TWO CENTURY Hans Christian Oersted, a Danish physicist previously, had shown that the motion of electric charge creates magnetism. This is the first observation of a large-scale phenomenon. Charged clouds of particles floating in the universe create vast interstellar magnetic fields as they move. The implosion of molten metal in Earth̵7;s core creates poles from the north and south of the planet. Even the firing of nerve cells in the human brain produces microscopic amounts of magnetism.
However, the ubiquity of such electrically generated magnetic fields brings problems from practical to esoteric. The doctors are looking MRI scanning, for example, must compensate for background magnetism. Meanwhile, experimentalists conducting precision tests may have to fabricate complex shields to obscure the magnetic field effects of something as simple as a wire running through a lab wall. their.
Hence, it is useful to be able to control, limit or shape the magnetic field from a distance. Useful, but unlikely. In 1842, Samuel Earnshaw, an English physicist, mathematically proved that the maximum strength of the magnetic field cannot be outside its source. In other words, all such fields must surround and radiate from the object that created it. And it all happened until Rosa Mach-Batlle of the Autonomous University of Barcelona discovered how Earnshaw’s conclusions could be hinged. She didn’t really prove him wrong. But she showed that multiple magnetic fields, each that obeys an individual Earnshaw’s theorem, can appear to overcome it.
As they describe in Letter of physical assessment, Dr. Mach-Batlle and her colleagues drew their tips in a surprisingly simple way, by arranging 20 straight ropes side by side in a cylindrical 40cm high and 8cm diameter, with 21st runs through the center of the cylinder. As they pass electric current through all 21 wires, a complex pattern of magnetic field lines expands around, forming shapes that change with the intensity and direction of each current.
By choosing the right combination of currents, the researchers found that they were able to generate a field pattern emanating from the virtual version of the 21st wire that does not pass through the middle of the cylinder but 2cm outside it. In other words, if the resulting device was shielded from an observer, Wizard of Oz type, with a curtain, it would see that observer as if this field had emerged from nothing.
Going from Dr. Mach-Batlle’s demonstration to something that can be practically used to control a magnetic field at a distance will be a long journey. But if that journey can be done, the potential applications will go beyond blurring MRI to scan. This type of remote casting fields can be used to direct medical nanobots to pass through someone’s bloodstream to deliver drugs to a specific tissue or alternatively to direct them to a malignant tumor. and raise their temperature from a distance when they arrive, to cook it to death. There may also be applications in quantum computing. Many designs for quantum computers rely on trapping atoms at precise locations in space – a difficult feat this hand can simplify.
The trick still requires tweaking. To achieve such desired applications, the team needs to be able to generate complex magnetic fields in three-dimensional space. Currently, due to the limitation in simulating the field generated by a single wire, they cannot do this. But it should be remembered that Oersted’s initial experiment, from which all electrical engineering went down, was even simpler. It consists of just a battery, a magnetic compass and a wire. Large oak trees grow from small oak trees.■
This article appeared in the Science & Technology section of the printed edition with the title “Out of the field on the left”