Recent content by adjklx

  1. A

    PVMs of commuting observables

    Homework Statement Consider two observables A and B such that [A,B]=0. Given the spectral resolutions of each operator: A = \sum_k a_k P_k B= \sum_j b_j Q_j where P_k and Q_j are projectors onto the eigenstates of their respective operator. Show that [P_k,Q_j]=0 for every k and jThe...
  2. A

    Hilbert space dimension contradiction

    Does anyone know the answer to this: Consider a rigged hilbert space \Phi \subseteq H \subseteq \Phi^*. I know that the nuclear spectral theorem says any member of \Phi can be expanded in the generalized eigenfunctions of the position operator. I was wondering if any member of \Phi^* can be...
  3. A

    Hilbert space dimension contradiction

    Is the domain of every bounded operator on a Hilbert space the entire space? I think I remember reading that so I'm wondering if this is what you're talking about. Also, a few small asides: 1) Many people in my theoretical chemistry department say a bounded operator is one which has bounded...
  4. A

    Hilbert space dimension contradiction

    Thanks very much, that was really help helpful. I think what you're saying is that since the generalized position eigenstates lie outside the Hilbert space they cannot be considered a basis by definition . This means that the size of \{|X\rangle\} says nothing about the dimension of the subspace...
  5. A

    Hilbert space dimension contradiction

    Hi, I was wondering how the state vector for a particle in a 1-D box can be expanded as a linear combination of the discrete energy eigenkets as well as a linear combination of the continuous position eigenkets. It seems to me that this is a contradiction because one basis is countable whereas...
  6. A

    Motion in a central potential

    Homework Statement What minimal speed do you need to throw a stone with so that it starts orbiting the Earth? What minimal speed do you need to throw a stone with so that it flies off to infinity (forgetting about the Sun)?Homework Equations The motion of the stone takes place in an effective...
  7. A

    Angular momentum in an electrostatic field

    If a charged particle is moving in an electrostatic field is angular momentum conserved? I'm thinking it's only conserved if the electrostatic potential is constant throughout space
  8. A

    Finding equation of motion from lagrangian

    Hi, I am trying to solve this problem here: http://img201.imageshack.us/img201/7006/springqo9.jpg We're supposed to find the equation of motion from the lagrangian and not Newton's equations. Attempted solution: L = T - U = \frac{I\omega^2}{2} + \frac{mv^2}{2} - \frac{kr^2}{2} I = m(r^2 +...
  9. A

    Time-dependent perturbation theory: hydrogen atom in electric field

    oh it was actually asking for the probabilities for the individual n=2 orbitals i received probabilities of 0 for 2s and the 2p orbitals corresponding to the quantum numbers m = +/- 1. the only non zero probability transition i received was for 2p corresponding to m = 0. the field is just a...
  10. A

    Time-dependent perturbation theory: hydrogen atom in electric field

    Homework Statement A Hydrogen atom in its ground state (n,l,m) = (1,0,0) is placed in a weak electric fieldE(t) = 0 if t < 0 Eo *e^{\frac{-t}{\tau}} if t > 0E is in the positive z direction What is the probability that it will be found in any of the n=2 states at time t > 0 ? use...
  11. A

    Finding the Taylor Series of (1+z)/(1-z) for |z|<1

    Homework Statement Find the taylor series of \frac{1+z}{1-z} where z is a complex number and |z| < 1 Homework Equations \sum^{\infty}_{0} z^n = \frac{1}{1-z} if |z| < 1 The Attempt at a Solution \sum^{\infty}_{0} z^n = \frac{1}{1-z} \frac{1+z}{1-z} =...
  12. A

    Measurement for a particle in a box

    It is known that a particle in a one dimensional box with walls at (-a/2, +a/2) has energy probabilities: P(E1) = 1/3, P(E2) = 1/3, P(E,3) = 1/3, P(En) = 0 for all other n. If the parity of the state is measured and +1 is found, what can you say about the value of the measurement of E sometime...
  13. A

    Ice cream and freezing point depression

    When you make ice cream using a couple of zip loc bags and a salt/ice mixture do the room and surroundings have any effect? Can you be in a warm room and still make the ice cream? Thanks.
Back
Top