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The Demon Theory of Friction

by Eric Rogers

How do you know that it is friction that brings a rolling ball to a stop and not demons? Suppose you answer this, while a neighbor, Faustus, argues for demons. The discussion might run thus:
You     I don't believe in demons.
Faustus I do.
You     Anyway, I don't see how demons can make frction.
Faustus They just stand in front of things and push to stop them from moving.
You     I can't see any demons even on the roughest table.
Faustus They are too small, also transparent.
You     But there is more friction on rough surfaces.
Faustus  More demons.
You     Oil helps.
Faustus Oil drowns demons.
You     If I polish the table, there is less friction and the ball rolls further.
Faustus You are wiping the demons off; there are fewer to push.
You     A heavier ball experiences more friction.
Faustus More demons push it; and it crushes their bones more.
You     If I put a rough brick on the table I can push against friction with more and more force, up to a limit, and the block…
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A kilobyte rewritable atomic memory

Imagem
Kilobyte atomic memory. STM image (96 × 126 nm, I = 2.00 nA,V = +500 mV, T = 1.5 K) of a 1,016-byte atomic memory, written to a passage from Feynman’s lecture ‘There’s plenty of room at the bottom’. The various markers used are explained in the legend below the images. The memory consists of 127 functional blocks and 17 broken blocks, resulting in an over all areal density of 0.778 bits nm−2.
Nature nanotechnoly letters, July 18 2016
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