Episode 2 Bang Goes the Theory


Episode 2

Science series. Liz hits the beach with the RNLI to experience the power of rip currents, while Dr Yan attempts to demonstrate evolution by drawing a couple of lines.


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Transcript


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Tonight, Jem investigates a new recycling phenomenon, urban mining

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and tries his hand at making pure gold from household scrap.

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What I'm about to do here is pretty much the alchemist's dream.

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I'm going to make pure gold

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appear from something that isn't gold.

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And Liz hits the beach with the RNLI

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to witness their number one problem, rip currents.

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It's easy to say don't panic, but it's quite difficult not to panic.

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It's SO cold! HE LAUGHS

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That's Bang Goes The Theory, revealing your world with a bang.

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Hello, welcome to Bang.

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This time of year we all love to head to the beach, don't we?

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But unfortunately what starts out as a bit of a splash around in the sea can often end up,

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even for the stronger swimmer, as a full-blown rescue operation.

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It's your typical British summer's day.

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But that won't stop you from getting into the water. You're made of sterner stuff than that!

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However, you may not know all the hidden dangers that a beach like this can hold.

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That's why these RNLI lifeguards are working very hard to understand

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those dangers better to prevent you from getting into trouble out there.

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Last summer on Perranporth beach in Cornwall alone,

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Life Guards had to make 144 daring rescues.

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Luckily this is just a training exercise.

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The number one threat is a hidden hazard called a rip current.

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Unlike surface waves, rip currents flow backwards out to sea,

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carrying unsuspecting swimmers with them.

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Rip currents essentially happen because of two things.

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One - fast-moving water like those crashing waves here on this beach.

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And two - raised areas of sea bed, for example,

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sandbanks, near to the shore. Here's how they form.

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Imagine this is my Ocean

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and up here is the beach.

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And close to the shore, you have two sandbanks.

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With a gap in between them.

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Kind of like so.

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Now the waves come crashing in over the sand banks towards the beach

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and then the water tries to retreat but it can't quite so easily,

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because of this raised area of sea bed.

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So instead the water starts to flow sideways,

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parallel to the beach in what is called a feeder current

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until eventually all that volume of water

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finds a gap between two sandbanks

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and rushes through it out towards the open sea at an incredibly

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fast speed, until eventually it dissipates back into the ocean.

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Now this is what we call a rip current.

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The water travels at its fastest

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at the surface of this rip current which is why you can get

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into trouble, because you can often get rushed out to sea

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in the rip current without even noticing.

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It's one thing to draw a rip in the sand.

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But I want to experience one for myself.

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And the perfect person to guide me safely through a rip

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is RNLI Life Guard, Dicken Berryman.

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What are the main things I need to remember if I get caught in a rip current?

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It's easy to say don't panic but it's quite difficult not to panic.

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There's no question we're in a rip current.

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-We're heading out this way.

-That's right.

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We must be two, 300 metres out from shore.

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And we haven't swum at all out.

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The things that are going to help you,

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I'd always say hold on to your flotation device.

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If you've got a surf, or body board, hold on to it. That keeps you floating.

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The rip current's not going to take to underneath the water.

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What's going to take you down is you getting tired and panicky.

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I'm knackered already!

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The temptation is to swim straight to the beach.

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That's usually going to be straight into the mouth of the rip current.

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The rip current is going that way. Towards where the waves will break again.

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If you can see waves breaking either side, swim across to those waves.

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You'll get hit by a few waves, but they're going to take you to the beach.

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So that's really what we recommend.

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I don't feel like I'm going anywhere.

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We swim for what feels like ages.

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What's deceptive is that it doesn't feel

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like the water is dragging us anywhere.

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But we are being drawn rapidly out to sea.

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Trying to get out of the rip is exhausting.

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It's always moving.

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You think you've beaten it then you can feel it dragging you out again.

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I thought I was a strong swimmer

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but Dicken's seen enough and calls another life guard for help.

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It's been a clear lesson for me.

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Rip currents are dangerous.

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It's far better to avoid getting caught in the first place,

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but the problem is, rip currents like these move around,

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making it very difficult to know when and where they will strike.

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No wonder then that the RNLI is keen to find out

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if rips can be predicted, allowing life guards to warn swimmers away.

