general relativity

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.

Veritasium explains magnetism as a consequence of special relativity. Length contraction of moving charges makes a current in a wire attract or repel a nearby moving charge.

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.

Veritasium explores why energy is not conserved in general relativity, using Emmy Noether's theorem linking symmetries to conservation laws. Physicists interviewed explain energy loss in an expanding universe.

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 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.

Veritasium explores what general relativity says about black holes, white holes and wormholes, with help from physicists Geraint Lewis and Juan Maldacena. It introduces Penrose diagrams and the idea that other universes may be implied.

PBS Space Time explains how general relativity permits warp drive in principle and covers recent theoretical advances toward solving the negative energy problem.

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.

A minutephysics explainer on the twins paradox in special relativity. It shows why the traveling twin ends up younger and how acceleration resolves the paradox.

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 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.

A PBS Space Time episode asking what black holes really are and whether events can happen inside them. It covers event horizons, time dilation and common misconceptions about black holes.

A Computerphile video in which Rob Miles warns against assuming a general AI will think like a human. He uses the thought experiment of a stamp-collecting AI to show how a goal-driven system could pursue its aim with dangerous results.

ScienceClic visualizes what you would see falling into a black hole, from the approach and the accretion disc to crossing the horizon, in 15 minutes.

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.

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 asking whether our universe could sit inside a black hole. It covers what physicists think happens inside black holes and the arguments for and against this idea.

A Veritasium video touring Relativity Space and explaining why 3D printing whole rockets cuts tooling costs, allows rapid iteration, reduces part count and enables new designs. It includes an interview with Scott Manley on aerospace engineering.

Veritasium explains why the one-way speed of light has never been measured, only the round-trip speed, since measuring it requires synchronized clocks that assume the answer. It explores the implications for relativity.

3Blue1Brown shows how the uncertainty principle arises from Fourier transforms. A wave packet cannot be narrow in both position and frequency, so the principle is a property of waves rather than of measurement.

AVweb's Paul Bertorelli explains why general aviation has failed to replace leaded avgas, blaming industry inertia, bureaucratic delay and an exemption that removes the incentive. This is part one of two.

AVweb's Paul Bertorelli explains in part two of a series why general aviation has not replaced leaded avgas. He covers industry inertia, bureaucratic delays and the exemption that lets the industry keep using lead.

Sabine Hossenfelder explains why she thinks faster-than-light travel may not be ruled out. She argues that the standard objections from special relativity are inconclusive.

A PBS Space Time episode explaining why faster-than-light travel is equivalent to travelling back in time, using relativity and Minkowski diagrams for different observers.

Tom Scott, with linguists Gretchen McCulloch and Molly Ruhl, examines whether the language you speak changes how you think. The short answer is mostly no, with caveats about the weak version of the Sapir-Whorf hypothesis.

A PBS Space Time episode asking what matter, mass, and energy really are, starting with inertial versus gravitational mass and what mass-energy equivalence means.

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.

A Wendover Productions video on how dollar store chains expanded across America and why they displace grocery stores in small towns. It covers their business model and supplier leverage.

AVweb's Paul Bertorelli analyzes the safety record of the Cirrus Airframe Parachute System (CAPS), looking at the 90-plus deployments over 20 years of Cirrus flying. He asks whether the whole-aircraft parachute has actually saved lives.

Robert Miles covers a paper where researchers ran real versions of his earlier mesa-optimizer thought experiments. They show inner misalignment, where an AI learns the wrong goal in training and misbehaves when deployed.

An animated introduction to geometric algebra, presented as a language that can describe most of physics. It was made with manim and covers multivectors and how they generalize familiar tools like cross products and quaternions.

Robert Miles asks whether corporations can be thought of as artificial general superintelligences and how far the analogy holds. He argues the differences, such as being limited by employees' capabilities, matter for AI safety.

Veritasium tells the history of how imaginary numbers arose from the quest for a general solution to the cubic equation, including the duels and secrecy among Renaissance mathematicians. It argues math had to give up the requirement that it mirror reality.

Tom Scott-style exploration by suckerpinch (Tom7) of generalized anagrams where letters can be broken into pieces, called anagraphs, with a whimsical computational approach.

Polylog explains how algorithms can be turned into circuits and encoded as satisfiability problems, which lets you effectively run them backwards. It uses this to motivate breaking RSA, general reductions to SAT, and what P vs NP is really asking.

Zack Freedman gives advice on why makers fail to finish projects, including scrapping bad ideas, showing work publicly and writing a plan that keeps projects fun. It is aimed at hardware DIY but generalizes.

CGP Grey explains how the 2015 UK general election showed the flaws of first-past-the-post voting, with parties like UKIP winning many votes but few seats.