–( music playing )
– Dan:We’re here for
the fun silly wave.That’s correct, yes. Okay, all right. Gav:It looks like
someone’s justpulling on space time.– ( grunts )
– Not really sure what
I’m looking at. Dan:Bath time.Gav:Those ducks
just went–Dan:Whoosh!Gav:How do you feel
about taking itright in
the face? Gav:Dan, are
you nervous?– Oh.
– ( water splashing ) – Gav:( chuckles ) Oh!
– ( laughter ) Well, that was
a very unique building we had
access to there. I love the fact
that they just let us mess around with it. It’s this incredibly
scientific and precise equipment and they
were like, “Go wild.” Your life jacket
going off, unexpectedly,
almost wet myself. I think I even
said, I was like, – ( chuckles )
– “Huh, I’m surprised this hasn’t gone off.” and then about two seconds
later it– – ( air whooshing )
– Both: Whoa! Both: ( laughing ) I think they’re
activated by salt aren’t they? Like
it dissolves and – then it activates–
– Yes, the salt in there to make salt
crystal, yeah. Did it hurt taking
the spike wave in
the mouth? – ( water splashing )
– Ooh! Dan:I thought
it was going to,but it actually didn’t. I really liked
that shot where –( music playing )
–it sort of tunnelsaround your face,
you look like you’rein a weird room that’s moving.Dan:Totally surreal.
No one had donethat before, it was
quite an honor reallyto be the first
smashed in the face with it.Gav:Yeah.So I think it’d
be a good idea if we learned more
about waves in general, but also learn a little
bit more about the facility. So we had a little
chat with Tom. Dr. Thomas Davey,
you’re the Senior
Experimental Officer here. Yeah, that’s correct,
yeah. Okay, so, you can tell us
all about what you do here essentially. Yes, so this is a facility
which essentially isjust a model sea,
about 20th scale.And we we use that for
lots of applications,testing things like
wave energy devices,tidal energy devices.Basically anything which
we put in the sea.Okay, so if you make a small
wave about this big in here, you imagine it’s
20 times the size. That’s what you’re imitating
essentially in the ocean. – Dr. Davey:Exactly.
– Dan:So how long did it take
to fill that thing?Uh, it did take us
three weeks, so– – Three weeks?
– …we don’t like taking
the water out of it.It’s two and a half thousand
tons of water in this tank.And what was the choice
behind making the tank this specific size? If you go much bigger, things start to get
very expensive. If you go much smaller
the scaling will start to work
against you, uh… – I imagine this was cheap,
– ( laughs ) Yeah, so you’re
looking atabout 6 millions pounds
of investmentjust to build the tank.And actually the whole
project’s probably around12 to 15 million.Might be one of the more
expensive things – we’ve messed around with…
– ( laughs ) Yeah. …if I’m honest.
Cool. So how do you get
the waves to do the exact thing
you want them to? Well, this is the only
large circular wave and tidal tank
in the world.So what we have is
168 wave makers around
the edge.These are basically paddles.So each individual paddle
on its own can generate a wave.But because we’re in a circle,you can imagine, you can
actually then generate
from any direction,so you can have this one wave
going in one direction,you can have thousands of waves
going from all directions.It’s a bit like playing
a musical instrument.You just combine all these
notes togetherto create a very complex sea
in the tank.– Whoa-ho-ho-ho!
– Whoa! ( water splashing ) And then on top of that
you then put tidal currents.So you make currents
as well underneath…Dr. Davey:
Yes, yes. It works a bit
like a conveyer belt.The current comes from
underneath the tank, over the top,
and back around again. – Oh, okay.
– So… You said you can replicate
any part of the sea. If I said to you,
I want to replicate
Brighton. I want Brighton,
could you do that for me? As long as you got
the data. If we could get good data
for a site and we can understand
the energy of that site and the directions
of the waves and so on,
then yes. That way, if you just
brought in a load of sand, and people didn’t fancy the,
like, eight hour drive, you could have people
just come in here – and enjoy the–
– Yeah, we’d be in the surfing
business. ( laughter ) Thanks, Tom,
that was really interesting and thanks for letting us use
your very expensive pool. Dr. Davey: No problem. Back to you,
Gav and Dan. Thanks, us. Why don’t we learn
some more about waves. Yeah, we’ve invited
someone along who’s travelled
the world, and written a book
about all the world’s scariest, largest,
fastest waves. It’s called “Tides.” Hi, Jonathan.
How’s it going? – Hi, Dan.
– Hey. Could you explain to us,
the difference between waves
and tides? Sure, waves, as we
talked about are generally created
in the storm, right? There’s a one pulse
that makes the wave and then the waves
travel away from that. But a tide is actually
also a wave, but it’s the largest wave
on the planet.And it’s a long low wavethat travels about
450 miles per hour
around the globe.We don’t experience it
as a fast moving phenomenon because if we’re on the coast,
we have to stay there all day to watch it pass, right? Six hours of trough,
which is low tide, and then about
six hours later, the crest,
high tide. So you could potentially
be on a plane, unknowingly flying
at the same speed – as a tide rolling through.
