Archive for the ‘Physics’ Category

Meet the 2011 Nobel Laureates in Science

October 10, 2011 Leave a comment


Bruce A. Beutler
Jules A. Hoffmann
Ralph M. Steinman

The Nobel Prize in Physiology or Medicine 2011 was divided, one half jointly to Bruce A. Beutler and Jules A. Hoffmann “for their discoveries concerning the activation of innate immunity” and the other half to Ralph M. Steinman “for his discovery of the dendritic cell and its role in adaptive immunity”.


Saul Perlmutter
Brian P Schmidt
Adam G Riess

The Nobel Prize in Physics 2011 was divided, one half awarded to Saul Perlmutter, the other half jointly to Brian P. Schmidt and Adam G. Riess “for the discovery of the accelerating expansion of the Universe through observations of distant supernovae”.


Dan Shechtman

The Nobel Prize in Chemistry 2011 was awarded to Dan Shechtman “for the discovery of quasicrystals”.


Graphene Found to be Generating Electricity Under Light

October 8, 2011 Leave a comment

“Graphene, an exotic form of carbon consisting of sheets a single atom thick, exhibits a novel reaction to light, MIT researchers have found: Sparked by light’s energy, the material can produce electric current in unusual ways.

The finding could lead to improvements in photodetectors and night-vision systems, and possibly to a new approach to generating electricity from sunlight.

This current-generating effect had been observed before, but researchers had incorrectly assumed it was due to a photovoltaic effect, says Pablo Jarillo-Herrero, an assistant professor of physics at MIT and senior author of a new paper published in the journal Science.

The paper’s lead author is postdoc Nathaniel Gabor; co-authors include four MIT students, MIT physics professor Leonid Levitov and two researchers at the National Institute for Materials Science in Tsukuba, Japan.

Instead, the MIT researchers found that shining light on a sheet of graphene, treated so that it had two regions with different electrical properties, creates a temperature difference that, in turn, generates a current.

Graphene heats inconsistently when illuminated by a laser, Jarillo-Herrero and his colleagues found: The material’s electrons, which carry current, are heated by the light, but the lattice of carbon nuclei that forms graphene’s backbone remains cool.

It’s this difference in temperature within the material that produces the flow of electricity. This mechanism, dubbed a “hot-carrier” response, “is very unusual,” Jarillo-Herrero says.”

OPERA May Have Ignored Einstein for Neutrino Speed Calculation

October 7, 2011 Leave a comment

The OPERA experiment's stopwatch is coming under scrutiny.CERN

“Less than two weeks after the revelation that ghostly particles called neutrinos had been spotted travelling faster than the speed of light, physicists are saying they have found flaws in the analysis that would stop the claim in its tracks…

Since the OPERA group’s 22 September announcement, more than 30 papers attempting to explain the result using various exotic theoretical models have been posted to the physics preprint server at

But one paper2, posted on 28 September by theorist Carlo Contaldi of Imperial College London, bears the distinction of being the first to challenge the experimental calculations.

The OPERA team timed the neutrinos using clocks at each location that were synchronized using GPS (Global Positioning System) signals from a single satellite. Contaldi’s paper says the group’s calculations do not take into account one aspect of Albert Einstein’s general theory of relativity: that slight differences in the force of gravity at the two sites would cause the clocks to tick at different rates.

Because of its location relative to the centre of Earth, the CERN site feels a slightly stronger gravitational pull than Gran Sasso. Consequently, a clock at the beginning of the neutrinos’ journey would actually run at a slower rate than a clock at the end. “It would reduce the significance of the result,” Contaldi says.”

Aquatic Invisibility Cloak Developed Using Carbon Nanotubes

October 5, 2011 Leave a comment

“Scientists have created a working cloaking device that not only takes advantage of one of nature’s most bizarre phenomenon, but also boasts unique features; it has an ‘on and off’ switch and is best used underwater.

