Physicist discovers strange forces acting on nanoparticles

April 10, 2017 by Aaron Hilf
Credit: University of New Mexico

A new scientific paper published, in part, by a University of New Mexico physicist is shedding light on a strange force impacting particles at the smallest level of the material world.

The discovery, published in Physical Review Letters, was made by an international team of researchers lead by UNM Assistant Professor Alejandro Manjavacas in the Department of Physics & Astronomy. Collaborators on the project include Francisco Rodríguez-Fortuño (King's College London, U.K.), F. Javier García de Abajo (The Institute of Photonic Sciences, Spain) and Anatoly Zayats (King's College London, U.K.).

The findings relate to an area of theoretical nanophotonics and quantum theory known as the Casimir Effect, a measurable that exists between objects inside a vacuum caused by the fluctuations of electromagnetic waves. When studied using classical physics, the vacuum would not produce any force on the objects. However, when looked at using , the vacuum is filled with photons, creating a small but potentially significant force on the objects.

"These studies are important because we are developing nanotechnologies where we're getting into distances and sizes that are so small that these types of forces can dominate everything else," said Manjavacas. "We know these Casimir forces exist, so, what we're trying to do is figure out the overall impact they have very small particles."

Manjavacas' research expands on the Casimir effect by developing an analytical expression for the lateral Casimir force experienced by nanoparticles rotating near a flat surface.

Imagine a tiny sphere (nanoparticle) rotating over a surface. While the sphere slows down due to photons colliding with it, that rotation also causes the sphere to move in a lateral direction. In our physical world, friction between the sphere and the surface would be needed to achieve lateral movement. However, the nano-world does not follow the same set of rules, eliminating the need for contact between the sphere and the surface for movement to occur.

"The nanoparticle experiences a lateral force as if it were in contact with the surface, even though is actually separated from it," said Manjavacas. "It's a strange reaction but one that may prove to have significant impact for engineers."

While the discovery may seem somewhat obscure, it is also extremely useful for researchers working in the always evolving nanotechnology industry. As part of their work, Manjavacas says they've also learned the direction of the force can be controlled by changing the distance between the particle and , an understanding that may help nanotech engineers develop better nanoscale objects for healthcare, computing or a variety of other areas.

For Manjavacas, the project and this latest publication are just another step forward in his research into these Casimir forces, which he has been studying throughout his scientific career. After receiving his Ph.D. from Complutense University of Madrid (UCM) in 2013, Manjavacas worked as a postdoctoral research fellow at Rice University before coming to UNM in 2015.

Explore further: The reins of Casimir: Engineered nanostructures could offer way to control quantum effect

More information: Alejandro Manjavacas et al. Lateral Casimir Force on a Rotating Particle near a Planar Surface, Physical Review Letters (2017). DOI: 10.1103/PhysRevLett.118.133605

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14 comments

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indio007
Apr 10, 2017
This comment has been removed by a moderator.
Shootist
not rated yet Apr 10, 2017
Nothing was discovered.


All hail Brainiac the Grand Nullity
GaryDp
not rated yet Apr 10, 2017
Could this be the precursor to zero point energy, and harnessing that energy using nano sized piezo electric devices? ( wondering )
JongDan
1 / 5 (1) Apr 10, 2017
In our physical world, friction between the sphere and the surface would be needed to achieve lateral movement. However, the nano-world does not follow the same set of rules, eliminating the need for contact between the sphere and the surface for movement to occur.

Huh, I always thought forces like friction, like most intramolecular forces that aren't of charge/dipole attraction origin, are exactly the result of Casimir forces.
JongDan
not rated yet Apr 10, 2017
Could this be the precursor to zero point energy, and harnessing that energy using nano sized piezo electric devices? ( wondering )

It is, like all Casimir force related phenomena are. But again, those lateral forces work because the particle is already moving. It's a bit like the gyroscopic effect which triggers precession in an already rotating object. Except that, well, here you're actually accessing states that are below what is considered ground energy (in isolation).
Mark Thomas
5 / 5 (2) Apr 10, 2017
"Manjavacas' research expands on the Casimir effect by developing an analytical expression for the lateral Casimir force experienced by nanoparticles rotating near a flat surface."

Sounds like scientific progress to me. Perhaps a precise description of the forces imparted by the Casimir effect in this situation will enable us to develop a better overall understanding of it.
Dingbone
Apr 10, 2017
This comment has been removed by a moderator.
vacuumforce
1 / 5 (1) Apr 10, 2017
So I guess my name is quite ironic in this situation.

Also, there are infinite dimensions. Chew on that, scientific community.
baudrunner
1 / 5 (1) Apr 10, 2017
It's gravity. Gravity is the cancellation of volume between two objects in space caused by the inverse phase relationship of the constituents that comprise the space which each object displaces. At the nano scale, the constant cancellation and rehabilitation of the volume between the particle and the surface causes the lateral motion (In physics the terms "particle" and "object" are interchangeable) . The nano sized particle never actually touches the surface because of the electro-negative repulsion of the particle's outer electron shell with the electro-negative property of the surface atoms' outer electron shell.
Osiris1
1 / 5 (1) Apr 10, 2017
Casimer forces are small but loom large in nanonano scale, not to sound like a tired old cancelled tv show. However, tera tera numners of these nanonano devices acting in unison could yelld tremendous forces. Combine this with making quantities of quark-gluon plasma and controlling it...directing quark forces many orders of magnitude over nucleic forces. Keys to the universe. Manipulate space itself....star travel. Key is using smaller forces to unlock and direct very large forces consisting of amalgams of ultra small forces acting together.
swordsman
not rated yet Apr 10, 2017
This is the type of experiment that was a long time in coming. It is another example of the importance in utilizing the electronic model of atoms, which was the foundation of the original Quantum Theory (Max Planck in the year 1900). The mechanical model of Einstein could not yield such a result.
Spaced out Engineer
not rated yet Apr 11, 2017
vacuumforce, Infinite dimensions is not a problem. Finistic proportions can emerge via canceling. It is more of a question of what is worth piece-wising over for order or what type of control processes we should use because of stochastics. You would be amazed at what we can inference about and construct with systems of systems bound/unbound, closed/open, but still cannot interpret.

I am more curious on how this may tie with the spectral gap being undecidable. Is the ground state meta-stable, groundless, or indiscernible from being undecidable. Are we looking at the tool or discovering something then, is the better question.

I'm not saying we have slain Eris or her sister Void, but merely that physics has always been conditional on models. Some are more falsifiable than others. None are completely independent, though some theoretical physics does try to elaborate of the thermodynamics of constants, for better or for worse.
ZergSurfer
5 / 5 (1) Apr 11, 2017
" Are we looking at the tool or discovering something then, is the better question."
I like this :) I think the true nature of Eris is elusive, the closer we look, the more She hides :)
/whimsical
swordsman
not rated yet Apr 17, 2017
"Photons colliding...". This is the problem, which is in assuming that the photon is a particle. A photon is an electromagnetic wave of very short wavelength that is traveling at the speed of light. Since the wavelength is very short and the frequency very high, it is very difficult to measure. However, it has been characterized at much longer wavelengths. Planck's model of the atom was an electronic model, whereas that of Einstein was physical. Einstein himself admitted that the most important problem of the future was resolving field and matter. Planck had already done that, and said that the model could as well be mechanical. In the following years, the conversions between electronic and mechanical models have been characterized and utilized in engineering efforts. This methodology is the future of this subject.

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