0:00:03 > 0:00:06Tonight, Jem investigates a new recycling phenomenon, urban mining
0:00:06 > 0:00:09and tries his hand at making pure gold from household scrap.
0:00:09 > 0:00:13What I'm about to do here is pretty much the alchemist's dream.
0:00:13 > 0:00:16I'm going to make pure gold
0:00:16 > 0:00:20appear from something that isn't gold.
0:00:20 > 0:00:22And Liz hits the beach with the RNLI
0:00:22 > 0:00:25to witness their number one problem, rip currents.
0:00:25 > 0:00:29It's easy to say don't panic, but it's quite difficult not to panic.
0:00:29 > 0:00:30It's SO cold! HE LAUGHS
0:00:30 > 0:00:36That's Bang Goes The Theory, revealing your world with a bang.
0:00:36 > 0:00:38Hello, welcome to Bang.
0:00:38 > 0:00:41This time of year we all love to head to the beach, don't we?
0:00:41 > 0:00:45But unfortunately what starts out as a bit of a splash around in the sea can often end up,
0:00:45 > 0:00:49even for the stronger swimmer, as a full-blown rescue operation.
0:00:51 > 0:00:55It's your typical British summer's day.
0:00:55 > 0:00:59But that won't stop you from getting into the water. You're made of sterner stuff than that!
0:00:59 > 0:01:04However, you may not know all the hidden dangers that a beach like this can hold.
0:01:04 > 0:01:09That's why these RNLI lifeguards are working very hard to understand
0:01:09 > 0:01:13those dangers better to prevent you from getting into trouble out there.
0:01:15 > 0:01:19Last summer on Perranporth beach in Cornwall alone,
0:01:19 > 0:01:24Life Guards had to make 144 daring rescues.
0:01:25 > 0:01:29Luckily this is just a training exercise.
0:01:29 > 0:01:33The number one threat is a hidden hazard called a rip current.
0:01:33 > 0:01:38Unlike surface waves, rip currents flow backwards out to sea,
0:01:38 > 0:01:41carrying unsuspecting swimmers with them.
0:01:41 > 0:01:45Rip currents essentially happen because of two things.
0:01:45 > 0:01:49One - fast-moving water like those crashing waves here on this beach.
0:01:49 > 0:01:52And two - raised areas of sea bed, for example,
0:01:52 > 0:01:56sandbanks, near to the shore. Here's how they form.
0:01:58 > 0:02:03Imagine this is my Ocean
0:02:03 > 0:02:05and up here is the beach.
0:02:05 > 0:02:09And close to the shore, you have two sandbanks.
0:02:09 > 0:02:12With a gap in between them.
0:02:12 > 0:02:14Kind of like so.
0:02:14 > 0:02:19Now the waves come crashing in over the sand banks towards the beach
0:02:19 > 0:02:24and then the water tries to retreat but it can't quite so easily,
0:02:24 > 0:02:28because of this raised area of sea bed.
0:02:28 > 0:02:30So instead the water starts to flow sideways,
0:02:30 > 0:02:36parallel to the beach in what is called a feeder current
0:02:36 > 0:02:39until eventually all that volume of water
0:02:39 > 0:02:41finds a gap between two sandbanks
0:02:41 > 0:02:46and rushes through it out towards the open sea at an incredibly
0:02:46 > 0:02:49fast speed, until eventually it dissipates back into the ocean.
0:02:49 > 0:02:53Now this is what we call a rip current.
0:02:53 > 0:02:55The water travels at its fastest
0:02:55 > 0:02:59at the surface of this rip current which is why you can get
0:02:59 > 0:03:02into trouble, because you can often get rushed out to sea
0:03:02 > 0:03:05in the rip current without even noticing.
0:03:07 > 0:03:11It's one thing to draw a rip in the sand.
0:03:12 > 0:03:15But I want to experience one for myself.
0:03:15 > 0:03:19And the perfect person to guide me safely through a rip
0:03:19 > 0:03:23is RNLI Life Guard, Dicken Berryman.
0:03:23 > 0:03:28What are the main things I need to remember if I get caught in a rip current?
0:03:29 > 0:03:32It's easy to say don't panic but it's quite difficult not to panic.
0:03:32 > 0:03:36There's no question we're in a rip current.
0:03:36 > 0:03:38- We're heading out this way. - That's right.
0:03:38 > 0:03:41We must be two, 300 metres out from shore.
0:03:41 > 0:03:43And we haven't swum at all out.
