– Just press play, you mean?

– [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


– 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

– 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.
Veritasium Published on Apr 17, 2014 Standing waves of fire! Check out Audible: http://bit.ly/AudibleVe Fysikshow: http://bit.ly/Fysikshow – I’m hosting Michio Kaku in Melbourne ONLY: http://bit.ly/VeKakuTickets Rubens’ Tube is an awesome demo and here we take it to the next level with a two-dimensional ‘Pyro Board’. This shows unique standing wave patters of sound in the box. The pressure variations due to the sound waves affect the flow rate of flammable gas from the holes in the Pyro Board and therefore affect the height and colour of flames. This is interesting for visualizing standing wave patterns and simply awesome to watch when put to music. Thank you to Sune Nielsen and everyone at Aarhus for sharing this demonstration with me! And thanks for having me at your conference. Music by Kevin MacLeod, www.Incompetech.com “Ice Flow”
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