The Aha! Moment: A Scientist's Take on Creativity

12 Physical Phenomena I Have Noticed

175 12 Physical Phenomena I Have Noticed Ihave spent a lot of time just playing with physical effects. I recommend this random play. It may be part of curiosity, which I salute in chapter 1 or it may help to develop physical intuition (see chapter 4). Thus, for no good scientific or technical reason, I have been distracted by the noises of steam and by the way certain objects can be levitated on an airstream. I have also played with the “convective cells” that form in a heated viscous fluid and with optical phosphorescence.At the time, I understood all these things badly, if at all. Yet I contrived to turn them all into demonstrations worth showing to an audience. I even learned in the process! The Noises of Steam Early in my career as an amateur steam technologist, I began to be aware of the noises that steam makes. I tried blowing it into water. It made a rapid banging, a lovely noise. Even better, the noise changed its tone and character as the water got hot. Ultimately the water reached its boiling point, and the noise changed character quite suddenly. I understood (maybe for the first time) something I had learned about in my physics lessons. Water exerts a vapor pressure, and the hotter it is, the greater is that pressure. But below the boiling point, it is always less than atmospheric pressure. So, cooled in water, a steam bubble condenses very sharply: it makes a bang as it contracts. But it also gives out latent heat and warms the water. The more steam you blow into water, the hotter the water gets. The bubbles of steam condense more slowly, and their noise changes. When the water reaches boiling point, its vapor pressure equals atmospheric pressure, and the steam no longer condenses. It just 176 The Aha! Moment goes through the liquid like any other gas, making only a vague bubbling sound. So at the boiling point, the sound of steam changes abruptly. Now I suspect that many of these experiences went “downstairs” for the RIG to play with. I gained a sense of steam as a physical medium.They probably meshed with my foolish but interesting scheme to make a steam balloon (see chapter 6). Years later, thinking about steam in television terms, I realized that nobody looks at an electric kettle. They listen to it. All this began to form a possible TV demonstration in my mind. I started to listen carefully to electric kettles. I decided that there were three noises to invite a TV audience to listen for. When you fill an electric kettle with cold water and turn it on, it gives an initial quiet fizz as air is expelled. Later there is a characteristic crackly, banging noise that changes as the water warms up. When the water boils, the noise goes suddenly much quieter and changes its character too. I could show these effects quite well with my steam-blowing system, without simply copying a kettle, which nearly every viewer would already have. I set up the kettle scheme for Yorkshire Television Ltd.; it made a neat item for Magnus Pyke. Later, I developed the idea further for Westdeutscher Rundfunk Cologne. I even managed to tell a human story— which I got from an employee at the Science Museum library.That library was heated by cast-iron steam radiators. When the steam was turned on, they warmed up with a fearsome banging noise. Their previous service had put water in them; this had cooled but was then heated and expelled by the fresh steam. In the 1930s, many refugees from European dictatorships came to London. Some of them worked in the Science Museum library. When the heating came on, and the radiators began their terrible banging, many refugees thought it was gunfire. Violence had come to London! Some of them hid under the tables in alarm. I even managed to illustrate my story with real sound! Those old steam radiators were still in use in the 1960s, and I made a recording of them while renovating an old portable BBC magnetic-tape recorder. Levitation A light beach ball can be levitated on the updraft of air from a vacuum cleaner used as a blower. The experiment is delightfully counterintuitive .You would expect a ball, or indeed any light object, to be blown Physical Phenomena I Have Noticed 177 away by...