This is a fantastically basic question, so it seems that if we could satisfactorily answer it, we could unlock Deep and Important Mysteries of the Universe.

The modern perspective of quantum field theory recognizes photons — bits of light — as the carriers of the electromagnetic force. Charles and Charlene are charged particles, so they interact with light. But obviously, Charles and Charlene aren't shooting lasers at each other, so the trite explanation for their brief dalliance is that "they exchange virtual photons."

What in the name of Feynman's ghost does that mean?

Enter the field

Let's take a step back. Back in the olden-days (i.e., the 19th century) view of physics, each charged particle generates an electric field, which is basically an instruction sheet for how other particles can interact with it. In the case of a particle, this field is strong nearby the particle and weaker farther out. That field also points out in every direction away from the particle. [The 9 Biggest Unsolved Mysteries in Physics]

So our Charles particle produces a field that permeates all of space. Other particles, like Charlene, can read this field and move accordingly. If Charlene is super-duper far away from Charles, the field she reads has very, very small numbers, so she barely notices any effect from Charles. But when she gets close, her field reader goes off the charts. Charles' electric field is very clearly saying "GO AWAY," and she obliges.

In this view, the field is just as real and important as the particle. The universe is full of stuff, and the fields tell that stuff how to interact with other stuff.

Revenge of the field

In the early to mid-20th century, physicists realized that the universe is a much, much stranger place than we had imagined. Marrying special relativity with quantum mechanics, they developed quantum field theory, and let's just say the results weren't what anybody expected.

As the name suggests, the field got a promotion. Instead of just being the bookkeeping device that showed how one particle should interact with another, it became — and here come some italics for emphasis — the primary physical object. In this modern, sophisticated view of the universe, the electron isn't just a lonely particle. Oh no. Instead, there's anelectron field, permeating all of space and time like milk in French toast.

This field is it — it's the thing. Particles? They're just pinched-off bits of that field. Or, more accurately, they're excitations (like, wiggles) of the field that can travel freely. That's important, and I'll get back to it soon.

A particle party

Here's where things start to get fuzzy. A particle traveling from one spot to another doesn't exactly stay a particle, or at least not the same kind of particle.

Let's go back to Charles, the charged particle. Since he's charged, by definition he interacts with light, which is the electromagnetic field. So wiggles in the electron field (a field made up of electrons) can affect wiggles in the electromagnetic field. So, literally, as Charles zips around, he spends some of his time as an electron-field wiggle and some of his time as an electromagnetic-field wiggle. Sometimes he's an electron, and sometimes he's a photon — a bit of the electromagnetic (EM) field!

It gets worse. Way worse. Charles-turned-EM-wiggle can become otherwiggles, like muon wiggles. For every fundamental particle in the universe, there's a corresponding field, and they all talk to one another and wiggle back and forth constantly.

The summation of all the wiggles and sub-wiggles and sub-sub-wiggles add up to what we call "an electron traveling from one spot to another." [Video: "What does it mean for particles to exist?"]

It all becomes really nasty mathematically very quickly, but folks like physicist Richard Feynman came up with handy tricks to get some science work done.

Virtually speaking

Now, after tons of backstory, we can get to the main question. The fields wiggle to and fro (and sometimes fro and to). If the wiggles persist and travel, we call them "particles." If they die off quickly, we call them "virtual particles." But fundamentally, they're both wiggles of fields.

When Charles encounters Charlene, they're not like two little bullets ready to slam into each other. Instead, they're complicated sets of wiggles in all sorts of fields, phasing in and out from one type of field to another.

When they do get close enough to interact, it's … messy. Very messy. Wiggles and counter-wiggles, a frenzied mishmash of intermingling. The machinery of quantum field theory — after many tedious calculations — does indeed provide the correct answer (Charles and Charlene bounce off each other), but the details are headache-inducing. [I break it down in more detail in this video.]

So, the shorthand — "they exchange virtual particles" — rolls off the tongue quite easily, a little slip of jargon to package up a very complicated process.

But, unfortunately, it's not very accurate.

Learn more by listening to the episode "What are virtual particles?" on the Ask A Spaceman podcast, available on iTunes and on the Web at http://www.askaspaceman.com. Thanks to @TanyaDavis, @AstroMatt99, Tomas A., Rae N., and many others for the questions that led to this piece! Ask your own question on Twitter using #AskASpaceman or by following Paul @PaulMattSutterand facebook.com/PaulMattSutter.

Boyajian and her colleagues suggested that a cloud of fragmented comets or planetesimals might be responsible, but other researchers noted that the signal was also consistent with a possible "alien megastructure" — perhaps a giant swarm of energy-collecting solar panels known as aDyson sphere.

Astronomers around the world soon began studying Tabby's star with a variety of instruments, and re-analyzing old observations of the object, in an attempt to figure out what exactly is going on. But they have yet to solve the puzzle.

