# Quantum Physics

- Mathematical description of the motion and interaction of subatomic particles. Quantum Mechanics & Field Theory
 Meta Thread / Thread Starter Last Post Replies Views Views: 137,981 Announcement: Follow us on social media and spread the word about PF! Jan16-12 Pinned: Quantum Physics Forum Rules Before posting anything, please review the Physics Forums Global Guidelines. If you are seeking help with a... Feb23-13 08:38 AM ZapperZ 1 36,164 Hello! For some time now I have been absolutely fascinated with quantum mechanics. Unfortunately for me, I am well... Aug13-14 10:32 PM atyy 3 244 I have some questions about this paper:http://users.phys.psu.edu/~radu/extra_strings/freedman_sigma_model.pdf In... Aug13-14 10:17 PM Greg Bernhardt 1 240 Suppose you have λø4 theory and calculate the bare 4-point function: ... Aug13-14 08:45 PM geoduck 1 173 Hi, I have been trying to get the expression for the transition dipole moment of hydrogen but I am not able to get the... Aug13-14 09:39 AM Meir Achuz 3 234 According to my teacher, for any two operators A and B, the commutators =df(A)/dA and =df(B)/dB He did not give any... Aug12-14 10:46 PM strangerep 8 262 I have read contrasting things about the issue. Can you explain briefly why the assumption of discrete space and... Aug12-14 07:51 PM bhobba 24 791 Author: ZapperZ Originally posted on Feb28-14 One of the most spectacular theoretical description that Einstein... Aug12-14 05:00 PM davenn 2 207 What is Quantum Entanglement, and what does it do? I attempted at learning via online articles. Aug12-14 03:29 PM BiGyElLoWhAt 17 446 Hello, The one-electron universe hypothesis, commonly associated with Richard Feynman when he mentioned it in his... Aug12-14 03:05 PM jtbell 3 285 Author: ZapperZ Originally posted on Jan17-13 {I have seen this type of question or scenario being presented on PF... Aug12-14 02:12 PM Greg Bernhardt 0 175 Position eigenstates ( 1 2 3 ... Last) When a particle's position is measured, does the wavefunction collapse to the eigenstate of the measurement (a delta... Aug12-14 12:28 PM jostpuur 89 2,363 Hi everyone, This is my first post. Years ago I read in a science magazine that (at least according to a certain... Aug12-14 09:46 AM mjsd 7 417 Hello Forum, When a system is in a particular state, indicated by a |A>, we can use any basis of eigenvectors to... Aug12-14 04:31 AM tom.stoer 26 537 One of the problems in QM i frequently encounter in all textbooks is the shifting of the wall problem which goes like... Aug12-14 02:08 AM tom.stoer 14 366 Hi. I will give you a question I have looked at and then tell you where I am confused. The wavefunction for a... Aug11-14 06:40 PM bhobba 7 305 Dear PF: I'm currently working in a problem that has had me stranded for several weeks now. The problem reads as... Aug11-14 01:00 PM Jilang 15 295 Hi, I have read that quantum fluctuations have created our universe through the Big Bang. The issue that I didn't... Aug11-14 09:42 AM bgq 2 263 I considered the covariance of 2 spin 1/2 as a non linear operator : A\otimes B-A|\Psi\rangle\langle\Psi|B. The... Aug11-14 08:48 AM jk22 9 1,173 Hello I am trying to solve the dirac equation. I want to solve the dirac eq say for 2 particle system. therefore i... Aug10-14 09:31 PM nakulphy 5 388 I want to discuss the theorem proved in the article "Quantum states and generalized observables: a simple proof of... Aug10-14 01:40 PM naima 37 3,943 Does having a momentum cutoff require space to be discretized? As an analogy, suppose you put your fields in a box... Aug10-14 12:08 AM atyy 1 250 So based on String theory, when doing a Double Slit Style Experiment when an observation is made it is a particle and... Aug9-14 09:49 PM bhobba 2 188 Hi guys, Sorry if this isn't quite the right place to post this, but I have a few conceptual questions that I'd... Aug9-14 08:05 PM "Don't panic!" 18 624 Hi, I had a look at Susskinds explanation about QM and this is pretty strange from my point of view. Video:... Aug9-14 07:45 PM Omega0 2 213 Hallo everybody. Foreword1: I am an engineer not a physicist Foreword2: I am reading a paper about diffusion MRI who... Aug9-14 07:40 PM bhobba 1 235 Is it purely coincidental that the internal symmetry related flavor quantum numbers(like isospin and weak isospin) and... Aug9-14 05:29 PM dextercioby 1 254 Suppose we want to get eigenfunctions of a One-Particle Hamiltonian corresponding to one of its eigenvalues, say E, in... Aug9-14 02:44 PM WannabeNewton 1 233 The spin of an arbitrarily oriented electron precesses in the presence of a magnetic field (see Feyman lectures 10-7).... Aug9-14 08:31 AM 43arcsec 11 451 is it true that 'Spread of Energy in Space' determines 'Spread of Matter in Space', at given point in time? i am... Aug9-14 02:03 AM neomahakala108 10 299 "E2" Quadrupole decay rate Problem Statement Obtain the angular dependence of the rate for the emission to a single... Aug9-14 01:24 AM MisterX 1 326 In Feynman's famous book QED, he repeatedly reminds us that we must include the possibilities of photons traveling... Aug8-14 08:42 PM WannabeNewton 3 315 I recognize the practical aspects of this would be absurd, but I must admit the premise of what it would take to put a... Aug8-14 07:50 PM bhobba 21 1,460 Suppose I want an expectation value of a harmonic oscillator wavefunction, then in what way will I write the Hermite... Aug8-14 03:13 AM Mniazi 4 260 Hi again, Another, possibly trivial, question. In quantum dynamics we consider maps containing the evolution of a... Aug7-14 08:22 PM bhobba 3 180 Hi, In many quantum physics books I see questions such as "what is the spin-orbit interaction in this case?" Sorry... Aug7-14 03:56 AM DrClaude 1 301 Is there a resonant frequency of light? I was just wondering because the higher the frequency of light, the higher the... Aug7-14 03:38 AM Rob Hoff 5 359 One theory I've heard and which I find interesting is that entanglement between any pair of two-state systems could be... Aug6-14 03:26 PM Jonathan Scott 3 371 I am curious what a photon looks like if we could observe it pass through space. It's also supposed to be oscillation... Aug6-14 05:40 AM Geometry_dude 39 1,485 I donot understand why we quantize the field by defining the commutation relation.What's that mean?And what's the... Aug6-14 02:59 AM bhobba 2 260 Hi all, Just a quick theory based question regarding the Zeeman Effect. The effect of the applied magnetic field... Aug5-14 03:06 PM WannabeNewton 1 244