0:03:43 > 0:03:46The things that are going to help you,
0:03:46 > 0:03:48I'd always say hold on to your flotation device.
0:03:48 > 0:03:52If you've got a surf, or body board, hold on to it. That keeps you floating.
0:03:52 > 0:03:55The rip current's not going to take to underneath the water.
0:03:55 > 0:03:58What's going to take you down is you getting tired and panicky.
0:03:58 > 0:04:01I'm knackered already!
0:04:01 > 0:04:04The temptation is to swim straight to the beach.
0:04:04 > 0:04:08That's usually going to be straight into the mouth of the rip current.
0:04:08 > 0:04:12The rip current is going that way. Towards where the waves will break again.
0:04:12 > 0:04:17If you can see waves breaking either side, swim across to those waves.
0:04:17 > 0:04:20You'll get hit by a few waves, but they're going to take you to the beach.
0:04:20 > 0:04:21So that's really what we recommend.
0:04:21 > 0:04:24I don't feel like I'm going anywhere.
0:04:26 > 0:04:30We swim for what feels like ages.
0:04:30 > 0:04:33What's deceptive is that it doesn't feel
0:04:33 > 0:04:35like the water is dragging us anywhere.
0:04:35 > 0:04:38But we are being drawn rapidly out to sea.
0:04:38 > 0:04:41Trying to get out of the rip is exhausting.
0:04:41 > 0:04:43It's always moving.
0:04:45 > 0:04:49You think you've beaten it then you can feel it dragging you out again.
0:04:49 > 0:04:52I thought I was a strong swimmer
0:04:52 > 0:04:56but Dicken's seen enough and calls another life guard for help.
0:05:00 > 0:05:02It's been a clear lesson for me.
0:05:02 > 0:05:05Rip currents are dangerous.
0:05:05 > 0:05:09It's far better to avoid getting caught in the first place,
0:05:09 > 0:05:13but the problem is, rip currents like these move around,
0:05:13 > 0:05:16making it very difficult to know when and where they will strike.
0:05:16 > 0:05:19No wonder then that the RNLI is keen to find out
0:05:19 > 0:05:24if rips can be predicted, allowing life guards to warn swimmers away.
0:05:26 > 0:05:29So they've teamed up with scientists from Plymouth University.
0:05:29 > 0:05:33To understand the complex patterns of water movement up and
0:05:33 > 0:05:38down the beach they're using mobile current recorders called drifters.
0:05:38 > 0:05:41- So what exactly are drifters? - A drifter is a unit
0:05:41 > 0:05:46that is designed to drift through the water, mimicking the flow pattern
0:05:46 > 0:05:48and where they go has been recorded
0:05:48 > 0:05:51with a little GPS recorder in here which is like a little sat-nav
0:05:51 > 0:05:53and the data that it's collecting,
0:05:53 > 0:05:57the position of the drifter is recorded on the small memory card.
0:05:57 > 0:05:59At any one time we might have 15 of these in the water,
0:05:59 > 0:06:01all recording where they move to.
0:06:01 > 0:06:06But then we do it for 20 to 30 days, a couple of hours each day,
0:06:06 > 0:06:09to deal with all the different types of conditions.
0:06:09 > 0:06:13You can imagine if this floats around for maybe three hours
0:06:13 > 0:06:17you get a good pattern of where the currents are.
0:06:17 > 0:06:19In addition to the drifters,
0:06:19 > 0:06:22Gerd and his team you static measuring rigs.
0:06:22 > 0:06:27These measure the speed of the currents at different tides.
0:06:31 > 0:06:34Once they've been deployed,
0:06:34 > 0:06:37the team send the drifters out from the shore.
0:06:37 > 0:06:41With Dicken and his colleague on hand to help from their boat.
0:06:41 > 0:06:46The university team release the units in sequence
0:06:46 > 0:06:49and they begin to drift around on the currents.
0:06:49 > 0:06:53Once they come back in again and run aground, we take them out,
0:06:53 > 0:06:58and the ones that go too far out the RNLI will bring that one in again.
0:06:58 > 0:07:01- So can you see that green one right at the back there?- Good grief!
0:07:01 > 0:07:03That's gone really far out.
0:07:03 > 0:07:06So that's basically taken by the rip current
0:07:06 > 0:07:08and just being moved offshore.
0:07:08 > 0:07:12That's amazing, compared to the other ones, it just shot out!
0:07:12 > 0:07:17Gerd has already recorded more than 200 million measurements.
