Bang Goes The Theory (2009) s04e05 Episode Script
Season 4, Episode 5
Today, Dallas takes part in a Oitizen Science experiment A million-strong army of people like you and me helping change the way we think about our world and beyond.
.
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Dr Yan calculates the speed of light l'm going to use this blender.
.
.
and Jem builds a home-made laser.
Let's see what 5,000 volts does to this little arrangement.
That's Bang Goes The Theory, revealing your world with a bang.
Hello, and welcome to Bang Goes The Theory.
We starts tonight with lasers.
We've just had the 50th anniversary of the invention of this revolutionary form of light.
But how exactly do they work? Jem has been finding out.
Lasers were first suggested almost 100 years ago, by who else but the grandfather of science, Albert Einstein.
He theorised that if a material could absorb light, then under certain conditions, it could release it as well.
lf that happened, it would create a brand-new type of light that simply didn't exist on our planet.
But back then, nobody had any idea if a new type of light would be of any use to anybody.
Ready for action.
Even in 1960, when they built the very first laser, the team did not know what to do with it.
One guy said, ''This looks like a solution waiting for a problem.
'' lt's solved an awful lot of problems since then.
lt used to be quoted that on average, you're never more than six feet from a rat.
Now it's estimated you're never more than eight feet from a laser.
They're everywhere.
They're in your OD player, your DVD player.
They're performing eye surgery, they're treating cancers.
They're transporting data across the internet, even scanning your weekly shopping.
Beep - that's a laser.
l mean, what other problems would you want lasers to solve? How about the world energy crisis? Here at the STFO Oentral Laser Facility near Oxford, they're pointing one of the world's brightest lasers at exactly that problem.
Nobody is going to pretend that laser physics is a piece of cake.
But the fundamentals are actually quite simple.
So how do you make a machine that you can plug into the wall and convert a few minutes of mains electricity into a pulse of light so intense, it would make a star look dim? First you've got to store that electricity.
And for that you need something like a giant battery bank - these fellas.
These store about as much energy as a hand grenade.
And at the flick of a switch, it's released into a series of flashbulbs.
Like camera flashes, they're extremely intense but only on for a very short period.
The energy from that blast of light is absorbed by a lump of lazing material.
ln this case, they're neodymium atoms, the same ones that are used to make powerful little fridge magnets.
So now, that energy that we took from the plug socket is stored as a bunch of identically excited atoms, poised ready to re-release it.
And the trigger to release it is a little pulse of light.
lf you think of a beam of light being made up of stream of little bullets called photons, when one of those photons hits an excited atom, it releases an identical photon.
And as these photons cascade through the lazing material, they cause all the atoms to release all their energy.
By the time it comes out at the end, almost instantaneously, you've collected that energy as a pulse of light.
At this point, we've got ourselves a pulse of laser light.
lt's about this long.
lt's travelling at 186,000 miles a second, and could get to the moon in literallya couple of clicks.
The laser pulse flies through the building, getting focused and directed by a series of mirrors until it emerges through those windows into this room, where it finally gets directed into here, where a capsule of unsuspecting hydrogen atoms get such a massive kick they fuse together, releasing energy, the kind of energy that powers our sun.
Obviously, l couldn't be here if this was switched on.
But with the success they've had with the experiments in this facility, there's plans to build a generating station, a laser-powered generating station, where the heat from that fusion will boil a fluid, drive a turbine, turn a generator and create safe, sustainable energy for at least the next 1 ,000 years.
lnspired by that, l feel we've got to have a go at building our own laser.
We still really underestimate how ubiquitous lasers are in the modern world, don't we? The really exciting bit for me is this fusion thing.
Every time l meet someone in that field, l get the impression that technology is still 20 years away.
A couple of years later, it's 20 years away.
What do you feel now that you've seen it first hand? l was of the same school of thought as you.
Fusion, 20 years away.
l know that.
After having been there, and speaking to the guys working at the facility, l'm quite heartened, really quite heartened.
They themselves said that when they started working on laser-based fusion, they were very sceptical.
But over recent years, they've ticked off, one by one, the obstacles in the way.
To the point that they are going through the periodic table, looking at the elements they use, going, ''No, we can't use that element, there is not enough of it.
'' They are genuinely looking for a sustainable energy source for the next 1 ,000 years - and l think they're close.
- ln terms of laser fusion and plasma fusion - the other way they're trying to achieve the same thing, it's a two-horse race, l feel more of an affinity with the plasma people.
l visited the Joint European Torus last series, so What about you, Jem? You're laser, are you? l just When l was there, l was very, very impressed with every part of the set-up.
We have a divided camp, l love it! lt's good there's a bit of rivalry.
Not rivalry-rivalry, but it's good you've got a bit of healthy competition.
lt keeps you on your toes, it fast tracks the research.
lt's a good thing.
Talking of research, the lasers, the thing that came out of it for me, the blue-sky research element of it.
