Light
Part of the Series: How We Got to Now

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Into the Atom
Part of the Series: The Mystery of Matter
Caught up in the race to discover the atom's internal parts--and learn how they fit together--is a young British physicist named Harry Moseley, who uses newly discovered X-rays to put the Periodic Table in a whole new light. And a young American chemist named Glenn Seaborg creates a new element--plutonium--that…
Time
Part of the Series: How We Got to Now
The world today is obsessed by time. Johnson boards a submarine to discover what a lack of natural light means for a sailor's working day and visits Heathrow, the world's busiest airport, to try to get timings right at air traffic control. The story of getting a grip on time…
Wave or Particle?
Einstein's resolution of the photoelectric effect problem suggests that light consists of particles (photons). But how can this be reconciled with the understanding of light as an electromagnetic wave?
Special Relativity
Discover the startling consequences of Einstein's principle of relativity: that the laws of physics are the same for all observers in uniform motion. One result is that the speed of light is the same for all observers, no matter what their relative motion: an idea that overturns the concept of…
Cold
Part of the Series: How We Got to Now
Only in the last 200 years have humans learned how to make things cold. Johnson explains how ice entrepreneur Frederic Tudor made ice delivery the second biggest export business in the U.S. and visits the place where Clarence Birdseye, the father of the frozen food industry, experienced his eureka moment.…
Out of Thin Air
Part of the Series: The Mystery of Matter
One of science's great odd couples--British minister Joseph Priestley and French tax administrator Antoine Lavoisier--together discover a fantastic new gas called oxygen, overturning the reigning theory of chemistry and triggering a worldwide search for new elements. Soon caught up in the hunt is science's first great showman, a precocious British…
How We Got to Now - with Steven Johnson
PBS
Join best-selling author Steven Johnson to discover extraordinary stories behind six remarkable ideas that made modern life possible, the unsung heroes who brought them about and the unexpected and bizarre consequences each of these innovations triggered.
Reflection and Refraction
Starting a new section of the course, discover that light often behaves as rays, which change direction at boundaries between materials. Investigate reflection and refraction, answering such questions as, why doesn't a dust mote block data on a CD? How do mirrors work? And why do diamonds sparkle?
Wave Optics
Returning to themes from episode 18 on waves, discover that when light interacts with objects comparable in size to its wavelength, then its wave nature becomes obvious. Examine interference and diffraction, and see how these effects open the door to certain investigations, while hindering others.
Faster than Light? Past, Future, and Elsewhere
Relativity implies that the time order of events can be different in different reference frames. Does this wreak havoc with cause and effect? Finally, why is it that nothing can go faster than light?
Particle or Wave?
In 1923, Louis de Broglie proposed that, like light photons, particles of matter might also display wave properties. The wave nature of smaller particles such as electrons is quite visible and leads to many unusual phenomena, including quantum tunneling mentioned in Lecture 1.
The Particle Zoo
By 1960 a myriad of seeming elementary particles had been discovered. Survey the standard model that restored order to this subatomic chaos, describing a universe whose fundamental particles include six quarks; the electron and two heavier cousins; elusive neutrinos; and force-carrying particles such as the photon.