August 20th, 2008
Nanospheres moving faster than light?
In recent years, I don’t think I’ve spent a month without a report about a new way to exceed the speed of light. Yesterday, University of Pennsylvania researchers announced a theoretical way to increase the speed of pulses of light which could bring optical computing closer to reality. The scientists claimed that their metallic nanosized particles could reach 2.5 times the speed of light. As said the research team, ‘application of this theory would use nanosized metal chains as building blocks for novel optoelectronic and optical devices, which would operate at higher frequencies than conventional electronic circuits.’ So when will see high-speed optical computers? Expect a few years, but read more…
This theory has been developed at the Department of Bioengineering of the University of Pennsylvania by Alexander Govyadinov, a post doctoral researcher, and by Vadim Markel, an assistant professor who also holds a job in the Department of Radiology. Both of them are members of the Penn Optics and Imaging Group.
So what is the team’s theory about? “Recent developments in nanotechnology have enabled researchers to fabricate nanoparticle chains with great precision and fidelity. Penn’s research team took advantage of this technological advance by utilizing metallic nanoparticles as a chain of miniature waveguides that exchange light. Currently, the advance is theoretical. But, from a practical standpoint, the creation of a metallic nanochain would provide the combination of smaller-diameter optical components coupled with larger bandwidth, making them optimal wave guiding materials. As the velocity of the light pulse increases, so too does the operating bandwidth of a waveguide. Increasing the bandwidth helps to increase the number of information channels, allowing more information to flow simultaneously through a waveguide.”
And what kind of results did the team reach? “Researchers investigated changing the shape of particles in an attempt to increase this bandwidth. Spherically-shaped nanoparticles, the shape used almost exclusively in early research, provide narrow bandwidths of light. As Markel and Govyadinov discovered, shaping the particles as prolate, cigar-shaped or oblate, saucer-shaped, spheroids boosted the velocities of surface plasmon pulses reflecting off the surface to 2.5 times the speed of light in a vacuum.”
I’m sure the vast majority of you thinks that the theory of relativity prohibits anything from moving faster than light. Here are some explanations by the researchers about their theory. “But what is a ‘thing’?’ Markel said. ‘A very powerful flashlight directed at the moon would theoretically create a bright spot on its surface. By simply turning the flashlight sideways, the flashlight’s beam streaks across the sky at speeds far exceeding the speed of light. This evidence has long been known and dismissed, since the bright spot cannot be used for superluminal, or faster-than-light communication, between the earth and the moon. The fast motion of the bright spot is simply a geometrical artifact, similar, in some ways, to the point at which the two blades of closing scissors intersect. The theory of relativity does not concern such purely geometrical objects.’”
If you’re not convinced by this explanation, this theoretical work has been published in Physical Review B under the title “From slow to superluminal propagation: Dispersive properties of surface plasmon polaritons in linear chains of metallic nanospheroids” (Volume 78, Number 3, Article 035403, July 15, 2008). Here is the end of the abstract. “We demonstrate superluminal propagation of Gaussian wave packets in numerical simulations. Both theory and simulations are based on Maxwell equations with account of retardation and, therefore, are fully relativistic.” If you want more information, here is a link to the full paper (PDF format, 12 pages, 1.09 MB), but be warned: reading it requires a solid mathematical background.
Sources: University of Pennsylvania news release, August 19, 2008; and various websites
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