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For 50 years, Horizon has provided us with an insight
into the very best of scientific discovery
and technological innovation from around the world.
Our films have featured some of the biggest names in science
and brought you the latest advances in everything from medicine
to computer technology - space science to biology.
As the 21st century marches on, the world faces a whole new set
of scientific challenges.
To celebrate Horizon's 50th anniversary,
we're inviting YOU to get involved.
The question is, if you had £10 million
to make one change to the world, what would that be?
This week, a Prize Fund is launched to help solve one key problem
facing our society today.
And we want you to decide what that is.
We've put together a team to help you choose.
From antibiotic resistance, to carbon emissions from planes...
I wasn't expecting that!
..from our thirst for fresh water,
to our hunger for food to feed the world.
They do provide a satisfying crunch.
And from the burden posed by dementia care,
to the difficulty of life in a wheelchair.
Everything I use is in the lower cupboards.
Don't like wasabi! All the stuff I don't like's at the top!
Which of these is most in need of ten million pounds?
It's your choice.
And that's not all, because if you or your team
are sitting on an idea which could solve the problem,
that £10 million could be yours.
This is the Royal Observatory, Greenwich -
a place of huge importance in the history of science.
And it's where the story of today's Prize Challenge started
300 years ago.
1714 saw the launch of perhaps the most famous
science prize in history - one that put Greenwich,
and British science, on the map for ever.
Just like the new prize,
it was prompted by the need for science to solve a grave problem -
one that faced every sea-faring nation on earth.
300 years ago, naval navigation was perilous,
because when they were out at sea, far from any landmarks,
it was extremely difficult for sailors to know precisely where they were.
That problem caused one of the most tragic accidents
in British naval history.
On one terrible night in 1707, four ships sank
near the Isles of Scilly, with the loss of over 1,400 lives.
The sailors died because they couldn't work out
exactly where they were.
The hardest task of all for any navigator was to work out their longitude.
To calculate their position around the globe, in theory
all they needed to know was the time difference
between where they were and London -
every four minutes would translate into one degree of longitude.
But in practice,
it was virtually impossible to keep track of the time back in London.
The clocks of the period were pendulum clocks,
and as soon the ship started to pitch and roll in the waves,
you can see it would've been very difficult to keep good time.
But ocean travel was booming in the 18th century -
something had to be done to make it safe.
Parliament appointed a committee of scientists -
the Board of Longitude - to solve the problem.
And in desperation they appealed to the nation,
offering a reward of £20,000 for the best solution.
That cash prize, worth several million today,
became the catalyst for one of the most world-changing innovations
in the history of technology.
Now, a new Longitude Committee has been formed,
to oversee a prize offered by Nesta, the UK's innovation foundation.
But the prize can only be offered for one of the six problems
on tonight's short list. And that's where you come in.
In this programme, we'll be revealing
the details of those six nominated challenges for the first time
and then asking you to vote
to decide which of the challenges is worth the £10 million.
You'll be able to vote right after this programme,
either by text, or by visiting bbc.co.uk/horizon.
There you'll find links to in-depth guides to the six choices.
Your decision will launch a five-year search
for prize-winning solutions that could change the world.
Let's look at the first problem on our list.
Bacterial resistance to antibiotics has been a growing problem
for decades, and now poses a very real threat to our health.
It presents a nightmare vision of the future,
in which the health of practically everybody alive on the planet
is at risk in a way that it hasn't been for almost a century.
Since Alexander Fleming discovered penicillin over 80 years ago,
it's been estimated that antibiotics have saved
more than 80 million lives.
But now, there are some bacteria that we're defenceless against.
Every year in the UK, 5,000 people die
because antibiotics can't kill the bacteria they're infected with.
Looking at the problem of antibiotic-resistant super-bugs,
here's Liz Bonnin.
Antibiotics have only been widely available for 70 years or so
but the effect they've had on our lives is nothing short of extraordinary.
In that time, life expectancy has increased by 20 years,
thanks in large part to the dramatic reduction in deaths
from all sorts of infections and infectious diseases.
Without antibiotics, modern medicine as we know it wouldn't exist.
Routine operations would be life-threatening
and everything from hip replacements to chemotherapy and organ transplants
would simply be impossible.
But it seems the heyday is over.
Infectious bacteria are becoming increasingly resistant
to the antibiotics we rely on for protection.
We urgently need to preserve this cornerstone of modern medicine
and to do that we need to understand why resistance is on the increase.
I've come to Birmingham to meet Professor Laura Piddock -
a specialist in antibiotic resistance.
So, Laura, how can bacteria become resistant to the antibiotics
that have been so effective against them for so long?
OK, so it's best demonstrated if we look at this plate here.
So you can see the bacteria growing on the top of the agar,
and there's a disc in the middle that's got antibiotic in it,
and the antibiotic is coming out into the agar
and there's this clear zone that's killing all those bacteria.
