Search Talks

Repeating the experiment from SR-3 using light rather than sound, and understanding what Einstein assumed regarding the speed of light.
Learning Outcomes:
• How to draw a spacetime diagram that represents the sending and receiving of a light signal.
• Understanding that Einstein's Speed of Light Principle: "For an observer at rest, the speed of light is c, independent of the motion of the source" is natural and easy to believe.
• Interchanging the words observer and source we arrive at Principle 2*: "For a source at rest, the speed of light is c, independent of the motion of the observer," which Einstein did not assume, because it is very hard to understand how it could be true.

Einstein"s Relativity Principle applies to both mechanical and electromagnetic phenomena.
Learning Outcomes:
• Understanding Einstein's Relativity Principle: "Given any two inertial observers in uniform relative motion, both are equally entitled to consider themselves to be 'at rest'."
• Einstein based special relativity on Principles 1 and 2, which are both natural and easy to believe.
• Logically, Principles 1 and 2 imply Principle 2*. It is the role of special relativity to show how Principle 2* makes sense, but it requires a complete revision of our concepts of space and time.

A demonstration of electron superposition using an electron diffraction apparatus, plus an introduction to quantum entanglement.
Learning Outcomes:
• Concrete demonstration related to the surprising 360/720 degree prediction discussed in QM-15.
• Understanding how an electron diffraction apparatus works, and how its surprising experimental results are explained by electron superposition, i.e. the electron behaving as if it can exist in multiple paths simultaneously.
• Understanding how superposition applied to two particles can lead to a remarkable phenomenon called quantum entanglement (or, as Einstein called it, “spooky action at a distance”).

Quantum teleportation as a fascinating application of quantum entanglement.
Learning Outcomes:
• Understanding precisely what “teleportation” could mean in our quantum universe.
• How quantum entanglement is the key to making quantum teleportation possible.
• How a quantum teleportation machine functions.

Development of a successful mathematical model of spin.
Learning Outcomes:
• A review of the mathematics of vectors.
• Applying the experimental results of QM-14 to construct a mathematical model of an electron spinning in any direction as a certain superposition of the spin up and spin down states.
• Discovering that this mathematical model predicts that an electron does not return to its original state when rotated once (through 360 degrees) – it must be rotated twice (through 720 degrees). A discussion of experimental tests of this remarkable prediction.

Making the connection between particle probability patterns and wave intensity patterns, leading to the famous de Broglie relationship.
Learning Outcomes:
• Repeating the single slit experiment with waves instead of particles. Seeing that the particle probability pattern is the same as the wave intensity pattern.
• Same as above, but for the double slit experiment.
• Putting it all together to derive the de Broglie relationship between the momentum of a particle and the wavelength of a corresponding wave.

Using the de Broglie relation as a foundation for understanding the quirky quantum behaviour of particles.
Learning Outcomes:
• Understanding how a particle in one-dimensional box behaves like a superposition of left- and right-moving de Broglie waves, implying that the particle is moving both left and right simultaneously.
• Understanding the relationship between the intensity of de Broglie waves and the probability of finding the particle at specific locations inside the box.
• The general concept that a bound particle corresponds to a bound wave, resulting in only a discrete set of allowed standing waves, and thus quantization of its energy.

A discussion of the surprising results of the single slit and double slit experiments.
Learning Outcomes:
• How the single slit experiment suggests that chance is at the heart of nature, and that the behaviour of particles might need to be described by something different from Newton’s laws.
• How the double slit experiment suggests that understanding the behaviour of particles will require a radically new way of thinking about how nature works at a fundamental level.
• A video of an actual double slit experiment done with a beam of electrons (in case you don’t believe it).

Continuation of a thought experiment from SR-2 leading up to a derivation of the familiar Doppler shift for sound in air. Learning Outcomes: The real meaning of Newton’s assumption of absolute (or universal) time; Understanding the Doppler shift for sound in terms of a spacetime diagram; How to derive the (non-relativistic) Doppler shift formula for sound as a consequence of assuming Newton’s universal time.

Drawing spacetime diagrams of simple thought experiments involving sound in air as a warm up exercise for light in vacuum.
Learning Outcomes:
• Deepening our understanding of how to draw and interpret spacetime diagrams.
• Measuring space and time in the same units – a first step towards unifying space and time into “spacetime.”
• Why, for an observer at rest with respect to still air, the speed of sound is independent of the motion of the source of sound.