Henry Carter Hull

How do you analyze a complex system in motion? One special point in the system, called the center of mass, reduces the problem to its simplest form. Also learn how a system's momentum is unchanged unless external forces act on it. Then apply the conservation of momentum principle to analyze inelastic and elastic collisions.

Look back at historical blizzards that paralyzed major U.S. cities. Then probe the official definition of a blizzard, the cold-weather cyclone systems that create them, and the revolution in forecasting blizzards since 1993. Focus on the role of the jet stream, and dispel a common misunderstanding of the polar vortex.

Mathematically trained players also have a decisive edge in backgammon, which trains you to make decisions in highly uncertain conditions. This course explains the rules of the game, the basic strategies for winning, the best ways to play your opening rolls, and how math constantly enters the picture-from figuring out the safest way to move your checkers to the all-important doubling cube.

What turns a remotely controlled machine into an autonomous robot? Self-control. So where does self-control in robots come from? Find out in this lecture on robot controllers: the computer-like part of robots that uses sensory information to decide how the robot should achieve its immediate and long-term goals.

Imagine a place where steam is so acidic that it can burn lungs, where flaming, liquid sulfur condenses from that steam, and a turquoise-colored lake is filled with the equivalent of battery acid. This hellish place is the crater lake of Kawah Ijen on the island of Java in Indonesia.

In the early 20th century, one of the most popular words in book titles was crisis, reflecting a widespread anxiety about a rapidly changing world. Study contrasting assessments of the stability of society from sociologists Max Weber, Pyotr Kropotkin, and Ferdinand Tönnies, as well as the influential analysis by industrialist Andrew Carnegie.

Use a simple analogy to understand how a time machine might work. Unlike movie scenarios featuring dematerializing and rematerializing, a real time machine would be a spaceship that moves through all the intervening points between two locations in spacetime. Also explore paradoxes of time travel.

Apply what you've learned so far to work out the details of Niels Bohr's model of the atom, which patches one of the cracks in classical physics from episode 44. Although it explains the energies of photons emitted by simple atoms, Bohr's model has serious limitations.

Einstein's special theory of relativity upends traditional notions of space and time. Solve the simple formulas that show the reality of time dilation and length contraction. Conclude by examining the twins paradox, discovering why one twin who travels to a star and then returns ages more slowly than the twin back on Earth.

Trace the history of the second law of thermodynamics, considered by many physicists to be the one law of physics most likely to survive unaltered for the next thousand years. The second law says that entropy-the degree of disorder in a closed system-only increases or stays the same.