-OK, so that's how antibiotics work?
But if you look very closely, you can see there's little dots,
little colonies, that have grown up overnight
so they are antibiotic resistant.
And the way that's happened is they have a mutation in one gene
that now allows them to resist that antibiotic.
And if we take one of those resistant colonies,
and then do them on this plate here...
One dot of that, grown out on this agar?
Yeah. And you can see that it's grown right up to the disc
with the antibiotic, there's no zone of inhibition.
And that's it, a completely resistant strain of bacteria to that drug.
And that drug becomes obsolete, that's the end of its working life.
-So what have we done to contribute to this resistance?
Well, we're awash with antibiotics.
We need to stop using them as much as we do,
not just in human medicine, we need to stop using them in animals,
as much as they are, we need to stop using them in the home.
We want to make sure patients get the drugs when they need them,
but what we don't want to do is have people using them
when they're just absolutely unnecessary.
It's clear we need to halt our excessive use of antibiotics.
50 million courses of antibiotics are prescribed in UK hospitals
and GP surgeries every year.
And the trouble is, up to half of those prescribed
are probably unnecessary.
If we could develop a quick and easy way to tell
the difference between viral and bacterial infections
then the use of antibiotics could be dramatically reduced.
You can see we're on a busy ward here.
We have sick patients coming in all the time.
And it's often quite difficult to work out clinically
whether they have a serious infection or not.
That's the real challenge.
We often give antibiotics just in case there's serious infection.
What we really need is good strategies to be able
to deliver antibiotics to the patients who really need them
with confidence they have a bacterial infection
and not some other condition or a viral infection.
So how do you go about discerning between a viral infection
and a bacterial one?
It can be very difficult
but we are helped with various blood tests
and there's a relatively new blood test, a biomarker
called procalcitonin, and we can use that in conjunction with
our clinical assessment of the patient
to try and help us establish if the patient has a bacterial infection.
Doctor Dryden is trialling a new technique to measure procalcitonin -
a molecule found in the blood which rises in concentration
when you have a bacterial infection but not if you have a viral one.
I'm not on the ward for long before a test is necessary.
We've just seen a very sick lady.
It's difficult to make a clear diagnosis in this patient.
She could well have pneumonia and septicaemia
but equally it may not be due to a bacterial infection.
By using a biomarker like procalcitonin that can help us
make a decision whether this patient needs antibiotics or not.
After just 90 minutes, Doctor Dryden gets the results.
We have just done the test on the patient we saw
and the procalcitonin level is below the cut-off.
So I presume you are not going to administer antibiotics.
We held off the antibiotics on the ward round this morning
and we'll continue to hold off.
We will continue to monitor her and keep a close eye on her
and if her condition changes, we may change that decision.
But at the moment, she doesn't need antibiotics.
Because of this test, the hospital has been able to have
the antibiotics it prescribes when diagnoses are unclear.
But the equipment remains bulky and expensive.
And as most antibiotics are prescribed by GPs,
the test is nowhere near fast enough.
Speed is absolutely of the essence in the community.
If you think about how short a consultation is with the GP,
a GP sees a patient for 10 minutes, that has to be done within that 10 minutes.
So, it's an exciting time for the research
for the technology of these types of tests, but how urgent is this?
I think it's really important to develop this as soon as possible.
We know antibiotics in the past have saved more lives
than any other drugs.
If we don't preserve our antibiotics, or find new ones,
the future of medicine is really in doubt.
Our massive overuse of antibiotics across the globe is crippling
one of the most effective weapons we have against infection.
We urgently need a solution
because this will affect all our lives in the future.
If this subject is picked for the Longitude Prize,
potential winners will need to develop
a cheap, rapid test for bacterial infections
that can be used easily by doctors and nurses all over the world.
Getting a rapid diagnostic so that we know we are treating bacteria
and ideally the right bacteria, will save lives every day of the week.
We believe the technology is out there
if only the little different bits of technology
were put together in a black box to make it work.
Our next nominated challenge will demand revolutionary advances
in medical engineering but has the potential
to transform the lives of those affected in many ways.
Over the last few decades, our ability to help people with
all sorts of physical disabilities has moved on in leaps and bounds.
But our ability to help people who are paralysed doesn't go much beyond
offering a wheelchair - just as we would have done decades ago.
And there are 50,000 people in the UK who are paralysed.
The loss of mobility and independence that results
can be an enormous challenge both physically and emotionally.
But for many people, technology can play a crucial role.
here's Dr Saleyha Ahsan.
I'm a doctor and I used to be an army officer.
In 1997, serving in Bosnia, I saw someone
who had just lost their leg after stepping on a land mine.
Watching him come to terms with the reality of his future
as an amputee was something that I've never forgotten.
He had this haunted, lost look on his face.
And he knew at that moment that his life was going to be
changed for ever.
