Well, it looks as if I belong to this small species of students not using online social networking tools like twitter or facebook. My friends, family, other OU students are all addicted to it. So why don't I use it, too? Well, here are my thoughts so far:

• Well, if I haven't spoken to someone since I left school, then there is probably a reason for this.
• I blog things about my life as a student that I think could be helpful for other students. I think the following information is less interesting and so I don't need to tell the world: "Inés is studying", "Inés is walking around.", "Inés is wasting valuable time describing what she is doing." ...
• I have 2 telephone numbers, 7 email addresses which I check regularly, 3 instant messaging accounts. If we want talk, there are already plenty of good ways to do it.
• I don't want others to have the ability to sell my data without my permission. There is something called data protection - at least in Europe. I am not so sure about the rest of the world.
• I already have less free time, so why should I spend it by reading: "OMG, look at that dog dressed as a person!" or "What do you mean Kelly’s been hitting on another guy?"
  Not using those online social networks saves my brain from information overload . As a result, I can put my full focus into things that really matter, and I can maintain an organized mind.
• And look at the bright side: Since I don’t use any online social networks, I am forced to actually talk to people face to face. My friendships are cultivated slowly and surely, with much less fickleness than it would be on Facebook etc. Furthermore, the way I treat people and the way I am treated is not by how I “friend” and “un-friend” people. I also speak more understandably because “my wrds r not wrttn lk dis.”

Yesterday evening 10 students met on Elluminate to discuss Jacobian's equation. We worked through Exercise 8.26 one student explained the way of solving this exercise and another student shared his desktop with us and used MathType for typing in the formulae. It was quite amazing, because we had a really good discussion and I think I now understand Jacobian's equation which can be used to establish if a functional has extrema.

We decided to meet again and then one or more people prepare an exercise which we then work through together. I am very much looking forward to this. :-)

The following youtube video shows 5 metronomes which oscillate with random phases and which are uncoupled, since no energy or information flows from one to another, so they cannot "know" each other. The metronome needles are at same speed, but started one after the other.

Then someone lifts the metronomes (standing on a board) on a pair of cans. Now we have coupled the metronomes. The cans move a little bit What happens next is that there is a transfer of angular momentum between the cans and the needles. Hence the transfer of angular momentum is the damping force and this is an example of damped harmonic oscillation.

You might find this page at scholarpedia interesting.

This was the title of a great lecture held by Gareth Williams two days ago. The lecture was held using Elluminate and about 60 students attended. In my opinion this is a large number of students, since this lecture was not part of the course or so ... it was held for those who were interested in why we need topology. ;)

But is the question "Can one knot untie the other?" important at all? Is it only theoretical or even practical?

Assume we are given a piece of string with a knot tied in it. Can we then tie another knot which will combine with the first knot to produce an unknotted piece of string? Answering this question is not only interesting it is of practical interest for sailors, biologists (DNA), bungee-jumpers etc. as well.

After considering Seifert's surfaces, adding some knots we then came to the conclusion that one knot cannot be tied after another in such a way as to make the result equivalent to the trivial knot, and so, one knot does not untie another. :)