I wrote my first exam for this semester yesterday. I think it went reasonably well; it was oddly satisfying to throw out the thirty-plus pages of notes I'd generated over the last few days. (Not the actual notes I made in class - I keep those. But I tossed the duplicates that ensured the class notes did actually (mostly) transfer to my memory.) There is now some danger that I begin to feel that having worked so hard for that course, I needn't worry about the others. Which would be foolish. To combat this assumption, I'm going to try to finish a section of Quantum Mechanics between writing each take here. (I'm stealing the general idea from here.)
I came across this writing competition yesterday, which asks for writing inspired by Benjamin Franklin's quote "If you would persuade you must appeal to interest rather than intellect." Now, physics is indubitably awesome because it allows us to harness the power of mathematics to understand the nature of the universe. It's pretty cool that way. But part of the fun - especially, perhaps, when it comes to revision - is things like my Q.M. lecturer's comment that there are physics-loving kittens who cry every time students try to explain the uncertainty principle without explicitly stating that it's fundamental. Doesn't sound plausible, you say? Well neither does quantum mechanics.
I don't think those two ideas are properly linked up there. If I figure out how to link them properly, I might have a competition entry.
I am going to use part three to write about the idea of determinism in classical mechanics so that I can refer to that idea in part four. It's pretty interesting for it's own sake too, though. Determinism starts with the sort of idea that if I know that a train leaves the station at two o'clock and travels at a constant speed of 60 km/h (I have no idea how fast trains actually travel) in a constant direction, I can tell you exactly where it will be at three o'clock. Of course, the train needn't travel at a constant speed in a constant direction, so I could be quite wrong. When it comes to Newton's laws of mechanics, however, the only thing that can cause a particle to change its state of motion is some kind of external force (that's basically Newton's first law). So if I know all the particles and all the forces they can exert, I can work out everything that will happen. This raises some rather interesting questions about free will, since although practically nobody could know what every single particle in the universe is doing, the idea that it's theoretically possible is rather creepy. Quantum mechanics saves the day here, though: it turns out that even theoretically it's not possible to know everything about even one particle. Of course, that's rather weird in its own right.
Four.This painting is awesome.
Il castello di Bentheim (Jacob Van Ruisdael)
I don't think you can explain why a painting is awesome by describing particles that fly around colliding and absorbing one another. They can be deterministic classical particles or random quantum particles, but they don't explain things like beauty. Or truth. (You can talk about my perception of truth in terms of particles in my brain, perhaps, but not about truth itself.) And they're not supposed to. That's why physics isn't metaphysics. It's kind of obvious in some ways and awfully hard to hold onto in others. Part of the appeal of physics (apart from the kittens) is trying to understand things. We understand more and more stuff, at a more and more fundamental level, as we go on, but at some point, in some directions, it has to stop working. Which is just as well, on the whole, but can be a little disappointing in the moment.
It is a mark of something, I'm sure, that I've quite lost track of my reading list. Probably the amount of work involved in a final year maths/physics course. I don't actually know if I've read (well, finished) anything (that's a book) since Silver on the Tree, although I suspect I haven't. And I don't remember exactly when I read that, so that it's an altogether sorry state of affairs. However, in my efforts to do something meaningful and productive that does not involve calculating the probability amplitude function for a particle on a ring for the umpteenth time, I realised that my average reading rate for the year is still a book a week. And I definitely read more academic papers than I used to, which ought to count for something. Perhaps not altogether a sorry state of affairs, then. But it's rather odd to say that I can't remember the last time I finished reading a book.If you have not encountered The Particle Zoo before, it's where you go to buy a universe in a box. No, seriously.
Do you still remember the physics-loving kittens? I suggested that such a thing might be implausible, but through the wonders of Google image search and The Particle Zoo, I have now found such kittens. Behold:
|You can click the image for more |
And that's that. I did not study a section of quantum mechanics between each post, because I couldn't make up my mind about how to define a section. So I did some studying and some writing and it all got mixed up together. As long as I don't start drawing kittens in my exam paper, I think that's okay. I missed the boat for keeping quantum mechanics off the blog a while ago.