Of course, injuries like that are not confined to the battlefield.
Every eight hours, someone in the UK becomes paralysed.
I'm meeting someone who knows only too well
how easily our lives can be changed in an instant.
Everything that I use is in the lower cupboards.
I can just reach some of these
but not that easily.
You won't reach that wasabi.
No, don't like wasabi. The stuff I don't like is at the top!
'Sophie has been in a wheelchair since a road accident in 2003.'
I fractured my skull, my cheekbone,
apparently my eye fell out of its socket.
My jaw was broken.
My collarbone was snapped and my spine was damaged.
Basically, on impact I was paralysed.
At the moment, the possibility of repairing spinal injuries,
whether through surgery or stem cell therapy, is a long way off.
Could engineering and robotics help instead?
Sophie is helping to trial a remarkable new device
designed by Richard Little.
It offers her the chance to stand and walk independently.
This was extremely surreal for me when I first got it.
To be able to select the option of stand.
LOW MECHANICAL WHIRRING
-Do you feel quite steady?
Yeah, I do, which is amazing.
Just seeing your face now, you've really lit up.
Can I see you walk?
Of course you can see me walk!
It may be slow and bulky
but the exoskeleton can transform perspectives.
Oh, my God. The view.
-Had you not seen the view?
-No, not seen the view. Seriously.
-There's my car!
I can open the window! I've not been able to do that.
For Sophie, a practical,
simple exoskeleton would also help her physically.
You can live a healthy life in a wheelchair. I mean...
But the time... The toll it takes on your body is bad.
Small things. I've noticed a slight scoliosis in my spine
and just from sitting because I am sitting every day all the time.
-That'll be straightening out your core and everything.
Richard, tell me about the amazing technology that's gone into this.
It looks a simple device on the outside
but it has 29 microcomputers on-board all talking to each other,
managing the different systems so there's a lot goes on behind it.
Sophie's increased mobility, the physical changes she's experienced -
not to mention her joy - is humbling to see.
But if paralysis is chosen to be the Longitude Prize,
technologists will need to develop exoskeletons
that are smaller, lighter and faster.
The hope is also that people who can't use a joystick
to control one could just use their thoughts.
Doctor Tom Carlson is honing mind-control technology by trying
to move a robot using his brainwaves.
So, Tom, you're going to be controlling that little robot
-with your mind.
-That's right, yes.
We've chosen 16 key electrode positions over the motor cortex.
This is the part of the brain that deals with me
trying to move my limbs.
To mimic the scenario of someone who is completely paralysed,
Tom will control the robot, not by moving his arms
but by thinking about moving them.
So, let's start this.
Oh, my God. He's walking.
As I keep this bar in the middle, the robot goes forwards,
if I imagine moving my left hand, the bar goes to the left
-and the robot turns left.
-And that is all coming from your brain.
-You're thinking about it.
Whilst you're talking to me,
-are you still thinking about moving left and right?
-If I don't, the robot will be running away.
-I thought men couldn't multitask!
'It takes a lot of concentration to control the robot.'
And you have cleverly stopped him from walking into the cupboard.
No, he's going to go into the cupboard!
Another problem lies in isolating Tom's directional intentions
from the surrounding interference.
So, these signals are very, very small.
The scale we're looking at here is just an order of a few microvolts.
If I clench my teeth...
-Oh, my word.
They completely saturate, so when we are processing the signals
we have to filter out all of this noise
so we can understand what's really going on and ignore the rest.
There's no harm in a robot bumping into a cupboard,
but developing this technology to the point that paralysed people
can safely control exoskeletons using their minds is a long way off.
To get this out into the real world, onto the streets,
I think you're looking at decades.
As a doctor, I'm fully aware that when I have a patient
who's paralysed, there's really little I can do for them
apart from offer support.
But imagine if ultimately, through robotics,
and better understanding of the brain, we could find a way to bypass
a broken spinal cord, and help a person to walk again.
If paralysis is chosen as the Longitude Prize,
the challenge will be to invent a system that gets closest to giving
paralysed people the same freedom of movement that most of us enjoy.
We're asking the world
to solve the problem of paralysis.
And the great thing is we don't tell you how to do it.
It could be engineering. It could be neuroscience.
It could be biology.
You might find a new way to grow new nerves.
We don't know.
The next problem on our list of nominations is malnutrition,
a subject that regularly hits the headlines.
But the tragic events that prompt such media attention
are just the tip of the iceberg.
Beyond disaster-related famine,
climate and soil type can leave people
with permanently restricted diets.
And of course social issues like poverty,
education and illness play a part.
As a result, over 800 million people around the world are undernourished,
with children the worst affected.
The vast majority are in developing countries,
where one in seven of the population suffers.
But it can affect us all.
In fact, just here in the UK,
over three million people are either malnourished
or at risk of malnourishment,
with the cost of ensuing health problems
running into billions of pounds every year.