When they started on lasers, it had no application at all.
They were just building it for the sake of building it.
And now they're everywhere.
ln science today, there just isn't so much of that blue-sky research.
- lt's something we should go back to.
- Definitely.
l guess it's economics, people worry.
Question - why build a laser? When most think of lasers, they think Death Stars, we think of people being strapped to metal gurneys, that kind of thing.
Talk us through the idea.
They're simply amazing! l mean But hideously dangerous.
Which is why anybody with designs on world domination, first thing they do is build a laser.
- Step one, build a laser.
- Step two, buy a white cat.
Moving on, time for more Dr Yan.
He's actually using a laser in this week's experiment, he's calculating the speed of light.
For centuries, measuring the speed of light was a great scientific challenge.
But about 150 years ago, a French bloke called Armand Fizeau managed it using just a light, some lenses, a mirror and a special sort of wheel.
What he did was, he sent light through the spokes of this wheel, so it went on, off, on, off, as the spokes blocked the light.
That sent pulses of light.
Fizeau wanted to measure the time it took for that signal to travel to a distant mirror and back again.
Now, ideally, a scientific experiment should be repeatable.
l've always wanted to have a go at this, so time to give it a go, Bang-style.
So l've come to the National Physical Laboratory, where Simon Hall and Richard Stevens are going to lend a hand.
While we are setting up, l'll show you what Fizeau did, and what l hope to achieve with my DlY set-up.
lncredibly, Fizeau's master craftsman made him a disc with 720 slots.
Now, all l've done is print one out onto a sheet of transparent paper, like this.
Let me show you how it works with a disc with fewer slots.
So, imagine that Fizeau had his light, and it was shining through the slot and bouncing off a mirror over there.
lf the disc is going slowly, then by the time the light goes to the mirror and back, it will just come through the same slot.
But if it's going fast, then it will zoom over there, and come back.
By that time, the disc will have turned a bit, and the light will be blocked.
Faster still, of course, and the light will go through the next slot in turn.
And so, if you know how fast the disc is turning, then we can use that to calculate the speed of light.
All it is, is the distance between here and the mirror, and back again, divided by the time it takes for the disc to turn from that to that.
Now, Fizeau turned his disc using clockwork.
l'm going to use this blender.
The instructions say it goes up to 1 7,000 revolutions per minute.
lt's pretty fast.
Now all we need is some light.
l'm just going to use this laser.
We've set up the laser in the NPL sports pavilion and pointed it across the fields.
Now l need to set up the mirror as far away as possible.
Whoa! Well, that's quite a long way, actually, isn't it? That's, l reckon, about Ooh, 466 metres to there.
That's 932 metres, almost a kilometre round trip.
So shall we put the mirror here? All right.
Yep, yep.
There we go, like that.
ls that right in the middle? - lt's not bad.
- lt's not bad, is it? l think that's adjusted just right.
This mirror should send the beam back in exactly the direction it came out.
l hope this is going to work.
Loads could go wrong.
l don't think anyone's tried doing it with a blender before! OK, fingers crossed.
- Excellent.
- Right.
OK.
So here's our set-up - we've got a laser here and it goes through this lens, which sends it all the way down there, and here, we have a disc that's in the way.
That's the slotted disc that's spinning round, and it's my blender that's making it spin.
Now, you can tell how fast it's going by the noise, but l've got this special piece of kit which will allow us to do it.
OK, so this beam of light whizzes off through this hole and way out to that mirror over there.
l can just see the light, that's cool.
Straight back again and back through this hole, which makes sure that the beam goes through the same spot on the disc, there, that it went out.
And then it comes back again through here, and then it hits the edge of that little mirror there, and we should be able to see, when the light starts getting blocked, that should tell us the speed of light.
OK, Simon, do you want to do the speed on the blender? Brilliant.
l'll just have a look in here.
Brilliant.
OK.
Start up the blender.
OK, lights off.
Now, this is proving really hard to see.
lgnore the bright red patch on the left, that's not the reflection from the mirror outside.
lnstead, look at the faint patch on the top right.
We're looking for the moment that patch almost disappears.
So, speed it up a bit.
Bit more, bit more.
Oh, there! lt's hard to see, but the disc's spinning fast enough to block the returning light, just as Fizeau's did.
Now all we need to know is how fast it's spinning, to calculate the speed of light.
l reckon that's probably about as dim as we're going to get.
OK.
That's really cool.
Right, lights on.
OK, so how fast do you reckon the disc was switching from on to off? 3.
3 microseconds.
3.
3 microseconds? That's 3.
3 millionths of a second? Right, time to do the calculations.
Right, we know the distance that the light travelled, that's 932 metres.
And we know how fast the disc turned from on to off - 3.
3 millionths of a second.
And that should be the speed of light.
282 million metres per second.
And the real number, well, it's basically almost exactly 300 million metres per second.
