Traditionally, physicists consider Relativity, Atoms, and Quantum Mechanics, the last three sections of this outline, as "Modern Physics" although the concepts were widely known and developed nearly 100 years ago. All of these topics employ mathematics beyond the capability of most secondary school students. However, we can explore the phenomena, ideas, and failures of classical physics that lead directly to the theories.
James Dalton hypothesized the existence of atoms and the atomic wight of elements. Students will use data similar to Dalton's and make their own hypothesis.
Dmitri Mendeleev classified elements and contributed to the invention of the periodic table. Students will use data similar to Mendeleev's and devise their own classifications schemes.
The students attempt to weigh a single atom by first devising a technique and then performing the operation.
J. J. Thomson weighed the electron. The students will attempt to perform his experiment and draw conclusions from the experimental result.
J. J. Thomson became a Nobel Laureate (discovery of electron, etc.). His Academic adviser was John W. Strutt, III (Lord Rayleigh) a Nobel Laureate for the discovery of Argon. Students of J. J. Thomson who become Nobel Laureates include Charles Glover Barkla (X-ray spectroscopy), Charles T. R. Wilson (cloud chamber), Ernest Rutherford (atomic nucleus), Francis William Aston (mass spectrograph), Owen Willans Richardson (thermionic emission), William Henry Bragg (X-ray diffraction), and Max Born (quantum mechanics). J. J. Thomson's son, George Paget Thomson also was a Nobel Laureate (electron diffraction).
In 1905, Albert Einstein used random motion of small particles in a liquid "prove" the existence of atoms. The students will watch a simulation of Brownian motion and make a general outline of the mathematical problem. They will then investigate how the mathematical formulation can provide the basis for an experiment to measure the properties of Brownian motion.
In 1909, New Zealand physicist Ernest Rutherford, along with Hans Geiger and Ernest Marsden at the University of Manchester, performed a famous experiment that revealed the nature of the atomic nucleus. If the instructor can find the proper equipment, the students can duplicate Rutherford's experiment. If not, the students will perform a "macro" version of the same experiment by scattering tennis balls off a simple array of weights.
In 1896, Antoine Henri Becquerel, discovered nuclear radiation (radioactivity) when he noticed that photographic plates were "exposed" when placed near uranium. Marie and Pierre Curie, working in Becquerel's laboratory, characterized radioactivity and discovered several naturally radioactive elements. The has two options for students in this section. First, if the instructor has a safe radioactive source and an inexpensive cloud chamber, the students can "see" radioactive emissions. The students can then conjecture about the source and nature of the radiation. Otherwise the students can use a large set of dice to study the concept of half-life.
The students should watch the color of a block of steel while the instructor heats it. If the instructor can measure the temperature of the block of steel and measure the intensity of light from the steel as a function of wavelength (spectrum). The students should conjecture about the relationship between the spectrum and the temperature. This is a profound experiment. Spend as much time as needed to allow all the students to understand its implications.
The instructor should provide a brief introduction to electron shells and their relationship to the elements in a periodic table. Using a discharge tube and a spectrograph, students should conjecture why the characteristic bands appear.
Albert Einstein suggested that energy stored in electron shells can be coerced out in such a way that electromagnetic emissions are "amplified". The instructor should lead the students through the elementary theory of "lasing". Then, the students should examine a laser and attempt to characterize the light emitted. They should be encouraged to think about design criteria for lasers.
Albert Einstein showed that the photo-electric effect occurs because light behaves as particles. The students will perform experiments using the photo-electric effect and discover that classical wave theory fails to explain the results.
In 1905, Albert Einstein published four papers which addressed several of the major problems in physics at that time. The papers, published in Annalen Der Physik (Annels of Physics), include "On a Heuristic Viewpoint Concerning the Production and Transformation of Light" (Photoelectric Effect), "On the Motion of Small Particles Suspended in a Stationary Liquid, as Required by the Molecular Kinetic Theory of Heat" (Theory of Brownian Motion), "On the Electrodynamics of Moving Bodies" (Special Relativity), and "Does the Inertia of a Body Depend Upon Its Energy Content?" (Equivalence of Matter and Energy). In 1917, he published "On the Quantum Mechanics of Radiation", which formulated the theoretical basis for MASER and LASER devices. About this time, Einstein also give a wave equation of de Broglie waves, which Einstein suggested was the Hamilton-Jacobi equation of mechanics. Schrodinger expanded this idea into a full mathematical expression of quantum mechanics.