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Brownian motion: Difference between revisions
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{{a|design|{{image|space tea|jpg|}}}}{{d|Brownian motion|/ˈbraʊniən ˈməʊʃᵊn/|n|}}The [[random]] movement of suspended particles resulting from their repeated collisions with each other. | {{a|design|{{image|space tea|jpg|}}}}{{d|Brownian motion|/ˈbraʊniən ˈməʊʃᵊn/|n|}}The [[random]] movement of suspended particles resulting from their repeated collisions with each other. | ||
{{drop|Y|ou will hear}} it said that the | {{quote|The principle of generating small amounts of finite improbability by simply hooking the logic circuits of a Sub-Meson Brain to an atomic vector plotter suspended in a strong [[Brownian motion]] producer (say a [[nice hot cup of tea]]) were well understood. | ||
It is said, by the Guide, that such generators were often used to break the ice at parties by making all the molecules in the hostess’s undergarments leap simultaneously one foot to the left, in accordance with the theory of indeterminacy. | |||
Many respectable physicists said that they weren’t going to stand for this, partly because it was a debasement of science, but mostly because they didn’t get invited to those sorts of parties. | |||
:—[[Douglas Adams]], {{hhgg}}}} | |||
{{drop|Y|ou will hear}} it said that the surface of the proverbial “nice hot cup of tea” tends to stillness only through the awesome force of entropy. The particles ricocheting this way and that in the liquid, colliding chaotically, and you only do not notice them because of the vast ''improbability'' that enough of the particles all move the same way at once. | |||
In this sense, entropy is just a statement of basic probability: the larger the number of particles there are, the more scope there is for chaos. | |||
The state of a system is considered “ordered” when there are only a few arrangements that could produce that state. A system is in a state of chaos when many arrangements could produce that state. There are far more ways for a system to be chaotic than ordered so systems if left alone, tend to towards disorder. That is, entropy. | |||
states than ordered ones | |||
That stable occupation of the cup is the state of maximum entropy towards which a random collection of molecules automatically tends. This is no more than the power of statistics over order; the number of recognisably “ordered” configurations of those atoms is so swamped by the colossal number of disordered configurations that the odds of an ordered configuration just never show up. It is logically possible for all the molecules in your cup of tea to spontaneously move to the right side of the cup at once, that is, just ''vanishingly unlikely''. It is a “twenty-five sigma” event: you could wait millions of times the life of the universe, and it never happened once. ''But it could happen''. | That stable occupation of the cup is the state of maximum entropy towards which a random collection of molecules automatically tends. This is no more than the power of statistics over order; the number of recognisably “ordered” configurations of those atoms is so swamped by the colossal number of disordered configurations that the odds of an ordered configuration just never show up. It is logically possible for all the molecules in your cup of tea to spontaneously move to the right side of the cup at once, that is, just ''vanishingly unlikely''. It is a “twenty-five sigma” event: you could wait millions of times the life of the universe, and it never happened once. ''But it could happen''. | ||