– That’s right.The oceans actually
aren’t deep enoughfor this free wave,
this wave of tide,
to travelas fast as it wants
to travel.So essentially it drags
its legson the bottom of the ocean,and slows down
and creates friction.Friction against
the entire Earth? – That’s right.
– Wow, yeah. ‘Cause I’ve heard that
they occasionally will add like a leap second
to the clocks to compensate for
the Earth slowing down. Tides have literally
slowed down the rotation
of the Earth. Acted as a break. ‘Cause the tides are
slowing down the world by friction on the bottom
of the sea. That means every millions
of years, there’s changes to
the amount of hours
in a day? Yeah, about 400 million
years ago, our day 21 hours long,
not 24. Because of the tide. I’m okay with it,
because I feel like I’d struggle to fit
a 21 hour day. Yeah, so you’re thinking
that millions of years when it’s a 30 hour day, – people are gonna be like…
– ( laughs ) ( sputters )
…a long day. Yeah, the days got longer
and then people started
having longer meetings. – ( laughs )
– That’s what happened. Yeah.So when we filmed
the footage in the wave pool,it looked a bit like
a sound wave in 3D space.And you’ve done experiments
before with vibrations
and frequencyto try and show
what’s happening with the tides and you’ve asked us
to get this stuff here. Yes, this is the Chladni
experiment and uh, that little device
over there is a sign wave signal
generator. And it’s gonna function
like the sun and the moon. The vibrations from
the sun and the moon. And this area here,
this is the ocean. and we’re gonna put some
salt on that and it’s gonna demonstrate
how the salt will dance around
or resonate with the various signals
from the sun and the moon. When scientist look
at tides, it’s really all about
the oceans responding to the vibrations,
or pulses, or beats from the sun
and the moon. So what I’ve got here
is a way to look at that. So go ahead and pour
the salt on there… – Okay.
– …and as you turn
the signal generator on, You wanna do it? Well, you’re the sun
and the moon. – That’s fair.
– Yeah. Jonathan: So as you turn
the signal generator on you’ll start to see patterns
form here. Gav: Why don’t we start
with 60? Oh, I see a bit moving
around the edges. Dan: Gibberin’. – It’s gibbering
– I like that. Whoa. – Jonathan: Oh, wow,
– Dan: Oh, wow. That’s cool. Gav: An “X.”
Get more salt on there. Sure, let’s get that
on there. None of that salt
wants to be in the middle, that’s interesting. – Dan: Oh, that’s really weird.
– ( Gav laughs ) Dan: It looks like static
from a TV. Oh, it’s spreading.
Circle’s getting bigger. Do it again. – Oh.
– Gav: Yeah. This made two lines
perfectly. And that’s not
a huge jump, and now that’s two completely
parallel lines. As the frequency alters,
so does the pattern. Which is an indication
of how the patterns and the tide change
with frequencies from the sun and the moon. 78, here we go. – ( grunts )
– Steady on. Oh. I need to put more on, eh? – Oh, it’s making like a–
– Gav: Like a plus sign. All right, go then. I’m gonna run out
of salt here. Oh, quick. – Oh, it’s making a circle.
– It’s a circle. Dan: A bit of acorn
that one. Do you like the little
tappy technique? – Gav: Yeah.
– Dan: That is so weird
looking, the middle part. So this shows how
the ocean tide is basically a response to the vibrations
of the sun and the moon. A patterned response. You know, it might be worth
whipping out the Phantom for some of this. – It’s what we do after all.
– Yeah. Okay, the Phantom’s set up
1,000 frames a second in 4K. Dan, what would be
for frequency? Well, I– I think
we started at 60 and went to 67 and there was a lot of activity
and jumping around. Yeah, there was a lot
in the middle, so I think we can
contain it. And also the sides
were pretty cool as well ’cause it just went
crazy on the sides
and everything that– Yeah. Well, as you can see
we’ve got the whole thing
in the shot, so whenever you’re ready. Okay, I’m gonna
whip it on and crank it up. – Are we ready?
– Yeah. – So this is sixty.
– Yeah. And then it goes 67. There you go. Whoa. Why don’t we walk over
and have a look at this. Okay. Gav: It almost looks
like a poker chip
at this point. Oh, there it is. Dan: Look, it’s starting
to change here. Now you got the corners
kicking up. Oh, yeah, these are getting
in the corners here. In the far corner
especially. You can already see
the parallel lines
Look at the wobblage here. It’s kind of mesmerizing, you can just stare at that
for ages. I love that experiment. – Dan: Very cool.
– Gav: I could watch this
all day. Dan: Very cool. Well, thanks very much,
Jonathan, for coming in… – Thank you, Dan.
– …and lending us your
expertise. – Thanks, Gavin.
– Thanks for your knowledge. Loved it. Well, that was a lovely
episode. I thought I learned
a lot about waves. Had a good time
in Scotland. So did I. I got slapped
in the face by a wave. – That you did.
– Pretty much lost
all the knowledge – about waves when I got hit.
– Punched straight out of
your head. – Yup, yup, yup.
– Hopefully, you also enjoyed
that video. Feel free to check out
other episodes of “Planet Slow Mo”
and you can subscribe to the “Slow Mo Guys”
if you want. – We would love that.
– Would we? – Yeah, we would.
– Yeah. Deeply. – Scotland rules.
– Haggis. Kilts.