Black Holes Explained
Examine one of the most exotic objects that exists in the universe in this fascinating course by a top astronomer.
Overview
About
01: A General Introduction to Black Holes
Widely featured in novels, movies, and other media, black holes are not just entertaining plot devices, they're real. Learn how the idea of black holes was proposed more than two centuries ago, and how more recently Einstein's general theory of relativity gave a firm theoretical basis for them.
02: The Violent Deaths of Massive Stars
Discover how black holes can form from stars that are much more massive than the sun. After exhausting their nuclear fuel, these behemoths end in a colossal explosion called a supernova, leaving behind a superdense neutron star, or in some cases something even denser: a black hole.
03: Gamma-Ray Bursts—The Birth of Black Holes
Trace the story of gamma-ray bursts. Long a mystery, these intense eruptions of high-energy radiation from random spots in the sky are now thought to be associated with the formation of black holes in distant galaxies. Their visibility from so far away means they are truly titanic explosions.
04: Searching for Stellar—Mass Black Holes
If black holes emit no light, how are they detected? Investigate the different clues that establish strong evidence for black holes. For example, a star orbiting an unseen object that exceeds the 3-solar-mass limit for neutron stars is probably circling a black hole.
05: Monster of the Milky Way and Other Galaxies
This lecture presents the most compelling evidence to date for black holes—found in the core of most galaxies. There, stars and gas clouds typically orbit at high speeds, signaling the presence of a central, supermassive black hole, millions to billions of times the mass of the sun.
06: Quasars—Feasting Supermassive Black Holes
Quasars are another astronomical mystery explained by black holes. Explore the history of these star-like objects that long baffled astronomers, until observers realized they were seeing matter falling into supermassive black holes during the early era of galaxy formation.
07: Gravitational Waves—Ripples in Space-Time
Gravity waves are an unexplored new window for studies of black holes. Learn how these hard-to-detect vibrations are the predicted ripples in the fabric of space-time that should result from violent phenomena such as the merging of two black holes.
08: The Wildest Ride in the Universe
What happens if you fall into a black hole? Take a wild ride into the supermassive black hole at the center of the Milky Way Galaxy with a vivid computer simulation showing the strange effects you would experience before being crushed to incredible density.
09: Shortcuts through the Universe and Beyond?
Mathematically, black holes seem to connect our universe with others through a gateway called an Einstein-Rosen bridge—nicknamed a wormhole by physicist John Wheeler, who also coined the term black hole. See a computer simulation of what passage through a wormhole would be like.
10: Stephen Hawking and Black Hole Evaporation
Learn why black holes may not be completely black. In 1975, physicist Stephen Hawking showed that they can evaporate via a quantum tunneling process, giving off a slow trickle of quantum particles before eventually ending in an explosion of gamma rays.
11: Black Holes and the Holographic Universe
The "no-hair" theorem says that black holes are utterly simple and preserve almost no information about what went into them. Discover why some physicists believe that the supposedly lost information is contained just outside the black hole in a form that resembles a hologram—and that the universe as a whole may display the same property.
12: Black Holes and the Large Hadron Collider
Professor Filippenko closes by looking at the possibility that a new particle accelerator called the Large Hadron Collider will produce microscopic black holes. Discover why there is no danger that they will devour the Earth, and why there is no risk from any known black holes in space.