General Overview


This project is funded by the National Science Foundation to establish a set of undergraduate laboratories to study the fundamentals of quantum mechanics that are otherwise theoretical, abstract or even unintuitive. Part of this project will be to develop laboratory experiments that undergraduates (at the sophomore level) will be able to run. An outcome of the research will be course materials, including a student laboratory manual, as well as a teacher’s laboratory manual, which compliment the experiments and that can be used in the Modern Physics Course (PHYS211).

Beginning in the 19th century physicists found themselves coping with a diverse and confusing mess of experiments. Out of this mess emerged a bizarre theory called quantum mechanics. As the theory was developed, more experiments were conducted which directly influenced the continuing development of the theory.

One problem with quantum mechanics, unlike other fields of physics, is that there are no comfortable conceptual analogs to aid us. This is because quantum systems behave unlike anything that we are used to. There is no analog in our everyday life to assist us in understanding the weird behavior of quantum systems.

Light has wave and particle properties

Young’s double slit experiment in 1802 provided solid evidence that light is a wave. Young’s conclusion was further supported by the work of Foucault and Maxwell. But, blackbody radiation and photoelectric effect were also discovered in 1880s and could not be explained by wave theory.

In 1900 Planck proposed the quantum, which was a particle like unit of light containing a specific set amount of energy. This idea was not accepted right away, but in 1905 the quantum gained a bit of acceptance when Einstein used it to explain the photoelectric effect. The quanta became a widely accepted concept for light as a particle about a decade later.

What we must accept is that sometimes light behaves like a wave and at other times it behaves like a particle. An example is if we perform the double slit experiment we will see a pattern that correlates with the particle prediction if we try to determine which slit the light goes through, but if we no longer observe this then we will observe the pattern predicted by wave theory. So back to the ultimate question, is light a particle or wave? The answer is, and this is an essential feature of quantum mechanics, that how we conduct our experiments affects what results we will obtain. An even more accurate answer is that it is something completely different from what we know.

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