Recent content by Anypodetos

I was thinking about, say, neutrinos from the sun which are νe to begin with and have an energy spectrum broad enough so that 1/3 of each flavour reaches us on average. Please tell me if I'm wrong. I hadn't thought about this possibility. Thanks!

The paint spray carries ions with it, and when it reaches the car, the ions sit there.

Not when they are going through the earthing, i.e. a good conductor. You get sparks when charges try going through the air, which is a bad conductor. The air gets ionised by the electricity, and ionised air (plasma) is a good conductor, facilitating the spark. But this won't happen if there is...

Yes, when the neutrino interacts, e.g. being measured, it will interact as a flavour eigenstate. But as the |νe> is (I think) somthing like 70-80% |1>, a bunch of |1> neutrinos will be measured as 70-80% electron neutrinos, but a bunch of oscillating neutrinos will be measured as 1/3 electron...

I didn't mean that. I was thinking of a process by which the neutrino could get rid of its energy when it dropped into a lower energy (eigen)state. Like when an electron precessing in a magnetic field emits a photon and drops into the lower energy eigenstate. Also, I thought that oscillation...

Do you mean a lightning rod or the earthing of an electric plug? In the latter case, no ions flow, just electrons. The earthing is connected to long wires (which run alongside the power wires), which are in turn connected to the ground, which isn't a bad conductor – there is a lot of moisture...

Yes, the electrons in the wall's atoms are found a bit farther away from the balloon than they were before, and the nuclei are a bit nearer. This means the atoms get a small positive charge on the side near the balloon, and a small negative charge on the other side. This is called electric...

Neutrino oscillation seems to have as one of its prerequisites the fact that the flavour eigenstates differ from the mass eigenstates, so the time-dependent Schrödinger equation applies. Can a neutrino "drop" into the lowest mass eigenstate (which is also the lowest eigenstate of the...

I was suspecting that :smile:

Thanks, I'll try to figure that out as time allows...

Yes, that's right. Thanks for pointing this out!

I assumed that the covariant derivative of ##\sqrt{|g|}## vanishes, of which I am not certain (that's the "?"). $$ \partial_μ \left( \sqrt{|g|} j^μ \right) = \sqrt{|g|} \partial_μ j^μ + j^α \partial_α \sqrt{|g|} \overset{?}= \sqrt{|g|} \partial_μ j^μ + j^α Γ_{μα}^μ \sqrt{|g|} = \sqrt{|g|}...

Yes. Setting μ0=1, If ##\nabla_μ (F^{μν} \sqrt{-g}) = \partial_μ (F^{μν} \sqrt{-g}) ##, then $$ (Γ^μ_{αμ} F^{αν} + Γ^ν_{αμ} F^{μα} - Γ^α_{αμ} F^{μν}) \sqrt{-g} =0$$ Then divide by ##\sqrt{-g}##, and then I'm stuck. I tried to express the Γ's by g's, but there doesn't seem to be anything I can...

I'm trying to understand how the various EM tensors work in General Relativity. The only source I've found is https://en.wikipedia.org/wiki/Maxwell%27s_equations_in_curved_spacetime, but there are two things I don't get. Why do they use ordinary partial derivatives instead of covariant ones...

2) The (3) is just a shorthand for the 3-dimensional Dirac delta, ## δ(p_x - q_x) δ(p_y - q_y) δ(p_z - q_z) ##. 1) My knowledge here is rather shaky, but since no one has answered you, I'll give it a shot. Think of a superposition of 2 sine functions with frequencies p and q. For p≠q, they...