Changes
::Yeah, I knew exactly what you meant with the "CP can't" part. I just thought it ''could'' be misinterpreted, y'know? I had no problem with the sentiment, just the possible interpretation of it. If we made it more verbose and said something like "Conservapedia is not a textbook," you know, along those lines, I think that could work. But at the same time, a single ''textbook'' can't explain ''all'' of general relativity. (Though I bet Misner, Thorne and Wheeler would slap my mouth for saying that. Or worse, they'd just hit me with their enormous, enormous book.) --[[User:KSorenson|KSorenson]] 23:30, 14 November 2009 (EST)
==Intro and related articles suggestions==
As I reread the intro over my morning coffee, a couple thoughts spring to mind. I'd like to hear what you guys think.
*One of the light-bulb moments for me, as an undergrad, was realizing the qualitative difference between metric and field theories. A field theory says that a field exists in space, and that objects within that field will take on some property as a consequence of being in that field. For gravity, it's a vector field and objects in it will accelerate. A metric theory says that spacetime ''itself'' takes on certain properties, and objects always behave the same ways; their behavior only looks different because we can't directly observe the properties of the spacetime around them. I'm explaining this poorly (see above, re: coffee), but it was a real "oh I get it now" moment for me as an undergrad. Maybe this distinction deserves some attention?
*Which brings me to my second point: What do you guys think of having one article each for vector field theory, metric theory, quantum field theory and gauge theory? I'm not talking about in-depth articles like this one; just simple, qualitative definitions. A vector field theory says there's an unobservable field there, and things in it will take on some potential energy from it. A metric theory says that spacetime is not uniform (curvature, torsion, etc) and that differences in apparent motion are caused by this observable distortion. A quantum field theory says fields work through the exchange of force particles, like little footballs being thrown around. A gauge theory is … actually pretty hard to explain simply. Anyway, I'm thinking in terms of basic physics concepts right now.
*Speaking of which: Lagrangian mechanics. We do have [[Lagrangian]]; it's just a stub, but I think we should do a qualitative introduction to the subject. We should make the point that the classical, Newtonian mechanics taught in high school is basically never used because it's not practical, but that the Lagrangian reformulation is the foundation of all of modern mechanics. (Yes, I know, Hamiltonians in quantum mechanics, but quantum mechanics makes my head hurt. I'm a macro-scale girl.) The principle of least action basically says, roughly speaking, that ''nature is lazy,'' and will only do what is absolutely required to get a particle from state A to state B, and that's a basic premise of physics.
Anyway, just some thoughts. I'd like a student who reads one of the physics articles here to come away with a basic understanding of what the subject of the article ''means,'' and I think it'd be cool if we could present the information in such a way that their understanding of the subtleties of the subject depends linearly on how far into the article they read.