0:07:17 > 0:07:20But I want to know how close he is
0:07:20 > 0:07:24to predicting when and where rip currents may strike.
0:07:24 > 0:07:28From up here it's kind of obvious where the rip currents are.
0:07:28 > 0:07:32- You can see them so well.- The blue streaks and the white patches in the middle
0:07:32 > 0:07:36of where the blue streaks are is where the waves are not breaking. That's where the rip currents are.
0:07:36 > 0:07:39So that's quite a few on this beach at any one time?
0:07:39 > 0:07:42There's usually about five, six, seven rips on the whole beach.
0:07:42 > 0:07:48- Let's talk data now.- OK. - First the info from the static rigs.
0:07:48 > 0:07:52Got a simple diagram showing two things - the top panel shows the water depth
0:07:52 > 0:07:56going from zero to eight metres water depth because the tides are very big.
0:07:56 > 0:08:00- We've got high tide.- Tide's coming in, tide's going out, great.
0:08:00 > 0:08:02The bottom one is the interesting one
0:08:02 > 0:08:05because that shows the velocity, the strength of the rip current...
0:08:05 > 0:08:07The speed of the water?
0:08:07 > 0:08:10..together over that day.
0:08:10 > 0:08:14So as the water depth goes up, the current goes down.
0:08:14 > 0:08:16So when there's a lot of water,
0:08:16 > 0:08:19you don't have a lot of waves breaking. Is that right?
0:08:19 > 0:08:23When it's high tide, the waves are not breaking on the bars.
0:08:23 > 0:08:25Therefore the currents are turned off.
0:08:25 > 0:08:29OK, when it's low-tide, you've got shallower water, the wave's are
0:08:29 > 0:08:32- going to break on the sand bars and create a rip current.- Yes.
0:08:32 > 0:08:36And next the data from the drifters.
0:08:36 > 0:08:37We're going to show you some
0:08:37 > 0:08:40movement of those drifters over a two-hour time period.
0:08:40 > 0:08:44We colour coded them so the blue ones do one sort of pattern,
0:08:44 > 0:08:48they go out on the rip and then come back on themselves.
0:08:48 > 0:08:50The red ones are doing a similar pattern
0:08:50 > 0:08:52but on the other side of the rip.
0:08:52 > 0:08:54They also go out and then come back in again.
0:08:54 > 0:08:56These green ones all pop out,
0:08:56 > 0:08:59they break through the surf zone and they are out in the water.
0:08:59 > 0:09:00And that's it, they stay out.
0:09:00 > 0:09:02I would have thought there'd only be one pattern.
0:09:02 > 0:09:04You go out to sea, that's the end of that.
0:09:04 > 0:09:08That's the thing about the dynamics, it changes from day to day and minute to minute.
0:09:08 > 0:09:12What exactly are you coming to with regards to a conclusion?
0:09:12 > 0:09:17If we put all the information together, the drift is telling us what the different patterns are
0:09:17 > 0:09:19and where on the beach things happen,
0:09:19 > 0:09:23then the static rig is telling us at what stage during the tidal cycle
0:09:23 > 0:09:27the currents are strong, we get a really good qualitative as well as
0:09:27 > 0:09:30a quantitative understanding of when the rips are at their most dangerous
0:09:30 > 0:09:32and where they are most dangerous.
0:09:32 > 0:09:36So that's the goal because then we can feed that information
0:09:36 > 0:09:37to the RNLI,
0:09:37 > 0:09:41it helps them manage their beaches and ultimately save lives.
0:09:41 > 0:09:45Great film, Liz, but I don't think rip currents are always a bad thing.
0:09:45 > 0:09:47Sometimes when surfing,
0:09:47 > 0:09:50they can be the only way out through a heavy beach break.
0:09:50 > 0:09:53Fair enough. We saw loads of surfers doing just that, when we were filming.
0:09:53 > 0:09:56But rip currents are very unpredictable
0:09:56 > 0:09:59and very dangerous so you have to really know what you're doing.
0:09:59 > 0:10:04Even if you are a surfer. It's not unheard of to have over 150 people in one day at one particular time
0:10:04 > 0:10:09of that day, all being rescued along the west coast of Cornwall and Devon.
0:10:09 > 0:10:12Because the conditions are absolutely perfect for loads of rip currents
0:10:12 > 0:10:16to form, the tide is right, the waves and all of that.
0:10:16 > 0:10:19So the research that these guys are doing is very important.
0:10:19 > 0:10:22And speaking of research, the RNLI and Plymouth Uni
0:10:22 > 0:10:27are now undertaking a massive survey to understand how people react when they are caught in rip.
