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Scott Menary Faculty of Science
Home » Miscellaneous Stuff for PHYS 2040 - Relativity and Modern Physics

Miscellaneous Stuff for PHYS 2040 - Relativity and Modern Physics

"Physicists use the wave theory on Mondays, Wednesdays and Fridays, and the particle theory on Tuesdays, Thursdays and Saturdays."

WH Bragg (1862-1942)

"So what's the speed of dark?"

Stephen Wright

Relativity by M. C. Escher

2025 is the International Year of the Quantum Science and Technology (see also Curtain Rises on the Year of Quantum). That's because it was in 1925, as the legend goes, that Werner Heisenberg took himself off to the island of Helgoland and invented the matrix mechanics version of Quantum Mechanics. Here are some highlights of the history of quantum physics from This Month in Physics History:

June/July 1925: Werner Heisenberg pioneers quantum mechanics

January 1928: The Dirac equation unifies quantum mechanics and special relativity

There are also Quantum Milestones from Physical Review Focus:

Quantum Milestones, 1905: Einstein and the Photoelectric Effect

Quantum Milestones, 1916: Millikan’s Measurement of Planck’s Constant

Quantum Milestones, 1923: Photons Are Real

The Tumultuous Birth of Quantum Mechanics

Quantum Milestones, 1927: Electrons Act Like Waves

Quantum Milestones, 1928: The Dirac Equation Unifies Quantum Mechanics and Special Relativity

Quantum Milestones, 1935: What’s Wrong with Quantum Mechanics?

The odd thing is that, even after a century of triumphs, physicists still don't really understand quantum mechanics. As a matter of fact, Physicists disagree wildly on what quantum mechanics says about reality, Nature survey shows (Nature, July, 2025). To try to come to some common understanding a conference was held on Helgoland (Quantum theory returns to Helgoland, CERN Courier, July, 2025) with mixed results ( ‘It’s a Mess’: A Brain-Bending Trip to Quantum Theory’s 100th Birthday Party, quanta magazine, August, 2025).

There continues to be a fascination with the German atomic bomb effort from World War II as evidenced by the May, 2022, article The elusive truth of Farm Hall. Below I discuss the play "Copenhagen" which made quite a stir several years ago. There is now a play based on the so-called Farm Hall Transcripts [PDF]. These are transcripts of secretly taped conversations of the German scientists (including Heisenberg) who were interned at Farm Hall in England after the War. It seems to be an endless game to try to interpret from these conversations what the Germans did and did not know during WWII about making a bomb. The play Copenhagen by the renowned playwright and author Michael Frayn (he wrote "Noises Off", for example) which explores the occasion in 1941 when Heisenberg paid a visit to Bohr in Copenhagen. The intriguing question, of course, is "what did they discuss?" Some speculate that Heisenberg was trying to obliquely warn Bohr about the German atomic bomb project. There has been some new (Feb. 2002) light shed on what transpired through the release of some letters from Neils Bohr (see also New letters expose war-time secrets). There is also a "Heisenberg letter" which can be found at the Who Was Werner Heisenberg? site maintained by the Heisenberg family. There one can find a number of Heisenberg's letters and writings translated into english. There is also a resources page. The London version of the play saw very enthusiastic reviews while the Broadway version won several Tony awards! The play opened in Toronto in January, 2004. There were good articles on the show and Frayn in the Toronto Star and Globe & Mail. I saw the opening-night show on January 7 (which was great) and there were reviews in the Star and Globe & Mail. A panel discussion of the scientific and ethical issues addressed by the play happened on February 8, 2004, and I was one of the panelists. There were a number of symposia, both in Europe and the U.S., discussing the issues surrounding the play. For example, there was a day-long symposium on the play "Creating Copenhagen" at the City University of New York which examined the scientific and historical issues brought up in the play as well as artistic issues associated with the writing and staging of the play. Several of the presentations at this symposium were reprinted in the July 2000 issue of Physics Today including: A Historical Perspective on Copenhagen, The German Uranium Project, and Werner Heisenberg and Albert Einstein. There is also a nice bit of detective work by Jeremy Bernstein in The Drawing or Why History Is Not Mathematics from the journal Physics in Perspective. I also recommend the book by Jeremy Bernstein entitled Hitler's Uranium Club. The play was the subject for the University of Pennsylvania's 1999 Reading Project. At this site you can find a number of fascinating essays about the play written by both artists and scientists. There are also articles in May 1999 CERN Courier and June 1998 PhysicsWeb discussing the play. (There is another article by Jeremy Bernstein on Heisenberg's trip to Poland in 1943.) Finally, there are a recent (January 2010) set of remarks entitled Quantum imaging: Scattered observations on "Copenhagen" which offer yet another take on the play.

