Physicists discover particle that is its own antiparticle


Physicists at Princeton University have found something that people have spent decades searching for: a particle that is its own antiparticle.

It's even cooler than it sounds. The physicists found a glowing image of a particle known as "Majorana fermion" at the end of an atomically thin wire while looking through a two-story-tall microscope in one of the labs at Princeton. They published their research in the journal Science on Oct. 2, 2014.

Researchers have speculated about this particle's existence since as early as the 1930s. The discovery of the particle could eventually lead to computers that use quantum mechanics.

The particle takes its name from Italian physicist Ettore Majorana who in 1937 predicted that a single, stable particle could be both matter and antimatter. Since then, physicists have found forms of antimatter, but it wasn't until now that they found a particle that also acts as its own antiparticle.

Before I go any further, let me just break down for you what this whole antimatter business is all about. In 1928, British physicist Paul Dirac created an equation to describe how an electron behaved at a relativistic speed. It turned out that the equation could have two solutions: one for an electron with positive energy and one for an electron with negative energy. So Dirac thought this meant that for every particle, there is an antiparticle that matched the particle in every way, except that it had an opposite charge. When matter and antimatter come together, it's even said to annihilate and disappear in a flash of energy.

For their experiment, the Princeton physicists placed a long chain of pure, magnetic iron atoms on a lead superconductor. They then cooled the materials to a temperature of -457 degrees Fahrenheit and watched them using the aforementioned two-story-tall microscope. The researchers found that the superconductivity in the iron wire matched the conditions needed to create the Majorana fermion.

The discovery of the Majorana fermion in a material like this is different than the discovery of other particles found in a vacuum in giant accelerators, such as the Higgs boson, where scientists collide particles at high speeds. When particles are found embedded in materials, the presence of the particles depends on or comes from the characteristics of the atoms and the forces around them.

The physicists found the Majorana fermion in a common form of magnetism in iron, even though many had previously thought it could only be found in "relatively exotic" forms. They expect to be able to find materials where Majoranas are even more stable in the future.


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