Malnutrition is a problem that affects the whole planet.
Dr Michael Mosley asks how close science is to finding a solution.
When you hear the word malnourishment,
you probably think of natural disasters, droughts, emergency aid.
But, in fact, malnourishment is much wider than that.
They may not be starving to death, but worldwide there are millions
of people who lack vital nutrients in their diet.
120 million don't have enough vitamin A
and many of those will go blind.
An astonishing billion,
maybe two billion people around the globe are iron deficient,
which means they feel tired and listless a lot of the time.
If you don't get enough vitamin C in your diet, you get scurvy.
If you don't have enough calcium or vitamin D, then you develop rickets.
One of the biggest problems is a lack of protein
which can cause a condition called kwashiorkor.
Now, much of our protein comes from meat,
but livestock farming can't feed everyone.
One option for a more sustainable solution
is being explored here in the Netherlands.
Scientists have teamed up with the chef to cook me the sort of meal
a celebrity stuck in the jungle might eat.
I like quiche, but I've never had a mealworm quiche.
I keep on thinking they're about to wriggle, come to life.
There's something of a novelty value to my meal.
Thank you. Great.
I'm going to, sort of, tuck in. Bon appetit.
Just when I cut into it, suddenly you see them, falling out.
Entomologist Marcel Dicke is serious about eating insects.
What, sort of, is the nutritional balance?
What have you got here in the way of fat and protein, things like that?
50% protein, but, especially important,
the minerals are very high - zinc, iron, magnesium.
In terms of composition, it's similar or even better than beef.
So I could get more iron from eating insects
-than I could from eating beef?
'Insects aren't just nutritious.'
They do provide a satisfying crunch.
'They're more efficient to farm than livestock,
'which makes them more sustainable.'
For producing 1kg of beef, we need 25kg of feed.
For producing 1kg of similar quality insect meat,
you need only 2.2kg of feed.
-Right, so that's 10%.
'Marcel's team helped compile a UN report showing that farmed insects
'produced fewer greenhouse gases and less ammonia than cattle.'
'They need less water and land, too.
'And 20,000 insect farms in Thailand show it can be done cheaply.
'The numbers all add up,
'but there is still one thing getting in the way.'
Well, the major barrier in the Western world is here,
psychological, people need to get used to it and I understand that.
If food technologists could find a way round our squeamishness,
insects might become more than a curiosity in the West.
But they aren't our only hope.
When it comes to easing global malnutrition,
there is one area of research where the potential is almost limitless,
and where they have recently also made huge advances.
Unfortunately, it is also incredibly contentious.
It is the genetic modification of crops.
In the US, more than 80% of corn, soya bean and cotton
produced in 2013 was genetically modified.
Here in the UK, you'd be pushed to find any GM food in the shops.
But there's lots of research going on,
because, as well as increasing yield,
GM can make food more nutritious.
This is Rothamsted Research.
Now, it is the longest running agricultural research station
in the world,
and the aim of this place is to get the most out of the crops we grow.
This remarkable Camelina plant contains omega-3 fish oil,
a vital nutrient thought to protect against heart disease and cancer
and to assist brain function.
Now, it isn't found naturally in plants.
But it is found in oily fish like salmon.
That's the root of a major problem,
which Johnathan Napier is trying to solve.
The global fish stocks that we have at the moment
are sufficient to provide our population,
our seven billion mouths, with about a teaspoon full of fish oil a week,
whereas we probably need at least double that, maybe more.
The situation's so bad that a recent US survey attributed
over 80,000 deaths a year to fish oil deficiencies.
So we're interested in trying to develop
an alternative, sustainable source of fish oils.
And these are our GM Camelina plants that we've engineered
to accumulate omega-3 fish oils.
Now that is pretty weird.
So this, presumably, this is the oil you produce, is it?
-How much is this?
I think in terms of the amount of time and effort to produce it,
-it's tens if not hundreds of thousands of pounds.
-You'll have to get the price down before you sell it.
Can I have a sniff? I promise not to swallow.
-You can have a sniff of it, as long as you don't...
-Not to taste, yeah.
Hold it to your lips and drain it. I would...
It's not at all fishy.
I mean, it's, sort of, if anything, slightly cabbagy.
Camelina is a brassica species
and so it would have a slightly cabbagy smell.
It is very strange, realising that I hold in my hands there
something that could have quite a significant impact on the future.
There are years of field trials and legal debate ahead
for crops like this.
But it does show what could be achieved.
I have seen two very different approaches
to the problem of malnutrition -
genetically-modified crops and insects.
Now, both could contribute significantly in the future
or perhaps solutions will come from
some completely unrelated area of research.
By 2050, there'll be nine billion people on the planet.
To feed them, we need to double food production.
