# starship-design: Re: I know this is off the subject but...

```Steve,

>Electromagnetism isn't exactly my strong point.  The English version of
>the relevant Maxwell equation is that magnetic flux, integrated over a
>complete surface (topologically equivalent to a sphere with no holes),
>is zero.  A magnetic monopole, on the other hand, would have a nonzero
>flux.  As electric monpoles already exist, the electric-field Maxwell
>equation basically says that electric field flux integrated over a
>surface is equal to the charge enclosed by the surface.

True, this surface flux integration is indeed the essential indicator.

>By the Maxwell approach, you don't need to worry about "center of
>magnetivity"; no matter where you place the surface you intregrate
>magnetic flux over, whether it's surrounding the magnet or not, you get
>zero for the total flux in the normal case and a nonzero flux if there's
>a magnetic monopole nearby.

I understood this, but with the superconducting loop, you won't be able to
measure a closed surface unless you change the radius of the superconducting
loop. (--> First make the radius 0, then enlarge it to move the monopole
through it, then close the loop to zero radius again.) So your theory is
right, but less practical to test with a more or less solid super conducting
loop.
I've to admit though that if you start at an "infinite" distance (100
meters) from the superconductor loop and end a similar distance, the surface
of the loop will become infinitely small compared to the total surface. So
unless you expect really small monopoles, you will likely not need closing
the loop.

>>To avoid this problem, you may turn around the monopole in the neighbourhood
>>of the superconductor. After a 360 degree turn, the current in the
>>superconductor before and after should be the same.

Hmmm, having rethought this method, it is almost 100% certain to fail since
it only integrates a small "orbit" from the surface. So, the method Steve
suggested with the modification of closing the loop should make the proof
indefinately.

>>(Of course if you have a big magnetic monopole, the crude method will give
>>results that speak for themselves)
>
>From what I remember (and I'm not claiming any great authority on this)
>hypothetical monopoles are essentially point-like particles, with
>"magnetic charge".

Sorry, instead of "big" I should have written "strong".

Timothy

```