Every once in a while, if you walk through the guts of the MIT Plasma Science and Fusion Center, you might see a man tinkering with what looks like a giant Lego wheel. But Dr. Jan Egedal isn’t just playing around: he’s trying to fix something called the theory of ideal magnetohydrodynamics.

Many people are skeptical about meddling with this theory, and until recently Egedal has had trouble grabbing his peers’ attention, he says. But if something’s broke, you should fix it — especially if it governs things like crashes in magnetic fusion devices or solar flares that can wipe out satellites.

The theory has to do with plasma, a collection of (rarely-colliding) charged atomic particles that shields itself from outside electric fields. These particles travel along magnetic field lines like cars on an expressway.

The magnetic field lines behave like elastic bands stretched taut, Egedal explains, as he draws two sets of lines moving in parallel but opposite directions on a whiteboard in his office. If you shorten one of the lines, it releases energy, like de-stretching the elastic band releases the potential energy stored up (and shoots it off your fingers, if you’re not careful). This shortening occurs when a field line breaks and reconnects as a loop with one of the lines going in the other direction. The energy is carried away by the plasma particles, which can shoot from the region “at 10 kilometers per second, which is like 10 times a rifle bullet,” he adds.

We see this magnetic reconnection on our Sun. Coronal mass ejections, for example, happen when a loop in a magnetic field line pinches off and blasts into space. This ejection — sometimes containing one billion tons of matter — can then collide with Earth’s magnetic field, catalyzing reconnection there and spiraling down to spew across our skies as the aurorae.

By Faraday’s law, a changing magnetic field creates an electric field, so this reconnection should induce an electric field. Herein lies the problem with the theory Egedal is investigating: the theory claims that within a plasma, the internal electric field is so small that it can be idealized to zero.

“It usually works really well,” Egedal says. But once in a while those magnetic field lines break and reconnect in a huge explosion of magnetic energy, inducing an electric field that makes a vivid red splotch on the team’s sensor images. “That’s not included in the theory,” he says.

The physicists study reconnection by manipulating currents to create their own magnetic loop inside “the Beast,” as Egedal calls the elephant-sized Lego. They then pinch the loop off like an hourglass by modulating the currents. When the magnetic energy changes, it affects current running through a second set of loops, explains Noam Katz, one of Egedal’s grad students. They study both the magnetic and electric fields in the plasma by watching the current’s behavior, he adds.

The team’s measurements show that the magnetic reconnection does not happen simultaneously throughout the region, which means neither does the electric field — another unpredicted result, Egedal says. The plasma carrying the magnetic energy follows the field lines, but it shoots out in filaments, favoring certain directions according to its pressure.

So far they’ve used these measurements to start filling in the theory’s idealized zero. While they still haven’t determined exactly what’s going on, their calculations represent a “huge correction,” Egedal says, that will hopefully bring theory closer to reality.