spacetime

A PBS Space Time episode hosted by Gabe Perez-Giz on the nature of spacetime and whether space and time are fundamental. It builds up reference frames and causality in a short, dense format.

Veritasium explains, with expert input, that in general relativity gravity is not a force and objects follow straight paths through curved spacetime, including why standing on the ground means you are accelerating.

PBS Space Time explains how spacetime geometry and light cones determine the order of events and what can cause what. It visualizes causality in special relativity.

PBS Space Time argues that the speed of light is better understood as the speed of causality, the universal limit on how fast cause and effect propagate. Light travels at that speed because it is massless, but the limit itself is a property of spacetime.

ScienceClic explains why the rubber sheet analogy for general relativity is misleading and offers a new visualization that includes the curvature of time and shows gravity as motion through curved spacetime.

PBS Space Time introduces Miguel Alcubierre's warp drive, explaining how spacetime itself could be warped rather than moving a ship through it, and whether it is physically possible.

PBS Space Time explains what happens as you approach and cross a black hole's event horizon, using Penrose diagrams and light cones as the tool for understanding spacetime there.

ScienceClic explains why nothing can go faster than light by treating motion through space and time together, so everything moves at the speed of light through spacetime. It uses animated visuals to cover relativity basics in 12 minutes.

A PBS Space Time episode explaining how space and time swap roles inside a black hole's event horizon. It is part of the channel's black hole series.

PBS Space Time explores whether time causes gravity, explaining that gravity does not truly warp the flow of time but arises from time gradients. It revisits how gravitational time dilation works in general relativity.

Sabine Hossenfelder explains how special relativity leads to the block universe, in which past, present and future all exist equally, and asks what that means for whether the past still exists.

A PBS Space Time episode on how gravitational wave observations of a neutron star merger, GW170817, can limit the number of spacetime dimensions. It is based on a 2018 paper.