- [Voiceover] Yeah, go for it. Whoa!

- Now, you may have seen a Ruben's tube before. That's basically a pipe with a bunch of holes

in it, and you pump in a flammable gas, and light it on fire, so you basically create

a row of Bunsen burners. What's really cool is to play some sounds into the tube, and

you can actually set up standing waves. That is, there are areas, there are patterns of

the vibration of the air where there's a lot of vibration in some parts, and not very much

vibration in other parts. Now, that affects the flow rate of the gas inside that tube

into the atmosphere, and so it affects the height of those flames. So basically, you

can visualize the standing wave pattern. I'm currently in Denmark with a team of physics

and chemistry demonstrators who have taken this experiment to the next level. They've

actually created a two-dimensional Ruben's tube, a whole plane of Bunsen burners, effectively.

How many holes in this tube?

- 2,500

- [Voiceover] 2,500 in this Pyro Board?

- Yeah

- [Voiceover] So we're gonna see 2,500 little flames. Yeah. So, do you want to light it

up?

- Yes, I really want to light it up.

- [Voiceover] Why did you make this?

- Because, we really liked the Ruben's tube, but then we thought, ah, when you put on more

fire, then it always gets better. And, let’s just turn it down. And then we can just try

to find a standing wave. So this is below the lowest standing wave. See that? It's really

difficult to see

- [Voiceover] So what are we seeing here?

- It's pretty much like the standing wave on the Ruben's tube. It's just in this direction.

This is the lowest frequency that makes a standing wave in this pulse.

- [Voiceover] So this is like the fundamental.

- It's the fundamental.

- [Voiceover] Can you show me what happens when you vary the volume a little bit?

- Yeah.

- [Voiceover] Whoa! That was awesome. Okay, should we try to find another standing wave?

- [Sune] Yes. You can see it. You can see it. You can hear it before you can see it.

- [Voiceover] Whoa! It's weird. With the microphones, I can actually hear, like here, I'm in a node.

Then here I'm in an anti-node. Here I'm in a node.

- [Sune] Because you can measure the sound pressure?

- [Voiceover] I can hear it. Like here is very much an anti-node.

- [Sune] I never thought about that.

- [Voiceover] This is a node, and you guys can hear it.

- [Sune] That's true.

- [Voiceover] It's incredible. The flames must be coming out in the anti-nodes.

- The flames are coming up in the anti-nodes, yeah.

- [Voiceover] And you can even hear it. That’s incredible.

- Yeah It's nice that it can do that.

- [Voiceover] That is awesome.

- [Sune] We just learned something.

- [Voiceover] What happens if we try to go higher frequency?

- [Sune] Yeah. We have something. Oh, that's a good one.

- [Voiceover] That is crazy. We're right in the anti-node.

- [Sune] Is your ears okay?

- [Voiceover] Oh, God!

- My ears are hurting now.

- [Voiceover] That was painful. Why don't we try to put something more pleasing to the

ear through the speaker and see what happens.

- I think that's a good idea.

- [Voiceover] Let's put some music on there. You ready?

- Go.

- So, you go around Denmark showing kids all about physics?

- We do. That's what we do.

- You show them the Pyro Board?

- We show them the Pyro Board, and we show them a whole lot of other stuff.

- You guys are also on YouTube?

- Yep, we have a YouTube channel. You can go to this link, right here.

- Go check it out if you want to see more of what these guys are up to. It's awesome.

- [Sune] It's great.

- Ahoy. That is the actual Czech word for hello. I have made it to Olomouc in the Czech

Republic, and this is partly thanks to support from Audible.com, the leading provider of

audio books, with over 150,000 titles in all areas of literature, including fiction, non-fiction,

and periodicals. Now, today I wanted to recommend a book, which is a little bit European, and

it's called Galileo's Daughter by Dava Sobel. I love this book because it includes the actual

letters written from Galileo's daughter to him during his life, and it really reveals

what he must have gone through as a human being. We all know about his science, and

about the trials that he went through, but to see this kind of insight into his personal

life, I think is remarkable, so you should really check out this book, and you can download

it for free by going to audible.com/veritasium, or you can pick any other book of your choosing

for a one month free trial. So I really want to thank Audible for supporting me, and allowing

me to go and meet great scientists, and filmmakers, and lots of people all around the world. Also,

I should note that I will be hosting Michio Kaku in Brisbane and Melbourne on June 5th

and 6th. Links in the doobly-doo. I would love to see you there. Thank you so much for

watching, and I will see you somewhere else in the world. Bye.