I've always loved physics, and the weirder it gets, the better. But even the physics of the everyday is so simple and fascinating; I was working on my car tonight, and just knowing how a lever and circular motion can be used to lift an entire car with a minimum of effort is really quite amazing. Or knowing the chemical reactions that cause an engine to be more than a lump of metal. Or knowing about how hydraulic pressure controls a brake line. It's all cool, all stuff I like to know about.
Feynman was talking in the lecture about how physicists discover laws in a way that's different from chemists or biologists... they have to come up with ideas first, about how things work, and those ideas, if they are good, are shown to be accurate through the observation of phenomena in repeated examples. It's not a theory or science without those experiments, but that idea, the imagination of it comes first. Feynman gave the example of hypothesizing about the structure of molecules and how those ideas could be proven by chemical experiments, and later by electron microscopes.
I was thinking more of how Einstein discovered all the things he did- it all started with thought experiments, with a giant WHAT IF. What if you were moving at the speed of light... and you looked in a mirror. What if you were moving upwards in an elevator really fast and somebody shone a light in one side. What if you were moving at 99% of the speed of light and your fellow traveler was moving at 95%, how would you each experience time?
And it occurred to me that in some ways, physicists and fic writers aren't that different. When you write fanfiction, you look at that world you're writing about, and you say... what if? What if we saw what Rose did after she was left in the other universe? What if Donna somehow met Gene Hunt? What if Susan used the skills she learned while ruling Narnia in this world, during the war? And so we write out these situations, seeing if they stand up to the way the characters really behave, and if they account for the laws that govern the internal logic of these worlds.
Sometimes they're bad ideas. Sometimes the way we've imagined them doesn't work, the characters just don't fit into those situations and so the fic falls apart, or maybe we just get no reviews or everybody goes "eh, that wasn't plausible". But sometimes they're great ideas. When people read the fics, they get a better idea of the motivations guiding that character, they find it consistent: a theory of behavior has been set forth and the situational evidence observed confirms that the original idea is more than just imagination, it's a legitimate predictor of further behaviors. The theory settles in people's heads and becomes something that guides their understanding of how the world works, whether that be how an atom is going to jiggle (Feynman's technical term!) or how Amy sees Rory.
I think that, in the end, that need to go "hey, what if..." is what really defines my interest in probably everything, making it a little less odd that I love literature and fandom and also physics, interests which have greatly confused people who think those can't go together (or, alternatively, have made people pretty much fall in love with me, which is a bit odder).
So that is how