0:10:27 > 0:10:30So if you've had an experience in a rip current,
0:10:30 > 0:10:34get on to our website and help them with their research.
0:10:34 > 0:10:36OK, enough about waves
0:10:36 > 0:10:39and on to somebody who's on a completely different wavelength.
0:10:39 > 0:10:42- Oh, dear.- Sorry, that was very bad.
0:10:42 > 0:10:45Dr Yan has been out and about and back in the day he actually
0:10:45 > 0:10:48used to teach evolutionary biology. In fact, he even wrote a book on it.
0:10:48 > 0:10:51So when he got the chance to wow the crowds with his vast knowledge,
0:10:51 > 0:10:54he just couldn't help himself.
0:10:55 > 0:10:59One of the things that fascinates me about evolution is how,
0:10:59 > 0:11:01from a single starting point,
0:11:01 > 0:11:04it's produced such an incredible variety of life on Earth.
0:11:04 > 0:11:09From single-celled bacteria to Venus flytraps to elephants.
0:11:09 > 0:11:11And, incredibly, at the root of it all
0:11:11 > 0:11:16are almost imperceptible random changes that accumulate over time
0:11:16 > 0:11:21to create huge differences and all that amazing variety.
0:11:21 > 0:11:23Now, it might seem hard to believe
0:11:23 > 0:11:26but I'm going to show you how it happens using simply this.
0:11:26 > 0:11:28A straight line.
0:11:30 > 0:11:33Now, every time an organism reproduces,
0:11:33 > 0:11:35its DNA is copied into the next generation.
0:11:35 > 0:11:38But that copying isn't 100% perfect.
0:11:38 > 0:11:42Tiny mistakes are made and those mistakes are what we call mutations.
0:11:42 > 0:11:45The same happens if I try to trace this line.
0:11:45 > 0:11:47No matter how hard I try,
0:11:47 > 0:11:51my copy isn't 100% perfect.
0:11:51 > 0:11:57Tiny mistakes creep in and so this child line,
0:11:57 > 0:12:00the next generation, if you like,
0:12:00 > 0:12:04looks ever so slightly different from the original parent line.
0:12:04 > 0:12:09Now, in just one generation, those differences are hardly noticeable.
0:12:09 > 0:12:13But let's see how quickly the mistakes build up if I get
0:12:13 > 0:12:16hundreds and hundreds of people to copy this line over and over again.
0:12:16 > 0:12:20And for that, I'm going to need lots of volunteers.
0:12:22 > 0:12:25Could you possibly just trace this?
0:12:26 > 0:12:29It's much harder than it looks!
0:12:29 > 0:12:33I was really rubbish at Operation.
0:12:33 > 0:12:36Loads of people. So...
0:12:36 > 0:12:38You mark this out of 10, do you?
0:12:38 > 0:12:41As careful as you can, take your time.
0:12:41 > 0:12:43Right, thank you very much.
0:12:43 > 0:12:45Now, this line has been copied 50 times now
0:12:45 > 0:12:48and it's looking quite different and, crucially, the people who were
0:12:48 > 0:12:52copying don't know that the original looked like a straight line.
0:12:52 > 0:12:55They could only see the previous copy and that means that when they
0:12:55 > 0:12:58made a little mistake, the next person copies that mistake, too.
0:12:58 > 0:13:00And as the line is copied and copied,
0:13:00 > 0:13:04then the mistakes build up and the line changes and moves, it evolves.
0:13:04 > 0:13:06Right, let's carry on.
0:13:08 > 0:13:10The same is true of DNA.
0:13:10 > 0:13:13With each generation, new changes, or mutations, are added and,
0:13:13 > 0:13:16in fact, on average, each of us contains
0:13:16 > 0:13:18hundreds of completely new mutations.
0:13:18 > 0:13:20Just like these minor changes in the line,
0:13:20 > 0:13:24they simply get passed down through the generations.
0:13:24 > 0:13:27- Thank you very much indeed.- No problem.- So as the generations go by,
0:13:27 > 0:13:30random changes in the DNA accumulate
0:13:30 > 0:13:33and so the organism also changes and evolves.
0:13:33 > 0:13:35Brilliant, thank you very much.
0:13:35 > 0:13:37- I have to find another 100 people now.- Thank you.
0:13:37 > 0:13:40- Copy next to it?- Just right on top of the line.
0:13:42 > 0:13:45So, after 200 generations, this is what it looks like.
