Why would anyone want to take a course called "The Strange World of Quantum Mechanics"?
Just over 100 years ago, physicists exploring the newly discovered atom found that the atomic world of electrons and protons is not just smaller than our familiar world of trees, balls, and automobiles, it is also fundamentally different in character. Objects in the atomic world obey different rules from those obeyed by a tossed ball or an orbiting planet. These atomic rules are so different from the familiar rules of everyday physics, so counterintuitive and unexpected, that it took more than 25 years of intense research to uncover them.
But it is really only in the last 10 or 20 years that we have come to appreciate that the rules of the atomic world (now called "quantum mechanics") are not just different from the everyday rules (now called "classical mechanics"). The atomic rules are also far richer. The atomic rules provide for phenomena like particle interference and entanglement that are simply absent from the everyday world. Every phenomenon of classical mechanics is also present in quantum mechanics, but the quantum world provides for many additional phenomena. (These are the phenomena currently being exploited in the emerging field of quantum computing.)
Here's an analogy: Some films are in black-and-white and some are in color. It does not malign any black-and-white film to say that a color film has more possibilities, more richness. In fact, black-and-white films are simply one category of color films, because black and white are both colors. Anyone moving from the world of only black-and-white to the world of color is opening up the door to a new world -- a world ripe with new possibilities and new expression -- without closing the door to the old world.
This same flood of richness and freshness comes from entering the quantum world. It is a difficult world to enter, because we humans have no experience, no intuition, no expectations about this world. Even our language, invented by people living in the everyday world, has no words for the new quantal phenomena -- just as a language among a race of the color-blind would have no word for "red".
This course is not easy: it is like a color-blind student learning about color from a color-blind teacher. The course is just one long argument, building up the structure of a world that we can explore not through touch or through sight or through scent, but only through logic. Those willing to follow and to challenge the logic, to open their minds to a new world, will find themselves richly rewarded.
Topics: This course introduces the three central concepts of quantum mechanics, namely: (1) The outcome of an experiment cannot, in general, be predicted exactly; only the probability of the various outcomes can be found. (2) These probabilities arise through the interference of probability amplitudes. (3) Probability amplitudes can be associated with two experiments done far apart from each other ("entanglement"). The ideas are developed through the example of an intrinsically simple system ("spin 1/2"), which is treated with complete rigor and honesty.
Course goal: An appreciation of the three central concepts of quantum mechanics. This appreciation has two aspects: (1) the mathematical and physical understanding necessary to work meaningful problems and (2) a conceptual understanding sufficient to realize the bizarreness of the quantum world, which is our own home.
Teacher:
Dan Styer,
Wright 215, 775-8183, Dan.Styer@oberlin.edu
home telephone 775-0959 (2:30 pm to 9:00 pm only).
Office hours: Please feel free to drop in between 8:30 am and 2:30 pm. (I am often in my office later, depending on my son's high school schedule.)
Add-drop warning: If you wish to add or drop this course, you must do so via PRESTO by 11:30 pm on Wednesday, 5 November.
Prerequisites: This course does not assume any background in science. High school algebra and geometry will be used as needed without apology.
Text: D.F. Styer, The Strange World of Quantum Mechanics.
Course web site (this document): http://www.oberlin.edu/physics/dstyer/StrangeQ
Grading: This is a one credit-hour, second-half-of-the-semester module, graded on a Pass/No Pass basis. To receive credit, you must react to classes regularly and satisfactorily complete six assignments (or four assignments and a project).
How do you react to classes? At the end of every class, hand in a slip of paper containing your name and a brief (one- or two-sentence) reaction to the state of your knowledge concerning quantum mechanics. I will use these reactions to plan the next class and the future path of this course. Your most useful reaction would be a specific question: for example, "What does it mean to say that an electron is at several places at once?" Other possible reactions would be indications of general interest ("I'd like to learn more about entanglement.") or general questions ("Why should I care about this stuff, anyway?"). Please avoid questions of marginal relevance to this course ("How can I get that cute redhead in the second row to notice me?").
Assignments are due at 11:55 pm on each Thursday, except for Thanksgiving day. They will be administered and graded through the Oberlin College Blackboard system. I cannot accept late solutions. To pass the course, you must earn at least 70% on the assignments.
The problem assignments are an opportunity for you hone your growing quantum-mechanical skills and knowledge by applying them to specific situations. It's easy to fool yourself into thinking that you understand quantum mechanics because you can follow the readings and grasp the outlines of the theory, whereas in fact understanding comes through knowing not just the theory, but also how to apply it. (Just as everyone wants a free, stable, and democratic Iraq, but no one seems to know how to get from where we are to this desirable goal.)
Project: In lieu of any two assignments you may submit a project. The project is usually an essay concerning quantum mechanics, the history of quantum mechanics, or the influence of quantum mechanics on philosophy, literature, culture, etc. Possible essay topics are listed in appendix D of the book, but I'm sure you will be able to come up with other good ideas yourself. Restrict the scope of your investigations...I would far prefer a short, well-thought-out investigation to a long discourse that merely parrots the opinions found in some library book. Your project may be a creative work such as a poem, short story, or piece of music, but it must involve quantum mechanics in some non-trivial way! I anticipate that your essay will be relatively short (three to six pages), but it should show evidence of considerable analytic thought.
Quantitative proficiency: You may receive half Quantitative Proficiency Certification by passing both this course and Physics 51, Einstein and Relativity. In order to receive this certification you must complete all the assignments rather than submit a project. (In addition, in Physics 51 you must have carried out a project with a quantitative aspect.)
Reserve list: The course textbook (call number Science QC174.12.S879 2000) is on reserve in the science library.
Course schedule:
Relevant readings are listed in square brackets.
Be sure to do these readings before class.
| 28 October | Introduction | |
| 30 October | Feynman on quantum mechanics (movie) [chap. 1] | |
| 4 November | Classical magnetic needles (demonstrations) [chap. 2] | |
| 6 November | Conundrum of projections; Repeated measurements [chaps. 3 and 4] | |
| 11 November | Probability [chap. 5] | |
| 13 November | Einstein-Podolsky-Rosen paradox [chap. 6] | |
| 18 November | Optical interference (demonstrations) [chap. 8] | |
| 20 November | Quantal interference [chap. 9] | |
| 25 November | History of quantum mechanics | |
| 27 November | No class [Thanksgiving] | |
| 2 December | Amplitudes [chaps. 10 and 11] | |
| 4 December | Quantum cryptography [appendix B and chap. 13] | |
| 9 December | Quantum mechanics of a bouncing ball [chap. 14] | |
| 11 December | Summary |
Want to know more?
Do you want to continue exploring our universe after this
course is over?