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Control a Live Physics Experiment Remotely From Your Computer

The Princeton Plasma Physics Laboratory's (PPPL) new experiment appears to be operated by a ghost: It will turn on by itself and emit a purplish glow without any researchers flipping a switch.

In fact, physicists at the lab aren't even using the experiment. Instead, people from around the world now have direct control of the experiment through their laptops, and you can too.

PPPL's Remote Glow Discharge Experiment is housed in New Jersey, but you can turn it on, tweak its voltages and control its pressure with your web browser from anywhere in the world.

As you conduct your own studies, a live webcam will show how your adjustments influence the experiment. If you do it right, you'll be able to make the experiment glow like in the picture below.

As PPPL's Head of Science Education Andrew Zwicker told me at the APS Division of Plasma Physics meeting last November, "It's just really cool."

A screengrab of the experiment's webcam I took earlier today.
Image Credit: RGDX/PPPL

Plasma Primer

So what is the experiment, exactly? Before we get into that, I'll give you a brief primer on the greatest unsung state of matter: plasma.

Plasma abounds in our universe; in fact, over 99 percent of the visible universe is plasma. Nonetheless, it's one of the least familiar states of matter behind solids, liquids, and gases.

You may remember that atoms are tightly packed together in a solid, conform to their container in a liquid, and conform and fill a container as a gas. Plasmas bear the closest resemblance to gases but with a twist: Plasmas are ionized. This means that plasmas are filled with atoms that are missing electrons (ions) and free electrons as well.

Ionization often happens during extreme heating, so you'll commonly find plasma in lightning, fire, the sun, and fusion reactors, for example. The RGDX is a less extreme example of plasma at work.

The experiment consists of a glass tube filled with low-pressure air (which is adjustable), two metal plates at either end of the tube, and a pair of electromagnets outside the tube. Once you turn on the experiment, you can turn up the voltage between the two plates, ionizing the air within the tube.

Ionization will cause electrons to jump from atoms and also jump from excited energy states back down to lower energy states. When this happens, the nitrogen and oxygen atoms will emit energy in the form of photons, causing the experiment's purplish and reddish glow.

Additionally, you can create a magnetic field within the tube with the electromagnets resting outside. By altering the magnetic field, you can induce a current in the tube, causing the free electrons to spiral around the field.

In my experience, there's been very little lag time between my inputs and the live stream's display of the experiment, making for a close resemblance to actually being in the lab. The only factor that takes a little time to settle down, understandably, is the air pressure.

An example of the webcam and the various controls at your disposal. To experiment yourself, click here.
Image Credit: RGDX/PPPL

Arturo Dominguez, a postdoctoral researcher at PPPL who's heading the team behind the RGDX (they were beta testing the experiment last November) hopes this will fill a void in the realm of online physics education.

"This is a really nice opportunity to get into the other half of physics, the experimental physics," Dominguez told me back in November.

But opening this experiment to anyone with a browser presented some obvious risks for abuse. The team had to develop safety protocols for both the hardware and the software, but there was one unforeseen consequence of having the experiment available 24 hours a day.

"It's really weird sometimes to be in the lab and have the light turn on," when someone accesses the experiment remotely, Zwicker told me. In fact, Dominguez surprised (or pranked, depending on who you ask) Zwicker a few times while testing the experiment.

Beyond Physics

Now that testing's out of the way and the experiment is live, Zwicker and Dominguez already have their vision set on expansion for this new brand of physics education.

"First, we're going to expand this experiment so it is basically the equivalent of an undergraduate or first year graduate student setup," Zwicker said.

Eventually, the team might integrate remotely-controlled experiments into the increasingly popular massive open online courses that have proliferated over the past few years.

"With enough control, you can do a whole bunch more experiments online," Dominguez said. "This could be the beginning of something great."

So go ahead and try out the experiment for yourself! Have fun, learn some physics, and try not to spook too many grad students in the PPPL lab.


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