This week on Spacetime, we take a detour into how geometry works in spacetime. Last time we talked about what curvature means, looked at geodesics, great circles on spheres, and tried to understand ...

A particle moves back and forth along a line, increasing in speed. Graph. How many equivalence classes in Galilean spacetime are there for a particle that is at rest? A particle that is moving at a ...

The Nature Index 2024 Research Leaders — previously known as Annual Tables — reveal the leading institutions and countries/territories in the natural and health sciences, according to their output in ...

What’s the difference between the past and the future? Not a great deal, if you take a purely relativistic view of the universe, say George Ellis from the University of Cape Town in South Africa and ...