Lesson 39: Maxwell's Equations
By the 1860s all the pieces of the electricity and magnetism puzzle were in place, except one. The last piece, discovered by James Clerk Maxwell and called (unfortunately) the displacement current was just what was needed to produce electromagnetic waves called (among other things) light.
Lesson 40: Optics
Maxwell's theory says that electromagnetic waves of all wavelengths, from radio waves to gamma-rays and including visible light, are all basically the same phenomenon. Many of the properties of light are really just properties of waves, including reflection, refraction and diffraction. Ordinary light can be used to see things on a human scale, X-rays to "see" things on an atomic scale.
Lesson 41: The Michelson-Morley Experiment
In 1887, in Cleveland, Ohio, an exquisitely designed measurement of the motion of the earth through the aether resulted in the most brilliant failure in scientific history.
Lesson 42: The Lorentz Transformation
If the speed of light is to be the same for all inertial observers (as indicated by the Michelson-Morley experiment) the equations for time and space are not difficult to find. But what do they mean? They mean that the length of a meter stick, or the rate of ticking of a clock depends on who measure it.
Lesson 43: Velocity and Time
Unlike Lorentz, Albert Einstein was motivated to perfect the central ideas of physics rather than to explain the Michelson-Morley experiment. The result was a wholly new understanding of the meaning of space and time, including such matters as the transformation of velocities, time dilation, and the twin paradox.
Lesson 44: Mass, Momentum, Energy
The new meaning of space and time make it necessary to formulate a new mechanics. Starting from the conservation of momentum, it turns out among other things that E = mc 2.
Lesson 45: The Temperature and Gas Law
The ups and downs of scientific research are reflected in Boyle's experiments, and Charles' investigations. Hot new discoveries about the behaviors of gases make the connection between temperature and heat, and raise the possibility of an absolute scale.
Lesson 46: Engine of Nature
There was a young man named Carnot
Whose logic was able to show
For a work source proficient
There's none so efficient
As an engine that simply won't go.
- David L. Goodstein, Physics undergraduate (1958)
Lesson 47: Entropy
This program illustrates the genius of Carnot, Part II, and the second aw of thermodynamics. The efficiency of Carnot's ideal engine depends on the ratio between high and low temperatures in the running cycle. Carnot's theory begins with simple steam engines and ends with profound implications for the behavior of matter and the flow of time throughout the universe.
Lesson 48: Low Temperatures
Solids, liquids, and gases are the substance of every substance in the physical world. With the quest for low temperatures came the discovery that, under the right conditions of temperature and pressure, all elements can exist in each of the basic states of matter.
Lesson 49: The Atom
This program explores the history of the atom, from the ancient Greeks to the early 20th century, when discoveries by J.J. Thomson and Ernest Rutherford created a new crisis for the world of physics.
Lesson 50: Particles and Waves
Even before the crisis of the atom, there was evidence that light, which was certainly a wave, could sometimes act like a particle. In the new physics, called quantum mechanics, not only does light come in quanta called photons, but electrons and other particles also interfere like waves.
Lesson 51: From Atoms to Quarks
Electron waves confined by electric attraction to the nucleus help resolve the dilemma of the atom and account for the periodic table of the elements. Nucleons themselves obey a kind of period table, following inner rules that lead to the idea of quarks.
Lesson 52: The Quantum Mechanical Universe
A last, lingering look at where we've been, and perhaps a timid glance into the future, marks the close of the series The Mechanical Universe and Beyond....