MOTION MOUNTAIN

72 1 electricity and fields
Challenge 69 e
Challenge 70 s
Ref. 38
Challenge 71 s
F I G U R E 41 Maxwell’s unsuccessful
model of the vacuum.
are related by the so-calledKramers-Kronigrelations,whichareimportantformanymaterialtopicsrelatedtowave
phenomena.The two curves in the graph do not follow them
completely.
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If an axis rotates, one can attach a magnet to its end. With such a rotating magnet an
extremely cheap tachymeter can be realized. How?
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In Maxwell’s 1890 book on electrodynamics, he includes Figure 41 as a model of magneticandelectricfieldsofthe
vacuum. What is the biggest problem of this model of the
vacuum?
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For how long can silicon-based integrated circuits be made smaller and smaller? The
opinions on this matter differ. Optimistic predictions, often called Moore’s ‘law’, alternatewithpredictionsthatfrom2011onwards,thesizereductionwillbemoderatedue
to the high cost of the required equipment. For example, the next generation of wafer
steppers,themostexpensive machines in the production of silicon chips, must work in
the extreme ultraviolet – usually13 nm – in order to achieve small transistor sizes. At
this wavelength air is an absorber, and lenses have to be replaced by mirrors. It is unclear
whether this will be technically and economically feasible. Future will tell.
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In the 1990s, microscope images showed, surprisingly, that the tusks of narwhals are full
of nerve endings. Thus the tusk may be a sensory organ. However, the details and the
exact use of the organ is not understood. How would you find out?
Motion Mountain – The Adventure of Physics copyright © Christoph Schiller June 1990–November 2015 free pdf file available at www.motionmountain.net