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So they've teamed up with scientists from Plymouth University.

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To understand the complex patterns of water movement up and

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down the beach they're using mobile current recorders called drifters.

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-So what exactly are drifters?

-A drifter is a unit

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that is designed to drift through the water, mimicking the flow pattern

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and where they go has been recorded

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with a little GPS recorder in here which is like a little sat-nav

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and the data that it's collecting,

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the position of the drifter is recorded on the small memory card.

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At any one time we might have 15 of these in the water,

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all recording where they move to.

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But then we do it for 20 to 30 days, a couple of hours each day,

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to deal with all the different types of conditions.

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You can imagine if this floats around for maybe three hours

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you get a good pattern of where the currents are.

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In addition to the drifters,

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Gerd and his team you static measuring rigs.

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These measure the speed of the currents at different tides.

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Once they've been deployed,

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the team send the drifters out from the shore.

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With Dicken and his colleague on hand to help from their boat.

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The university team release the units in sequence

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and they begin to drift around on the currents.

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Once they come back in again and run aground, we take them out,

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and the ones that go too far out the RNLI will bring that one in again.

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-So can you see that green one right at the back there?

-Good grief!

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That's gone really far out.

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So that's basically taken by the rip current

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and just being moved offshore.

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That's amazing, compared to the other ones, it just shot out!

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Gerd has already recorded more than 200 million measurements.

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But I want to know how close he is

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to predicting when and where rip currents may strike.

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From up here it's kind of obvious where the rip currents are.

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-You can see them so well.

-The blue streaks and the white patches in the middle

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of where the blue streaks are is where the waves are not breaking. That's where the rip currents are.

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So that's quite a few on this beach at any one time?

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There's usually about five, six, seven rips on the whole beach.

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-Let's talk data now.

-OK.

-First the info from the static rigs.

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Got a simple diagram showing two things - the top panel shows the water depth

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going from zero to eight metres water depth because the tides are very big.

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-We've got high tide.

-Tide's coming in, tide's going out, great.

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The bottom one is the interesting one

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because that shows the velocity, the strength of the rip current...

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The speed of the water?

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..together over that day.

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So as the water depth goes up, the current goes down.

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So when there's a lot of water,

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you don't have a lot of waves breaking. Is that right?

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When it's high tide, the waves are not breaking on the bars.

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Therefore the currents are turned off.

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OK, when it's low-tide, you've got shallower water, the wave's are

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-going to break on the sand bars and create a rip current.

-Yes.

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And next the data from the drifters.

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We're going to show you some

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movement of those drifters over a two-hour time period.

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We colour coded them so the blue ones do one sort of pattern,

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they go out on the rip and then come back on themselves.

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The red ones are doing a similar pattern

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but on the other side of the rip.

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They also go out and then come back in again.

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These green ones all pop out,

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they break through the surf zone and they are out in the water.

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And that's it, they stay out.

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I would have thought there'd only be one pattern.

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You go out to sea, that's the end of that.

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That's the thing about the dynamics, it changes from day to day and minute to minute.

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What exactly are you coming to with regards to a conclusion?

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If we put all the information together, the drift is telling us what the different patterns are

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and where on the beach things happen,

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then the static rig is telling us at what stage during the tidal cycle

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the currents are strong, we get a really good qualitative as well as

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a quantitative understanding of when the rips are at their most dangerous

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and where they are most dangerous.

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So that's the goal because then we can feed that information

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to the RNLI,

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it helps them manage their beaches and ultimately save lives.

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Great film, Liz, but I don't think rip currents are always a bad thing.

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Sometimes when surfing,

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they can be the only way out through a heavy beach break.

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Fair enough. We saw loads of surfers doing just that, when we were filming.

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But rip currents are very unpredictable

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and very dangerous so you have to really know what you're doing.

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Even if you are a surfer. It's not unheard of to have over 150 people in one day at one particular time

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of that day, all being rescued along the west coast of Cornwall and Devon.

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Because the conditions are absolutely perfect for loads of rip currents

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to form, the tide is right, the waves and all of that.

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So the research that these guys are doing is very important.

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And speaking of research, the RNLI and Plymouth Uni

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are now undertaking a massive survey to understand how people react when they are caught in rip.

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So if you've had an experience in a rip current,

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get on to our website and help them with their research.

