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Category: physics – Page 218

Congratulations from Ogba Educational Clinic.

The 2020 Nobel Prize for Physics has been awarded to Roger Penrose, Reinhard Genzel and Andrea Ghez for their work on black holes.

The prize is worth 10 million Swedish krona (about $1.1 million) and half goes to Penrose, with Genzel and Ghez sharing the other half of the prize.

The Nobel Committee cites Penrose “for the discovery that black hole formation is a robust prediction of the general theory of relativity”, and Genzel and Ghez “for the discovery of a supermassive compact object at the centre of our galaxy”.

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Compressing simple molecular solids with hydrogen at extremely high pressures, University of Rochester engineers and physicists have, for the first time, created material that is superconducting at room temperature.

Featured as the cover story in the journal Nature, the work was conducted by the lab of Ranga Dias, an assistant professor of physics and mechanical engineering.

Dias says developing materials that are superconducting—without electrical resistance and expulsion of magnetic field at room temperature—is the “holy grail” of condensed matter physics. Sought for more than a century, such materials “can definitely change the world as we know it,” Dias says.

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Einstein’s theory of special relativity gave us the speed limit of the Universe — that of light in a vacuum. But the absolute top speed of sound, through any medium, has been somewhat trickier to constrain.

It’s impossible to measure the speed of sound in every single material in existence, but scientists have now managed to pin down an upper limit based on fundamental constants, the universal parameters by which we understand the physics of the Universe.

That speed limit, according to the new calculations, is 36 kilometres per second (22 miles per second). That’s about twice the speed of sound travelling through diamond.

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Could this be the energy source of the future?

The secret to the SPARC reactor is that its magnets will be built from new high-temperature superconductors that require much less cooling and can produce far more powerful magnetic fields. That means the reactor can be ten times more compact than ITER while achieving similar performance.

As with any cutting-edge technology, converting principles into practice is no simple matter. But the analysis detailed in the papers suggests that the reactor will achieve its goal of producing more energy than it sucks up. So far, all fusion experiments have required more energy to heat the plasma and sustain it than has been generated by the reaction itself.

The SPARC reactor is designed to achieve a Q factor of at least two, which means it will produce twice as much energy as it uses, but the analysis suggests that figure might actually rise to ten or more. The papers used the same physics and simulations as the ITER design team and other previous fusion experiments.

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Applying a temperature gradient and a charge current to an electrical conductor leads to the release and absorbtion of heat. This is called the Thomson effect. In a first, NIMS and AIST have directly observing the magneto-Thomson effect, which is the magnetic-field-induced modulation of the Thomson effect. This success may contribute to the development of new functions and technologies for thermal energy management and to advances in fundamental physics and materials science on magneto-thermoelectric conversion.

The Seebeck effect and the Peltier effect have been extensively investigated for their application to thermoelectric conversion technologies. Along with these effects, the Thomson effect has long been known as a fundamental thermoelectric effect in metals and semiconductors. Although the influence of magnetic fields and magnetism on the Seebeck and Peltier effects has been well understood as a result of many years of research, the influence on the Thomson effect has not been clarified because it is difficult to measure and evaluate.

This NIMS-led research team observed heat release and absorption induced in an electrical conductor by simultaneously creating a temperature gradient across it, passing a charge current through the gradient, and applying a magnetic field. The team precisely measured temperature changes in the conductor associated with the heat release and absorption using a heat detection technique called lock-in thermography. As a result, the amount of heat released and absorbed was found to be proportional to both the magnitude of the temperature gradient and charge current. In addition, the team observed strong enhancement of the resultant temperature change when a magnetic field was applied to the conductor. The systematic measurements performed in this study demonstrated that the heat release and absorption signals detected under a magnetic field were indeed generated by the magneto-Thomson effect.

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They can be made up of just two surfaces, bouncing the wave between them, but the more surfaces that are added, the more resonance is achieved. The ultimate is therefore to create a perfect sphere, creating surfaces in every direction within a three-dimensional object. At that point, the creation of a resonator moves from being a physics question to one of engineering, since even a stem holding the sphere can create distortion that reduces the impact of the resonator.

According to the Technion, the world’s first micro-resonator was demonstrated in the 1970s by Arthur Ashkin, winner of the 2018 Nobel Prize in Physics, who presented a floating resonator. Yet, despite the success of his innovation, the research direction was soon abandoned.

Now graduate student Jacob Kher-Alden, under the supervision of Prof. Tal Carmon, has built upon Ashkin’s work, creating a floating resonator which can exhibit resonant enhancement by ten million circulations of light, compared to about 300 circulations in Ashkin’s resonator.

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