98 reputation
6
bio website
location
age 23
visits member for 2 years
seen Aug 22 at 13:42

Ready to graduate from college!


Jul
2
awarded  Curious
Apr
3
comment What is the action for an electromagnetic field if including magnetic charge
I understand that it will break gauge invariance. But the classical equation still exists, is there a way to quantize it?
Apr
3
asked What is the action for an electromagnetic field if including magnetic charge
Mar
19
comment Why the temperature is getting lower when the universe is expanding
That is very interesting. It seems that the photon's energy density is proportional to the fouth power of T is very important. And this comes from the fact that it is massless. This is amazing!
Mar
10
comment Why path integral approach may suffer from operator ordering problem?
I know there is approximation. But where is the operator ordering issue?
Mar
7
awarded  Commentator
Mar
7
comment Why path integral approach may suffer from operator ordering problem?
But I still don't understand Where is the non-commuting contributions?
Mar
6
asked Why path integral approach may suffer from operator ordering problem?
Mar
5
comment Why the temperature is getting lower when the universe is expanding
Thx a lot. The reading material helps me a lot!
Mar
5
comment Why the temperature is getting lower when the universe is expanding
@Michael Brown: why the energy is not conserved? So the universe is not an isolated system? I am feeling that it is related to the black hole which may give entropy and energy exchange.
Mar
5
awarded  Teacher
Mar
5
answered Is there a Lagrangian formulation of statistical mechanics?
Mar
5
asked Why the temperature is getting lower when the universe is expanding
Feb
4
comment Does a quantum phase transition have latent heat?
Oh, now I think you are right. At the critical regime, ground state A and B have almost the same energy. Quantum fluctuation is enough to change the system without more external energy input. Thank you very much! @Peter Shor
Feb
3
asked Why the peak of spectrum gets vague when the dimension is lower?
Feb
3
comment The equilibrium temperature distribution of a pan in vacuum
Yes, I agree with the result you get. I believe a more accurate explaination is that thermal radiation is proportional to the expectation value of photon number(not the same rate everywhere). At the corner, the electricomagnetic mode's electric field is larger(The same reason with point discharge) and thus with larger expectation value of photon number. In this sense, the radiation from the corner is larger as there are more photons couple to the electron to emitt heat.
Feb
3
awarded  Scholar
Feb
3
awarded  Supporter
Feb
3
accepted Does a quantum phase transition have latent heat?
Feb
3
comment Does a quantum phase transition have latent heat?
The energy is conserved. But still we need energy to change the ground state from A to B and B to A. As the energy cost is not simply the energy difference of two ground states A and B. The reason that they are stable is because they are in a energy minimum. Thus to move them away from a stable ground state A to B by a phase transition, we move the system from one energy minimum to the other. At least we need the energy of about the energy barrier in both direction.