In this episode, investigate cosmic antigravity, starting with cosmic inflation, a phenomenon that exponentially increased the size of the universe during the big bang. Then, learn why dark matter cannot be made of ordinary protons and neutrons, and explore the recent discovery that the expansion of the universe is accelerating, powered by a mysterious dark energy inherent in space itself.

Probe the mystery of the Great Blue Hole, an enormous submerged sinkhole ringed by a coral reef off the coast of Belize. Study the processes that create sinkholes, and investigate the nature of karst topography, which is produced by the erosion of limestone.

Pound for pound, the supercell is the most powerful thunderstorm on Earth. Explore the mechanics of this system, which produces the strongest straight-line winds, the most violent tornadoes, and the largest hail. Close by looking at the formation of a record-breaking hailstone weighing almost two pounds!

In this introduction to magnetism, discover that magnetic phenomena are really about electricity, since magnetism involves moving electric charge. Learn the right-hand rule for the direction of magnetic force. Also investigate how a current-carrying wire in a magnetic field is the principle behind electric motors.

It's one of the most famous puzzles ever invented. But Professor Benjamin has an easy-to-learn, eight-step method for solving this mind-bending puzzle quickly and accurately-every time. After examining the mathematics behind the cube, you'll follow him step-by-step through an algorithm that will have you solving any Rubik's Cube in less than three minutes.

Begin your study of musical rhythm by distinguishing periodic from non-periodic rhythmic patterns. Periodicity can be thought of as beat; non-periodicity involves expressive techniques such as timing variations and phrasing. Close by asking whether composers write music in the rhythmic patterns of their native language.

The Rock of Gibraltar marks the gateway from the Mediterranean Sea into the Atlantic Ocean, a connection that has been closed on and off through recent geologic time. Explore the currents, catastrophic floods, and drastic sea-level changes that have occurred at the strait of Gibraltar and throughout the Mediterranean basin.

Embark on the final section of the course, which covers the revolutionary theories that superseded classical physics. Why did classical physics need to be replaced? Discover that by the late 19th century, inexplicable cracks were beginning to appear in its explanatory power.

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.

Emergency department doctors should always assume every patient has a life-threatening illness-even though only 10% to 20% actually do. How do doctors manage this healthy paranoia? And how do they prepare themselves and their patients for the worst outcome while planning for the best?