Posted on 26 September 2011 at 11:55h

My students have been doing an experiment to measure the time for a ball to roll down an inclined plane and today's lesson was spent discussing uncertainties and how important they are.

Taraah....

That was good timing. One of the biggest physics news stories ever and its all about uncertainties. The measurements have big random errors but by repeating many times they can be averaged out. However if there is a systematic error then no amount of repeating will get rid of it. By reading the headlines one would think that measuring the velocity of a neutrino was just like measuring the velocity of a ball. Make two markers and time how long it takes to go between, the problem is you can't see neutrinos, they are detected somewhere at the start and dissappear somewhere at the end. If you can't be sure where they are how can you be sure how fast they go - you can't. One might also think that the speed of neutrino's had never been measured before. It has and guess what, less than the speed of light. So my money is on Einstein.

Anyway it was, for me at least, a great teaching moment when the point I was trying to make suddenly became reinforced rather strongly.

Some interesting information here at wired science

And for some more details on how thhe velocity is measured Ethan's blog