Vote for food to be the subject of the Longitude Prize
and the challenge will be to create a historic innovation.
Something that offers everyone enough to eat that's nutritious,
sustainable and delicious.
It could be immensely exciting.
You know, we're talking about innovations that could
change the world, and if you look at the history of innovations in food,
you think about things like irrigation,
things like refrigeration,
things like fertilisers, industrial fertilisers.
These have quite literally changed the world
and changed the way the human race has developed.
One thing that links each of the nominated problems
is that a world-changing solution
needn't come from renowned scientists.
Back in the 18th century,
as astronomers struggled to solve the Longitude problem,
the Board appealed to the British public for help.
And that was where a man named John Harrison came in.
He wasn't from a university, or a big engineering company -
he was a lone carpenter and clock-maker from Yorkshire.
Harrison was convinced the solution to the problem lay
not in astronomy, but in inventing a clock
that would keep perfect time at sea.
I've come to the Horology Workshop at Greenwich,
to find out how he solved the problem -
with his revolutionary Marine Chronometer, H4.
-This is H4.
-This is H4.
Wonderful, it does look like an oversized pocket watch.
People are often confused,
thinking it would've been worn in an enormous waistcoat pocket.
This wasn't Harrison's first attempt to solve the problem.
For over 25 years,
he'd set his sights on designing a clock that could handle
life at sea. After all, watches at the time were hopelessly inaccurate.
It was to Harrison's great credit that he was the one who
realised that was the wrong course and that he needed to rethink
the technology completely, that's when he started looking at watches.
He asked himself - why don't watches keep time well? And he realised
there was a very specific reason and that he could get round that reason.
-Would you like me to open it up and show you?
It's very exciting to see this.
If you think that's beautiful, prepare to be astonished.
It's a wonderful thing.
Oh! Wow! Look at that.
-Isn't that something?
-Incredible! That's really beautiful.
It's OK to start it if you'd like to hear it?
I won't wind it very much.
That should do it...
To start it, you have to give it a swift swing...
There it goes. Yeah.
So what was so special about the timekeeper,
-what was Harrison's breakthrough?
-His improvement was
the specification of the large oscillating wheel, the balance.
In a clock, the oscillator is the pendulum,
but in a watch, the oscillator is a little wheel that swings to and fro.
-You can see it flashing away through the holes in the engraving.
Harrison was the first to recognise that with this balance
you needed to have large swings,
that is, not just swinging through a few degrees,
but big circles of swings, if you get me,
and also fast, it has to swing very fast.
In H4 the balance swings five times a second,
so that's really thrashing away in there.
So moving it around on a ship
you're not going to disturb that movement in the clock?
Yes, but received wisdom was you must not do this.
Every trained professional watchmaker had been told as an apprentice
never design a watch like this.
So Harrison was knowingly going against perceived wisdom,
so it required someone prepared to think completely outside the box
to enable him to succeed.
On its maiden voyage to the West Indies, after nine weeks at sea,
Harrison's clock was accurate to within just five seconds,
well inside the target of almost two minutes for such a journey.
And though it was several more years before he convinced the Board
that H4 wasn't a fluke, he finally received
over £23,000 in prize money, rewarding 43 years of work.
Thanks to John Harrison's clocks,
countless lives have been saved at sea ever since.
It really was a world-changing innovation.
It cemented Britain's position as a global power, allowing sea trade
to flourish, and played a part
in fixing Greenwich at the centre of world time once and for all.
This is the international meridian or zero longitude line.
Now I'm in the Western hemisphere,
over here I'm in the Eastern hemisphere.
300 years ago, a clockmaker from Yorkshire changed the world.
Can the new Longitude Prize inspire someone else to do the same?
In its report published in April this year,
the Intergovernmental Panel on Climate Change made it clear
that the world faces an enormous challenge.
If we're to avoid dangerous climate change in the 21st century,
we need to cut global greenhouse gas emissions by 70%.
The effects of climate change are already being felt.
And by raising sea levels, changing our weather patterns,
and affecting our ability to grow food,
climate change will leave its mark on all of us.
And there'll be no single solution to this problem -
it will demand multiple technological innovations.
Most urgently we need to tackle the world's top three
sources of emissions - energy, industry and transport,
which alone accounts for 13% of emissions.
Dr Helen Czerski is investigating flight.
Ten years ago this would've been a revolutionary vehicle.
Because this is an electric car.
Today, electric cars are entering the mainstream.
Offering the potential for road travel to be carbon-free.
But one form of transport is miles behind
when it comes to low carbon innovation.
And that is air travel.
If you're in one of those, you know you're burning jet fuel.
And there are tonnes of carbons belching from those engines.
If we're going to hit current emissions targets,
just one return flight across the Atlantic would use up
a passenger's entire annual carbon budget.
To keep up with our appetite for flight,
we need a low carbon alternative.
There aren't many yet.
