### Samothraki: Day 2

Back on Samothraki:

Notes on the slide show are included below.

The pictures shown were taken in early September. The island is beautiful then. Most of the tourists have gone home and there's just a slight chill to the air in the mornings.

Day two starts in Kamariotissa. The picture shows the main street of the little port town. At Mike's car and bike rentals you can rent a scooter, a motorcycle, a car, or sometimes even a house. I lucked out and got everything I needed in one stop!

There's a great internet cafe next to a coffee shop if you need to send messages home, or upload photos. The cafe is shown in the lower right-hand corner of this photo.

This is all you need to get around to get around Samothraki! There's not a whole lot of traffic on the roads. Even on the rougher roads in the country, a scooter does just fine. Make sure you learn how to use the kick starter as well as the electronic ignition, the knowledge will come in handy. Also, keep in mind that the only gas station is located in Kamariotissa, so fill up before heading out.

The first full day, I rode up to capital city of Χορασ. The ride is easy and only takes about thirty minutes. The city is nestled into the hills of the island. It can actually be seen from the ferry on the ride to Samothraki. The remaining slide show photos are of Χορασ.

The Locations:

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### Cool Math Tricks: Deriving the Divergence, (Del or Nabla) into New (Cylindrical) Coordinate Systems

The following is a pretty lengthy procedure, but converting the divergence, (nabla, del) operator between coordinate systems comes up pretty often. While there are tables for converting between common coordinate systems, there seem to be fewer explanations of the procedure for deriving the conversion, so here goes!

What do we actually want?

To convert the Cartesian nabla

to the nabla for another coordinate system, say… cylindrical coordinates.

What we’ll need:

1. The Cartesian Nabla:

2. A set of equations relating the Cartesian coordinates to cylindrical coordinates:

3. A set of equations relating the Cartesian basis vectors to the basis vectors of the new coordinate system:

How to do it:

Use the chain rule for differentiation to convert the derivatives with respect to the Cartesian variables to derivatives with respect to the cylindrical variables.

The chain rule can be used to convert a differential operator in terms of one variable into a series of differential operators in terms of othe…

### The Valentine's Day Magnetic Monopole

There's an assymetry to the form of the two Maxwell's equations shown in picture 1.  While the divergence of the electric field is proportional to the electric charge density at a given point, the divergence of the magnetic field is equal to zero.  This is typically explained in the following way.  While we know that electrons, the fundamental electric charge carriers exist, evidence seems to indicate that magnetic monopoles, the particles that would carry magnetic 'charge', either don't exist, or, the energies required to create them are so high that they are exceedingly rare.  That doesn't stop us from looking for them though!

Keeping with the theme of Fairbank[1] and his academic progeny over the semester break, today's post is about the discovery of a magnetic monopole candidate event by one of the Fairbank's graduate students, Blas Cabrera[2].  Cabrera was utilizing a loop type of magnetic monopole detector.  Its operation is in concept very simpl…