0:13:45 > 0:13:48You can see that just through tiny changes and mistakes building up
0:13:48 > 0:13:52and up and up, the line just moves and changes and evolves.
0:13:52 > 0:13:55It's incredible.
0:13:55 > 0:13:56Now, let me show you something else.
0:13:56 > 0:14:00After 25 people had copied this, I actually took an exact duplicate
0:14:00 > 0:14:02of that on to another computer
0:14:02 > 0:14:05and used that as a starting point for a whole new set of copying.
0:14:05 > 0:14:08Creating, if you like, a new branch of the family tree.
0:14:08 > 0:14:11And that ended up looking like this.
0:14:11 > 0:14:14It's completely different from the original.
0:14:14 > 0:14:18You'd never guess that the two have evolved from the same ancestor line.
0:14:18 > 0:14:20And the same can happen in nature.
0:14:20 > 0:14:22So if I had a population of animals
0:14:22 > 0:14:25and it was divided, for example, by a mountain range, then
0:14:25 > 0:14:27those two groups would take quite
0:14:27 > 0:14:31different evolutionary paths and would end up looking very different.
0:14:31 > 0:14:35And that's not all. After 175 generations,
0:14:35 > 0:14:38I branched yet another copy off from the original.
0:14:38 > 0:14:40And that ended up looking like this.
0:14:40 > 0:14:41You can see all these three
0:14:41 > 0:14:44look really quite different from each other.
0:14:44 > 0:14:47But these two, well, they look a bit more similar
0:14:47 > 0:14:50and this one looks different from either.
0:14:50 > 0:14:54And we can draw an evolutionary tree that looks something like this.
0:14:54 > 0:14:57These two are closely related. And this one is more distant.
0:14:59 > 0:15:02And in real life, analysing the differences
0:15:02 > 0:15:06between the DNA of various species is actually how we map out
0:15:06 > 0:15:08their evolutionary family trees.
0:15:08 > 0:15:13It's an area of science that is revolutionising our understanding of the natural world.
0:15:13 > 0:15:18So it's how we know, how we are more closely related to chimps than we are to orang-utans.
0:15:18 > 0:15:22And even that mushrooms are more closely related to us than they are to plants.
0:15:22 > 0:15:27But, of course, this random change isn't the whole story of evolution.
0:15:27 > 0:15:30In real life, natural selection plays an important part, too.
0:15:30 > 0:15:34But it all depends on these tiny, random changes.
0:15:34 > 0:15:41Without them, selection would have nothing to work on because all organisms would always be the same.
0:15:41 > 0:15:44So, it's like we're all the result of a badly drawn line?
0:15:44 > 0:15:47Yeah, pretty much. If you think about it
0:15:47 > 0:15:51in another way, about 250,000 lines ago or generations ago,
0:15:51 > 0:15:53we were on the same line as chimpanzees.
0:15:53 > 0:15:57A few mutations and a few errors here and there and here we are. Two different species.
0:15:57 > 0:16:01Yup. Nothing in biology makes sense except in the light of evolution.
0:16:01 > 0:16:05While we're on the subject of Dr Yan,
0:16:05 > 0:16:07I have a Dr Yan pub quiz thingy for you.
0:16:07 > 0:16:1327 jelly beans. Imagine one of these is a bit lighter than the rest
0:16:13 > 0:16:16and you have a pair of scales there.
0:16:16 > 0:16:19How would you work out which is the lightest jelly bean,
0:16:19 > 0:16:22and you're only allowed to use the scales three times?
0:16:22 > 0:16:26- That is the tricky bit. Any idea? - I want a jelly bean.- You can have a jelly bean in a minute.
0:16:26 > 0:16:30If you want to know the answer, it's all up there on the website.
0:16:30 > 0:16:32And while you're on the website,
0:16:32 > 0:16:35check out the dates of our Bang Live shows...
0:16:38 > 0:16:41I need frenzy, I need super excitement.
0:16:41 > 0:16:44..taking place all across the UK this summer.
0:16:44 > 0:16:46This is what Bang Live is all about.
0:16:46 > 0:16:49A beautiful day helps,
0:16:49 > 0:16:52an interactive area full of Bang fans and a live show up above.
0:16:52 > 0:16:55We're having such a lovely time here.
0:16:55 > 0:16:57You get to meet the people who watch the show and
0:16:57 > 0:17:01articulate about why we love science, why we love doing Bang so much.
0:17:01 > 0:17:03Who is your favourite Bang presenter?