So we weren't too bad, actually.
That's really cool.
And Fizeau, amazingly, with much simpler apparatus than this, managed to get within 5% of that value.
That's just incredible.
Here's a little nuggety fact for you.
You know the guy who discovered the speed of light? Fizeau.
- Do you know what his first names were? - l don't, actually, no.
Armand Hippolyte.
Hippolyte.
- Hippolyte? Apparently it means charging horse.
- lt sounds like a sports energy drink or something.
lmagine when you're naming your child, you go down the list, get to the Hs, and you're like, Harry, Henry, Hippolyte.
Hippolyte.
lt's nice.
lt's good.
Dr Yan, getting better every week.
Love that.
That was a great film.
To think you can measure the fastest thing in the universe, using a blender.
l love it! You say the fastest thing in the universe, you're forgetting one thing.
- Hold on, it is the fastest thing, the speed of light.
- The tachyon.
- Tacky.
Have you come across tachyons? - No.
Hypothetical subatomic particles, which they think may go faster than the speed of light.
- So how fast? - Really, really quickly.
Quicker than the quickest thing ever, which is the speed of light! lf Dr Yan finds and measures a tachyon, we'll let him in the studio.
That's harsh.
l think it's fair.
Harsh, but fair.
Now then, l'm obsessed with science now, but l really struggled with science subjects at school.
Unfortunately, a lot of people, when they hear the word ''science'', can recoil in fear and are tempted never to think about science again.
Which is sad when you consider that, at its heart, science is about our inherent, natural curiosity.
That's where Oitizen Science comes in, opening the doors of scientific research and making the adventure available to everybody.
Scientists really do need you.
Science isn't just for scientists.
Perhaps, like me, you've got a passion for science, whatever your walk of life.
But what if you wanted to get more practically involved? What if you want to roll up your sleeves a bit and get stuck in? Welcome to Oitizen Science, a million-strong army of people like you and me doing real science, making genuine discoveries and helping change the way we think about our world and beyond.
Oitizen Science has been around for a while, but it really kicked off in the 1990s, when scientists started using people's home computers to help them analyse data.
Since the '90s, Oitizen Science has moved on from just data crunching by harnessing idle computer power, and instead it's about getting us to observe, to experiment, and to record.
So, less about computer power, and more about people power.
You see, before scientists can come up with any meaningful conclusions, they might have to make millions of observations.
Now, that could take one scientist 50 years, but a crowd of citizens just a few months.
lt's a no-brainer.
Say when we get to 10.
Hang on, slow down! 'Scientists from all disciplines have cottoned on to the power of Oitizen Science.
' 'Today, Mark McOarthy from the Open Air Laboratories Network has come to my local park' - Morning, everyone.
- '.
.
on a recruitment drive for their latest project.
' Mark, do you want to just explain a little bit about what you are doing with my poor friends and neighbours on this cold, blustery morning? Absolutely.
This is a Oitizen Science project, looking at aspects of the atmosphere.
How we influence climate and how climate affects us.
Here's my question - why can't you scientists just do this yourself? Why can't you just turn up today and a measure your own bubbles? We need sampling at a scale that we just can't get from our standard monitoring equipment.
And the local knowledge that goes with that.
What experiments are we doing today? Using a mirror and a compass, we track how the clouds are moving across the sky to determine the direction of the wind at the height of the cloud.
So, we've got a compass, we've got a mirror, and you look down and find a cloud.
And then, you follow it and see which way it's moving.
- Yes.
- lt's genius.
lt's fantastic.
And sticking with the theme of wind, coming right down, is when we use the bubble.
So this is the other component of the experiment where we use bubbles to track winds at our level.
So we can make comparisons between what the clouds are doing up there and what the wind's doing Yeah, and this is important for us, because we don't have the observations from the spaces and places that people are actually inhabiting.
The data that we retrieve from all of the people that contribute in this project will feed into genuine science papers which will, ultimately, help us improve the advice that we provide to policymakers.
But it's not all about the weather, there's a Oitizen Science project for everyone.
Now, l'm really passionate about space.
Even though l've got this niggling doubt that l might not make it as an astronaut, l can still conduct my very own space research and, hopefully, further our understanding of the universe.
That's where a very special project called Zooniverse comes in.
And what better place to find out about it than the Royal Observatory, Greenwich? Robert, can you give me a little bit of background about what Zooniverse is all about? Well, the Zooniverse is basically the internet's largest collection of Oitizen Science projects.
lt started in 2007, it was called Galaxy Zoo, the original project, and we got people to look at images of galaxies from a massive online catalogue called the SDSS.
They were to look and decide whether they were elliptical, whether they were small, round blob galaxies or whether they were spirals, whether they had those beautiful spiral arms.
That was the basic gist of the project.
Two years in, we've had 60 million clicks and the thing has run away with itself.
Why do you need humans to look at these images? Well, computers can do it, to a degree, but their error rate is not as good as humans.