Martha Henry as Margrethe Bohr in the Toronto Production of Copenhagen- PHOTO CREDIT: SWD Photography

Over a hundred years ago (November 25, 1915 to be precise) Einstein submitted his paper on the General Theory of Relativity. Here are a few articles that commemorated this event:

There has been an increasing interest in science shown by artists and vice versa. which has lead to some interesting artworks - like those shown in the exhibit Signatures of the Invisible. There is also an interest from the scientist's side to see how artists perceive science. Towards this end, the British Institute of Physics commissioned the Rambert Dance Company to produce a new work to celebrate the achievements of Albert Einstein - Celebrating Einstein with Dance, Constant Speed (brochure) premiered in 2005. The originators of the project were interviewed in New Scientist.

This is actually old, not new, but back in 2002 the electron double slit experiment was voted as Science's most beautiful experiment. There are some other great one's in the list as well as described in Here They Are, Science's 10 Most Beautiful Experiments.

There is a new American Institute of Physics site on my hero Rutherford. There is also the Rutherford site maintained by his biographer John Campbell.

There is a nice book by David Bodanis called E=mc2 (naturally) which dissects, in a very entertaining manner, each of the terms (including, the most important one "=") in Einstein's most famous equation. See also Fermilab Today from July 5, 2013 for another discussion of the famous equation. There are further discussions in Fermilab Today about "Proving special relativity" - episode 1 - Friday, March 21, 2014 and episode 2 - April 4, 2014.

There is a special issue of Nature on The Quantum Atom which explores "the origin and legacy of Niels Bohr's radical view of the nuclear atom, published one hundred years ago." We can now "see" the Bohr orbitals as discussed in Direct view of atomic orbitals (June, 2013), 'Quantum microscope' peers into the hydrogen atom, and A New Look at the Hydrogen Wave Function (May, 2013) or watch electrons in motion as summarized in Electron spectroscopy: Not just snapshots, real movies (July, 2013). There is also the theoretical question about how big atoms can be which is covered in Theoretical physics: Sizing up atoms.

The foundations of the quantum world are still hotly debated. For discussions of this have a look at: The Oxford Questions on the foundations of quantum physics (July, 2013), Science and Philosophy: A Love-Hate Relationship (July, 2013), and Einstein as armchair detective: The case of stimulated radiation (July, 2013). See also A Quantum of Solace - Timeless Questions About the Universe. Entanglement and the Uncertainty Principle are always hot topics. See, for example, Measurement Uncertainty: Reply to Critics (February, 2014), Proof mooted for quantum uncertainty (June, 2013), Spooky action gets collective (June, 2013), Quantum uncertainty not all in the measurement (September, 2012), Experimental demonstration of a universally valid error-disturbance uncertainty relation in spin measurements (January, 2012), Quantum theorem shakes foundations (November, 2011), and A quantum take on certainty (June, 2011).

Or how about the lowly photon. Read here for the unlikely origin of its name. It is still being studied, as evidenced by the July, 2013 articles How Stable is the Photon? and Detection of single photons via quantum entanglement.

You can read a reconstruction of a lecture Einstein gave on the equivalence of mass and energy in Pittsburgh in 1934. Included in the article this picture of Einstein lecturing that was in the newspaper.

See how Albert Einstein did on his performance review at the patent office in Bern for the year 1905.

Ride a relativistic rocket! Physicists at the Australian National University have created a computer program called Real Time Relativity that "allows the user to fly through a virtual world governed by relativistic physics." You can download the program from here.

I also highly recommend the book Einstein's Dreams by Alan Lightman who is John E. Burchard Professor of Science and Writing and senior lecturer in physics at the Massachusetts Institute of Technology. The book is a beautifully lyrical, thoroughly entertaining, and wonderfully short, meditation on time through the artifice of imagining the daydreams of Einstein in 1905. The book has spawned a theatrical adaptation, performed by Raleigh, NC's Burning Coal Theater Productions, which garnered very good reviews.

There is has always been a lot of contention about the central principle of the Special Theory of Relativity - namely, that the speed of light in vacuum is a constant independent of the source and receiver relative speed. Further, maintaining causality in Special Relativity requires that nothing can go faster than the speed of light in a vacuum and many attempts have been made to circumvent this, thus obtaining "superluminal" speeds. For example, see the article " Cosmic Laws Like Speed of Light Might Be Changing", where the possibility that the speed of light has changed value over time is discussed. A few years ago a number of experiments involving light propogation through dense media generated a lot of controversy and juicy headlines like "Light Pulses Flout Sacrosanct Speed Limit" (2002 - note the website), "Faster than a Speeding Light Wave" (2000), and "Laser Smashes Light-speed Record" (2000). Controversy also surrounded a paper in Nature bearing the innocent sounding title of "Gain-assisted superluminal light propagation." The abstract contained the line, "The observed superluminal light pulse propagation is not at odds with causality ..." although you wouldn't know it based on some of the media coverage about it. This is nothing more than the old group versus phase velocity confusion according to Bob Park in What's New.

