@ConstantineBlack I've seen it sometimes already, but it is probably not a big one. There is no "usual mailing service" in Germany. The usage of gmail is surprisingly low, compared to other countries, and many use yahoo or some local services (like gmx.de).

It is so sad that no massless spin-half field exists. It would behave probably so interesting. Maybe if the Higgs field could be somehow reduced to zero.

@Korra A solid one. The aim is to show that when the source is placed on the boundary rather than in the bulk the soliution remains the same.

The potential inside a solid sphere is not constant.

@NaveenBalaji Suppose in your case it is then all you have to do is solve for the potential of a hollow sphere

As I said before the potential inside a hollow sphere is constant

Outside the hollow sphere is same as outside a solid one of same radii at a same point p

In the case of a hollow sphere, the charges are only at the boundary

@Korra I do know that, my question was whether the potential variation would be similar to that of a hollow sphere if we were to rearrange the charge in the bulk and put em on the boundary

I said above that it would

2 questions: Will the voltage multiplier work with polarized capacitors? I bought a 9V to 230V, 0.5A transformer. Will it work?

@Korra yeah but to prove it mathematically, consider the Laplace equation and the solution to it via the Green function. Now, at the boundary defining a radial coordinate and space coordinates, we’d see that the potential expressed as an integral of the Green function and a source, say J(r,x), placed locally at the boundary. would be constant since the bulk is sourceless.

Can this set be used to show that the potential inside is constant? If so how? And similarly, to show that the pontential outside goes as 1/r

@NovaliumCompany As I said a few days ago, unpolarised caps would be better, but according to electronics.stackexchange.com/questions/163738/… it should be ok, especially since your e-ink cell is basically a capacitor, not a resistive load. However, the relatively low voltage of your capacitors does worry me. But please check with the people on EE.

@PM2Ring My capacitors withstand up to 63V, which is well above the voltage that will go through them

@PM2Ring What about the transformer? Should I worry about something there?

I have a question concerning QFT (causality) ref. Pesking & Shroeder p.26-27 and related pages. The confusion I stuck in is, why ther is no Lorentz transformation that takes (x-y) -> -(x-y) in the case (x-y)^2>0 ?

the case of timelike region

@Student404Mus See physics.stackexchange.com/q/273617/50583

Whatta answer

Everything is clear

I have reached nirvana

Einstein's spirit is manifesting unto me

@ACuriousMind What do we do about a question that is a Mathematics SE duplicate but is still somewhat a physics question? physics.stackexchange.com/questions/497668/…

@AaronStevens Not much, there's no cross-site duplicate function and if it's on-topic for us we can't really close it as off-topic.

@ACuriousMind Should an answer that links to the Mathematics SE answer and summarizes what it says be made then?

Would be a valid answer, yes

@ACuriousMind It is done :)

thanks :)

@ACuriousMind Nevermind, just found a Physics SE duplicate. Oh well haha