Recent content by Nick R

There seems to be a lot of political concern about long-lived radioactive byproducts of nuclear power stations, to the point where nuclear power has been regulated out of existence in the united states. But the intensity of emissions from material with a long halflife should be very low. Why...

Faraday's law is often stated in SI units as \nabla x E(x,y,z,t) = \frac{\partial B(x,y,z,t)}{\partial t} But x, y, z (or some other set of coordinates) are variables not functions and thus have no "t dependence". So it would seem that the "total derivative" of B is the same as the partial...

Congratulations. You've just figured out that grades, exams and other audits in school are a big, gay game. But if you want to stay in the game, you have to play the game. And trust me, it only gets gayer in grad school - grad school for physics is more like an initiation than a learning...

Would this be a good thing to take? More specifically, will a introduction to this shed light on/put on more solid ground many of the techniques/organizations in physics that are presented as "tricks"? I just want to be sure it will be worth it, since i'll be taking it alongside...

OK so yesterday I somehow lost sight of how you actually do separation of variables when I typed out the above. Yesterday I said we assume \Phi = \Phi=A(a)B(b)C(c) Where A(a)=\sum E_n A_n(a) B(b)=\sum F_m B_m(b) C(c)=\sum G_l C_l(c) And then find coefficients using boundary...

Usually, we use the technique of "separation of variables" as follows: In a "separable coordinate system", we assume a separable solution \Phi=A(a)B(b)C(c) Then we obtain 3 ODEs for A(a), B(b), C(c) We note that there are actually entire families of solutions to each ODE, that happen to be...

Wow sounds like a lose-lose situation. I guess this is why we were making more progress when science was controlled by rich hobbyists. Seems like accountability systems basically just load you down with overhead until you're spending all you time doing things that aren't useful (and they're...

Here is a question: experimental physics requires lots of money because it relies on equipment... Lots of big and expensive equipment. theoretical physics - pen, paper, computer? What expensive equipment could you possibly need? So wouldn't going with theory put you in a position...

That the derivative of 0 is 0 means that zero doesn't vary at all when some independent variable is varied. edit: actually I guess you'd need to know that all derivatives (second, third and so on) of 0 are 0 to say that. But yeah any order derivative of a constant wrt to any variable is 0 -...

I have been trying to understand and articulate why I can't do the following. Please confirm or point out misunderstanding. There is an integral in the "hatted" system, \int_{R}\bar{f}(\bar{x}^{1},...,\bar{x}^{n})d\bar{x}^{1}...d\bar{x}^{n} I want to express this as an integral in the...

Thanks.

That isn't quite what I did - I should have posted exactly how I did the first step so now I will. In fact, I will show two different approaches to get the same thing (that this term is zero). What is the implication if this term is zero? It means that the ordinary partial derivative of a...

PSI is a relative scalar field of weight w in the sense that it transforms between the hatted and unhatted coordinate systems according to, \bar{\psi}=J^{w}\psiWhere J is the jacobian. According to the book, the ordinary partial derivative of a relative scalar field is not a relative tensor...

The math you want to study is differential geometry/tensors for general relativity. With your current experience, you probably don't want to attack this just yet - it won't be very productive. Maybe get a dover book on linear algebra and work though the material and all the problems?

So basically, the only way a "bottom up" hierarchy exists is if you personally think there is an approach that is more "well motivated" by real/physical examples... Is it sometimes true that, people concerned with "pure mathematics" may often choose an approach to things that is completely...