So with visual recognition on the galaxies in the project, the computer could get it right, 80-something per cent of the time, whereas people get it into the 90 per cent range.
- So, l'm potentially better than a computer? - Yes.
Like a ZX81 , or something.
My challenge as a Oitizen Scientist is to decide whether the spot at the centre of this image reveals a supernova.
The first two images are of the same bit of space but taken at different times.
lf there is a supernova, there will be a change in brightness, shown as a bright spot in the third image.
- ls there a supernova? - Err, yes.
- And is there a supernova in this one? - No, l'm going to say no.
l'm going to say that that is not a supernova.
- Yes.
- And do you think there's supernovae in that one? Yes, definitely, definitely.
- How did l do? - Actually, 100%.
Well done.
You got them all correct.
So the computer would make mistakes? So, the computer thinks that all of these are supernovae.
Every single one.
And what you've shown, this is a good example, there is nothing going on there, it's made a mistake.
That's interesting, because all these pictures, you don't need a great deal of science, you just look for a bright blob, if you can see that Yeah.
People are able to look and see things that are unusual, or interesting and of course a computer can't do that.
So it really does go into contributing to furthering the knowledge of astrophysics.
l am thrilled.
We seem to be returning to the great age of the amateur scientist.
l totally agree.
lt's really important.
l think there's a wider point here which is that, you don't need to have a PhD to be interested, to be passionate about science and to get involved in science.
That's not to sort of detract from the importance of academia.
lt just means that that fear that people have about science sometimes is starting to recede, l think.
lt's good.
lt's also interesting to think about people that most people consider to be academics, like Darwin, for example.
- He was an amateur to start with.
- Absolutely.
As was Faraday, as was Wallace.
- Gromit? - Exactly.
- Sorry.
- No, it's fine.
The other thing l love about that film, actually, is the reminder that, as much as we really do rely on them in the modern world, sometimes human beings just do the job better than computers will.
No, we do.
The human brain is just very good at pattern recognition.
And when it comes to observation, which is the foundation stone of science, we can just do that.
The more people you have doing that, the better your observations are going to be, the better the data you're going to get.
Long live the amateur scientist.
Now back to my homemade laser.
lt turns out that without very specialist equipment, making your own laser is not only phenomenally difficult it's also extremely dangerous.
Butl still want to make one.
With a bit of research we've stumbled across a 1960s design for a laser that can just about be knocked together from things lying around a workshop.
Add some nuts a string of resistance a few diodes and a pad of sticky notes.
And believe it or not, that might be a laser.
l've not switched it on yet because it's very dangerous.
l'll talk you through it.
The tin foil and plastic is to make a capacitor, to store electrical energy.
The nuts here are weights to stop the things moving around.
This bit here is a kind of switch.
When the voltage gets high enough, it rips the air apart between those two, makes a spark and switches it on.
This little gap here between those two pieces of aluminium is where the lasing should take place.
The vast laser facility l visited used neodymium atoms to produce the laser.
We haven't got any of those.
l don't even know where to get them from.
So we a cheaper, easier to get hold of lasing material.
l'm going to try fresh air.
About 80% of the air around us is made of nitrogen.
And, it's the nitrogen in that little air gap there that gets excited by the electricity and is able to hold itself in that excited state long enough that when a photon of light gets released down here somewhere, it stimulates all those nitrogen molecules to release their photons of light and that comes out as a laser beam.
Because it'll be nitrogen doing the lasing l can predict the kind of laser we'll get.
Now, there's a problem with that laser beam.
You can't see itvery easily.
lt's an ultra-violet laser which kind of makes it doubly dangerous - you don't know where it is and it will definitely burn your eyes out.
So, for that reason, before l switch it on, l'm going to wear these.
You only get two eyes.
lt's hard to believe this kit really is going to produce a laser from thin air, even if we do hit it with some frightening voltages, but here goes.
Let's see what 5,000 volts does to this little arrangement.
Now, that might be working but we can't see it.
lf l put this piece of paper here.
Look at that! That dot is my laser.
The white paper fluoresces where it's hit, just like white clothes do under disco lights.
Brilliant! But one little spot isn't enough for me, l want to see the whole beam.
lt's the chemicals in washing powder that makes your clothes fluoresce under UV lights.
So if l add some to a tank of water l should be able to reveal the laser beam.
There it is! Our own homemade laser.
OK, before we go any further, l've just got to say, don't make one of those.
Fair enough.
As much as l want everybody to be as involved in science as possible, not lasers.
Not this bit, not this bit.
l'm amazed about how you made a laser out of all that junk lying around your workshop.
What were the sticky notes for exactly? l don't understand them.
They were a little nod towards health and safety.
The thing is, the laser can emerge from either end.
OK.
And the sticky notes just half the danger.
What would happen if l put my hand in front of the UV laser? Just don't.
lntense UV light on the human skin - not a good combination.