"I'd say we have no good explanation right now for what's going on with Tabby's star," Jason Wright, an astronomer at Pennsylvania State University, said earlier this month during a talk at the Search for Extraterrestrial Intelligence (SETI) Institute in Mountain View, California. "For now, it's still a mystery."

More surprises

That mystery may even have deepened over the past 12 months.

For example, in January, Bradley Schaefer of Louisiana State University determined that, in addition to the weird short-term dimming events, the brightness of Tabby's star had dropped by about 20 percent overall between 1890 and 1989 — a pattern very difficult to explain by known natural means, he said.

Schaefer came to this conclusion after poring over old photographic plates of the night sky that captured Tabby's star. Other researchers suggested that the trend Schaefer saw could have been caused by changes in the instruments used to take those photos over the century-long timespan. However, a new study bolsters Schaefer's interpretation.

In the new work, Benjamin Montet (of the California Institute of Technology in Pasadena and the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusets) and Joshua Simon (of the Observatories of the Carnegie Institution of Washington) re-analyzed Kepler observations of Tabby's star from 2009 through 2013. They found that the object dimmed by 3 percent over that span, with a rapid 2-percent brightness dip over one 200-day period.

"Of a sample of 193 nearby comparison stars and 355 stars with similar stellar parameters, 0.6 percent change brightness at a rate as fast as 0.341 percent [per year], and none exhibit either the rapid decline by > 2 percent or the cumulative fading by 3 percent of KIC 8462852," Montet and Simon wrote in the new study, which they uploaded to the online preprint site ArXiv on Aug. 5. "No known or proposed stellar phenomena can fully explain all aspects of the observed light curve."

Schaefer's results, combined with those of Montet and Simon, make the comet hypothesis look less and less likely, Wright said in his SETI talk.

"Why would comets, over a century, make the star dimmer?" he said. "What's going on?" [5 Bold Claims of Alien Life]

Alien megastructure?

The sustained dimming of Tabby's star is still consistent with at least some variants of the "alien megastructure" hypothesis, Wright said.

"Some people have sort of facetiously offered that perhaps this is a Dyson sphere under construction: You're seeing lots of material getting built," he said. "In just 100 years, they've blotted out 20 percent of the starlight. That seems kind of fast to me, but, you know, aliens, right?"

It's also possible that the alien megastructure — if it exists — is fully constructed, and some parts are just denser than others, Wright added.

"That would naturally make the star get brighter and dimmer, as dense parts of the swarm came around," he said. "So if I had to invoke megastructures to explain it, that seems consistent. You've got lots of panels of different shapes, different sizes, and the big ones make big dips and the little ones make little dips, and the whole swarm is sort of like a translucent screen that makes the whole thing dimmer."

But Wright and others have always stressed that "E.T. did it" is a very unlikely scenario, and that a more prosaic explanation will probably rise to the top eventually. And indeed, other recent observations throw some cold water on the alien-megastructure idea — and any other hypothesis that invokes some object or phenomenon near Tabby's star.

Any structure surrounding the star, be it alien-made or naturally occurring, would heat up and give off infrared radiation, Wright said. But he and his colleagues saw no signatures of such "waste heat" in data gathered by NASA's Wide-Field Infrared Explorer spacecraft. And another research team — which analyzed observations by the Submillimeter Array telescope and Submillimeter Common-User Bolometer Array-2 instrument, both of which are in Hawaii — also came up empty.

Whatever is blocking the starlight from Tabby's Star is "not surrounding the whole star — it must be along our line of sight," Wright said. "So you can do that if it's in a disk of some kind. And that hopefully will help constrain what the heck is going on."

Wright has a hunch that the answer lies far away from Tabby's star, out in the dark depths of space.

"I think I've all but abandoned circumstellar explanations, and I think now we're going to have to talk about bizarre structure in the interstellar medium, and stuff like that," he said.

Still, Wright hasn't given up on the alien-megastructure hypothesis. While the lack of waste heat is "almost a fatal blow" for the idea, he said, it's still viable if the purported aliens are doing something with the waste heat — turning it into matter, for example, or converting the heat into radio waves for communication purposes.

Astronomers have already searched for such signals coming from Tabby's star using the Allen Telescope Array, a network of radio dishes in northern California operated by the SETI Institute. They found nothing. But Wright and his colleagues plan to conduct another search beginning in October; they've secured time on West Virginia's huge Green Bank Telescope for this purpose.

"This is a 1-in-300,000 object," he said. "People have gone looking for more, and it's the only one. So that also says you're allowed to invoke one really rare thing, because it is a rare phenomenon."

Follow Mike Wall on Twitter @michaeldwall and Google+. Follow us@Spacedotcom, Facebook or Google+. Originally published on Space.com.