Physicists spend a lot of time thinking about impossible things, since probing the constantly shifting bounds between the possible and impossible is one of the best ways to discover unexpected phenomena and new laws of nature. And for nonscientists, exploring this extraordinary realm is one of the best introductions to the immensely rich subject of physics.
Consider these questions:
- Can machines produce limitless energy?
- Is time travel possible?
- Can anything travel faster than light?
- Is it possible to escape from a black hole?
Each is a puzzle that requires pieces from different parts of physics to solve. And after investigating these and other questions, you begin to see how all of physics is tied together in a system that is consistent, logical, beautiful, and often very surprising.
For example, the question about whether time travel is possible leads you to a study of the nature of time and space. The paradoxes you encounter there are directly related to Einstein's concepts of space-time and the constancy of the speed of light from his theory of relativity. This, in turn, takes you to exotic ideas such as black holes and wormholes, which some theorists believe may be potential shortcuts through space-time.
Before you know it, a staple subject of science fiction—time travel—has taken you through many layers of investigation to reveal profound truths about the universe.
Impossible: Physics beyond the Edge uses this ingenious approach in 24 delightful half-hour lectures that will entertain and nourish your mind, while teaching you more physics than you ever imagined. Your guide into the realms of the impossible is veteran Great Courses Professor Benjamin Schumacher of Kenyon College, a pioneering theorist in quantum information, which is a field dealing with things once deemed impossible.
Is It Possible?
Designed for those with no previous knowledge of physics, Impossible: Physics beyond the Edge will also appeal to the spirit of whimsy and adventure in those already well grounded in the subject. The course is illustrated with hundreds of diagrams, 3-D animations, and images to convey fundamental ideas at the core of physics—all in pursuit of the answer to the question, "Is it possible?"
Thanks to today's science-fiction-rich media, people are more inclined than ever to think that the fanciful is real, that imaginary creations such as perpetual motion machines and warp-drive space engines are feasible technologies. Impossible: Physics beyond the Edge serves as an enlightening corrective to this outlook.
On the other hand, modern physics is full of real phenomena that are so counterintuitive that they seem like science fiction. Here are a few that you encounter in this course:
- Near-absolute zero: Reaching the coldest possible temperature—absolute zero at -273.15º C—is probably impossible. But as some substances approach this limit, electrical resistance and viscosity drop to zero, and a strange new form of matter emerges.
- Time dilation: According to Einstein's special theory of relativity, a clock in motion keeps time more slowly than one at rest—from the point of view of an observer at rest. However, an observer accompanying the moving clock notices no time slowdown at all.
- Quantum tunneling: In the quantum world, particles can do the equivalent of walking through walls—appearing on the other side of an apparently impassable energy barrier. The effect has many uses, including the scanning tunneling microscope, which can "see" atoms.
- Entanglement: In the strangest of all quantum effects, a pair of particles acts together as a system; if something happens to one particle, the other responds instantly, even if it is millions of miles away. It seems like a violation of faster-than-light communication, but it isn't.
From Thermodynamics to Information Theory
Professor Schumacher begins the course by investigating three ways that scientists interpret the impossible and how these approaches inspired important breakthroughs by Euclid, Isaac Newton, and James Clerk Maxwell. Historically, some inventions and discoveries were called impossible shortly before they were actually achieved, and you learn how there is a danger of being like the eminent scientist Simon Newcomb, who in 1903 declared that humans would never fly, just a few weeks before the Wright brothers took off over Kitty Hawk.
The opposite risk is chasing a dream that the laws of physics won't allow. The most notorious example is a device that produces limitless energy—a perpetual motion machine. Professor Schumacher's discussion of this long and fruitless quest leads you to one of the most important sets of ideas in physics: the three laws of thermodynamics, which were developed in the 19th century in concert with the technological innovations of the industrial revolution.
From here, you survey the advancing frontier of physics, as startling new theories changed our perception of what's possible and what's not, including such revolutions as these:
- Relativity and quantum theory: Starting in the early 20th century, these two groundbreaking theories have done more than anything else to remap the border between the possible and impossible.
- Chaos theory: The discovery that the future is hostage to unpredictable, chaotic fluctuations in present conditions destroyed the dream that the future can ever be forecast with any certainty or precision.
- Noether's theorem: In the early 20th century, mathematician Emmy Noether made the remarkable discovery that the great laws of physics, such as the conservation of energy, result from symmetrical features of space and time.
- Information theory: Information is a powerful idea in physics and at the heart of many impossible phenomena, such as the impossibility of anything traveling faster than light—in which "anything" means "information."
You will also see how the square-cube law in mathematics was used as long ago as the 17th century to conclusively dismiss an idea that still won't die: that gigantic insects and other larger-than-life creatures are plausible life forms.
Impossibility as a Tool of Understanding
By the end of the course, you will have probed the nature of the impossible from many points of view and in many branches of physics—discovering that racing a light beam, hovering over a black hole, chasing quantum particles, trying to reverse the flow of time, and other astounding adventures make an excellent education in the fundamental laws of nature. These laws work together to create the sometimes perplexing, frequently surprising, and always wonderful world in which we live. As Professor Schumacher says, "If our goal is understanding, then there is nothing more practical than the impossible."