Makes sense.
We shall see you next week.
Say, goodbye, boys.
Bye.
Bye.
.
.
Dr Yan calculates the speed of light l'm going to use this blender.
.
.
and Jem builds a home-made laser.
Let's see what 5,000 volts does to this little arrangement.
That's Bang Goes The Theory, revealing your world with a bang.
Hello, and welcome to Bang Goes The Theory.
We starts tonight with lasers.
We've just had the 50th anniversary of the invention of this revolutionary form of light.
But how exactly do they work? Jem has been finding out.
Lasers were first suggested almost 100 years ago, by who else but the grandfather of science, Albert Einstein.
He theorised that if a material could absorb light, then under certain conditions, it could release it as well.
lf that happened, it would create a brand-new type of light that simply didn't exist on our planet.
But back then, nobody had any idea if a new type of light would be of any use to anybody.
Ready for action.
Even in 1960, when they built the very first laser, the team did not know what to do with it.
One guy said, ''This looks like a solution waiting for a problem.
'' lt's solved an awful lot of problems since then.
lt used to be quoted that on average, you're never more than six feet from a rat.
Now it's estimated you're never more than eight feet from a laser.
They're everywhere.
They're in your OD player, your DVD player.
They're performing eye surgery, they're treating cancers.
They're transporting data across the internet, even scanning your weekly shopping.
Beep - that's a laser.
l mean, what other problems would you want lasers to solve? How about the world energy crisis? Here at the STFO Oentral Laser Facility near Oxford, they're pointing one of the world's brightest lasers at exactly that problem.
Nobody is going to pretend that laser physics is a piece of cake.
But the fundamentals are actually quite simple.
So how do you make a machine that you can plug into the wall and convert a few minutes of mains electricity into a pulse of light so intense, it would make a star look dim? First you've got to store that electricity.
And for that you need something like a giant battery bank - these fellas.
These store about as much energy as a hand grenade.
And at the flick of a switch, it's released into a series of flashbulbs.
Like camera flashes, they're extremely intense but only on for a very short period.
The energy from that blast of light is absorbed by a lump of lazing material.
ln this case, they're neodymium atoms, the same ones that are used to make powerful little fridge magnets.
So now, that energy that we took from the plug socket is stored as a bunch of identically excited atoms, poised ready to re-release it.
And the trigger to release it is a little pulse of light.
lf you think of a beam of light being made up of stream of little bullets called photons, when one of those photons hits an excited atom, it releases an identical photon.
And as these photons cascade through the lazing material, they cause all the atoms to release all their energy.
By the time it comes out at the end, almost instantaneously, you've collected that energy as a pulse of light.
At this point, we've got ourselves a pulse of laser light.
lt's about this long.
lt's travelling at 186,000 miles a second, and could get to the moon in literallya couple of clicks.
The laser pulse flies through the building, getting focused and directed by a series of mirrors until it emerges through those windows into this room, where it finally gets directed into here, where a capsule of unsuspecting hydrogen atoms get such a massive kick they fuse together, releasing energy, the kind of energy that powers our sun.
Obviously, l couldn't be here if this was switched on.
But with the success they've had with the experiments in this facility, there's plans to build a generating station, a laser-powered generating station, where the heat from that fusion will boil a fluid, drive a turbine, turn a generator and create safe, sustainable energy for at least the next 1 ,000 years.
lnspired by that, l feel we've got to have a go at building our own laser.
We still really underestimate how ubiquitous lasers are in the modern world, don't we? The really exciting bit for me is this fusion thing.
Every time l meet someone in that field, l get the impression that technology is still 20 years away.
A couple of years later, it's 20 years away.
What do you feel now that you've seen it first hand? l was of the same school of thought as you.
Fusion, 20 years away.
l know that.
After having been there, and speaking to the guys working at the facility, l'm quite heartened, really quite heartened.
They themselves said that when they started working on laser-based fusion, they were very sceptical.
But over recent years, they've ticked off, one by one, the obstacles in the way.
To the point that they are going through the periodic table, looking at the elements they use, going, ''No, we can't use that element, there is not enough of it.
'' They are genuinely looking for a sustainable energy source for the next 1 ,000 years - and l think they're close.
- ln terms of laser fusion and plasma fusion - the other way they're trying to achieve the same thing, it's a two-horse race, l feel more of an affinity with the plasma people.
l visited the Joint European Torus last series, so What about you, Jem? You're laser, are you? l just When l was there, l was very, very impressed with every part of the set-up.
We have a divided camp, l love it! lt's good there's a bit of rivalry.
Not rivalry-rivalry, but it's good you've got a bit of healthy competition.
lt keeps you on your toes, it fast tracks the research.
lt's a good thing.
Talking of research, the lasers, the thing that came out of it for me, the blue-sky research element of it.
When they started on lasers, it had no application at all.
They were just building it for the sake of building it.
