the glories of physics, and one of the most exciting frontiers of current research. For most of history, people measured time using the sun and moon.

In physics, the treatment of time is a central issue. In physics, the treatment of time is a central issue. It has been treated as a question of geometry. One can measure time and treat it as a ...

Scientists have measured the shortest unit of time ever, the time it takes for a particle of light to cross a hydrogen molecule.

In physics, they are all the same thing. But to you, me, and everyone else, time moves in one direction: from expectation, through experience, and into memory. This linearity is called the arrow ...

A group of physicists has measured gravity using the effects of time dilation — the slowing of time imparted by increased velocity or gravitational force — on atoms.

Melvyn Bragg and guests discuss the measurement problem in physics.