But in Slovenia,
one family-owned company has been
experimenting with carbon-free flight, on a small scale.
Launched in 2012,
The Taurus Electro won't be replacing Jumbo jets any time soon,
but it's one of the most eco-friendly planes in the world.
What is it that's so special about this plane?
Well, there's no fuel involved with this aeroplane at all.
it's an electric-powered aeroplane that takes energy
from the battery and moves about by using this little electric motor.
-This is the battery.
-It's really small!
It's really small!
It may seem small, but it carries
about tenfold of what a car battery would -
and it's only three times the size.
In fact we're using the highest energy density batteries
that are available on the market.
We're starting to see lots of electric cars on the road,
why aren't there more electric aircraft?
Because it's much more difficult - the aeroplane has to lift the weight
of the battery pack, plus the aeroplane and the people up aloft.
Well, let's see what it can do.
OK, electric aircraft, here we go.
It's so smooth.
The batteries contain enough power to get the aircraft up to
an altitude of 2,500 metres.
At which point we go into economy mode.
ENGINE DROPS OFF
-Stop the engine.
SHE LAUGHS NERVOUSLY
I wasn't expecting that!
-Actually, now we are a glider.
At the push of a button, the engine shuts down, the propeller tucks away,
and the plane becomes a glider.
It really is carbon-free flight.
But with only an hour or so's battery life in total,
you can't get very far without thermals providing extra lift.
That's no use for a passenger plane which needs to fly
anywhere in the world.
And bigger batteries would just add weight and demand even more power.
The flight today was just two people on a fun trip,
but what we want
is to transport hundreds of people for hundreds of miles.
And the problem with scaling up this technology is that
the best batteries we can foresee just can't do that job.
Another approach to the problem might be to abandon batteries
and explore completely new power systems.
Like those being developed to drive the next generation of spacecraft.
Here in Oxfordshire,
a team of engineers are developing a revolutionary engine.
Its fuel has greater energy density than batteries or fossil fuels.
It runs on liquid hydrogen.
How much better is hydrogen than other available fuels?
It's about two-and-a-half times the calorific value
per kilogram of a hydrocarbon.
Which means that gives you the best fuel consumption
possible for the engine.
This isn't just about getting into space,
you can use these ideas for commercial flight as well.
Yes, and such a vehicle could fly halfway round the world at Mach 5,
which would reduce the journey time
to Australia from something like 24 hours down to about four-and-a-half.
You'll just have time to drink a few gin and tonics
and watch the movie, then you'll land.
So it's got the power for a passenger plane, but the real bonus is
that burning hydrogen leaves an exhaust of almost pure water vapour.
So why isn't hydrogen used to power our planes normally?
Because it's incredibly expensive is the simple answer.
You've got to make the hydrogen somehow,
and then you have to liquefy it.
And the liquefaction absorbs a lot of energy,
and that makes it very expensive.
Sadly, it's not just the cost.
To make hydrogen fuel in the first place relies mostly on fossil fuels.
And that means carbon emissions.
We need a cheap, clean hydrogen source before this technology
can truly offer carbon-free passenger flight.
It's just over 100 years since humans first achieved powered flight,
and for all of that time it's been powered by fossil fuels.
But now, there are hints that it could be different.
There are new ideas - battery technologies, hydrogen, biofuels -
and all we need is a spark that will take us on
to a revolution in air travel and give us carbon-free flight.
If you choose this problem as the subject of the Longitude Prize,
the winner would need to build a plane that can fly from London
to Edinburgh at a comparable speed to today's planes -
with no carbon emissions.
The selection of flight was partly
motivated by the fact that it is a challenge that can be
addressed by small groups of creative individuals.
It doesn't require vast resources
to try and make a different sort of aircraft.
The world's population is still growing at an alarming rate.
In fact, there are nearly twice as many people
alive on the planet today as there were when I was born,
placing the planet's precious natural resources
under ever-increasing pressure.
In its 2014 report, the Intergovernmental Panel on Climate Change
identified the supply of fresh water
to the global population as an area of major concern,
and the World Health Organisation has predicted that by 2025
half of the world's population will be living in water-stressed areas.
Professor Iain Stewart is looking at the immense challenge
of supplying the world with fresh water.
There's a reason we call Earth the Blue Planet.
There's a lot of water on it.
Something like a billion trillion litres in fact.
Of course, only a tiny proportion of that is water clean enough
that you can drink or put on your crops.
97% of it is sea water, full of salt.
And if you try and drink that, the consequences can be fatal.
The obvious solution is to convert this vast water resource
into something you can drink, by separating the water from the salt.
But that isn't quite as easy as it sounds.
So this is a solar still, which is designed to take the heat
of the sun and convert dirty, salty water into lovely drinking water.
It's basically an inflatable bag, and I'm going to fill it with
a blend of water, salt and coffee for an authentic muddy look.