And now they're everywhere.
ln science today, there just isn't so much of that blue-sky research.
- lt's something we should go back to.
- Definitely.
l guess it's economics, people worry.
Question - why build a laser? When most think of lasers, they think Death Stars, we think of people being strapped to metal gurneys, that kind of thing.
Talk us through the idea.
They're simply amazing! l mean But hideously dangerous.
Which is why anybody with designs on world domination, first thing they do is build a laser.
- Step one, build a laser.
- Step two, buy a white cat.
Moving on, time for more Dr Yan.
He's actually using a laser in this week's experiment, he's calculating the speed of light.
For centuries, measuring the speed of light was a great scientific challenge.
But about 150 years ago, a French bloke called Armand Fizeau managed it using just a light, some lenses, a mirror and a special sort of wheel.
What he did was, he sent light through the spokes of this wheel, so it went on, off, on, off, as the spokes blocked the light.
That sent pulses of light.
Fizeau wanted to measure the time it took for that signal to travel to a distant mirror and back again.
Now, ideally, a scientific experiment should be repeatable.
l've always wanted to have a go at this, so time to give it a go, Bang-style.
So l've come to the National Physical Laboratory, where Simon Hall and Richard Stevens are going to lend a hand.
While we are setting up, l'll show you what Fizeau did, and what l hope to achieve with my DlY set-up.
lncredibly, Fizeau's master craftsman made him a disc with 720 slots.
Now, all l've done is print one out onto a sheet of transparent paper, like this.
Let me show you how it works with a disc with fewer slots.
So, imagine that Fizeau had his light, and it was shining through the slot and bouncing off a mirror over there.
lf the disc is going slowly, then by the time the light goes to the mirror and back, it will just come through the same slot.
But if it's going fast, then it will zoom over there, and come back.
By that time, the disc will have turned a bit, and the light will be blocked.
Faster still, of course, and the light will go through the next slot in turn.
And so, if you know how fast the disc is turning, then we can use that to calculate the speed of light.
All it is, is the distance between here and the mirror, and back again, divided by the time it takes for the disc to turn from that to that.
Now, Fizeau turned his disc using clockwork.
l'm going to use this blender.
The instructions say it goes up to 1 7,000 revolutions per minute.
lt's pretty fast.
Now all we need is some light.
l'm just going to use this laser.
We've set up the laser in the NPL sports pavilion and pointed it across the fields.
Now l need to set up the mirror as far away as possible.
Whoa! Well, that's quite a long way, actually, isn't it? That's, l reckon, about Ooh, 466 metres to there.
That's 932 metres, almost a kilometre round trip.
So shall we put the mirror here? All right.
Yep, yep.
There we go, like that.
ls that right in the middle? - lt's not bad.
- lt's not bad, is it? l think that's adjusted just right.
This mirror should send the beam back in exactly the direction it came out.
l hope this is going to work.
Loads could go wrong.
l don't think anyone's tried doing it with a blender before! OK, fingers crossed.
- Excellent.
- Right.
OK.
So here's our set-up - we've got a laser here and it goes through this lens, which sends it all the way down there, and here, we have a disc that's in the way.
That's the slotted disc that's spinning round, and it's my blender that's making it spin.
Now, you can tell how fast it's going by the noise, but l've got this special piece of kit which will allow us to do it.
OK, so this beam of light whizzes off through this hole and way out to that mirror over there.
l can just see the light, that's cool.
Straight back again and back through this hole, which makes sure that the beam goes through the same spot on the disc, there, that it went out.
And then it comes back again through here, and then it hits the edge of that little mirror there, and we should be able to see, when the light starts getting blocked, that should tell us the speed of light.
OK, Simon, do you want to do the speed on the blender? Brilliant.
l'll just have a look in here.
Brilliant.
OK.
Start up the blender.
OK, lights off.
Now, this is proving really hard to see.
lgnore the bright red patch on the left, that's not the reflection from the mirror outside.
lnstead, look at the faint patch on the top right.
We're looking for the moment that patch almost disappears.
So, speed it up a bit.
Bit more, bit more.
Oh, there! lt's hard to see, but the disc's spinning fast enough to block the returning light, just as Fizeau's did.
Now all we need to know is how fast it's spinning, to calculate the speed of light.
l reckon that's probably about as dim as we're going to get.
OK.
That's really cool.
Right, lights on.
OK, so how fast do you reckon the disc was switching from on to off? 3.
3 microseconds.
3.
3 microseconds? That's 3.
3 millionths of a second? Right, time to do the calculations.
Right, we know the distance that the light travelled, that's 932 metres.
And we know how fast the disc turned from on to off - 3.
3 millionths of a second.
And that should be the speed of light.
282 million metres per second.
And the real number, well, it's basically almost exactly 300 million metres per second.
So we weren't too bad, actually.
That's really cool.
And Fizeau, amazingly, with much simpler apparatus than this, managed to get within 5% of that value.
