This puzzle is known as the problem of time, and it remains one of the most persistent obstacles to a unified theory of ...

A growing body of theoretical and experimental work in physics is converging on a striking possibility: time, the dimension humans experience as a constant forward flow, may not be a fundamental ...

Physicists have demonstrated that waves can bounce off boundaries in time, not just in space, producing signals that behave ...

Whether space-time exists should neither be controversial nor even conceptually challenging, given the definitions of “space-time,” “events” and “instants.” The idea that space-time exists is no more ...

Exploring the BTZ black hole in (2+1)-dimensional gravity took me down a fascinating rabbit hole, connecting ideas I never expected—like black holes and topological phases in quantum matter! When I ...

Oftentimes, we think of space as an endless, mostly empty vacuum, a silent backdrop where planets, stars, and galaxies play out their dance. We also think of time as something separate, a steady ...

Decadal surveys of the National Academies of Sciences, Engineering, and Medicine bring together leading experts to identify a field’s most compelling science challenges and frontiers for the next ...