The researchers, from the University of Texas at Dallas, have demonstrated the device’s ability to make objects disappear in a fascinating video.

This novel design, presented today, Tuesday 4 September, in IOP Publishing’s journal Nanotechnology, makes use of sheets of carbon nanotubes (CNT) – one-molecule-thick sheets of carbon wrapped up into cylindrical tubes…

Through electrical stimulation, the transparent sheet of highly aligned CNTs can be easily heated to high temperatures. They then have the ability to transfer that heat to its surrounding areas, causing a steep temperature gradient. Just like a mirage, this steep temperature gradient causes the light rays to bend away from the object concealed behind the device, making it appear invisible.

With this method, it is more practical to demonstrate cloaking underwater as all of the apparatus can be contained in a petri dish. It is the ease with which the CNTs can be heated that gives the device its unique ‘on and off’ feature.”

Two Light Beams Make One Photonic Crystal?

October 3, 2011 Leave a comment

“Photonic crystals have been one of the hottest topics in optics in the last 10 years. This research is born out of a desire to have precise control over light—similar to the semiconductor industry’s control over electrons. The current favorite way to do this is to construct devices that have a refractive index that varies on the scale of the wavelength of light.

These metamaterials are made by combining two different materials in a very precise way, leading to all sorts of fabrication headaches. This may change in the near future because a pair of researchers have shown that you might be able to create temporary photonic crystals in a single material simply by shining a couple of light fields on it.

As a starting point, the researchers noted that the refractive index experienced by light changes dramatically when the material it’s passing through can absorb the light—that is, the light frequency is coincident with an atomic resonance. So, if you choose a light field that has a frequency that is slightly higher than an atomic resonance frequency, it will experience a lower refractive index.

On the other hand, if you choose light with a frequency slightly lower than the atomic resonance, it will experience a larger refractive index and some absorption. This doesn’t appear to help though—to get a useful difference between the two refractive indices, the light field has to be very nearly resonant with the atomic resonance. Over very short distances, the light is lost to absorption.

In a fit of creativity, and, seemingly, ignoring reality, the researchers asked themselves what would happen if a light field were simultaneously at a frequency that was both higher and lower than an atomic resonance? Of course, this can’t be the same atomic resonance, that would be too bizarre. Instead, the light is sandwiched between two neighboring resonances. One atomic resonance provides gain and the other absorption, with the two balancing exactly. Under these circumstances, the refractive index could be made to vary strongly.”

US Military Air Drones May Get Insect Hair Coats

October 3, 2011 Leave a comment

“For years, the military has turned to the birds and the bees for inspiration, churning out mechanical hummingbirds and remote-controlled insect cyborgs.

Now the Pentagon wants its mini-drones to have hairy wings and bug eyes, too. It’ll help the tiny machines spy on — and creep out — any enemies, military researchers promise…

Nature will be the engineers’ muse. A project to equip MAVs with hair-like sensors hopes to produce “the flight efficiency and agility of the hawkmoth,” the insect known for its hovering flight patterns.

To figure out how MAVs could keep flying smoothly even when the wind pipes up, another group is looking at how hair cells on bees’ bodies sense changes in air flow.”

Plastic “Magic Carpet” Created – Inspired By Indian-Origin Scientist

October 1, 2011 Leave a comment

“A miniature magic carpet made of plastic has taken flight in a laboratory at Princeton University.

The 10cm (4in) sheet of smart transparency is driven by “ripple power”; waves of electrical current driving thin pockets of air from front to rear underneath.

The prototype, described in Applied Physics Letters, moves at speeds of about a centimetre per second.

Improvements to the design could raise that to as much as a metre per second.

The device’s creator, graduate student Noah Jafferis, says he was inspired by a mathematical paper he read shortly after starting his PhD studies at Princeton…

Harvard University’s Lakshminarayanan Mahadevan, who wrote the 2007 paper in Physical Review Letters that inspired the whole project, expressed a mixture of surprise and delight at the Princeton team’s success.”