0:17:03 > 0:17:05Dr Yan?!
0:17:12 > 0:17:15You can come and ask me questions, we can show you stuff.
0:17:17 > 0:17:20Oh, wow!
0:17:20 > 0:17:23Make sure you book your free tickets.
0:17:23 > 0:17:26It's all at /bang. That's why you should come to Bang Live.
0:17:28 > 0:17:30It's like riding a little wave of science.
0:17:33 > 0:17:35Back to slightly more real-world issues.
0:17:35 > 0:17:38We chuck out a lot of electric equipment in the UK.
0:17:38 > 0:17:42Every year, one million tons. What happens to it?
0:17:42 > 0:17:46Well, it has given rise to something that's called urban mining.
0:17:51 > 0:17:55They've been mining gold out in the Welsh hills since before Roman times.
0:17:55 > 0:17:59But they have never hit a source of precious metals as rich as this.
0:17:59 > 0:18:02Believe it or not, in these mountains of junk,
0:18:02 > 0:18:07is a far richer seam of gold than any goldmine.
0:18:09 > 0:18:14So, how come all this stuff is literally a goldmine?
0:18:14 > 0:18:17Well, you can ignore the steel and plastic casings.
0:18:17 > 0:18:20You can recycle them and get a couple of hundred quid a tonne.
0:18:20 > 0:18:24That's not what we're after. You want to get deep into the electronics.
0:18:24 > 0:18:27This fella. I promised you gold.
0:18:27 > 0:18:30And that's all gold.
0:18:30 > 0:18:35The reason why it's used is because as well as being a very good conductor of electricity,
0:18:35 > 0:18:39it doesn't tarnish. It stays exactly the same, year after year.
0:18:39 > 0:18:42For connections, it's absolutely perfect.
0:18:42 > 0:18:46So where these connections need to go into here, very important,
0:18:46 > 0:18:48these RAM boards, look at that.
0:18:50 > 0:18:51Big strip of gold.
0:18:51 > 0:18:55And because we got all these resources heaped up in one place,
0:18:55 > 0:18:58this whole process has become known as urban mining.
0:19:02 > 0:19:03Here, on an industrial scale,
0:19:03 > 0:19:08they're mining all sorts of metals from our waste electrical appliances.
0:19:09 > 0:19:14Firstly, all the batteries and hazardous stuff is taken out carefully by hand.
0:19:14 > 0:19:18Then the appliance's journey starts with simple crushing.
0:19:22 > 0:19:26And then they're shredded and the iron plucked out by magnets.
0:19:26 > 0:19:29Once all the big bits have been pulled out,
0:19:29 > 0:19:32all that's left is these little chips of plastic,
0:19:32 > 0:19:38tiny wires and fragments of those all-important circuit boards.
0:19:38 > 0:19:41Now, to separate that lot they use a good old gold-rush technique,
0:19:41 > 0:19:43panning.
0:19:45 > 0:19:48Jets of water and a sieving process pan out the light bits of plastic,
0:19:48 > 0:19:51leaving the heavier stuff at the bottom.
0:19:55 > 0:19:59This is all metal, so you've got copper in there,
0:19:59 > 0:20:03iron and steel, but, more importantly, you've go your gold,
0:20:03 > 0:20:05silver and even platinum.
0:20:05 > 0:20:09Huge quantities of this stuff is taken to vast refineries
0:20:09 > 0:20:12to be separated, purified and recycled.
0:20:12 > 0:20:15It's a multi-billion pound international business,
0:20:15 > 0:20:19but I'm going to have a bit of a go at it myself.
0:20:19 > 0:20:22I mean, how hard can it be?
0:20:22 > 0:20:26All you need is a bit of nerve and some vicious chemicals.
0:20:29 > 0:20:31If you're going to try and sort out gold from electronics
0:20:31 > 0:20:34without multi-million-pound machinery,
0:20:34 > 0:20:37you're best off trying to pick out the richest bits first.
0:20:37 > 0:20:40I've plucked out some pretty rich bits of circuit board
0:20:40 > 0:20:42that I can see some obvious gold on.
0:20:42 > 0:20:47But now I want to cut away all this lot that I don't want,
0:20:47 > 0:20:49just for the nice bits that I do.
0:20:53 > 0:20:55This is pretty time-consuming,
0:20:55 > 0:20:58but at least it satisfies my destructive streak.
0:20:58 > 0:21:00Impressive as it looks,
0:21:00 > 0:21:04the gold layer on these contacts is actually thinner than a human hair,
0:21:04 > 0:21:06so I'm going to sacrifice my old phone,
0:21:06 > 0:21:09because I reckon it should have plenty more.
