Thursday, April 1, 2010

The shoulders of giants

As my pupils are aware, I have a great admiration of the works of Galileo. His name crops up time and time again in my lessons and I often herald him as the world’s first true physical scientist. I am probably wrong about this, but it is certainly the case that in Galileo’s time Physics was in its infancy and not at that stage recognized as a science in its own right. The thing that changed this was the realization that in order to learn about the world theory is not enough: You have to perform experiments.

Now there is a lot of debate about whether Galileo every carried out some of his most famous experiments but irrespective of this, Galileo certainly appreciated the importance of experimentation. Unfortunately he lived in an age where measurement was often very crude. The techniques we now take for granted did not, at that stage, exist; in fact many modern methods of measurement have their roots in some of Galileo’s discoveries - in particular all methods of accurately measuring time.
Time is very important for Physics since Physics concerns change and, in particular, rates of change. Despite not having access to the sorts of time keepers we now take for granted Galileo knew about a very accurate instrument for measuring time - the human ear. It turns out that we are very good at determining time just by listening to things - in fact we can detect time intervals far more accurately by listening to something than by using visual judgement. The reason for this comes down to the functioning of the brain. The left hand side of the brain is predominantly used for listening and for verbal communication; the same side of the brain is also dominant in temporal processing (i.e. keeping track of time). The right hand side, on the other hand, is predominantly responsible for visual processing and spatial awareness. The separation of temporal processing from this side of the brain means that whilst it is easy to judge, by looking, the distance to a moving car, determining whether you have sufficient time to pull out before the car reaches you is much more difficult - just ask any learner driver!
Why not try the following experiment for yourself:
One of my YouTube videos concerns the regularity of various oscillations (i.e. whether they rock back and forth at a constant steady rate). Try watching the video, first with the sound switched off, and try to determine whether the oscillations are regular. For some of the oscillations the answer is obvious - but for others it is less so.
Now switch the sound on, and this time listen to the noise made by the oscillations - the results may surprise you! Simply by listening you can determine slight changes in the regularity of an oscillation which would be hard to detect using a stopclock or even a datalogging device.
This brings us in a nice little circle because in medieval Europe, although Physics was not recognized as a science, music was.

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