The hunt for the 'angel particle' continues
In 2017, researchers believed they had found evidence for the elusive Majorana fermion. Now, a new study found that the exotic class of particles may still be confined to theory.
- In 2017, researchers believed they had found evidence for the so-called "angel particle"; that is, a Majorana fermion.
- Majorana fermions differ from regular fermions in that they are their own antiparticles.
- New research shows that the previous finding was due to an error in the scientists' experimental device. Thus, it's back to the drawing board in the search for the Majorana fermion.
A theoretical class of particles called Majorana fermions remains a mystery. In 2017, scientists believed they had uncovered evidence for the existence Majorana fermions. Unfortunately, recent research shows that their findings were actually due to a faulty experimental device, bringing researchers back to the drawing board in the search for the exotic particles.
What are Majorana fermions?
The Standard Model of particle physics currently is our best means of explaining the fundamental forces of the universe. It classifies the various elementary particles, like photons, the Higgs boson, and the various quarks and leptons. Broadly, its particles are divided into two classes: Bosons, like the photon and Higgs, and fermions, which comprise the quarks and leptons.
There are a few major differences between these types of particles. One, for instance, is that fermions have antiparticles, while bosons do not. There can be an anti-electron (i.e., a positron), but there's no such thing as an antiphoton. Fermions also can't occupy the same quantum state; for instance, electrons orbiting an atom's nucleus can't both occupy the same orbital level and spin in the same direction — two electrons can hang out in the same orbital and spin in opposite directions because this represents a different quantum state. Bosons, on the other hand, don't have this problem.
But back in 1937, a physicist named Ettore Majorana discovered that there a different, unusual kind of fermion could exist; the so-called Majorana fermion.
All the fermions in the Standard Model are referred to as Dirac fermions. Where they and Majorana fermions differ is that the Majorana fermion would be its own antiparticle. Because of this quirk, the Majorana fermion has been nicknamed the "angel particle" after the Dan Brown novel "Angels and Demons," whose plot involved a matter/anti-matter bomb.
A "smoking gun"?
Until 2017, however, there remained no definitive experimental evidence for Majorana fermions. But during that year, physicists constructed a complicated experimental device involving a superconductor, a topological insulator — which conducts electricity along its edges but not through its center — and a magnet. The researchers observed that in addition to electrons flowing along the edge of the topological insulator, this device also showed signs of producing Majorana quasiparticles.
Quasiparticles are an important tool that physicists use when searching for evidence of "real" particles. They aren't the real thing themselves, but they can be thought of as disturbances in a medium that represent a real particle. You can think of them like bubbles in a Coca Cola — a bubble itself isn't an independent object, but rather a phenomenon that emerges from the interaction between carbon dioxide and the Coca Cola. If we were to say there was some hypothetical "bubble particle" that really existed, we could measure the "quasi"-bubbles in a Coca Cola to learn more about its characteristics and provide evidence for this imaginary particle's existence.
By observing quasiparticles with properties that matched theoretical predictions of Majorana fermions, the researchers believed that they had found a smoking gun that proved these peculiar particles really existed.
Regrettably, recent research showed that this finding was in error. The device that the 2017 researchers used was only supposed to generate signs of Majorana quasiparticles when exposed to a precise magnetic field. But new researchers from Penn State and the University of Wurzburg found that these signs emerged whenever a superconductor and topological insulator were combined regardless of the magnetic field. The superconductor, it turns out, acted as an electrical short in this system, resulting in a measurement that looked right, but was really just a false alarm. Since the magnetic field wasn't contributing to this signal, the measurements didn't match theory.
"This is an excellent illustration of how science should work," said one of the researchers. "Extraordinary claims of discovery need to be carefully examined and reproduced. All of our postdocs and students worked really hard to make sure they carried out very rigorous tests of the past claims. We are also making sure that all of our data and methods are shared transparently with the community so that our results can be critically evaluated by interested colleagues."
Majorana fermions are predicted to appear in devices where a superconductor is affixed on top of a topological insulator (also referred to as a quantum anomalous Hall insulator [QAH]; left panel). Experiments performed at Penn State and the University of Würzburg in Germany show that the small superconductor strip used in the proposed device creates an electrical short, preventing the detection of Majoranas (right panel).
Cui-zu Chang, Penn State
Why does this matter?
Beyond the intrinsic value of better understanding the nature of our universe, Majorana fermions could be put to serious practical use. They could lead to the development of what's known as a topological quantum computer.
A regular quantum computer is prone to decoherence — essentially, this is the loss of information to the environment. But Majorana fermions have a unique property when applied in quantum computers. Two of these fermions can store a single qubit (the quantum computer's equivalent of a bit) of information, as opposed to a regular quantum computer where a single qubit of information is stored in a single quantum particle. Thus, if environmental noise disturbs one Majorana fermion, its associated particle would still store the information, preventing decoherence.