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OK, enough about waves

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and on to somebody who's on a completely different wavelength.

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-Oh, dear.

-Sorry, that was very bad.

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Dr Yan has been out and about and back in the day he actually

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used to teach evolutionary biology. In fact, he even wrote a book on it.

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So when he got the chance to wow the crowds with his vast knowledge,

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he just couldn't help himself.

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One of the things that fascinates me about evolution is how,

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from a single starting point,

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it's produced such an incredible variety of life on Earth.

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From single-celled bacteria to Venus flytraps to elephants.

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And, incredibly, at the root of it all

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are almost imperceptible random changes that accumulate over time

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to create huge differences and all that amazing variety.

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Now, it might seem hard to believe

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but I'm going to show you how it happens using simply this.

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A straight line.

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Now, every time an organism reproduces,

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its DNA is copied into the next generation.

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But that copying isn't 100% perfect.

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Tiny mistakes are made and those mistakes are what we call mutations.

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The same happens if I try to trace this line.

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No matter how hard I try,

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my copy isn't 100% perfect.

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Tiny mistakes creep in and so this child line,

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the next generation, if you like,

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looks ever so slightly different from the original parent line.

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Now, in just one generation, those differences are hardly noticeable.

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But let's see how quickly the mistakes build up if I get

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hundreds and hundreds of people to copy this line over and over again.

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And for that, I'm going to need lots of volunteers.

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Could you possibly just trace this?

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It's much harder than it looks!

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I was really rubbish at Operation.

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Loads of people. So...

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You mark this out of 10, do you?

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As careful as you can, take your time.

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Right, thank you very much.

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Now, this line has been copied 50 times now

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and it's looking quite different and, crucially, the people who were

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copying don't know that the original looked like a straight line.

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They could only see the previous copy and that means that when they

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made a little mistake, the next person copies that mistake, too.

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And as the line is copied and copied,

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then the mistakes build up and the line changes and moves, it evolves.

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Right, let's carry on.

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The same is true of DNA.

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With each generation, new changes, or mutations, are added and,

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in fact, on average, each of us contains

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hundreds of completely new mutations.

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Just like these minor changes in the line,

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they simply get passed down through the generations.

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-Thank you very much indeed.

-No problem.

-So as the generations go by,

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random changes in the DNA accumulate

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and so the organism also changes and evolves.

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Brilliant, thank you very much.

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-I have to find another 100 people now.

-Thank you.

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-Copy next to it?

-Just right on top of the line.

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So, after 200 generations, this is what it looks like.

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You can see that just through tiny changes and mistakes building up

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and up and up, the line just moves and changes and evolves.

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It's incredible.

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Now, let me show you something else.

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After 25 people had copied this, I actually took an exact duplicate

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of that on to another computer

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and used that as a starting point for a whole new set of copying.

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Creating, if you like, a new branch of the family tree.

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And that ended up looking like this.

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It's completely different from the original.

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You'd never guess that the two have evolved from the same ancestor line.

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And the same can happen in nature.

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So if I had a population of animals

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and it was divided, for example, by a mountain range, then

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those two groups would take quite

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different evolutionary paths and would end up looking very different.

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And that's not all. After 175 generations,

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I branched yet another copy off from the original.

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And that ended up looking like this.

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You can see all these three

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look really quite different from each other.

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But these two, well, they look a bit more similar

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and this one looks different from either.

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And we can draw an evolutionary tree that looks something like this.

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These two are closely related. And this one is more distant.

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And in real life, analysing the differences

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between the DNA of various species is actually how we map out

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their evolutionary family trees.

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It's an area of science that is revolutionising our understanding of the natural world.

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So it's how we know, how we are more closely related to chimps than we are to orang-utans.

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And even that mushrooms are more closely related to us than they are to plants.

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But, of course, this random change isn't the whole story of evolution.

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In real life, natural selection plays an important part, too.

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But it all depends on these tiny, random changes.

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Without them, selection would have nothing to work on because all organisms would always be the same.

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So, it's like we're all the result of a badly drawn line?

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Yeah, pretty much. If you think about it

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in another way, about 250,000 lines ago or generations ago,

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we were on the same line as chimpanzees.

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A few mutations and a few errors here and there and here we are. Two different species.

