Key Points from Chapter 1:
· Electrons in atoms can only have certain well-defined energies. The emission spectra of these atoms (ie the specific wavelengths at which atoms excited by heating emit light) provide direct evidence of these levels. This is an example of quantisation of energy.
· Light shows wave-particle duality: it behaves like a wave when it diffracts but like a particle when it is absorbed by a molecule.
· Standing waves in a space of a defined size are restricted to certain possible wavelengths. There is a possible connection here: if matter, like light, exhibits wave-particle duality, then the confinement of matter to an individual particle could be linked to formation of a spatially-localised standing wave with defined possible energy levels.and therefore – in the case of light waves – to certain photon energies.
· Electrons and other small particles can experience diffraction which is evidence of their wave-like properties.
· Photons, despite their zero mass, have momentum. We have resolved to explore this strange phenomenon, as a starting point in our quest to find a mathematical model for wave-particle duality. And this is going to require us to learn about special relativity.