Why are you left-handed?

Are you left-handed? I.e. do you do the following things with your left hand.

1. Hold a pen
2. Throw a ball, play tennis or tennis table

Most likely, you are a right-handed person. Left-handed persons are believed to be about 10% of the population only.

But why is it that way? Why this ratio? Why not 50% ?

That is a question science doesn't currently know the answer.

Our brain is used to control our body. As we grow up, the left part and right part of our brain specialize into different functions. A left-handed person's brain can be seen as the symmetric (mirror image) of a right-handed person. Have we answered our question? Not really.

We know the organization of the brain explains a person's preference for one hand over another. We don't know why the brain develops 90% of the time to make a right-handed person and 10% to give a left-handed person. Some of us believe it ought to be a very simple mechanism, in the early stages of the embryo development. Maybe one day a scientist will publish an image showing the cellular development of the brain responsible for this ratio. Maybe some stem cells get pushed into a blood vessel that divides into two extremities - one large, and a second one that is a tenth of the first one. Something at some microscopic level ought to be responsible for this particular ratio.

Maybe you want to be a scientist yourself to research this area. Please post a comment when your article has been accepted by Nature. I am a left-handed person myself and I am very very interested in the answer...

Sending photons between 2 villages in Switzerland

We often imagine scientists hiding in the basement of some mysterious building, working with weird machines and not paying much attention of what happens outside. Wrong! A very curious experiment took place between two villages in Switzerland.
The experiment was conducted by five scientists named Daniel Salart, Augustin Baas, Cyril Branciard, Nicolas Gisin and Hugo Zbinden. It was published in Nature Aug. 14th 2008. The scientists used a network of optical fiber connecting two villages distant from 18 kms. They vehiculed light back and forth and verified a property called 'entanglement'. We won't go in detail about that phenomena here. We will focus on the geography of the villages.
Swiss villages Satigny and Jussy are aligned along the east-west direction. Why is that interesting? Well the earth rotates around the north-south axis in one day, as you know - that's why we have day and night every 24 hours, right! The scientists repeated their experiment throughout the day and verified they obtained the same result!
You are not surprised? No, we expect things to work the same regardless of the time of the day - our cell phones, cars, dish washers, etc. Most machines work regardless of their orientation in SPACE. The experiment verified it is also the case for 'entangled photons' with a very good accuracy. It showed that Albert Einstein's spooky action either does not exist or needs to be faster than 10,000 times the speed of light.
Do you know other weird experiments? I.e. experiments that require measuring small things between very weird or distant locations?