Scientists have come up with ways to create and counteract magnetic fields from a distance.
In this method, a current is passed through a special wire arrangement, magnetic field It looks as if it came from another source. This illusion has real uses. Imagine an anticancer drug that can be delivered directly to a deep tumor in the body by a capsule made of magnetic nanoparticles. It is not possible to pierce a tumor with a magnet to induce the movement of nanoparticles, but if a magnetic field can be created from outside the body around the tumor, the drug can be delivered without invasive procedures.
The strength of the magnetic field decreases with distance from the magnet, and Earnshaw’s theorem, a theorem proved in 1842, states that it is impossible to create a spot of maximum magnetic field strength in empty space. I am.
“If you cannot set the maximum magnetic field in the empty space, it means that you cannot remotely create the magnetic field of the magnetic source without placing the actual magnetic field. [magnetic] Rosa Mach-Batlle, a physicist at the Istituto ItalianoDi Tecnologia Center for Biomolecule Nanotechnologies in Italy, who led the new study, said:
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Make the hypothesis a reality
However, Mach-Batlle and her colleagues thought that the problem could be avoided. They use engineering materials known as metamaterials (designed to have properties not found in naturally occurring materials) to avoid the resolution limitation set by the wavelength of light. Inspired by my research. Similarly, they thought that virtual magnetic materials might make the impossible possible in the world of magnetic fields.
Researchers have assumed a material with a negative magnetic permeability of 1. The magnetic permeability of a material indicates how much the magnetic field is increased or decreased when the material is exposed to a magnetic field. For materials with a negative magnetic permeability of 1, Magnetism induced in the material It is opposite to the direction of the initial magnetic field.
Of course, new methods of inducing magnetic fields that depend on non-existent materials are not particularly useful. However, there is no fictitious material with this negative permeability, but physicists can create a kind of temporary “material” from the current flowing through a particular wire arrangement. This is because the electric current induces magnetism and vice versa. This is the result of Maxwell’s electromagnetic equation.
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“In the end, we don’t use any material, we use the exact placement of the current that can be considered an active metamaterial,” Mach Battle told Live Science.
To create the field from a distance, Mach-Batlle and her team created a hollow cylinder made up of about 20 wires surrounding one long internal wire. Current flow through these wires creates a magnetic field that makes the long internal wires appear to be actually outside the device. This is electromagnetically equivalent to a ventriloquist speaking out. The source of the field is not really outside the device, but the field itself is indistinguishable from the field that occurs when the source is outside the device.
“We create the illusion that this source is far apart,” said Mach Battle.Researchers published their findings in the journal on October 23 Physical Review Letter
Biomedical application
There are still questions about how well this method works in real-world applications. One of the quirks of this system is that there is a very strong magnetic field region between the wire cylinder and the distance field. According to Mach Battle, the region can hinder some applications of research, but problems will probably depend on what you are trying to do in the area.
Possible applications other than drug delivery include magnetic field cancellation from a distance. This is a technique that can be useful in quantum computing to reduce “noise” from external magnetic fields that can interfere with measurements. Another use may be to improve transcranial magnetic stimulation. It uses magnets to stimulate and treat neurons in the brain. depression .. Physicians say that being able to control the magnetic field at a distance may improve the targeting of transcranial magnetic stimulation. Human brain ..
Researchers then want to build a wire configuration that allows them to create a 3D magnetic field from a distance.
Originally published in Live Science.
Physicists can do the “impossible”: create and destroy a magnetic field from a distance
