Recent content by Gigel

Maybe the dark matterless galaxies are the result of a weird collision and the presence of a much larger galaxy that they orbit. Now if a small galaxy rotating around a much larger one is collided by another galaxy as in the Bullet Cluster collision, with the second galaxy going radially (say...

On the other hand, two pies are better than one. Is there a constant called cookie?

##\pi = - i \ \ln(-1)## or ##\pi = - 2 \ i \ \ln(i)## There you have it. :)

Interesting. Could it be done at high altitude (say 5-10 km), where temperatures are lower and there are probably not enough particles for clouds to form? A high cloud may also last longer, especially if it borders or is inside the stratosphere.

As Khashishi said, it is something like: dy = y'(x) dx, where dx, dy are absolute deviations. Relative deviations are dx/x, dy/y: dy/y(x) = y'(x)/y(x) * x * dx/x Here x,y,y(x),y'(x) should be computed for x=reference value of x (the one supposedly without errors). If you take errors dx, dy to...

I'm thinking about destructive interference at a certain site - say a given coastline. I don't take into consideration much what happens farther away. This is because the waves will reduce in amplitude the farther they go away anyway. But I want to see if a given site close to the impact area...

Would it be possible to use nuclear explosions in order to reduce the amplitude of a tsunami wave? This refers to tsunamis caused both by earthquakes and asteroid impact. Imagine a 100-500 meter asteroid falls into an ocean and produces a tsunami. In this case the tsunami can be anticipated...

phyzguy, I agree with you, but still can't get rid of all the weirdness.

That is Feynman's argument too. phyzguy is right in the post above. I was trying to eliminate the wire powering the inner spherical plate that crosses the space between plates and thus gives an ugly conduction current between plates. I was trying to hold only a displacement current. So far the...

I understand it is DC voltage applied to the plates. If B=0 then what is the Poynting vector, especially in the case with increasing voltage and σ=0? Normally it is S=E x B/μ0, but if B=0 that would make S=0 so the capacitor is not charging? 0.o Also, the wires powering the plates don't seem...

Well in the case I presented the current is not brought by any wire. It is indeed a radially symmetric current and it appears because the plates move one towards the other, while PRESERVING the spherical shape with respect to the center of the system. They change their radius as they do so, but...

Sorry, I forgot that his capacitor was leaking. You are right, it is Feynman's case there. Anyway, there is always the possibility of a non-leaking spherical capacitor. In that case there is no current, yet the electric field may vary. That produces a magnetic field generally. In a spherically...

Now about my results, I considered a capacitor in the form of a spherical cap (plates extend for 0<θ<θ0, so they are not full spheres). The two plates have very close radii, so that the fringe effect can be neglected (but can it?). A took a surface S between the plates (say in the middle) and...

I have tried to solve the same problem as in the first post with Ampere's law, with some results which are probably wrong. Feynman considered an example which I don't think is very relevant here. He considered a radial distribution of both currents and electric fields, so that the current j is...

About 80% of BaSO4 is used for drilling, according to Wikipedia.