When two objects are placed extremely close together, they will be attracted to
each other by this only recently proven to exist quantum force. Instead of the
objects' masses pulling them together, Casimir force works as an external
force, almost like hydrodynamic pressure.
In this case, the empty space between the two objects isn't actually empty. All
space is filled with electromagnetic fields and the virtual particles
associated with them. These particles, in quantum physics, also exist as waves,
and here's where things start to make sense. Around the objects, these
particle/waves can be of any varying wavelength, but only a smaller number of
shorter wavelength particles can fit between them. This creates a sort of low
versus high pressure system where the force of the “heavier” longer wavelength
particles acts to push the masses together.
UF's research into this interesting force may, in the future, help the ever
growing miniaturization of electronic components. As MEMS
(microelectricalmechanical) devices get smaller and stacked closer together,
the likelihood of the Casimir force becoming a problem gets larger. “Stiction”
is already a problem in super-fine structure assembly, and though it can be
caused by a number of variables, the Casimir force can easily contribute to it.
In a paper published in Physical Review Letters, lead-author Ho Bun Chan
explains, “We are not talking about an immediate application, we are talking
about, if the devices continue to be smaller and smaller, as the trend of
miniaturization occurs, then the quantum effects could come into play.”
With integrated circuits and other electronic parts rapidly
losing size but gaining parts and complexity, these effects could easily occur
in the next decade.
To study how Casimir
force can be affected by structure, the UF team created a metal panel
resembling a fin radiator, with fin structures of approximately 200nm separated
by the same distance. This effectively cut the gapped surface area in half
compared to two flat plates that were used as a control. They found that,
though having more area between the plates for longer wavelength particles to
occupy and half the accessible surface area, the comb-like structure only
reduced Casimir force by 30 to 40 percent.
While the experiment didn't show the expected 50 percent reduction, it helped
prove that, instead, the strength of the Casimir force depends on the geometry
of the objects in question. This may be useful in the future for MEMS and other
nanomachinery engineers as they need to design nanoscopic parts that would not
work well if they were heavily affected by the mysterious quantum particles.