Recent content by ala

For that x, I have asymptotic solution. I want to find numerical solution in the middle, but don't know how. (I don't have 1 ODE, I have system of ODE)

I have system of first order ordinary diff equations, indipendent variable is x cordinate. I know asymptotic solution in left and right region (i.e. when x->-infinity or x->infinity, e.g. when abs(x)>1000), it's const plus exponentially falling function. I want to find numerical solution in...

Yes, that is equivalent to p^2=m^2*c^2 (p is 4-vector of momentum). So for x, I can watch hypersurface given by equation x^2=c*\tau (x is 4-vector, and \tau proper time). So the rest is same and conclusion is worng (namely that dxdydz/t is invariant)

If we introduce four-dimensional coordinate sistem with component of four-momentum on axis, then dp1*dp2*dp3 can be considered as zeroth component of an element of hypersurface given by p^2=m^2*c^2. Element of this hypersurface is parallel to 4-vector of momentum so we have that dp1*dp2*dp3/E is...

When one want to find selection rules for matrix element of (for example) electric quadrupole moment tensor Qij, irreducible components of Qij are needed to apply Wigner-Eckart theorem. When symmetry group is SO(3) irreducible component can be found using what we know from addition of angular...

Is there any problem book in atomic physics?

Well my question was (among others) about possibility that measurement changes eigenvalue of continuous spectra significantly. (because from Landau's derivation and don't see why should fi_n be close to PSI_n)

I am not quite sure that I understand what you are saying. (because of notation) If fi_n and PSI_n are not same that means that measurement changed state that gives result f_n with certainty. (meaning it changed eigenstate) So you say that it is just possible for continuous spectra, but can...

So how do you see that for discrete spectra fi_n(x) is equal to PSI_n(x)? Well I don't see the connection between this and my question.

I have just realized that I should write Landau's argumentation because many of you don't have his book. 1) QM cannot be founded without classical mechanics (which is not case for relativistic and classic mechanics), because particles don't have definite path or other dynamical characteristics...

In this chapter authors are not using Dirac notation but they say that measuring device's spectra is generally speaking continuous (but they didn't say that it has to be). I don't see why their reasoning cannot be applied to discrete spectra. It's really odd thing that for continuous spectra...

I was talking about discrete spectra (but I forgot to say that), Landau is also talking about discrete spectra. It seems that Landau is wrong but it is hard to believe in that. Any other explanations?

Many books on QM state this so called von Naumann projection postulate i.e. that after the measurement system is in eigenstate of operator whose eigenvalue is measured. But in Landau Quantum Mechanics in chapter 7, author explicitly says that after the measurement system is in a state that...

Yes, you are right, I forgot to say that they are finite dimensional. (In all statements where representation is used)

4'. Goes directly from Artin-Cartan theorem. But still I don't know what to do with rest of statements?