To make this a reality, researchers are still persistently searching for the angel particle. As promising as the 2017 research appeared, it looks like the hunt continues.
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Whether or not women think beards are sexy has to do with "moral disgust"
- A new study found that women perceive men with facial hair to be more attractive as well as physically and socially dominant.
- Women tend to associate more masculine faces with physical strength, social assertiveness, and formidability.
- Women who display higher levels of "moral disgust," or feelings of repugnance toward taboo behaviors, are more likely to prefer hairy faces.
Beards and perceptions of masculinity<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjU5OTg0MC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY0NzkxMjM3N30.cH-GqNwP5GVqvstgJWAhBPn1B_lYpVEAI0I7iax7EQw/img.jpg?width=1245&coordinates=0%2C1900%2C0%2C849&height=700" id="caae6" class="rm-shortcode" data-rm-shortcode-id="cb0a355a4e8e1899789bc45f3f7aef56" data-rm-shortcode-name="rebelmouse-image" />
Photo Credit: Wikimedia<p>The study used 919 American (mostly white) women ages 18-70 who rated 30 pictures of men they were shown with various stages of facial hair growth. The photographs depicted men with faces that had been digitally altered to look more feminine or more masculine, with a beard and without a beard. The women rated the men according to perceived attractiveness for long-term and short-term relationships. The study found that the more facial hair the men had, the higher the men were rated on their attractiveness, particularly for their suitability for a long-term relationship.</p><p>Part of this might be attributed to facial masculinity — i.e. protruding brow ridge, wide cheekbones, thick jawline, and deeply set narrow eyes — which conveys information to a woman about a man's underlying health and formidability. Women tend to associate more masculine faces with physical strength and social assertiveness. It can also indicate a man with a superior immune response. The researchers suggested that their findings favoring bearded men could be due to the fact that facial hair enhances the masculine facial features on a man's face, like creating the illusion of a thicker jaw line. This could communicate direct benefits to women like resources and protection that would enhance survival among mothers and their infants. In other words, while a beard doesn't mean superior genetics in and of itself, it might be a primitive, ornamental way of saying, "Hey girl, I'm a testosterone-fueled lean, mean, pathogen fighting machine." <br></p><p>It could also be that a beard becomes its own destiny. The researchers in this study cite prior research that found that by growing a beard, men felt more masculine and had higher levels of serum testosterone, which was linked to a higher level of social dominance. They also tended to subscribe to more old-school beliefs about gender roles in their relationships with women as compared to men with clean-shaven faces.<span></span><br></p>
What does disgust have to do with beard preference?<p>Obviously, not all women dig beards. The researchers were particularly interested in what traits make a women prefer bearded men over clean-shaven faces. They looked into several factors including a woman's disgust levels on various concepts, her desire to become pregnant, and her exposure to facial hair in her personal life. </p><p>According to the study, women who were not into facial hair were turned-off by potential parasites or other critters they imagined could be in the hair or skin. Women ranking high on this "ectoparasite disgust" scale might have viewed beards as a sign of poor grooming habits. However, women who ranked higher in levels of "pathogen" did find the bearded men to be desirable, possibly because they perceived beards as a signal of good health and immune function. An intriguing discovery in the study was links to morality. Women who displayed higher levels of "moral disgust," or feelings of repugnance toward taboo behaviors, were more likely to prefer hairy faces. The authors opined that this could reflect a link between beardedness, politically conservative outlooks, and traditional views regarding performances of masculinity in heterosexual relationships.</p>
Additional findings<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjU5OTg1My9vcmlnaW4uZ2lmIiwiZXhwaXJlc19hdCI6MTYyNDI1NjUyOX0.P9B8WbmJR0q4nfzYZKbuNSA-2SAigVWJgrQE-_Gxlds/img.gif?width=980" id="49143" class="rm-shortcode" data-rm-shortcode-id="2ed3b1d6f20fc170bf2974646e565e8d" data-rm-shortcode-name="rebelmouse-image" />Giphy<p>The correlations that existed between married and single women's rating on the attractiveness of beards were not particularly clear, although the researchers noted that single and married women who wanted children tended to find beards more attractive than the women who didn't want children. They also found that women with bearded husbands found beards to be more attractive, which might indicate that social exposure to beards influences how desirable they are perceived of as being. Or it could be that men with wives who like beards grow beards.</p><p>It's important to note that culture plays a huge role in how attractive women perceive certain male characteristics as being. This study looked at a small, culturally specific group of American women, so no big, universal claims should be made about masculinity, facial hair, and male desirability to women. However, research like this is important in highlighting how human grooming decisions are driven by much more than fashion trends. Sociobiological, economic, and ecological factors all play a part in the way we choose to present ourselves.</p>
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