Recent content by Electric to be

I'm just getting into 3D quantum mechanics in my class, as in the hydrogen atom, particle in a box etc. But we have already been thoroughly acquainted with 1D systems, spin-1/2, dirac notation, etc. I am trying to understand some of the subtleties of moving to 3D. In particular, for any...

According to decoherance. Say there is a pure state initially in state: |ψ⟩=α|0⟩+β|1⟩ After decoherance (interaction with environment), the system will transform into the improper mixed state of: ρ=|α|2|0⟩⟨0|+|β|2|1⟩⟨1| This is the "apparent" collapse that decoherance refers to. With the...

I guess what I mean is, in situations where it isn't possible to describe energy E as K+U in shrodingers equation, does the energy simply become some quantity that can be increased by the absorption of photons and their energy? And not simply K+U.

I think I would have loved to study pure physics, especially advanced quantum and theoretical particle. But I just didn't/don't see the opportunity for a assured job and the standard of living I desired. Instead I'm going to be finishing up my EE degree & pursuing a master's as well. I've found...

Yes agreed just the system. And in this case the system is the particle. However, as I mentioned - even in classical Lagrangian mechanics the energy of a single particle isn't really defined for such changing fields since there is no concept of a scalar potential. As a result - do we simply...

Well sure it can be in a superposition of possible energies as well. But the energy possibilities are defined as the eigenvalues, and when measured is one of these possibilities. I feel like this is certainty true in QED where the electron field and em field are both part of an interacting...

Well no I'm not expecting energy to be conserved. I'm perfectly fine with the energy having some time dependence - what I am concerned with is how "energy" is defined in these situations. It seems that the basic definition of energy in QM is simply the eigenvalue of the Hamiltonian. While in...

But the operator for the "energy" observable is defined as the Hamiltonian.

I am unfortunately not super familiar with Lagrangian mechanics, and mainly have just studied its' connection to QM. From what I saw here, the quantity known as energy was defined in some sense using generalized potentials. But I don't believe this is the same as the traditional energy which...

So my question still kind of remains. If there is a non-conservative field, say an E field with Curl. The Hamiltonian will still be defined as the operator for energy in QM, but how is energy in general defined then? (since there isn't any scalar potential energy). Is it simply some quantity...

Notice however, they do assume that a scalar electric potential can at least be written (even if it happens to be zero). However, if you have a non-conservative e-field (so time varying EM field) then this concept breaks down. That link also talks about that (must be time independent).

Well I think there is some form of "Hamiltonian field theory" for classical fields that can describe evolution of fields and particles within it. Though if I had to guess this would probably only work for relatively simple configurations, and would otherwise have to be numerically solvable? I'm...

For a classical system - a charge interacting with an electric field will always have the total energy conserved. However, instead of attributing the potential energy to saw energy associated with the charge, the energy is store in the field. (Energy density is proportional to B^2 and E^2) I...

The force caused by a magnetic field on a moving charge isn't the same thing as the magnetic (electromagnetic) field itself. You have the field, and then you have the interaction of charges with the field. That is known as the force. There is energy stored in the electromagnetic field. Energy in...

So if the speed of light did ever somehow "change", it would be our measure of the meter that would suddenly be off, huh?