

Superlubricity – tuning friction to the point where it disappears - Sami_Lehtinen
http://newsoffice.mit.edu/2015/tuning-friction-nanomachine-development-0604

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akallio9000
This seems to me to go a long way toward explaining why dissimilar metals make
the best bearing interfaces, i.e. the atomic lattices don't match up.

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leni536
I would be surprised if this phenomenon caused the friction between metallic
surfaces. The surface of metals aren't that flat on nanoscale (even if they
are well polished).

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powertower
This also kind of seems analogous to the electron Cooper pairs moving through
a superconductor... As one electron moves down into a trout, the other moves
up into a peak, and because of the push/pull balancing interaction of their
paired up connection, energy is not dissipated (as heat), and in-turn no
additional energy is required for propagation... They just keep on moving.

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andrewflnr
I haven't heard this theory of superconductivity before. Is it new?

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chm
It isn't new. That would be BCS Theory[1].

[1]:
[http://en.wikipedia.org/wiki/BCS_theory](http://en.wikipedia.org/wiki/BCS_theory)

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im3w1l
It's pretty funny, when we can finally build a machine in perpetual motion,
nobody cares anymore.

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fiatmoney
Even if there is zero surface-surface friction, there is still friction and
resistance generated by, eg, the flexing of the materials making contact.

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im3w1l
Good point, this will bar more complicated mechanisms. But a ring spinning
forever around a dimple (in vaccuum of course) should work. Constant pressure
so no flexing.

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cbd1984
"Perfect vacuum" is a classical physics concept which abstracts away quantum
effects. In short, it isn't real, and it can never exist.

[https://en.wikipedia.org/wiki/QED_vacuum](https://en.wikipedia.org/wiki/QED_vacuum)

So, your perpetual motion device will inevitably interact with virtual
particles with momentum contrary to its own, and therefore run down.

Even if you have problems with that, consider this: It's impossible to cool
anything to 0K (absolute zero); all warm bodies (warmer than absolute zero)
give off photons; therefore, your moving parts will interact with photons
carrying momentum contrary to their own, and therefore be slowed and
eventually halted. Again, this is unavoidable.

So the simple classical picture of a rock in simple inertial motion through
the vacuum of space is valid as a simplification. Remember, though, that it's
equally valid to construct a coordinate system where the rock is stationary
and everything else is in perpetual motion.

