The Dish

On Tuesday, we visited the Parkes radio telescope. This was made famous by the film The Dish. Here is a picture of the telescope not doing much:



Unfortunately, the telescope was undergoing maintenance when we visited. I'm sure it wouldn't have looked much different if it was actually doing something, mind. The telescope is in use most of the time (when it is not being maintained) so the general public can't get any closer than the visitor's center. From there, we looked at lots of exhibits and fun activities which almost managed to make Hannah become enthusiastic about science.

Very interesting were the "whispering dishes" outside the visitor center. These were a pair of parabolic dishes 20 metres or so apart, positioned such that someone whispering at the focal point of one of the dishes could be heard clearly at the focal point of the other dish. This was naturally very exciting. Here is a picture of Hannah bigging up one of the dishes:



I was so excited by this that I attempted to reproduce the mathematical proof that a parabolic dish will focus parallel light (or sound or radio waves or whatever) to a focal point. Unfortunately, I failed, due to having forgotten pretty much all the maths that I learned in school.