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Yup. Nothing in biology makes sense except in the light of evolution.

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While we're on the subject of Dr Yan,

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I have a Dr Yan pub quiz thingy for you.

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27 jelly beans. Imagine one of these is a bit lighter than the rest

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and you have a pair of scales there.

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How would you work out which is the lightest jelly bean,

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and you're only allowed to use the scales three times?

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-That is the tricky bit. Any idea?

-I want a jelly bean.

-You can have a jelly bean in a minute.

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If you want to know the answer, it's all up there on the website.

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And while you're on the website,

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check out the dates of our Bang Live shows...

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I need frenzy, I need super excitement.

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..taking place all across the UK this summer.

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This is what Bang Live is all about.

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A beautiful day helps,

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an interactive area full of Bang fans and a live show up above.

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We're having such a lovely time here.

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You get to meet the people who watch the show and

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articulate about why we love science, why we love doing Bang so much.

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Who is your favourite Bang presenter?

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Dr Yan?!

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You can come and ask me questions, we can show you stuff.

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Oh, wow!

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Make sure you book your free tickets.

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It's all at /bang. That's why you should come to Bang Live.

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It's like riding a little wave of science.

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Back to slightly more real-world issues.

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We chuck out a lot of electric equipment in the UK.

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Every year, one million tons. What happens to it?

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Well, it has given rise to something that's called urban mining.

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They've been mining gold out in the Welsh hills since before Roman times.

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But they have never hit a source of precious metals as rich as this.

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Believe it or not, in these mountains of junk,

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is a far richer seam of gold than any goldmine.

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So, how come all this stuff is literally a goldmine?

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Well, you can ignore the steel and plastic casings.

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You can recycle them and get a couple of hundred quid a tonne.

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That's not what we're after. You want to get deep into the electronics.

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This fella. I promised you gold.

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And that's all gold.

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The reason why it's used is because as well as being a very good conductor of electricity,

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it doesn't tarnish. It stays exactly the same, year after year.

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For connections, it's absolutely perfect.

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So where these connections need to go into here, very important,

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these RAM boards, look at that.

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Big strip of gold.

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And because we got all these resources heaped up in one place,

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this whole process has become known as urban mining.

0:18:550:18:58

Here, on an industrial scale,

0:19:020:19:03

they're mining all sorts of metals from our waste electrical appliances.

0:19:030:19:08

Firstly, all the batteries and hazardous stuff is taken out carefully by hand.

0:19:090:19:14

Then the appliance's journey starts with simple crushing.

0:19:140:19:18

And then they're shredded and the iron plucked out by magnets.

0:19:220:19:26

Once all the big bits have been pulled out,

0:19:260:19:29

all that's left is these little chips of plastic,

0:19:290:19:32

tiny wires and fragments of those all-important circuit boards.

0:19:320:19:38

Now, to separate that lot they use a good old gold-rush technique,

0:19:380:19:41

panning.

0:19:410:19:43

Jets of water and a sieving process pan out the light bits of plastic,

0:19:450:19:48

leaving the heavier stuff at the bottom.

0:19:480:19:51

This is all metal, so you've got copper in there,

0:19:550:19:59

iron and steel, but, more importantly, you've go your gold,

0:19:590:20:03

silver and even platinum.

0:20:030:20:05

Huge quantities of this stuff is taken to vast refineries

0:20:050:20:09

to be separated, purified and recycled.

0:20:090:20:12

It's a multi-billion pound international business,

0:20:120:20:15

but I'm going to have a bit of a go at it myself.

0:20:150:20:19

I mean, how hard can it be?

0:20:190:20:22

All you need is a bit of nerve and some vicious chemicals.

0:20:220:20:26

If you're going to try and sort out gold from electronics

0:20:290:20:31

without multi-million-pound machinery,

0:20:310:20:34

you're best off trying to pick out the richest bits first.

0:20:340:20:37

I've plucked out some pretty rich bits of circuit board

0:20:370:20:40

that I can see some obvious gold on.

0:20:400:20:42

But now I want to cut away all this lot that I don't want,

0:20:420:20:47

just for the nice bits that I do.

0:20:470:20:49

This is pretty time-consuming,

0:20:530:20:55

but at least it satisfies my destructive streak.

