Untold numbers of galaxies have merged across the 13.8-billion-year life of the universe, and those blasts should still be echoing in the background of space-time today.

1. Experienced time. Over the static drawing of a floor plan, my eyes and fingers wander in time. In the computer animation of a future residence, I fly through the rooms.

Gravitational lensing is an effect on light from a background source that arises as a result of the curvature of spacetime, the three dimensions of space and time united into a single entity ...

Scientists have evidence for a sea of ripples in space-time, called the gravitational wave background.; Their experiment used dead, spinning stars to hack our galaxy and turn it into a wave ...

Time begins when it starts ticking, that is, when physical processes take place in the background of a classical space-time. So in our Universe time had a beginning.