And if it lands in a person with a weak immune system, it might start a new colony, growing slowly until new bacteria are ready to be coughed out all over again. Like the miniaturized fat droplets in today’s homogenized milk, it’s just a passenger. ![]() Wherever the air goes, the bacterium goes. The gravitational pull on this new parcel is no match for the buffeting of the air. Storm in a Teacup by Helen Czerski: 9781524757175 : Books A physicist explains daily phenomena from the mundane to the magisterial. If it was originally a droplet of spit with a tuberculosis bacterium floating about in it, it’s now a tuberculosis bacterium neatly packaged up in some leftover organic crud. What was a droplet big enough for gravity to pull it through the viscous air now becomes a mere speck, a shadow of its former self. Most of that droplet is water, and in the first few seconds in the outside air, that water evaporates. Just as the cream rises slowly through viscous milk to the top of the bottle, these droplets are on course to slide through the viscous air to reach the floor. As the droplets drift downwards, they are bumped and jostled by air molecules that slow their descent. ![]() Air is too – it has to be pushed out of the way as things move through it. But it doesn’t happen quickly, because it’s not just liquids that are viscous. Click here to order a copy for £15.57 Topics Helen Czerski The Observer Physics Science and. These droplets are being pulled downwards by gravity and once they hit the floor, at least they’re not going anywhere else. Storm in a Teacup: The Physics of Everyday Life by Helen Czerski is published by Bantam, £18.99. ![]() The fluid droplets themselves start off fairly big, perhaps a few tenths of a millimetre. Some of them will contain the tiny rod-shaped TB bacteria, each only three-thousandths of a millimetre long. Jim Al-Khalili Our world is full of patterns. Czerskis enthusiasm is infectious because she brings our humdrum everyday world to life, showing us that it is just as fascinating as anything that can be seen by the Hubble Telescope or created at the Large Hadron Collider. Carried out of the lungs with each cough are thousands of fluid droplets, plumes of minuscule crusaders. A quite delightful book on the joys, and universality, of physics.
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