IT鈥橲 one of the most outrageous claims in science since cold fusion鈥攁nd
it has been greeted with similar scepticism. Last week, a materials scientist
announced that she can make everyday circuits that are superconducting at room
temperature.
Deborah Chung of the State University of New York at Buffalo told the Fifth
International Conference on Composites Engineering in Las Vegas that tiny carbon
fibres, set into epoxy or cement at high temperature, become 鈥渘egative鈥�
resistors. This means that electrons in a circuit made from the material would
be attracted to the side of the circuit with more negative charge and would flow
towards it, instead of being repelled by it鈥攔ather like water flowing
uphill.
Such a system would, in theory, provide a limitless source of energy. But
this violates the second law of thermodynamics, which in essence says you can鈥檛
get something for nothing. 鈥淭hat鈥檚 part of the dilemma,鈥� admits Chung.
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By combining negative resistors with normal conductors, Chung says she can
create circuits that superconduct鈥攖hey have zero resistance鈥攁t room
temperature. The highest temperature at which superconductivity has been
confirmed at atmospheric pressure is about 鈭�140 掳C.
Physicists can鈥檛 understand Chung鈥檚 claims. Negative resistance is real, but
it has only been observed at higher voltages. In these cases electrons don鈥檛
flow backwards; instead, fewer electrons flow through a circuit as you increase
the voltage.
Chung鈥檚 data come from a voltmeter and an ammeter. Other researchers say they
will only be convinced by other key tests of superconductivity鈥攕uch as
showing that the material can be levitated over a magnet. 鈥淢y suspicion is that
there鈥檚 something wrong with the measurement,鈥� says Steven Anlage, a physicist
at the University of Maryland at College Park.