To my understanding, QED is about electromagnetic interaction, and in a solid system, the interaction is only electromagnetic
So why there are stills lots of research in solid state physics ? Is there something not explained by QED ?
I am learning some basic solid state physics idea, like density of state ...etc.
For particle in a 1D box,
E = n^2 (pi)^2 (h_bar)^2 / 2mL^2
But why it is written as
E = (h_bar)^2 k^2 /2m
does it means that energy eigenvalue E is related to momentum k ?
I guess it is not because momentum is...
I am reading some papers about astroparticle physics and I see something like Parker limit (monopole).
So what is the purpose of setting up this limit ? It is be used to get the expected number of particles per unit area per unit time for later experiments ?
Thanks
I got some questions about QM (not well organized)
There is wave-particle duality. To my understanding, particle can behave as billard ball and wave.
Is the wave property means that we can represent the particle by wavefunction ?
The modulus of wavefunction in Schrodinger equation is...
Suppose a point charge is accelerating uniformly. It emits EM radiation.
If an observer is co-moving with the point charge, the point charge remains at rest in his/her frame.
So I guess it does not radiate relative to the co-moving frame.
But someone told me that acceleration is absolute...
I read some of the articles related to particle physics experiment and don't know the meaning of it.
1. minimum bias event
2. pile up
Also, η (pseudo-rapidity) is used instead of θ to describes the angular distribution, but why ?
Can someone explains to me ?
To find a new particle, the energy and momentum of the (decayed) particles are measured
Evaluate the expression m^2 = E^2 - p^2 and plot a histogram.
I just don't understand why there is a resonance particle if there is a peak in the histogram.
Is it because the probability is very high...
From wikipedia, differentiate mv with respect to time by product rule gives wrong result.
It claims that F = dp/dt can only be used in closed system.
http://en.wikipedia.org/wiki/Newton_second_law#Variable-mass_systems
So, there is a non conservative force in this problem.
if I am able to formulate the new "potential", is it still possible to use Lagrangian formulation ?
From (Marion 5th ed. Problem 9-15)
A smooth rope is placed above a hole in a table. One end of the rope falls through the hole at t = 0, pulling steadily on the remainder of the rope. Find the velocity and acceleration of the rope as a function of the distance to the end of the rope x...
In classical mechanics, we say angular momentum is conserved when its magnitude and direction are constant for all time.
But in quantum mechanics, the direction of angular momentum is uncertain.
So, can I say its direction is changing all the time ??
You can try the method "seperation of variable"
For simplicity, we stick in 1-D
Step 1 let ψ(x,t) = X(x)T(t)
now the equation(PDE) becomes ODE (second order)
Step 2 divide both sides by X(x)T(t)
then you should get LHS(depends on t only) = RHS(depends on x only)...
In a central force problem,
angular momentum is conserved.
we quantized one of the component of L, say Lz.
Also, we quantized the angular momentum, L = √l(l+1)h_bar
If we know Lx and Ly without uncertainty,
then we know the direction of L.
Hence we know the motion of the particle is confined...