0:20:550:20:58

Impressive as it looks,

0:20:580:21:00

the gold layer on these contacts is actually thinner than a human hair,

0:21:000:21:04

so I'm going to sacrifice my old phone,

0:21:040:21:06

because I reckon it should have plenty more.

0:21:060:21:09

There's gold contacts everywhere.

0:21:090:21:11

There's gold there, on the battery contacts,

0:21:110:21:14

gold there on the SIM card contacts,

0:21:140:21:16

and gold here where the charger goes in.

0:21:160:21:19

This thing's practically a nugget.

0:21:190:21:21

Look at that!

0:21:210:21:23

I'm having that as well. Right.

0:21:230:21:26

Angle grinders, I'm used to handling.

0:21:270:21:30

But the next process is way out of my comfort zone.

0:21:300:21:33

I'm going to need some protection.

0:21:330:21:36

This is concentrated nitric acid.

0:21:370:21:39

Really nasty stuff. Especially when it's heated up.

0:21:390:21:44

It will dissolve practically all the metals from the circuit boards

0:21:440:21:48

but it won't affect the gold.

0:21:480:21:50

In industry, they'd extract the silver and copper from this,

0:21:520:21:55

but I've only got eyes for one thing, gold.

0:21:550:21:59

But it still leaves us with the problem of separating the gold

0:22:010:22:05

from all the undissolvable rubbish that's in circuit boards.

0:22:050:22:10

Which means, unfortunately, we're now going to have to dissolve the gold.

0:22:100:22:14

It sounds like a gamble, but I'm hoping it will pay off in the end.

0:22:150:22:19

Because gold is so un-reactive, I'm going to need

0:22:190:22:22

some really powerful acid to dissolve it.

0:22:220:22:24

This is way beyond school chemistry.

0:22:240:22:27

I'm making up what medieval alchemists called aqua regia, or royal water.

0:22:270:22:32

It's a mix of very concentrated and strong acids,

0:22:320:22:36

strong enough even to dissolve gold.

0:22:360:22:39

If I get it right, it shouldn't affect the other stuff

0:22:390:22:43

the gold is mixed up with,

0:22:430:22:44

but it would happily burn right through my skin, given the chance.

0:22:440:22:48

A lot of mining processes involve some pretty nasty chemistry.

0:22:480:22:53

This is about as noxious as it gets for me.

0:22:530:22:56

With a bit of added heat, all that gold I've worked

0:22:560:22:59

so hard to get starts to vanish.

0:22:590:23:02

If I don't get the next stage of the recipe right,

0:23:020:23:05

it could be gone forever.

0:23:050:23:07

If you look at that dirty, black liquid I've just made,

0:23:090:23:14

it's difficult to be confident that it's full of gold.

0:23:140:23:17

It's a bit of a leap of faith.

0:23:170:23:21

Another few minutes of stirring at gas mark four, and we're done.

0:23:210:23:25

Now I've dissolved my gold into a liquid, all I need to do is

0:23:260:23:30

pour it through a filter to separate the gunk from the good stuff.

0:23:300:23:34

I'm not sure about this.

0:23:350:23:37

I seem to have made pure green, not gold.

0:23:370:23:40

No matter, I shall keep following the recipe.

0:23:400:23:43

Add a pinch of urea.

0:23:430:23:45

Quite lively.

0:23:460:23:48

Now comes the chef's secret ingredient.

0:23:490:23:52

What I'm about to do here is pretty much the alchemist's dream.

0:23:520:23:56

I'm going to make pure gold appear from something that isn't gold.

0:23:560:24:01

This is sodium metabisulphite,

0:24:010:24:04

not an everyday compound for folk like me,

0:24:040:24:07

but chemists use it quite a lot.

0:24:070:24:09

What it's going to do, effectively,

0:24:090:24:11

is add a couple of electrons to that gold,

0:24:110:24:13

to turn it back to gold metal.

0:24:130:24:15

In it goes.

0:24:180:24:19

Give that a good stir.

0:24:190:24:21

I'm still not seeing any gold.

0:24:240:24:26

I'm going to need more sodium metabisulphite, lots more.

0:24:260:24:31

Time to start getting a bit more free form with the quantities.

