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