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Now you see me, now you don't
Prof Yash
Pal
THIS UNIVERSE
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Now you see me, now you don't
As far as 800 BC the concept was being discussed in the Greek Myths. Perseus is said to have worn the invisible cap of Hades to defeat Medusa. Forget the space race, the rat race; it’s the dawn of the invisibility race. Around the globe teams of researchers are undertaking the task of creating the first functioning cloaking devices. So what’s on offer to muggles craving to camouflage? Perhaps the most well-known are cloaks developed at the University of Tokyo. Don a retro reflective coat and you vanish! Maybe not; remember to buy a video camera, computer and projector first. The background is captured, processed via a computer before projecting the image on a coat with aid of a combiner (special mirror). As light is reflected in the same path it enters from one perspective our wizarding trio would be invisible. Whilst from another completely visible if not A more interesting avenue is of using artificially created “meta materials” engineered to have properties not found in nature. They gain all their properties from structure alone and like rocks in a river divert water, cause light waves to curve around an object. Thereby allowing the observer to not see what lies before them. This could also eliminate noise when applied to sound waves. Recently researchers at the Karlsruhe Institute of Technology, made a breakthrough — the first meta material to work in 3-D. Although at its current size it hides gold 0.0005 inches in width, lead researcher Tolga Ergin told the Guardian: “In principle, the cloak design is completely scalable; there is no limit to it”. Another landmark in the field of transformation optics arrived when researchers at the University of St Andrew’s produced the first flexible meta material capable of creating a smart fabric. At the same time naturally occurring calcite crystals have been utilised to hide paperclips amongst other stationary. Why capture invisibility? Of course it’s innately fascinating but there is more to such technology than meets the eye. If and when created it is likely to have an impact on fields that have previously not been thought of. One possibility currently being explored are cars capable of optical camouflage – blind spots such as pillars would be simply see through when required (what would Jeremy Clarkson say?). Imagine a pilot looking below at the cockpit floor to see the runway instead of relying on computers or autopilot to land. Consider surgical equipment that projects images of organs beneath while retaining a visible shape reducing obstruction. All this without mentioning MI5 or the SAS! Although one thing is for certain: once a definitive invisibility cloak is established another hunt is likely to ensue – the race for the de-cloaking device. —The Independent |
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THIS UNIVERSE
Paper consists of a large number of short and long entangled fibres. When you tear the paper these fibres stretch and scratch each other. The stretched fibres also vibrate at a low frequency. This might be the reason for the sound that emerges. You might also note that tearing wet paper does not make that much noise, in fact none at all. This might be due to the fact that lubricated fibres slide out easily — small fibres get disentangled and slip out quietly. Also water laden heavy fibres do not vibrate.
Why is the flame of a match-stick or a lamp always in the upward direction? Shouldn’t the gravitational force attract it downwards? A flame is a happening in which a fuel burns to produce energy in an environment that supports convection. Take an oil lamp, for an example. When we light the lamp the oil on the wick begins to burn. Burning implies that the oil vapour and oxygen in the air combine to produce energy. This energy heats up the carbon particles which begin to glow. The energy is produced through burning of carbon and hydrogen that is in the hydrocarbon in the oil. The chemical reaction that produces energy also results in production of new products like carbon dioxide and water vapour. These gases are hot, as is the air that comes in to sustain burning. Carbon particles become red hot and emit light. The heated gases rise because they are lighter than the air that is supplied from below. This is called convection and exists because of gravitation. Gravitation is the cause of hot gases rising. It does not stop them from rising as you suggested. What happens is just the reverse of what you suspect. Indeed flames of about similar shape are produced because of convection. I might mention that if we light a candle in the weightless environment of a spacecraft we will not see a flame of the kind we see on earth. In a weightless condition there is no convection. An inverted image of what we see falls on our retina and the optic nerves send that image to our brain. However, everything that we see is everted? How? I could reply simply by saying: “Please give the fantastic computer in our head at least as much respect as you do to your laptop which can rotate or tilt a screen image any way you like”. You also know that your brain combines two different images by your two eyes to give one three dimensional image. Basically, our eye is not a simple box camera with a lenses and a screen. It also includes our brain. Readers wanting to ask Prof Yash Pal a question can e-mail him at palyash.pal@gmail.com |
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Trends
MOSCOW: Six astronauts were forced to take refuge aboard the International Space Station’s “lifeboat” crafts on Tuesday, bracing for the threat of a collision with floating space debris, the Russian space agency said. “A situation arose linked to unidentified ‘space trash’ passing very close to the space station. The crew was told to take their places aboard the Soyuz spacecraft,” Roskomos said in a statement. E.coli seen spawning bio-fuel in five years ASPEN, Colorado: The bacteria behind food poisoning worldwide, the mighty E.coli, could be turned into a commercially available bio-fuel in five years, a U.S. scientist told technology industry and government leaders on Tuesday. Several companies are working on the technology, which has been proven in laboratories but is not yet yielding enough fuel to be commercially viable, scientist Jay Keasling told the Aspen Ideas Festival on Tuesday. NASA clears last space shuttle for blast-off CAPE CANAVERAL, Florida: NASA managers cleared space shuttle Atlantis on Tuesday for a July 8 launch, approving it for a cargo run to the International Space Station and the final flight in the 30-year-old shuttle program. Lift-off of the shuttle manned by a minimal crew of four astronauts is set for 11:26 a.m. EDT from the Kennedy Space Center in Florida. Near-Earth asteroid passes over Atlantic Ocean LOS ANGELES: An asteroid with an estimated girth as large as a garbage truck soared within 7,500 miles of the Earth on Monday as it passed harmlessly over the Atlantic Ocean, according to NASA’s Jet Propulsion Laboratory. The space rock, measuring 5 to 20 meters in diameter, followed the same near-Earth path that scientists had earlier predicted, looping around the planet in a boomerang-shaped trajectory, JPL spokesman D.C. Agle said. Benefit of mammograms even greater than thought CHICAGO: The longest-running breast cancer screening study ever conducted has shown that regular mammograms prevent deaths from breast cancer, and the number of lives saved increases over time, an international research team said on Tuesday. The study of 130,000 women in two communities in Sweden showed 30 percent fewer women in the screening group died of breast cancer and that this effect persisted year after year. Gene machines may help save Tasmanian devil CHICAGO: Scientists are using high-tech gene sequencing machines in a desperate attempt to save the Tasmanian devil from an infectious cancer called devil facial tumour disease that is threatening to wipe out the species. “The disease is like nothing we know in humans or in virtually any other animal. It acts like a virus but it actually is spread by a whole cancerous cell that arose in one individual several decades ago,” Penn State University’s Stephan Schuster, who is working on the project, said in a statement. — Reuters |
When J.K Rowling penned Harry Potter and the Philosopher’s stone, she captured the minds of teenagers and adults alike to the endless possibilities posed by an Invisibility Cloak – not to mention the mischief.
