Hello, Majorana: Reminding the Higgs That Particle Physics Doesn’t Revolve Around It

There is a delicate symmetry in the world of particle physics. For every particle, there is an antiparticle of the same mass but opposite charge. Antimatter is not just the stuff of science fiction- it is a very real thing, but we can’t run across it when out for a walk. When a particle and its antiparticle meet, they annihilate, releasing photons. Due to CP violation (which we discussed a few years ago), we have an abundance of matter in the universe, but little antimatter.

But what if I told you there was a particle that spit on that symmetry? A particle that is its own antiparticle.

Galleons, meet the Majorana fermion.

Back in the 1930s, a physicist by the name of Ettore (you guessed it) Majorana¹ predicted that quantum theory allowed for a special little fermion that hovered right on the border between matter and antimatter, making that single fermion its own particle-antiparticle pair.

Over the years, most predicted particles have been found. Noted exceptions are the attention-whore Higgs boson and the quieter Majorana fermion.

Well, looks like we can check the Majorana fermion off the list, dear galleons, because a group of scientists at TU Delft’s Kavli Institute and the Foundation for Fundamental Research on Matter have found it. Led by nanoscientist Leo Kouwenhoven, the scientists created a rather unique way of finding the elusive Majorana fermion. See, we usually detect particles by smashing beams of protons or protons/anti-protons or what-have-you together in supercolliders. The resulting particle spray hits the detectors and is analyzed for anomalies, which leads to the discovery of new particles. But even the LHC, beast though it may be, isn’t quite sensitive enough to detect the super-elusive Majorana. However, our scientists realized there was another solution: nanostructures.

Kouwenhoven and his team created a nanoscale electrical device out of indium antemonide nanowire,  superconducting niobium contact, and a strong magnetic field:

Between the name of the fermion and the picture of the device created to detect it, I can't help but think that some sort of subatomic symphony was played to find the Majorana. Then again, I've always had a soft spot for correlations between music and physics (re: superstring theory).

Two particles appeared at either end of the device, particles that the team says can only be Majorana fermions. I’m going to trust them, because I’m too tired to slog through the technical specs of the experiment (maybe I’ll get around to it later- if so, I’ll update you with more information on the hows and whys of the Majorana detection).

Beyond the fact that they are interesting and unique particle specimens, Majorana particles are special for a few other reasons. There’s a theory that suggests that dark matter, that unknown quantity in our universe, is comprised of Majorana fermions (though it’s by no means the only, or even most popular, theory surrounding dark matter composition). What’s even more tantalizing about the Majorana fermion is the potential for use in quantum computing. A quantum computer based on Majorana fermions, due to their unique nature, is far more stable than your average quantum computer. It would be quite exciting if the stability of the Majorana fermion helped us move quantum computing out of the realm of theory and into the realm of reality.

Regardless, new particle.

Exciting stuff, my galleons.

1 Okay, I have to add this bit in here because Majorana himself was a rather interesting man. A brilliant Italian physicist, he was drawn to the field from a young age, and his prediction that the Majorana fermion existed arose from a previously unknown solution to the equations from which possible particles are deduced. Indeed, Majorana seemed a force to be reckoned with. He worked with legends like Heisenberg and Bohr. And yet… in 1938, on a boat trip from Palermo to Naple, Majorana disappeared. There are many proposed explanations for his disappearance: he committed suicide, he ran off to a monastery, he was kidnapped/killed to prevent him from working on atomic weaponry, he changed identities and became a beggar, etc. Regardless of all these theories, no one actually knows what happened to him. Majorana was never seen or heard from again.

Virtual Reality

it’s like this
there is a mirror and
there is a mirror
and they’re looking at each other
the question is
what do they see

~from The Casimir Effect, Chris Mansell

Okay, galleons, we get to talk about some exciting news in an area of quantum field theory that we have only briefly touched on once when discussing time travel way back when:

The Casimir effect.

Now, before we can discuss said news, we’re going to have to get some background on virtual particles, the physics of the vacuum of space according to quantum field theory, and a brief run-down on the Casimir effect itself.

Get comfortable, galleons.

***

When we imagine a vacuum, we imagine space devoid of matter. Completely. Empty.

Of course, that’s not entirely accurate. We consider outer space to be a high-quality vacuum, but it is, of course, not empty. It may contain only a few hydrogen atoms per cubic meter on average, but it is not completely empty. And even if we were to suck every last particle and bit of matter from a region of space… it still would never be entirely empty.

WHAT?!

You heard me. See, quantum physics is weird. There’s a reason Richard Feynman himself once said, “I think I can safely say that nobody understands quantum mechanics.” It’s confusing, defying all logic. Remember that, according to quantum physics, at the smallest levels (Planck levels), spacetime is a roiling, ever-shifting foam:

Like those wacky quantum fluctuations, there’s a thing called vacuum fluctuations, which yield things called virtual particles.

And what is a virtual particle? On occasion, things like particle decay happen via force carrier particles. And sometimes, these force carrier particles have more mass than the initial particle. What’s weird about these high-mass force carrying particles is that they seem to come out of nowhere, violating the laws of conservation of mass and energy.

However, these oddities are a side effect of Heisenberg’s uncertainty principle. High-mass force carrying particles like this are allowed to come into existence out of nothing… so long as they are incredibly short-lived. These are virtual particles.