I know it doesn't look nice.
But now we just let the sun do its work.
Under the sun's heat, pure water evaporates inside.
It condenses on the lid, and eventually collects in the bag.
Of course, there's only one real test of all of this.
Well, that's all right really. But actually, there's not a lot of it.
We've had about five hours of pretty constant sunshine.
And that's the problem really.
Generating fresh water from saltwater using just
the energy of the sun is a slow business.
It might be OK for occasional use, but for a permanent supply,
we need a lot more energy.
Even here in London engineers are turning to sea water
to boost dwindling water supplies.
This is one of the most advanced desalination plants in the world.
This is where it all starts. This is the Thames.
London is up there, and the sea's down here,
so this water is really pretty salty.
The water itself gets sucked up by these huge pipes here,
up to 220 million litres every day.
Once all the muck has been filtered out, the real job begins.
But instead of evaporation, this place relies on pure brute force.
So, Simon, how do you get the salt out of the water?
We've got to force the water from the salty solution,
and we use these membranes to do that.
So these rolls here...is kind of what's in these tubes, is it?
Absolutely, we've got about 10,000 of these on site.
And that's exactly what's in each one of these tubes.
So how does this work then?
So you've got the salty solution,
and it works its way through the membrane,
and really, you get the clean water coming out through the centre.
So this is where it ends up then, is it?
-Down that kind of tube there?
The system is fighting against a natural process called osmosis,
which normally drives water INTO salty solutions, not out of them.
It's fighting that process that takes all the effort.
So, if you think, the normal pressure
-in a car tyre is about, what, two bar?
This is about 84 bar - 40 times higher, the pressure,
to force the salty solution against this.
It's the cost of actually providing the pressure behind that,
that's the challenge.
At these pressures, the valuable membranes quickly clog up with dirt,
making drinking water from here around about 15 times
more expensive than regular water.
We desperately need a cheaper, more efficient way
to convert large volumes.
No-one's found the answer yet.
But here in Gibraltar, engineers are trying something new.
-You must be Iain.
'This new system separates salt from water by
'taking advantage of osmosis, rather than fighting it.
'And it can handle 18,000 litres a day.'
So what's actually going on inside?
If we could cut one of them open, what would we see?
What you'd see inside of these is some hollow fibres.
-So this is a hollow fibre membrane.
-These are tubes?
-These are tubes. Very, very fine.
-Oh, like hair.
Sea water flows on the outside of these fibres,
and through the fibres we pump what we call draw solution.
'That draw solution's the key,
'because it's more concentrated than sea water.'
So, by the natural process of osmosis,
we draw across, effectively, almost pure water.
I guess the point is that there's really no energy involved.
In this step there's very little, it just happens naturally.
'It's a step forwards, although for now, they still need to use
'pressure to separate the water from the draw solution.
'Overall, it's more efficient, but only just.'
OK, so let's have a...
No, that's really nice.
'New systems like this are setting the scene for a revolution
'in water treatment, but the real goal is still a long way off.'
So the big question is, is there an even better way
to take the almost limitless supplies of that stuff
and turn it into water we can use?
'Fresh water is increasingly precious yet essential.
'If this is the problem you choose as the most important to tackle,
'then the prize will be awarded to whoever can create a cheap
'and environmentally sustainable technology
'to produce fresh water anywhere in the world.'
You just have to read headlines,
whether it's in Beijing or California and so on,
to know that the existing fresh water infrastructure is
really under colossal strain and we need some radical
new approaches to plumb the planet in a fundamentally different way.
An undeniable benefit of modern medicine is that all of us
can expect to live longer.
But an ageing population brings challenges of its own,
in particular the task of caring for those living with dementia,
including its most common form, Alzheimer's disease.
According to the Alzheimer's Society the number of people living with
the disease is set to double in the next 25 years,
placing an immense burden not just on the healthcare system
but on individuals, on their families and care networks.
'As many as 50,000 people are expected to leave work this year
'to cope with the demands of caring for sufferers.
'Finally, Dr Kevin Fong investigates how technology
'might also help with this imminent crisis.'
-Hello, how are you?
-Fine, good, come in. Do come in.
'I've come to see Anne Delve.'
-Hello, nice to see you.
'Five years ago, she was diagnosed with dementia.'
Things aren't quite right sometimes
but you have to get that in the right place in the head.
'Her sister Joy has moved in to give her constant care,
'and their mother Joan also helps.'
For Anne, I think knowing that she was ill was hard initially,
but also, when you've got to accept that you've got to have help,
as with anyone with any kind of illness, it's really hard.
Yeah, because, I used to...
-used to go anywhere.
Erm, but, you know, that's how things are.
It's the loss of independence, isn't it?
'For people with dementia, even simple chores can become difficult,
'as memory fades and decision-making gets harder.
'But encouraging the keep-up of everyday tasks
'can help slow the decline.
