5 Baffling Subatomic Particles

Riddle me this, Batman: How does gravity work?

Look, it's not a subject Batman likes to discuss all that much. According to physicists at University of Leicester, gravity would have the curious habit of pulling Batman to his death every time the costumed vigilante tried to use that physically impractical cape. So he tends to leave the whole gravity conundrum alone and chase after Edward Nigma instead.

For physicists, however, the question carries a lot more -- yes -- weight. Sure, we have a decent hands-on understanding of gravity's effects. We know how its power factors into celestial mechanics and the formation of cosmic bodies. Yet still we don't have a firm answer to the riddle of gravity.

One possible answer leads us right to another baffling particle in the subatomic rogues gallery: the graviton. If it actually exists, this hypothetical particle transmits the force of gravity, causing objects to attract each other. Oh yeah, and its existence would also enable us to unite general relativity with quantum mechanics. Gravity, you see, often acts as a monkey wrench in various all-encompassing theories.

So yeah, the graviton is kind of a big deal -- unless it doesn't exist.

Fast. Sexy. Hard to catch.

Batman has his Catwoman, and particle physicists have to contend with the elusive -- and possible erroneous -- existence of tachyons. One's a sexy burglar dressed in leather, and the other is a subatomic particle that travels faster than the speed of light.

I know what you're wondering: How can a tachyon travel faster than the speed of light if light speed is indeed the "universal speed limit"? That's like saying "no ducks can wear pants," and then the camera pans over to a mallard wearing friggin' corduroys. We have universal laws for a reason, people.

It gets even worse: If the principles of special relativity hold true, tachyons aren't just breaking the universal speed limit, they're also violating causality itself. In this universe at least, cause always comes before effect. Without that law in effect, the fabric of the universe unravels.

If tachyons exist, it's likely due to this loophole: While relativity prevents matter from accelerating to the speed of light (as this would require infinite energy), it doesn't apply to particles that always travel faster than light. For tachyons, the minimum speed is the speed of light, and it would necessitate infinite energy just to slow them down to subluminal speeds.

Tachyons: They're total speed demons, and they might just actually exist.

Can something be its own opposite?

Yeah, Batman knows a thing or two about this.

You remember the story: Heroic attorney Harvey Dent suffers horrible burns on 50 percent of his body, and his mind snaps. An evil, criminal persona rises to the surface, and he becomes Two-Face, the coin-obsessed maniac with ridiculous taste in half-and-half clothing.

Particle physicists also have a paradoxical two-face in their rogues gallery: the Majorana fermion, a particle that act as its own antiparticle.

Let's refresh. According to the standard model, particles and quasi particles fall into two categories: fermions and bosons. The fermion camp includes quarks and leptons like electrons, among others. We call these Dirac fermions. Here you'd find negatively charged electrons squaring off with antiparticle counterparts called positrons, which pack a positive charge. When these particles come in contact with each other, they annihilate each other.

That's exactly the sort of duality Two-face would appreciate. The coin has two sides, and it's either one or the other, heads or tails. Slip him a two-headed coin or something and it drives him up the wall.

The boson camp includes the photons that make up light; these brilliant particles are their own antiparticles, producing a thoroughly neutral charge. Really, you expect this sort of thing from a boson.

But is such a thing possible in the fermion camp? Back in the 1930s, physicists predicted it was, but no one ever actually spotted a so-called Majorana fermion. In 2012, a team of Dutch particle physicists indirectly detected these tiny two-faces in lab experiment, but this falls short of an official confirmation that they exist.

Once we catch the experimental evidence, however, exciting things may occur. Majorana fermions would boast a unique ability to "remember" past positions in reference to each other, making them very useful in the realm of quantum computing. One theory even holds that all the dark matter in the universe is actually made up of Majorana fermions.

Dark matter computers. Just think about that for a moment.

Batman tends to have a rather tumultuous time with the ladies. If he's not dodging lethal kisses from Poison Ivy, then it's some sort of drama with Catwoman. Look, either marry her or throw her in prison already.

And then there's Harley Quinn, the homicidal she-clown with an undying (and unhealthy) love for Batman's arch nemesis the Joker. Sure, plenty of super villains have their hangers-on and henchmen, but she stands apart as a true sidekick.

In the subatomic world, physicists continue to keep an eye out for a hypothetical particle known as an axion. The axion is of particular note because its existence would plug a major gap in the standard model of particle physics. It's also a possible dark matter component.

But let's get back to the Batman comparisons. If axions are Harley Quinn, then who's the Joker? Why none other than black holes. That's right, scientists theorize that while black holes suck in everything from photons to stars, axions are immune to their destructive power. Instead of falling into the crushing singularity, axions would orbit the collapsed star in an enormous boson cloud.

Even crazier, this cloud eventually becomes quite massive, despite the extremely low mass of its axions. Should the cloud finally collapse into the black hole, the resulting bosenova would rock the very fabric of space-time [source: O'Neill]. Talk about an unbalanced relationship.

Even with all the crazy costumes, it's hard to keep track of the super-villain activity in Gotham City -- especially when you have a shape-shifter like Clayface running about. He can take the form of anybody: a bank teller, Bruce Wayne, you name it. He adapts his physical appearance to fit his environment, making him a rather crafty adversary.

Particle physicists have their own Clayface in the form of chameleon particles. So far, we can only speculate on these peculiar bosons that may or may not be powering the expansion of the universe. Scientists first predicted their existence in 2003 as a possible explanation for all that mysterious dark energy that makes up 70 percent of our universe [source: Johnston].Like criminal shape-shifters, the chameleon particles adjust their properties to fit their local environment. For example, if a chameleon particle hangs out here on Earth, where the matter density is high, it would exhibit high mass, too, but its matter interactions would be very weak and short-range.

But that's here on Earth. Out in the void of space, chameleon particles would exhibit low mass and react strongly with matter over great distances. In theory, these speculative particles could be pushing the universe apart in what we call cosmic inflation.

Not surprisingly, chameleon particles would be rather difficult to detect here on Earth. We'd have to go out into deep, empty space to register their presence.

Still, physicists have a number of high-tech detection schemes up their sleeves, and the search continues for the elusive chameleon.

And so the Dark Knight returns once more to his underground Bat Cave and physicists vanish as well, to manage their underground particle colliders.