That's just incredible.
Here's a little nuggety fact for you.
You know the guy who discovered the speed of light? Fizeau.
- Do you know what his first names were? - l don't, actually, no.
Armand Hippolyte.
Hippolyte.
- Hippolyte? Apparently it means charging horse.
- lt sounds like a sports energy drink or something.
lmagine when you're naming your child, you go down the list, get to the Hs, and you're like, Harry, Henry, Hippolyte.
Hippolyte.
lt's nice.
lt's good.
Dr Yan, getting better every week.
Love that.
That was a great film.
To think you can measure the fastest thing in the universe, using a blender.
l love it! You say the fastest thing in the universe, you're forgetting one thing.
- Hold on, it is the fastest thing, the speed of light.
- The tachyon.
- Tacky.
Have you come across tachyons? - No.
Hypothetical subatomic particles, which they think may go faster than the speed of light.
- So how fast? - Really, really quickly.
Quicker than the quickest thing ever, which is the speed of light! lf Dr Yan finds and measures a tachyon, we'll let him in the studio.
That's harsh.
l think it's fair.
Harsh, but fair.
Now then, l'm obsessed with science now, but l really struggled with science subjects at school.
Unfortunately, a lot of people, when they hear the word ''science'', can recoil in fear and are tempted never to think about science again.
Which is sad when you consider that, at its heart, science is about our inherent, natural curiosity.
That's where Oitizen Science comes in, opening the doors of scientific research and making the adventure available to everybody.
Scientists really do need you.
Science isn't just for scientists.
Perhaps, like me, you've got a passion for science, whatever your walk of life.
But what if you wanted to get more practically involved? What if you want to roll up your sleeves a bit and get stuck in? Welcome to Oitizen Science, a million-strong army of people like you and me doing real science, making genuine discoveries and helping change the way we think about our world and beyond.
Oitizen Science has been around for a while, but it really kicked off in the 1990s, when scientists started using people's home computers to help them analyse data.
Since the '90s, Oitizen Science has moved on from just data crunching by harnessing idle computer power, and instead it's about getting us to observe, to experiment, and to record.
So, less about computer power, and more about people power.
You see, before scientists can come up with any meaningful conclusions, they might have to make millions of observations.
Now, that could take one scientist 50 years, but a crowd of citizens just a few months.
lt's a no-brainer.
Say when we get to 10.
Hang on, slow down! 'Scientists from all disciplines have cottoned on to the power of Oitizen Science.
' 'Today, Mark McOarthy from the Open Air Laboratories Network has come to my local park' - Morning, everyone.
- '.
.
on a recruitment drive for their latest project.
' Mark, do you want to just explain a little bit about what you are doing with my poor friends and neighbours on this cold, blustery morning? Absolutely.
This is a Oitizen Science project, looking at aspects of the atmosphere.
How we influence climate and how climate affects us.
Here's my question - why can't you scientists just do this yourself? Why can't you just turn up today and a measure your own bubbles? We need sampling at a scale that we just can't get from our standard monitoring equipment.
And the local knowledge that goes with that.
What experiments are we doing today? Using a mirror and a compass, we track how the clouds are moving across the sky to determine the direction of the wind at the height of the cloud.
So, we've got a compass, we've got a mirror, and you look down and find a cloud.
And then, you follow it and see which way it's moving.
- Yes.
- lt's genius.
lt's fantastic.
And sticking with the theme of wind, coming right down, is when we use the bubble.
So this is the other component of the experiment where we use bubbles to track winds at our level.
So we can make comparisons between what the clouds are doing up there and what the wind's doing Yeah, and this is important for us, because we don't have the observations from the spaces and places that people are actually inhabiting.
The data that we retrieve from all of the people that contribute in this project will feed into genuine science papers which will, ultimately, help us improve the advice that we provide to policymakers.
But it's not all about the weather, there's a Oitizen Science project for everyone.
Now, l'm really passionate about space.
Even though l've got this niggling doubt that l might not make it as an astronaut, l can still conduct my very own space research and, hopefully, further our understanding of the universe.
That's where a very special project called Zooniverse comes in.
And what better place to find out about it than the Royal Observatory, Greenwich? Robert, can you give me a little bit of background about what Zooniverse is all about? Well, the Zooniverse is basically the internet's largest collection of Oitizen Science projects.
lt started in 2007, it was called Galaxy Zoo, the original project, and we got people to look at images of galaxies from a massive online catalogue called the SDSS.
They were to look and decide whether they were elliptical, whether they were small, round blob galaxies or whether they were spirals, whether they had those beautiful spiral arms.
That was the basic gist of the project.
Two years in, we've had 60 million clicks and the thing has run away with itself.
Why do you need humans to look at these images? Well, computers can do it, to a degree, but their error rate is not as good as humans.
So with visual recognition on the galaxies in the project, the computer could get it right, 80-something per cent of the time, whereas people get it into the 90 per cent range.
