The most mind-blowing moment I've ever had was the course Relativistic Electrodynamics.
If you assume static electricity (charges attract or repel), then apply special relativity to see what the situation looks like to an observer travelling by, you get magnetism!
Turns out half of Maxwell's laws is a direct consequence of the other half once you know about special relativity.
Yes! Finally someone else who is amazed by this! It's crazy to think, that magnetism can be understood as nothing more than a relativistic phenomenon.
The workings of electromagnetic forces have long been postulated¹
¹ Insane Clown Posse et al, 2009
Yet researchers should not explain these phenomenon as they tend to fornicate with matriarchal individuals and deal in misinformation, which I find upsetting