Free Fall and Inertia

The Great Courses
Show More

Related videos

The Falling Laboratory
Einstein focused on gravity in his general theory of relativity. Hear about his "happiest thought"--the realization that a man in free fall perceives gravity as zero. This simple insight resolved a mystery going all the way back to Newton and led Einstein to the startling discovery that gravity affects light…
Spacetime Tells Matter How to Move
See how gravity affects Minkowski's spacetime geometry, discovering that motion in a gravitational field follows the straightest path in curved spacetime. The curvature in spacetime is not caused by gravity; it is gravity. This startling idea is the essence of Einstein's general theory of relativity.
The Strangest Force
Begin your exploration of gravity with Isaac Newton and the famous story of the apple. Why was it such a breakthrough to connect a falling apple with the faraway moon? Review the essential characteristics of gravity and learn why small asteroids and large planets have such different shapes.
Spacetime in Zero Gravity
In an influential interpretation of relativity, Einstein's former mathematics professor Hermann Minkowski reformulated the theory in terms of four-dimensional geometry, which he called spacetime. Learn how to plot events in this coordinate system in cases where gravity is zero.
Gravitomagnetism and Gravitational Waves
The general theory of relativity predicts new phenomena of gravity analogous to those of electromagnetism. Discover how ultra-sensitive experiments have detected the gravitomagnetism of the Earth, and follow the search for elusive gravitational waves that travel through space.
From Forces to Fields
For the rest of the course, focus on the revolutionary view of gravitation launched by Albert Einstein. Review new ideas about fields that allowed physics to extend beyond Newtonian mechanics. Then see how Einstein modified Newton's laws and created the special theory of relativity.
The Search for Exoplanets: What Astronomers Know
As recently as 1990, it seemed plausible that the solar system was a unique phenomenon in our galaxy. Thanks to advances in technology and clever new uses of existing data, now we know that planetary systems and possibly even a new Earth can be found throughout galaxies near and far.…
What Are Tides? Earth and Beyond
Trace the origin of tides to the simple fact that gravity varies from point to point in space. This leads not just to the rise and fall of the ocean, but to the gradual slowing of Earth's rotation, Saturn's spectacular ring system, volcanoes on Jupiter's moon Io, and many other…
Finding Planets with Gravitational Lensing
Get a lesson in Einstein's general theory of relativity to understand an effect called gravitational microlensing, which allows astronomers to deduce a planet's existence without recording any light from the planet or its host star. This technique reveals exoplanets that would otherwise go undetected.
Light in Curved Spacetime
See how Einstein's general theory of relativity predicts the bending of light in a gravitational field, famously confirmed in 1919 by the British scientist Arthur Eddington. Learn how this phenomenon creates natural gravitational lenses--and how the bending of light reveals invisible matter in deep space.
Abell 2218: A Massive Gravitational Lens
Episode 10 of Experiencing Hubble
One of the consequences of Einstein's general theory of relativity is evident in Hubble's picture of the galaxy cluster Abell 2218. Investigate the physics of this phenomenon, called gravitational lensing, and discover how Hubble has used it to study extremely distant galaxies as well as dark matter.
Pioneers of Planet Searching
Chart the history of exoplanet hunting--from a famous false signal in the 1960s, through ambiguous discoveries in the 1980s, to the big breakthrough in the 1990s, when dozens of exoplanets turned up. Astronomers were stunned to find planets unlike anything in the solar system.