Make Plasma With Grapes In The Microwave!

So today I'm at the University of Sydney with Steve Boie, and we are exploring everyone's favorite state of matter: a plasma. Well, actually, my favorite state of matter is the Bose-Einstein condensate, but that's just me—that's for another episode.

So for now, we are trying to replicate these videos that you can see on the web where people use a simple grape and a microwave to produce plasma. We took a grape and cut it partway through, so you'd have two halves with a tiny little piece of grape skin holding the two halves together. Put that in the microwave oven. Now try to prop that up so that's sitting in the middle.

All set? Is this going to be dangerous? I don't think so, but we are experts, so be careful if you're trying this at home! And bingo, where's the plasma? Whoa, there’s the plasma! Holy wow! Well, that was some pretty amazing plasma that we made in this microwave.

Um, what is plasma for people who don't know? Okay, if you take a gas and you put lots of energy into it until it gets very hot and the particles are very, very energetic, you start to rip electrons off the molecules. So you end up with a soup made up of negatively charged electrons mixed in, but moving freely with a bunch of positively charged air molecules.

And why does that give off light? Well, anytime that you put energy into atoms and molecules, the electrons start moving around, changing orbits and that kind of stuff. So anytime the electrons are being excited and de-excited, you're going to get light. Who needs drugs? And we also imagine that it's very hot, so it would be glowing white hot anyway. Yeah, possibly.

Also, some of the ingredients in that plasma have actually been heated up very high, so they’re incandescent—they just glow because they're hot. Don't know.

So what did we find worked the best with microwaving our grape? What lessons did we learn? Okay, first thing we discovered was we got better results if we dried the grape up before we put it in. We found too much water gave too much steam. They tend to extinguish the plasma.

Then Steve came up with a great idea of actually cutting the grape completely in half but using these dangling flaps of grape skin and grafting them together—just laying them over the top of each other. And that seemed to work better because we could reduce the volume of the grape, and that seemed to help.

Yeah, but because we used smaller pieces of grape, we had less steam also—less thermal mass and possibly less grape absorbing less microwave energy. So we got higher fields.

Oh yes! Holy! Oh yes! Did you see that fireball? That was an example of multiple plasma. And then, of course, the trick was to try to capture the plasma so that we didn't do damage to the microwave for one thing, and second of all, so that we could observe it quite nicely in a container.

But we had trouble with the glass that we were using. The few glasses we tried to get it to work—my guess is that the glass was absorbing too much of the microwave energy, and so we weren't getting very high fields you need to make the plasma.

Oh yeah! Oh no! So we moved over to a plastic container, which seemed to do much better.

Yeah, if you can just tolerate the fact that the plastic container melted afterwards! Plastic container to capture the action and adventures. Well, what are the laws of physics?

Yeah, oh yeah, it’s still going. The [Music] physics! Yeah, oh yeah, it’s still going. Do you smell that? Is that a new smell? Is that melting plastic? Are you still filming? Oh my! Catch that! Look, it's got a smiley face! Even this, even the container's got a smiley face after that run!

Yeah, it's only like a one-hit gig. So what sort of future investigations would you like to do here? Okay, now in order to understand exactly why this happens, we really need to be able to control the variables inside that grape.

Okay, we can't control the ingredients of a grape; they come to us as is. So what we'd like to do is make an artificial grape! So, I don't know, get cotton balls—we can put conductive liquid in it. You know, we could put salty water in it, we can put grape juice and control the volume of these things.

So one by one, we can actually nail down the different variables, and we'll have to find some artificial skin to replace the grape skin. I don't know if it has to be grape skin—maybe a wet piece of paper might do the job! I don't know.

Okay, so you should look forward to that on another episode of Veritasium. Care for a grape? Thank you very much!

M physics is tasty! Holy! Oh, see what did I tell you? What did I tell you? But wait, this, m... no, there's a—I think that's it.