So you’ve decided to jump into a black hole. Good news: as long as the black hole is big enough you can sail through the event horizon without harm and get to experience the interior of the black hole before you’re annihilated by the...

From hoverboards to flying cars to cloud cities, anti-gravity is a staple of science fiction and our dream of a less Earth-bound future. But in the real universe gravity appears to be a purely attractive force. Feels like its main MO is...

Meet Alice and Bob, famous explorers of the abstract landscape of theoretical physics. Heroes of the gerdankenexperiment—the thought experiment—whose life mission is to find contradictions in the deepest layers of our theories. Today our...

Black holes are inevitable predictions of general relativity—our best theory of space, time and gravity. But they clash in multiple ways with quantum mechanics, our equally successful description of the subatomic world. One such clash is...

A few weeks ago a large team of gravitational wave astronomers announced something pretty wild. The moderately confident detection of pervasive ripples in the fabric of space time that presumably fills the cosmos, detected by watching...

There’s a deep connection between gravity and time - gravitational fields seem to slow the pace of time in what we call gravitational time dilation. And today we’ll explore the origin of this effect. And ultimately, we’ll use what we...

Challenge question: if 1kg of apples is $5 and 2kg is $10, how much is -1kg of apples? The answer? Priceless. Because you could use negative-mass apples to build warp drives, travel in time, and construct a perpetual motion machine. In...

Mercury’s path through our solar system is, well, a little eccentric, and some of its movements were a mystery astronomers couldn’t explain for a long time. Then, in the early 20th century, Einstein reran the numbers and proved a whole...

In this video Paul Andersen explains how inertial mass and gravitational mass are equivalent. He shows you too simple methods for calculated individual inertial mass and gravitational mass. Albert Einstein used this principle to build...

This video discusses the concept of redshift and the expansion of the universe, starting with the discovery of the universe's expansion through the redshift of light from distant galaxies. It explains the three types of redshift: Doppler...

Lesson 8 (Gravitation and Orbits) of Dianna's Intro Physics Class on Physics Girl. Never taken physics before? Want to learn the basics of physics? Need an AP Physics 1 review before the exam? This course is for you! Exercises in this...