On Wed, 27 Apr 2005 18:08:52 -0700, I.Care wrote:

NASA is funding a new type of wire that can transmit power 10 times
better than normal wire. Will this make a difference in Audio?

Only to those who sincerely wish while closing their eyes very, very
hard.

http://www.wired.com/news/space/0,2697,67350,00.html

An OK general announcement that is rather a hodge-podge of facts and
characteristics. Wired is hardly a cutting edge science venue. One
particular howler is the construction of a "quantum wire" from a
wrapping of several many nanotubes. This is a contradiction in terms.
The nanotubes are already quantum wires, in fact they are called 1D
forms.

Being "quantum" anything, they are consistent in exhibiting non-linear
electrical/physical properties. Ohms law (being yet another model
that those who lambaste models would be surprised to learn) fails to
uniquely express what resistance this wire would exhibit (Onsager's
Relation drawn as a Landauer curve). However in conductance
measurements, carbon nanotubes will support a billion Amperes per
square centimeter.

However, no carbon nanotube is a square centimeter, being more often
10s of nanometers in diameter, they are still not square (area)
defined (that "quantum" thingy again). The problem of the article is
that it is mixing the bulk carbon nanotube properties with the quantum
carbon nanotube properties - not at all the same thing. This is why
the conductance of a quantum nanotube wire in billions of Amperes
plunges to a rather more mundane 1/10th the resistance of copper for a
nanotube bundle.

The quantum properties quite rightly dismiss any notion of skin
effect, current travels inside the tube. In fact, it also distorts
the shape of the tube like a snake swallowing a golf ball. Even more
interesting is that current will flow in the opposite direction of the
applied EMF if there is a sufficient heat differential between the
ends (it doesn't take much heat because carbon nanotubes are
exceptionally good heat conductors). Firstly, getting current into a
carbon nanotube is not a pretty thing as they exhibit what is called
"non-reproducible behavior" by their nature of having a great variety
of conduction configurations that all arise out of their binding to a
contact material. For nano-conductors, contacts dominate everything.

All-in-all, the introduction of a new technology is frequently
confused as a better version of an old technology - something like
saying facsimile would replace the newspaper - or that the utilities
would pay us to use nuclear power. All the "forecasts" mentioned in
this article rank right up there with these world class pipe dreams.

73's
Richard Clark, KB7QHC