- So, l'm potentially better than a computer? - Yes.
Like a ZX81 , or something.
My challenge as a Oitizen Scientist is to decide whether the spot at the centre of this image reveals a supernova.
The first two images are of the same bit of space but taken at different times.
lf there is a supernova, there will be a change in brightness, shown as a bright spot in the third image.
- ls there a supernova? - Err, yes.
- And is there a supernova in this one? - No, l'm going to say no.
l'm going to say that that is not a supernova.
- Yes.
- And do you think there's supernovae in that one? Yes, definitely, definitely.
- How did l do? - Actually, 100%.
Well done.
You got them all correct.
So the computer would make mistakes? So, the computer thinks that all of these are supernovae.
Every single one.
And what you've shown, this is a good example, there is nothing going on there, it's made a mistake.
That's interesting, because all these pictures, you don't need a great deal of science, you just look for a bright blob, if you can see that Yeah.
People are able to look and see things that are unusual, or interesting and of course a computer can't do that.
So it really does go into contributing to furthering the knowledge of astrophysics.
l am thrilled.
We seem to be returning to the great age of the amateur scientist.
l totally agree.
lt's really important.
l think there's a wider point here which is that, you don't need to have a PhD to be interested, to be passionate about science and to get involved in science.
That's not to sort of detract from the importance of academia.
lt just means that that fear that people have about science sometimes is starting to recede, l think.
lt's good.
lt's also interesting to think about people that most people consider to be academics, like Darwin, for example.
- He was an amateur to start with.
- Absolutely.
As was Faraday, as was Wallace.
- Gromit? - Exactly.
- Sorry.
- No, it's fine.
The other thing l love about that film, actually, is the reminder that, as much as we really do rely on them in the modern world, sometimes human beings just do the job better than computers will.
No, we do.
The human brain is just very good at pattern recognition.
And when it comes to observation, which is the foundation stone of science, we can just do that.
The more people you have doing that, the better your observations are going to be, the better the data you're going to get.
Long live the amateur scientist.
Now back to my homemade laser.
lt turns out that without very specialist equipment, making your own laser is not only phenomenally difficult it's also extremely dangerous.
Butl still want to make one.
With a bit of research we've stumbled across a 1960s design for a laser that can just about be knocked together from things lying around a workshop.
Add some nuts a string of resistance a few diodes and a pad of sticky notes.
And believe it or not, that might be a laser.
l've not switched it on yet because it's very dangerous.
l'll talk you through it.
The tin foil and plastic is to make a capacitor, to store electrical energy.
The nuts here are weights to stop the things moving around.
This bit here is a kind of switch.
When the voltage gets high enough, it rips the air apart between those two, makes a spark and switches it on.
This little gap here between those two pieces of aluminium is where the lasing should take place.
The vast laser facility l visited used neodymium atoms to produce the laser.
We haven't got any of those.
l don't even know where to get them from.
So we a cheaper, easier to get hold of lasing material.
l'm going to try fresh air.
About 80% of the air around us is made of nitrogen.
And, it's the nitrogen in that little air gap there that gets excited by the electricity and is able to hold itself in that excited state long enough that when a photon of light gets released down here somewhere, it stimulates all those nitrogen molecules to release their photons of light and that comes out as a laser beam.
Because it'll be nitrogen doing the lasing l can predict the kind of laser we'll get.
Now, there's a problem with that laser beam.
You can't see itvery easily.
lt's an ultra-violet laser which kind of makes it doubly dangerous - you don't know where it is and it will definitely burn your eyes out.
So, for that reason, before l switch it on, l'm going to wear these.
You only get two eyes.
lt's hard to believe this kit really is going to produce a laser from thin air, even if we do hit it with some frightening voltages, but here goes.
Let's see what 5,000 volts does to this little arrangement.
Now, that might be working but we can't see it.
lf l put this piece of paper here.
Look at that! That dot is my laser.
The white paper fluoresces where it's hit, just like white clothes do under disco lights.
Brilliant! But one little spot isn't enough for me, l want to see the whole beam.
lt's the chemicals in washing powder that makes your clothes fluoresce under UV lights.
So if l add some to a tank of water l should be able to reveal the laser beam.
There it is! Our own homemade laser.
OK, before we go any further, l've just got to say, don't make one of those.
Fair enough.
As much as l want everybody to be as involved in science as possible, not lasers.
Not this bit, not this bit.
l'm amazed about how you made a laser out of all that junk lying around your workshop.
What were the sticky notes for exactly? l don't understand them.
They were a little nod towards health and safety.
The thing is, the laser can emerge from either end.
OK.
And the sticky notes just half the danger.
What would happen if l put my hand in front of the UV laser? Just don't.
lntense UV light on the human skin - not a good combination.
Makes sense.
We shall see you next week.
Say, goodbye, boys.
Bye.
Bye.