Recent content by xcrunner2414

- If you measure the particle to have z-component spin of hbar, that means it's in the |1,1> state. If its z-component is 0, it's in the |1,0> state. If its z-component is -hbar, it's in the |1,-1> state.

- the coefficients 1, 2, and 3 are probability amplitudes. you know that if you square the probability amplitude, you get a probability. Right now, your probability adds up to 1^2 + 2^2 + 3^2. You want to do something to these coefficients so that their squares add up to 1... instead of 1^2 +...

- I see. Neither my teacher nor my textbook explained this (directly). Thank you. - Ahhh... now I get it. I didn't really understand why I had to integrate Schrödinger's equation, other than the fact that it seemed to work. Is that the general approach to getting the boundary condition on...

- Yea, I know the general approach. It's essentially the same as a finite potential barrier. The left has incident and reflected plane waves, i.e. \psi_{left}=Ae^{ikx} + Be^{-ikx} and on the right of the barrier there is only a transmitted plane wave, with coefficient C. Apparently the potential...

Ok, I'm totally stuck. Schrödinger's Equation for this problem is, \frac{d^2 \psi (x)}{dx^2} =[ \frac{-2mE}{\hbar^2} + \frac{\lambda}{b}\delta (x) ] \psi (x) and integrating gives, \frac{d\psi}{dx} |_{-\infty}^{0^-} + \frac{d\psi}{dx} |_{0^+}^{\infty} = \frac{-2mE}{\hbar^2}...

- So... dirac delta functions don't go to infinity?

- The reason for the z-component of the final velocity is because there is a y-component to the initial velocity. The magnetic field is in the x-direction, and \hat j \times \hat i = -\hat k

Homework Statement I'm asked to calculate the reflection and transmission coefficients for scattering from a potential energy barrier. The potential energy barrier is, V(x)=\frac{\hbar^2}{2m} \frac{\lambda}{b} \delta(x) where \delta (x) is the Dirac delta function. Homework Equations See...

k. thanks for the replies :-) I'll probably apply to about 3 REUs

I am mostly interested in knowing which REU's don't require letters of recommendation... if any. Thanks.

So, I've applied for the SMART scholarship (DoD), the SULI program (DoE), Johns Hopkins APL, and now I want to apply to a few REUs (NSF). But, I have a couple questions: 1. Are there any REU's that do not require letters of recommendation? 2. Is it inadvisable to ask a professor to write a...

"So in the limit, perhaps you could say that the photon's entire history is traversed instantly, since it's going zero distance and all the different clock-readings it passes are squashed together on this zero-length path." - That's the kind of stuff I was looking for. Thank you JesseM...

- Right... because it's division by zero. - Who said anything about false? Perhaps what I'm asking, quite simply, is how light and time are related.

- Do you really think I don't know what a Lorentz transformation is? t' = t0 / sqrt( 1 - v2/c2 ) let v = c t' = t0 / 0 I know! It's division by zero! I'm asking you to use your abstract thinking skills to make a conjecture about what that would be like.

- No, I'm not interesting in winning an argument, I simply want to read other people's thoughts. - Because I'm willing to bet that a large percentage of philosophers can't do Lorentz transformations.