IRA FLATOW, host: Up next, Flora Lichtman is here. Hi, Flora.
FLORA LICHTMAN: Hi, Ira.
FLATOW: With our Video Pick of the Week.
LICHTMAN: It's a hot one. Oh, that's a bad joke.
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LICHTMAN: Sorry, everybody. Because this week's Video Pick is about fire...
FLATOW: Fire. So, yeah.
LICHTMAN: ...and about recreating a flame in digital 3-D, which apparently has never been done before.
FLATOW: It seems like - doesn't it seem like with all the 3-D that's going on, that someone would have made...
LICHTMAN: A 3-D flame. Well, I mean, maybe people have, but this actually measuring what a flame is and then transferring it into a digital version. And that is not trivial. So the setup is - it's Tadd Truscott is - and he's at Brigham Young University, and he's pioneering this method of tracking movement of fluids and things like flames over time. And so he has like a bunch of, 12 high-speed cameras from different angles. And so they're taking pictures of this flame from different angles, and then he puts them together as a composite. And then he can make a 3-D version of this. So this is what this video is, sort of explaining this process. But I learned a lot about fire this week.
FLATOW: It's fascinating, isn't it, fire?
LICHTMAN: It was amazing.
FLATOW: And the fact - just what a flame is, right?
LICHTMAN: I - oh, yeah. So I had a lot of moments this week where I was, whoa. I can't believe it. I was just outside of the studio doing this.
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LICHTMAN: But - here's one that I thought was pretty amazing. A flame, a candle flame, for example, is just an envelope of fire around this sort of center area. So the wax, which is the fuel, goes up through the wick. It melts, goes up through the wick, and then evaporates into a gas. And that is - the part around the wick is actually not on fire. So the wick is actually not on fire.
FLATOW: That's why it doesn't burn away, I guess.
LICHTMAN: That's why.
FLATOW: Yeah. Hey, you're right. You know, the wick is not on fire - so there's an envelope of gas around the wick, and it's the gas that's burning.
LICHTMAN: And it's the gas that's burning, and it only burns when it hits oxygen. So the gas on the inside that doesn't have access to oxygen isn't burning, and it's actually cool inside the flame.
FLATOW: Ah.
LICHTMAN: I know.
FLATOW: This is - I'm Ira Flatow. This is SCIENCE FRIDAY, from NPR, talking with Flora Lichtman. My hair is not hurting. It's feeling better.
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FLATOW: You know, this is a great idea, that, you know...
LICHTMAN: Yeah.
FLATOW: ...it's such a simple thing. We see it all the time.
LICHTMAN: All the time, and you never knew. Actually, Tadd, he's working with another professor, Dale Tree, who's an expert on combustion, said that he's been learning stuff like this all the time. Like, he thought maybe he just couldn't see the flame, because if you look at a candle, if you light a candle and look at it, you can see the sort of empty, clear part...
FLATOW: Right.
LICHTMAN: ...and think: Maybe I just can't see it. But no, it's not there. The flame is in the surroundings. So that was one thing that made my jaw drop.
FLATOW: Wow.
LICHTMAN: And you can see it in the video, actually. We have this neat footage of wax sort of just getting slurped up the wick.
FLATOW: That is the best.
LICHTMAN: It's pretty cool.
FLATOW: It's a great video. It's up on our page, on our Video Pick of the Week at sciencefriday.com. But the part of it where you watch the wax, you have a really - almost looks like slow motion, but it's in real time.
LICHTMAN: It's in real time.
FLATOW: And you - we - you have zoomed in on it so far, you can watch the wax go up the wick.
LICHTMAN: It's pretty cool. You can - it's streaming like a river, just getting slurped up through surface tension, apparently. That was one thing. Another thing that amazed me was that the reason why some flames are yellow is because of the soot in the flame. And I was like, well, what is soot, actually? And it's the carbon particles that have gone into a gas, but there hasn't been enough oxygen to light them on fire. So they go back into a solid, and they get heated up, and then they give off this yellow, incandescently light.
FLATOW: Ah.
LICHTMAN: So candles are really sooty flames, and that's the yellow you see.
FLATOW: It's the soot part.
LICHTMAN: It's the soot, actually, making the light.
FLATOW: And so when you see your gas burner, it's a blue flame with no yellow in it.
LICHTMAN: Right.
FLATOW: There's no soot in there.
LICHTMAN: No soot.
FLATOW: What... Wow. What a video.
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LICHTMAN: So many mysteries.
FLATOW: And in such a simple thing, like a candle.
LICHTMAN: Yeah. It's pretty neat. And you can actually do this - you know, I think people have probably put a butter knife over a candle by accident. Me, it's usually, I'm, like, a plate is going over, and you get this black mark. That's the soot.
FLATOW: Right. Right. And they have captured this with cameras from all different angles and recreated a 3-D image after all that.
LICHTMAN: A 3-D version of the flame. And this was sort of the first one they had come up with. They're really at the beginning of this project. And for Dale Tree, who's the combustion guy, the idea is that if you understand flames better, sort of their dynamics, then you can burn fuel more efficiently - you can sort of get rid of the soot and the other pollutants, and more cleanly.
FLATOW: You know, it's - once again, it just shows to go you that the most simple things in the universe, we still don't understand.
LICHTMAN: Well, that's the amazing thing. I mean, man was - you know, it's 500,000 years ago we started using controlled fire. That's the thought, anyway. And here we are, you know, half a million years later, just starting to quantify it.
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FLATOW: Well, we learned this hour we don't know what Mars is made out of yet. We don't know why the universe has all this dark energy in it. And we're just learning about a candle.
LICHTMAN: Yeah.
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FLATOW: We've run the gamut, from the beginning of candles, all the way to the dark energy and what we don't know about it.
LICHTMAN: I'm glad we could end with this small, thinking of...
FLATOW: The small - thinking of the - well, that's a good thought. Thank you, Flora.
LICHTMAN: Thanks, Ira.
FLATOW: Flora Lichtman, our multimedia editor. It's our Video Pick of the Week. Well, do we have a name for the video on this one?
LICHTMAN: "3-D Up in Flames."
FLATOW: Oh, I like it. "3-D Up in Flames." It's on our website at sciencefriday.com. And you can also download it as a podcast on iTunes. We'll have it up there, and you can take it with you. Thank you. Transcript provided by NPR, Copyright NPR.