# Recent content by v0id

1. ### Concise and complete textbook on non-relativistic QM

Thanks, I had never heard of Dirac's book until now. By "complete", I mean self-contained, so the reader does not have to refer to external sources due to the author imprecisely glossing over important topics. Landau, Shankar and Ballentine are complete/comprehensive. Griffiths, Scherrer and...
2. ### Concise and complete textbook on non-relativistic QM

I've searched high and low for a terse (yet complete) introduction to the foundations of non-relativistic QM. Shankar is unparalleled in terms of completeness, yet it is infuriatingly verbose. Landau's presentation is a bit dated and difficult to follow in many instances. It is also not as...
3. ### Higher mathematics learning techniques

Math is indeed hard, mathwonk. I suppose one cannot substitute for intrinsic ability. Thank you for the excellent advice, maze & quasar987. Considering special cases is invaluable for getting the gist of things, but I find it difficult to reconstruct (or even remember) the more general...
4. ### Higher mathematics learning techniques

What are some methods of training one's mind to absorb and understand rigorous mathematical texts? I have been facing great difficulty as of late in studying fields like abstract algebra, complex analysis and calculus of variations. These are all fields where I am unable to formulate graphical...
5. ### Grad-school chances looking slim: how can I improve them?

Thanks for the responses. Dr. Courtney: I'm averse to flipping burgers for http://pictures.pichaus.com/95b70d92c70703496ea27d0c4ca3289315f1775f?AWSAccessKeyId=0K4RZZKHSB5N2XYJWF02&Expires=1207860000&Signature=a9%2BcuJEeSMway7k3BOxa5KokPxM%3D" [Broken]. Getting hooked onto that job will...
6. ### Grad-school chances looking slim: how can I improve them?

I'm a 3rd year Physics undergraduate student at the University of Toronto, and my academic career seems to have hit rock bottom. The grades from my past term were absolutely dismal and I have (consequently?) been rejected by various professors for summer work. Since I am effectively unemployed...
7. ### Changing the order of integration: surefire method?

Thanks Hurkyl and gammamcc.
8. ### Changing the order of integration: surefire method?

Is there a way to transform the limits of integration for a multivariable integral without appealing to geometrical manipulations? For example: \int_a^b \int_{y_1(x)}^{y_2(x)} \int_{z_1(x,y)}^{z_2(x,y)} f(x,y,z) \; dz \; dy\; dx \rightarrow \int_c^d \int_{y_3(z)}^{y_4(z)}...
9. ### Computing luminosity from surface brightness

Homework Statement I'm trying to find the central luminosity per square parsec of a galaxy with central surface brightness I(0) = 15 \; mag \; arcsec^{-1}. I need the answer to be in multiples of the solar bolometric luminosity per square parsec. Homework Equations m_1 - m_2 =...
10. ### Projecting an abstract state onto position/momentum/energy spaces

Homework Statement Consider the quantum harmonic oscillator in the state | \psi (t) \rangle = \frac{1}{\sqrt{14}}\left( 3 | 0 \rangle \exp{\left( -\frac{1}{2}i \omega t\right)} + 2 | 1 \rangle \exp{\left( -\frac{3}{2}i \omega t\right)} + | 5 \rangle \exp{\left( -\frac{11}{2}i \omega t\right)}...
11. ### Computing Potential of a Spherical Shell w/o using Newton's theorems

Thanks everyone, I finally figured it out. Converting to spherical coordinates and using the law of cosines to represent the norm of the vector difference is needed.
12. ### Computing Potential of a Spherical Shell w/o using Newton's theorems

My apologies. I had originally meant a spherical shell, from which the potential of an arbitrary spherically symmetric distribution can be computed. Gauss's theorem is certainly very useful, but the objective here is to compute the potential using the equation for \Phi only, without applying any...
13. ### Computing Potential of a Spherical Shell w/o using Newton's theorems

Homework Statement I'm well aware of how to compute the gravitational [electric] potential \Phi due to a spherical mass [charge] distribution of radius R by using Newton's theorems for spherical shells. However, how does one find an analytic expression for \Phi without invoking these theorems...
14. ### Expectation value of an operator (not its corresponding observable value)

That makes sense. I mistakenly thought there is a difference between \langle Q \rangle and \langle \hat{Q} \rangle, but that may have resulted from an abuse of notation. Thanks a lot, dextercioby.
15. ### Expectation value of an operator (not its corresponding observable value)

Well yes, but that's simply the generalized form of the first equation I posted. So what you're saying is that they are the same? \left\langle \frac{\hat{p}}{m} \right\rangle = m^{-1}\int_{-\infty}^{\infty}\Psi^*\left(-i\hbar\frac{\partial}{\partial x}\right)\Psi \; dx?