Imagine travelling back to the turn of the 18th century and having a conversation with Newton, armed with your knowledge of modern physics, in particular, quantum theory. You try to "explain" the new theories to him: what have we observed, and how does this change our ideas of fundamental physics? My question is the following:
- What experiments could have been performed while Newton was alive, which could illustrate the need for quantum theory? For example, I imagine that using telescopes and prisms, they could observe discrete spectral lines from celestial bodies, but they wouldn't be able to observe the photoelectric effect in the usual way.
- What is the "minimal set of concepts" that you would have to introduce to explain the key part of the theory (I realize this is subjective, so take this to mean the postulates of the Copenhagen interpretation)? This can include concepts from mathematical analysis - for example, I imagine you would need to define the idea of a Hilbert space - but also from physics or philosophy.
Please include any other issues you think may be relevant. Thanks!
Edits after question was closed due to being opinion-based:
I would like to clarify that I am not asking a question about pedagogy, i.e. what didactic methods you would use to explain quantum theory to him. I am also not asking a question about engineering, i.e. how you would use the technology available at the time to construct experiments that would be convincing.
I am asking about what the essential elements are in the gap between the knowledge of a very advanced 18th century physicist (or, as pointed out by someone in the comments, a very intelligent high-school student today with knowledge of Newtonian mechanics) and say, a second- or third-year undergraduate student today, who although may not be familiar with more advanced aspects and subtleties of quantum theories, has an appreciation of phenomena which point to the need for quantum mechanics, as well as the mathematical formalism used in the theory (states, operators, measurements, etc.).
So in a nutshell, my question (which may need to be split into several questions) is about what is contained in the conceptual gap and the technological gap (this is the part about what experiments we would have been able to talk to him about) between Newton's time and today.