Due to unplanned maintenance of the back-end systems supporting article purchase on Cambridge Core, we have taken the decision to temporarily suspend article purchase for the foreseeable future. We apologise for any inconvenience caused whilst we work with the relevant teams to restore this service.
Thomas Kuhn, in his pathbreaking book, The Structure of Scientific Revolutions, notes that prevailing scientific paradigms determine how, or even if, we observe specific phenomena. One of the examples he uses to illustrate this is that of the motion of a heavy object tethered to the end of a chain:
Since remote antiquity most people have seen one or another heavy body swinging back and forth on a string or chain until it finally comes to rest. To the Aristotelians, who believed that a heavy body is moved by its own nature from a higher position to a state of natural rest at a lower one, the swinging body was simply falling with difficulty. Constrained by the chain, it could achieve rest at its low point only after a tortuous motion and a considerable time. Galileo, on the other hand, looking at the swinging body, saw a pendulum, a body that almost succeeded in repeating the same motion over and over again ad infinitum. And having seen that much, Galileo observed other properties of the pendulum as well and constructed many of the most significant and original parts of his dynamics around them.
I was reminded of this a few years ago when I came across an article in the Guardian newspaper in Britain on the water crisis faced by the Chinese city of Shanghai. The city's rapid industrial expansion had brought with it almost irremediable pollution to its main river, the Huangpu.