Friday morning, and with it the weekly column "A Taste of Physics" — issue #46.
This time: how to make objects levitate, and the connection to the climate crisis and quantum computing.
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The ability to make objects levitate carries enormous significance.
We know it from the world of transportation, where maglev trains fly along magnetic tracks, but the potential implications reach into many other fields as well.
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There are many ways to make objects levitate.
In the video you can see quantum levitation of a superconductor.
It occurs when certain materials are cooled to an extremely low temperature (around minus 200 degrees!), causing them to generate a magnetic field that opposes the surrounding magnetic field — and thus to levitate.
Although we tend to picture this as ordinary repulsion between magnets, there is an important difference between the two phenomena.
When ordinary magnets repel each other, each magnet's field penetrates the other to some degree.
A cooled superconductor is diamagnetic — the magnetic field cannot penetrate it at all; instead it flows around it. This is known as the Meissner effect.
Not every superconductor levitates in a stable and perfect manner.
Superconductors like the one in the video allow tiny magnetic fields to penetrate the defects on their surface and become pinned there like pegs, thereby locking the superconductor in place.
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Microscopic particles can also be made to levitate using a laser.
Photons — particles of light — carry energy that pushes the particles they strike.
This technology is found in "optical tweezers," which use a laser to control the movement of levitating particles.
The inventor of optical tweezers was awarded the Nobel Prize for this work in 2018.
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An even stranger method is making ultra-thin sheets of material levitate via the Casimir effect.
Casimir was a Dutch physicist who hypothesized that because even a vacuum contains energy, slight variations in that energy would cause surfaces to attract each other even in a perfect vacuum.
In particularly complex theoretical scenarios, Casimir forces can also produce repulsion and thus create levitation — a phenomenon that has not yet been observed in reality.
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Despite the efficiency of existing maglev trains, finding a way to develop a superconductor that works at normal temperature and pressure could constitute a genuine revolution.
There has been considerable progress in researching the subject, yet an effective solution for commercial use does not yet exist.
All the devices we use wear down and lose enormous amounts of energy through friction and resistance, and using superconductors for electricity transmission and transportation would reduce energy emissions by a tremendous margin.
In the world of quantum computing, levitating qubits could in the future prove especially efficient, because levitation within a magnetic field would better isolate them from the waves and fields that interfere with their proper functioning.
Shabbat Shalom 😊
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