-You've got the tap here for the sink.
-D'you remember how to turn it on?
If you want to turn the tap on,
you'd use the little switch here, d'you remember? Just over there?
You can do that, and pull it towards you. Just pull it.
-I suppose I could.
-Give it a go.
-I'm not going to burn myself.
No, that's cold water.
-And then you can wash the cups up for me, is that all right?
-You don't mind, do you?
-Shall I wash this off now, then?
-Leave this on here?
Do you want to put it on the drainer? That's it, Anne, brilliant.
'While many people with dementia have to move into care homes,
'sufferers are normally much better off in a familiar environment.'
It seems important for you that you're at home and not
-I think so, definitely.
-..being looked after by strangers.
That is great for Anne's health and her wellbeing
because we're carrying on doing what is normal in the home.
'But this sort of care can be a huge burden on the family,
'so the hope is that technology might offer help.
'At Birmingham University,
'researchers are one step closer to the ultimate answer.
'A robot carer. He's called Bob.'
Bob can learn, in somebody's home,
where they typically leave their newspaper or their slippers or
their keys, and use the information so he can quickly find things.
And you can see that what he's done is
he's found the keyboard and a bottle.
Bob can monitor the positions of people,
so we're looking to detect, has someone fallen over?
And also remind people or notify carers that someone's
forgotten to take their medicine or they haven't got up at the time they should,
or they're getting up at the time they shouldn't,
so they've gone out and walked around in the middle of the night.
'With today's technology, Bob's abilities are restricted.
'Stairs are a problem, it doesn't have useful arms yet,
'and its decision-making is limited.
'For now, domestic robots are still the stuff of science fiction.'
Of course, these things are a very long way away.
Things are maturing at different rates in robotics,
but one day we'll be able to put these things together.
'Another approach scientists are exploring
'is to make the home itself part of the caring system.'
Pretty ordinary looking kitchen. Tell me what's special about it.
OK, so, physically it's meant to be unremarkable in that it's
meant to be like the sort of kitchen you might have in an everyday home.
We've got sensors in the utensils, sensors in the appliances
and sensors in the worktops themselves to give you
a little bit of a nudge at an appropriate time.
Well, let's have a look at making a cup of tea in this automated kitchen.
So, kettle on.
The kettle itself has a sensor in that measures how much water
is in there, so it knows that you've got enough for a cup of tea.
The cups have a sensor in.
Open the tea caddy to get a teabag.
And as you've just seen there, our environment's reasoned
that our kettle's boiled, our cup's out, we're making a cup of tea.
And it knows that we want to go for a teabag,
and I'm assuming you can't instrument that as well.
Well, actually, we do in this case.
So we use sensors in the teabag's tag here.
Pour hot water into the cup.
'With sensors attached to everything I need to make a cuppa,
'the computer guides me through every step...'
Pour some milk into the cup.
-There you go.
-It wants me to get on with making your tea, yeah.
'..and monitors what I'm doing all the way.'
And so it knows that that's a stirring action,
it's seeing that through the motion of the accelerometer.
Whereas if you put the sensor down...
-I'll just leave it there.
-..it'll know that you're not stirring.
That's pretty impressive.
'This system gives us a glimpse of what technology could make possible.
'But the reality is it doesn't yet have
'the artificial intelligence needed to replace a human carer.'
Dementia is one of the most difficult
and devastating problems that we face in science and society today.
We're a long way from any meaningful treatment, much less a cure.
But in the meantime there's the hope that technology might allow us
to live our lives as fully as possible for as long as possible.
'Most of us will know someone with some form of dementia
'during our lives, and it's a growing problem.
'If this gets your vote,
'then the challenge to potential winners will be to develop
'an affordable technology that's truly capable of giving independence
'to people living with the condition.'
It's a cruel disease, as you watch the person you love change,
and you lose them, but you still want to support them.
We can't throw the money at a human caring system, so we need to think
about how we can use technology and smart devices to enable them
to live on their own with dignity for longer.
Carbon free flight, paralysis or food?
Dementia care, fresh water or antibiotics?
'Six vital problems facing us today,
'but only one can benefit from the £10 million Longitude Prize Fund.'
We want to get the whole country involved in deciding
which of these challenges the £10 million prize fund should be
offered for, and in just a few moments,
when this programme finishes,
you can cast your vote by text or online.
'Texts will be charged at your standard rate.
'Or you can vote for free online at bbc.co.uk/horizon.
'There you'll find Terms and Conditions
'and lots more information on the challenges too.
'Voting will close at 7.10pm on the 25th of June with the result
'announced live on The One Show that night.'
It may take several years
but eventually someone somewhere will come up with
an effective solution to the challenge you choose,
and a genuine claim to the new Longitude Prize.
300 years ago, that someone was a clockmaker from Yorkshire.
This time, could it be you?