0:21:09 > 0:21:11There's gold contacts everywhere.
0:21:11 > 0:21:14There's gold there, on the battery contacts,
0:21:14 > 0:21:16gold there on the SIM card contacts,
0:21:16 > 0:21:19and gold here where the charger goes in.
0:21:19 > 0:21:21This thing's practically a nugget.
0:21:21 > 0:21:23Look at that!
0:21:23 > 0:21:26I'm having that as well. Right.
0:21:27 > 0:21:30Angle grinders, I'm used to handling.
0:21:30 > 0:21:33But the next process is way out of my comfort zone.
0:21:33 > 0:21:36I'm going to need some protection.
0:21:37 > 0:21:39This is concentrated nitric acid.
0:21:39 > 0:21:44Really nasty stuff. Especially when it's heated up.
0:21:44 > 0:21:48It will dissolve practically all the metals from the circuit boards
0:21:48 > 0:21:50but it won't affect the gold.
0:21:52 > 0:21:55In industry, they'd extract the silver and copper from this,
0:21:55 > 0:21:59but I've only got eyes for one thing, gold.
0:22:01 > 0:22:05But it still leaves us with the problem of separating the gold
0:22:05 > 0:22:10from all the undissolvable rubbish that's in circuit boards.
0:22:10 > 0:22:14Which means, unfortunately, we're now going to have to dissolve the gold.
0:22:15 > 0:22:19It sounds like a gamble, but I'm hoping it will pay off in the end.
0:22:19 > 0:22:22Because gold is so un-reactive, I'm going to need
0:22:22 > 0:22:24some really powerful acid to dissolve it.
0:22:24 > 0:22:27This is way beyond school chemistry.
0:22:27 > 0:22:32I'm making up what medieval alchemists called aqua regia, or royal water.
0:22:32 > 0:22:36It's a mix of very concentrated and strong acids,
0:22:36 > 0:22:39strong enough even to dissolve gold.
0:22:39 > 0:22:43If I get it right, it shouldn't affect the other stuff
0:22:43 > 0:22:44the gold is mixed up with,
0:22:44 > 0:22:48but it would happily burn right through my skin, given the chance.
0:22:48 > 0:22:53A lot of mining processes involve some pretty nasty chemistry.
0:22:53 > 0:22:56This is about as noxious as it gets for me.
0:22:56 > 0:22:59With a bit of added heat, all that gold I've worked
0:22:59 > 0:23:02so hard to get starts to vanish.
0:23:02 > 0:23:05If I don't get the next stage of the recipe right,
0:23:05 > 0:23:07it could be gone forever.
0:23:09 > 0:23:14If you look at that dirty, black liquid I've just made,
0:23:14 > 0:23:17it's difficult to be confident that it's full of gold.
0:23:17 > 0:23:21It's a bit of a leap of faith.
0:23:21 > 0:23:25Another few minutes of stirring at gas mark four, and we're done.
0:23:26 > 0:23:30Now I've dissolved my gold into a liquid, all I need to do is
0:23:30 > 0:23:34pour it through a filter to separate the gunk from the good stuff.
0:23:35 > 0:23:37I'm not sure about this.
0:23:37 > 0:23:40I seem to have made pure green, not gold.
0:23:40 > 0:23:43No matter, I shall keep following the recipe.
0:23:43 > 0:23:45Add a pinch of urea.
0:23:46 > 0:23:48Quite lively.
0:23:49 > 0:23:52Now comes the chef's secret ingredient.
0:23:52 > 0:23:56What I'm about to do here is pretty much the alchemist's dream.
0:23:56 > 0:24:01I'm going to make pure gold appear from something that isn't gold.
0:24:01 > 0:24:04This is sodium metabisulphite,
0:24:04 > 0:24:07not an everyday compound for folk like me,
0:24:07 > 0:24:09but chemists use it quite a lot.
0:24:09 > 0:24:11What it's going to do, effectively,
0:24:11 > 0:24:13is add a couple of electrons to that gold,
0:24:13 > 0:24:15to turn it back to gold metal.
0:24:18 > 0:24:19In it goes.
0:24:19 > 0:24:21Give that a good stir.
0:24:24 > 0:24:26I'm still not seeing any gold.
0:24:26 > 0:24:31I'm going to need more sodium metabisulphite, lots more.
0:24:33 > 0:24:36Time to start getting a bit more free form with the quantities.