Because virtual particles exist for such a short time, they can never be observed.

At least, not directly.

One more thing we need to discuss before we get to the actual news is the Casimir effect itself. Now, a central concept of quantum mechanics is wave-particle duality, that all particles exhibit both wave and particle properties. It’s essential to remember that as we delve into the Casimir effect. Because if a vacuum is full of fluctuating virtual particles, that means it’s full of fluctuating virtual waves as well.

Take two uncharged metal plates (or mirrors) and put them in a vacuum. Place them just a few micrometers apart. Now, there is no outside electromagnetic force acting on the plates (because we’re in a vacuum). One would think that, with no electromagnetic field outside the plates, there wouldn’t be one inside the plates either, and thus no force would be measured between them.

Except… that’s not entirely true. Somehow, the plates are attracted to one another.

Why is this? Well, if we remember our virtual particles/waves, we know that there are waves of every wavelength flickering in and out of existence all the time in the vacuum. So when we put those plates close to one another, some wavelengths can fit between the plates… and some can’t. Because fewer waves can fit between the plates, the total amount of energy in the vacuum between the plates will be slightly less than that of the vacuum outside the plates, causing the plates to move toward one another.

That, dear galleons, is the Casimir effect.

***

And now for the news:

Scientists at Chalmers University of Technology in Sweden have successfully captured some of those virtual photons and caused them to shuck their virtual selves, becoming real photons (i.e. measurable light).

Essentially, they just pulled light from the void.

Suck it, God. Science is all up in your shit.

Back in the 70s, it was predicted that virtual photons could become real photons if they were allowed to bounce off a mirror moving at a speed that is almost as high as the speed of light. This was called the dynamical Casimir effect, and it had never actually been observed. Until now.

Because they couldn’t get a mirror to actually move fast enough, Chalmers scientists decided to try a different approach. They created a faux mirror by using a quantum electronic component referred to as a SQUID (Superconducting quantum interference device), which is extremely sensitive to magnetic fields. Instead of varying the physical distance between actual mirrors, they varied the electrical distance to the electrical component, which acts as a mirror for microwaves. By using the SQUID (SQUIDMAN! ASSIST ME!) to change the direction of the magnetic field several billions of times a second, the scientists were able to make a “mirror” that vibrated at a speed of up to 25 percent of the speed of light.

Remember, we can’t actually observe virtual particles. But that’s okay- we don’t need to measure them directly. Instead, the SQUID mirror transferred some of its kinetic energy to the virtual photons, which allowed them to materialize as pairs of real photons. Which we can measure.

Why photons? Why, because photons lack mass, of course.

“Relatively little energy is therefore required in order to excite them out of their virtual state. In principle, one could also create other particles from vacuum, such as electrons or protons, but that would require a lot more energy,” said Göran Johansson, Associate Professor of Theoretical Physics.

Now, this is one of those experiments that doesn’t have any direct, practical applications. Its value lies in bettering our understanding of vacuum fluctuations. It’s science for the sake of science.

It’s also really cool.

Light being created from the vacuum? Come on. You gotta admit, that’s pretty good.

The Standard Model Saturation Situation or Fermilab and the Technicolour Tevatron

Though it’s due to be shut down in just a few short months, the Tevatron is spending its last weeks setting the physics world aflutter with hints of a new particle not found in the Standard Model and not the Higgs Boson. Apparently, the Tevatron refuses to go out quietly.

Dylan Thomas would be proud.

When examining collisions from Fermilab’s CDF experiment that produced a W boson (carrier of the weak force) and two jets, scientists discovered a strange bump in the number of events when the jets’ mass was about 145 GeV, suggesting that, at this energy level, a new particle was produced. A particle our dilapidated, barely limping along Standard Model can’t account for.

And, while this potential particle signature came as a surprise to many, it didn’t for Kenneth Lane and Estia Eichten. Over 20 years ago, Lane and Eichten worked on a theory which proposes a fifth fundamental force (in addition to gravity, electromagnetic, strong, and weak):

No, not that Force. This theoretical fifth force is known as technicolour and is very similar to the strong force (the force that binds quarks together), except that it works at much higher energies.

But what’s really interesting about the technicolour force is that it’s capable of giving particles their mass. Which is the job of the as-yet-unseen Higgs boson. The technicolour force would render the need for the Higgs boson obsolete.

“If this is real, I think people will give up on the idea of looking for the Higgs and begin exploring this rich world of new particles,” Lane said.

Of course, there’s a big ol’ if floating around that statement. There’s a 1 in 1000 chance this funky bump is just a statistical anomaly. The gold standard for a discovery, however, is a 1 in a million chance of error. So, while there’s only about a 0.1%  chance of error… we’re going to need further analysis and verification. Which Fermilab is working on- between studying the remaining piles of data from the CDF experiment and turning the Dzero detector on the problem to corroborate or refute the possible particle signature. And the LHC will soon gather enough data to join the party as well.

This is the first I’d heard of this theoretical fifth force, so I must say I found this science tidbit rather intriguing. But I have to say one thing:

…The technicolour force? Really? That was the name we settled on?

Stuff and nonsense, galleons. Stuff and nonsense.