Amen to that.
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All you need is science.
Invisibility cloaking goes thermodynamic
Researchers in France have shown how to isolate or “cloak” objects from sources of heat – a breakthrough that could help cool down electronic devices and thereby pave the way towards more powerful computers. They also show how the same technique could be used to concentrate heat, which might prove useful in advanced solar technologies.
Invisibility cloaks are based on the mathematics of transformation optics – bending light such that it propagates round a space, rather than through it – and were proposed by John Pendry of Imperial College in London and Ulf Leonhardt of the University of St Andrews in 2006. Now, Sebastien Guenneau of the University of Aix-Marseille and colleagues at the French national research council (CNRS) wondered whether a similar thing could be done with heat. While intuitively, it might seem unlikely that the same mathematics could be applied to thermal diffusion, given that heat does not propagate as a wave but simply diffuses; the researchers found that the transformed equation worked.
How wings really work
It’s one of the most tenacious myths in physics and it frustrates aerodynamicists the world over. Now, University of Cambridge’s Professor Holger Babinsky has created a 1-minute video that he hopes will finally lay to rest a commonly used yet misleading explanation of how wings lift.
“A wing lifts when the air pressure above it is lowered. It’s often said that this happens because the airflow moving over the top, curved surface has a longer distance to travel and needs to go faster to have the same transit time as the air travelling along the lower, flat surface. But this is wrong,” he explained. “I don’t know when the explanation first surfaced but it’s been around for decades. You find it taught in textbooks, explained on television and even described in aircraft manuals for pilots. In the worst case, it can lead to a fundamental misunderstanding of some of the most important principles of aerodynamics.”
To show that this common explanation is wrong, Babinsky filmed pulses of smoke flowing around an aerofoil (the shape of a wing in cross-section). When the video is paused, it’s clear that the transit times above and below the wing are not equal: the air moves faster over the top surface and has already gone past the end of the wing by the time the flow below the aerofoil reaches the end of the lower surface.
One step closer to controlling nuclear fusion
Using a heating system, physicists have succeeded for the first time in preventing the development of instabilities in an efficient alternative way relevant to a future nuclear fusion reactor. It’s an important step forward in the effort to build the future ITER reactor.
Scientists have achieved a milestone: they have managed to stop the growth of instabilities inside a nuclear fusion reactor. How? Here’s a look at this energy source, which despite being challenging to control, is nevertheless extremely promising.
Nuclear fusion is an attempt to reproduce the energy of the Sun in an Earth-based reactor system. When gas is heated to several million degrees, it becomes plasma. Sometimes in the plasma, an instability will appear and grow large enough to perturb the plasma, making it vibrate despite the presence of the magnetic field in which it is contained. If the plasma touches the walls of the reactor, it will cool rapidly and create large electromagnetic forces within the structure of the machine.
The challenge is to reduce the instabilities deep within in the interior of the plasma so that they don’t amplify, while at the same time allowing the reactor to continue to function normally. Thus it is necessary to work within the specific configuration of these fusion reactors, where the plasma is strongly confined by a magnetic field. By adjusting an antenna that emits electromagnetic radiation, physicists from EPFL’s Center for Research in Plasma Physics were able to quench the instabilities when they appear, in the precise region where they are forming, and without perturbing the rest of the installation.
Physicists propose test for loop quantum gravity
As a quantum theory of gravity, loop quantum gravity could potentially solve one of the biggest problems in physics: reconciling general relativity and quantum mechanics. But like all tentative theories of quantum gravity, loop quantum gravity has never been experimentally tested. Now in a new study, scientists have found that, when black holes evaporate, the radiation they emit could potentially reveal “footprints” of loop quantum gravity, distinct from the usual Hawking radiation that black holes are expected to emit.[more]
cwnl:
Lasers Measure Earth’s Rotation and Wobble
The Earth spins around once every 24 hours on its axis, creating the continuous cycle of day and night. But this rotation isn’t as straightforward as it sounds: Forces large and small cause the Earth to wobble as it spins. This wobbling can pose a problem for navigation systems like GPS.
Scientists working with lasers and mirrors are refining a new system to track the Earth’s rotation and its kinks.
The pull of gravity from the sun and the moon contribute to the planet’s wobble. So do variations in atmospheric pressure, ocean loading and the wind, which change the position of the Earth’s axis relative to the surface. Together their effect is called the Chandler wobble, and it has a period of 435 days.
Another force causes the rotational axis to move over a period of a year. This “annual wobble” is due to the Earth’s elliptical orbit around the sun.