The fascination with superluminal speeds is that it is related to the least understood subject in physics (and philosophy) - time. The onset of the new millenium produced a renewed fascination with time. You can take A Walk Through Time, a site on the evolution of time measurement from The National Institute of Standards and Technology (NIST) in the U.S. The article Seeing Faster by James Gleick in the New York Times Magazine gives a fascinating glimpse into how flash photography has changed our perception of time. The site also includes plenty of interesting links. There seems a particular fascination with time travel including "Time Travel" from NOVA as well as a site with "explanations" of relatvity and time travel.

Einstein lecturing in Pittsburgh in 1934

Not only has there been renewed interest in the speed of light but there has also been an explosion of interest in the brain of the man who made c a universal constant. You could see Samples of Albert Einstein's brain on display at the Mutter Museum in 2011. And Albert Einstein's brain continues to fascinate - in Hamilton (2015). In 1999, researchers at McMaster University concluded that Einstein really was smarter than the rest of us. Specifically, "the parietal region of his [Einstein's] brain, the area thought to be related to mathematical reasoning, was found to be 15 per cent wider than average." For complete coverage of the rather interesting history of the travels of Einstein's brain (after his death, of course), have a look at What Became of Albert Einstein's Brain? There are also a number of books on the travels of his brain including Driving Mr. Albert which was the cover review for the July 30, 2000, New York Times Review of Books (see also the review in the Globe & Mail) as well as Possessing Genius: The True Account of the Bizarre Odyssey of Einstein's Brain. The story is covered in Chapter 14 of Postcards from the Brain Museum. There's even a children's book called Nibbling on Einstein's Brain. Einstein's Brain is the source of much art including a 1994 documentary Relics: Einstein's Brain which chronicles the quixotic search for the brain by a Japanese professor, a folk album, and an art-science collaboration called the einstein's brain project.

  • Who says that relativistic effects aren't relevant to our everyday world! A while ago I put a link to Santa at Nearly the Speed of Light, the article "explaining" how the answer to that age old question, "Just how does Santa Claus get to all of those homes in one night?", lies in the Special Theory of Relativity. There was actually a challenge to the physics of the article which is gently responded to in Santa's World Revisited, an article in the May, 2000 issue of FermiNews, the newsletter from Fermilab, the high energy particle accelerator near Chicago. In the article is a link to a website where there are animations of how, for example, the Eiffel Tower would look if you passed by at 90% the speed of light. It's worth a look.
  • Check out the letter to the editor by Cyril E. Challice, Professor Emeritus, University of Calgary, that was in the March 2000 issue of Physics in Canada. It gives an interesting Canadian twist to the story of the observation of the wave nature of the electron by Davisson and Germer.
  • The Experimental Evidence link from the Particle Adventure is a very nice web-based description of the experimental origins of quantum physics, and in particular of Rutherford's groundbreaking experiments on the structure of matter. There is also All About Light from Fermilab which, through a discussion of light, cover much of the course material.
  • In honour of the centenary of the American Physical Society, the journal Reviews of Modern Physics devoted an entire issue to reviews of physics of the twentieth century. The following articles seemed particularly relevant for this course:
    • "A Century of Relativity" by Irwin I. Shapiro [pdf]
    • "Historic Foundations: Quantum Theory" by Hans Bethe [pdf]
    • "Experiment and the Quantum Effects in One-photon and Two-photon Interference" by L. Mandel [pdf]
    • "Experiment and the Foundations of Quantum Physics" by Anton Zeilinger [pdf]
  • There are a lot of good websites devoted to Einstein. Besides the AIP History site given already, there is Albert Einstein Online. There is also Einstein Revealed from the science program NOVA. The complete text of Einstein's Relativity - The Special and General Theory can be found here.
Book review
Typical Brain

Articles from Quanta magazine, Physics Update, Physics World News, Physical Review Focus, PhysOrg Physics News, Science News, and other sites on topics related to Special Relativity and the foundations of Quantum Mechanics.

Although the actual material covered in the course ends in 1925 with the birth of quantum mechanics, the various topics are still "living" issues in the sense that scientists continue to ponder and probe the foundations of relativity and quantum theory.[Be warned that these are NOT refereed papers so some of the conclusions reached here could be, and probably are, utter nonsense.]