0:24:330:24:36

A little bit of gold panning later and I've reduced all the gold

0:24:400:24:44

from my pile of circuit boards to this.

0:24:440:24:48

OK, I've got myself my gold mud.

0:24:490:24:51

At the moment it looks a bit brown and uninspiring.

0:24:510:24:54

Let's see what happens when I put a flame to it.

0:24:540:24:57

Or perhaps two.

0:24:590:25:01

Now, I'm not going to lie to you, I don't hold out much hope

0:25:010:25:04

for whatever is left in that tiny crucible.

0:25:040:25:08

But there is one thing that should survive.

0:25:080:25:10

There it is.

0:25:110:25:12

From a bunch of obsolete old electronics,

0:25:120:25:16

add yourself some potentially lethal chemicals,

0:25:160:25:20

hit it with over 1,000 degrees of heat,

0:25:200:25:23

and you end up with one of those.

0:25:230:25:25

A nugget of pure gold.

0:25:250:25:27

And here it is, the fruits of Jem's labour.

0:25:310:25:35

You know what, it's kind of weighty.

0:25:350:25:36

-I love it. Do you want to know how much it's worth?

-I'd love to know.

0:25:360:25:40

So that's 1.7 grammes.

0:25:400:25:42

Which, at today's prices comes in at a mahoosive £56.90.

0:25:420:25:46

-Not too shabby.

-I think that's brilliant.

0:25:460:25:48

I'd be a lot happier if it weren't that, for a handling error,

0:25:480:25:52

-I probably tipped about £100 worth of gold into the sink.

-You didn't!

0:25:520:25:55

The interesting thing about Jem's gold is it's too pure to make into jewellery,

0:25:550:26:00

so the jewellery you have in your wedding rings and other things

0:26:000:26:04

is actually an alloy, so it's mixed with zinc and copper. This is too soft.

0:26:040:26:07

How many carats are we talking about?

0:26:070:26:10

-This is almost 24 carat gold.

-That's nice.

0:26:100:26:13

It's good gold. It got me thinking, what do you reckon you'd be worth

0:26:130:26:16

if you were actually worth your weight in gold?

0:26:160:26:20

If 1.7 grammes is £56.90...

0:26:200:26:21

I'm going to undervalue myself a bit because I don't want to give away my weight,

0:26:210:26:25

but round about £2 million.

0:26:250:26:27

-And worth every penny.

-Thank you!

0:26:270:26:30

There's plenty more about gold and the other precious metals at /bang.

0:26:320:26:36

Follow the links to the Open University's great new, interactive periodic table.

0:26:360:26:41

Before we go, talking about recycling,

0:26:410:26:43

this is my favourite recycled gadget of the week.

0:26:430:26:46

It's been invented by Jake Tyler from Loughborough University.

0:26:460:26:49

It's a fully recycled and recyclable vacuum-cleaner.

0:26:490:26:54

The actual body is made from the box

0:26:540:26:57

that it comes in and this plastic, the green plastic,

0:26:570:27:00

is actually nylon that has been printed on a 3D printer.

0:27:000:27:03

How awesome is that?

0:27:030:27:05

-I love it.

-Do you like that?

-Yes, very good.

-It's cute.

0:27:050:27:07

-Does it actually vacuum?

-It actually vacuums.

0:27:070:27:10

Probably enough of this week. On to next week.

0:27:100:27:13

When I get to hang out with the Bloodhound Crew,

0:27:130:27:16

who are building the world's first 1,000 mph car.

0:27:160:27:20

It's going to be part powered by a massive rocket

0:27:200:27:23

and massive rockets is what we'll be checking out.

0:27:230:27:26

And I'm on the hunt for this, the ultimate personal robot.

0:27:260:27:29

That's the ultimate one?

0:27:290:27:31

-This isn't the ultimate one, I'm looking for the ultimate one.

-It's all sounding good.

0:27:310:27:35

-We'll see you next week, take care.

-Bye.

0:27:350:27:37

Subtitles by Red Bee Media Ltd

0:27:490:27:51

E-mail [email protected]

0:27:510:27:54

In the second episode of the science series, Liz hits the beach with the RNLI to experience the power of rip currents; Dr Yan attempts to demonstrate evolution by drawing a couple of lines; and Jem is back in the workshop, turning everyday scrap into gold.


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