0:24:40 > 0:24:44A little bit of gold panning later and I've reduced all the gold
0:24:44 > 0:24:48from my pile of circuit boards to this.
0:24:49 > 0:24:51OK, I've got myself my gold mud.
0:24:51 > 0:24:54At the moment it looks a bit brown and uninspiring.
0:24:54 > 0:24:57Let's see what happens when I put a flame to it.
0:24:59 > 0:25:01Or perhaps two.
0:25:01 > 0:25:04Now, I'm not going to lie to you, I don't hold out much hope
0:25:04 > 0:25:08for whatever is left in that tiny crucible.
0:25:08 > 0:25:10But there is one thing that should survive.
0:25:11 > 0:25:12There it is.
0:25:12 > 0:25:16From a bunch of obsolete old electronics,
0:25:16 > 0:25:20add yourself some potentially lethal chemicals,
0:25:20 > 0:25:23hit it with over 1,000 degrees of heat,
0:25:23 > 0:25:25and you end up with one of those.
0:25:25 > 0:25:27A nugget of pure gold.
0:25:31 > 0:25:35And here it is, the fruits of Jem's labour.
0:25:35 > 0:25:36You know what, it's kind of weighty.
0:25:36 > 0:25:40- I love it. Do you want to know how much it's worth?- I'd love to know.
0:25:40 > 0:25:42So that's 1.7 grammes.
0:25:42 > 0:25:46Which, at today's prices comes in at a mahoosive £56.90.
0:25:46 > 0:25:48- Not too shabby. - I think that's brilliant.
0:25:48 > 0:25:52I'd be a lot happier if it weren't that, for a handling error,
0:25:52 > 0:25:55- I probably tipped about £100 worth of gold into the sink.- You didn't!
0:25:55 > 0:26:00The interesting thing about Jem's gold is it's too pure to make into jewellery,
0:26:00 > 0:26:04so the jewellery you have in your wedding rings and other things
0:26:04 > 0:26:07is actually an alloy, so it's mixed with zinc and copper. This is too soft.
0:26:07 > 0:26:10How many carats are we talking about?
0:26:10 > 0:26:13- This is almost 24 carat gold. - That's nice.
0:26:13 > 0:26:16It's good gold. It got me thinking, what do you reckon you'd be worth
0:26:16 > 0:26:20if you were actually worth your weight in gold?
0:26:20 > 0:26:21If 1.7 grammes is £56.90...
0:26:21 > 0:26:25I'm going to undervalue myself a bit because I don't want to give away my weight,
0:26:25 > 0:26:27but round about £2 million.
0:26:27 > 0:26:30- And worth every penny. - Thank you!
0:26:32 > 0:26:36There's plenty more about gold and the other precious metals at /bang.
0:26:36 > 0:26:41Follow the links to the Open University's great new, interactive periodic table.
0:26:41 > 0:26:43Before we go, talking about recycling,
0:26:43 > 0:26:46this is my favourite recycled gadget of the week.
0:26:46 > 0:26:49It's been invented by Jake Tyler from Loughborough University.
0:26:49 > 0:26:54It's a fully recycled and recyclable vacuum-cleaner.
0:26:54 > 0:26:57The actual body is made from the box
0:26:57 > 0:27:00that it comes in and this plastic, the green plastic,
0:27:00 > 0:27:03is actually nylon that has been printed on a 3D printer.
0:27:03 > 0:27:05How awesome is that?
0:27:05 > 0:27:07- I love it.- Do you like that? - Yes, very good.- It's cute.
0:27:07 > 0:27:10- Does it actually vacuum? - It actually vacuums.
0:27:10 > 0:27:13Probably enough of this week. On to next week.
0:27:13 > 0:27:16When I get to hang out with the Bloodhound Crew,
0:27:16 > 0:27:20who are building the world's first 1,000 mph car.
0:27:20 > 0:27:23It's going to be part powered by a massive rocket
0:27:23 > 0:27:26and massive rockets is what we'll be checking out.
0:27:26 > 0:27:29And I'm on the hunt for this, the ultimate personal robot.
0:27:29 > 0:27:31That's the ultimate one?
0:27:31 > 0:27:35- This isn't the ultimate one, I'm looking for the ultimate one. - It's all sounding good.
0:27:35 > 0:27:37- We'll see you next week, take care. - Bye.
0:27:49 > 0:27:51Subtitles by Red Bee Media Ltd
0:27:51 > 0:27:54E-mail subtitling@bbc.co.uk