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Welcome to a new and very strange world of nature.
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It's been taken over by the weird subatomic particles of
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quantum physics.
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As a physicist, I've spent my working life studying
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how these particles behave in the laboratory.
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But now I'm heading out into the natural world.
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I'm on a mission to prove that quantum physics can solve
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the greatest mysteries in biology.
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This is a real adventure for me.
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I'm very much out of my comfort zone trying to apply
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the very careful ideas I'm familiar with in a physics laboratory
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to the messy world of living things.
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I believe that quantum physics could hold many of life's secrets.
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That deep in the cells of animals,
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particles glide through walls like ghosts.
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That when plants capture sunlight...
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...their cells are invaded by shimmering waves
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that can be everywhere at the same time.
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And that even our human senses
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are tuning in to strange quantum vibrations.
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In the fantastic world of quantum biology,
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life is a game of chance,
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played by quantum rules.
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This is what I hope to convince you of,
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to show you that quantum mechanics is essential in explaining
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many of the important processes in life, and potentially, that
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quantum mechanics may even underpin the very existence of life itself.
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My quest begins with one of the most majestic sights in nature.
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Migration.
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Every winter, barnacle geese arrive right on cue
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at the same Scottish river.
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The end of an epic 2,000-mile voyage from Svalbard,
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high above the arctic circle.
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Of course, many birds head South for winter
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then back home for summer.
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But for decades, exactly how birds navigated with such accuracy
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was one of the greatest mysteries in biology.
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So the most recent discovery has caused a sensation.
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In the past few years,
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one species of bird has helped create a scientific revolution.
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I was one of many physicists who was shocked to discover that it
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navigates using one of the strangest tricks in the whole of science.
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It utilises a quirk of quantum mechanics,
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one that bamboozled even the greatest of physicists,
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from Richard feynman to Albert Einstein himself.
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So you might be surprised to discover the identity of this
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mysterious creature.
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Say hello to the quantum Robin.
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This is the European Robin.
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Every year, she migrates from northern Europe
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to the tip of Spain and back.
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In this laboratory in the woods,
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biologist Henrik mouritsen is trying to solve the mystery
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of how she does it.
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But he's found himself in my world,
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the strange world of quantum mechanics.
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Quantum mechanics describes the very weird behaviour of
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subatomic particles.
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Down in this realm of the very small,
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we have to abandon common sense and intuition.
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Instead, this is a world where objects can spread out like waves.
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Quantum particles can be in many places at once
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and send each other mysterious communications.
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I set out to understand how the bird finds its way,
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but it just turned out that the data
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more and more pointed towards this as
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the only explanation that could bring all the different results together.
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Henrik's investigating a longstanding theory -
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that Robins navigate by the earth's magnetic field.
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His laboratory is an ingenious magnetic birdcage.
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And these plastic cones lined with scratch-sensitive paper
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provide the key measurements.
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Henrik's artificial magnetic field is like the earth's, except that.
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He can point it in any direction he likes.
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Inside their cones, the Robins always respond to the field,
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leaving scratches in a single direction.
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The big mystery is how.
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The earth's magnetic field is incredibly weak,
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far too weak for any living creature to detect.
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But Henrik has found an intriguing clue
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by giving the quantum Robin a mask.
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We have a little leather hood similar to what you put on a falcon,
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you know, but just for a Robin,
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and you have then a hole in front of one eye
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or a hole in front of the other eye.
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And what we can see is that if you cover up the right eye, you turn off
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their magnetic compass processing in the left part of the brain.
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If you cover up this eye,
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you turn the compass off in this part of the brain.
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The Robin's magnetic compass seems to be in her eyes.
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I can show you what's going on using my own eye.
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Now, we use our eyes for vision,
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but we also have a second light-detecting mechanism.
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If I shine this torch into my eye,
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you can see that my pupil closes down.
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It's basically a defence mechanism to protect my eyes.
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My eye is responding to particles of light - or photons.
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The energy provided by the photons
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is clearly enough to activate chemical reactions.
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After all, that's what controls my eye muscles.
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Light must be causing similar chemical reactions
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in the Robin's eyes.
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In fact, it's the power supply for a unique form of magnetic compass...
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...inside her cells...
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...in the weird world of subatomic particles...
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...a place where only quantum physics
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can explain what's going on.
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To see why, imagine the chemical reactions in the Robin's eye
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taking place in mountains and valleys of energy.
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To get a reaction to start,
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you have to push molecules to the top of a mountain.
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Thanks to Henrik's experiments,
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we now know that light does most of the hard work.
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But when it reaches the very peak,
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the molecule becomes incredibly sensitive to the slightest touch.
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The key point here is that the Robin's chemical compass is now
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balanced on an energy peak between two valleys.
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Going one way produces one set of chemical products -
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the other, a different set.
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Now, even a tiny change in the earth's magnetic field can tip the
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molecule over the top, but the way this happens defies common sense.
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The final piece of the puzzle
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depends on one of the truly
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mind-boggling ideas in physics.
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But don't worry if you find it
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hard to understand -
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even Albert Einstein
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called it "spooky".
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The idea is called quantum entanglement.
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It involves particles that seem to communicate faster
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than the speed of light.
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In 1935, Einstein published a famous paper
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arguing that it was impossible.
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But Einstein was wrong.
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In recent years, extremely delicate experiments have shown that
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subatomic particles really are entangled.
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It means they can subtly
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and instantaneously influence each other across space.
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And now it seems the same thing is going on inside the Robin's eye.
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When a photon enters the Robin's eye,
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it creates what's called an entangled pair of electrons.
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Here's how it works. Each electron has two possible states.
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For simplicity, I'm choosing to call them red and green.
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Now, here's the weird thing.
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Until I measure it, it's neither one nor the other,
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but both at the same time.
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Think of the electrons like spinning discs.
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They're simultaneously red and green.
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But by firing a dart...
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...i can force the first electron to be one or the other.
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So far, it's just a game of chance.
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I don't know what I'll get until I try it.
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So I know my first electron is red.
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Suppose I now measure the second electron.
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You'd think I'd have a 50/50 chance of getting red or green.
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After all, that's what you'd expect in the normal, everyday world.
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But you'd be wrong.
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In quantum entanglement, the electrons are mysteriously linked.
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For example, if I get red on the first...
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...i always get red on the second.
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It's not a game of chance any more.
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It's as if the first electron is telling the second one what to do.
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That's why Einstein called it spooky.
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The electrons seem to know that they should both have the same colour,
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no matter how far apart they are.
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The really important part is that
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the two electrons needn't be the same colour.
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They can be entangled in a different way,
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so that if the first electron is red...
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...the second one is always green.
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It seems that this mysterious connection is the ultimate secret
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of the quantum Robin's compass...
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...because the direction of the earth's magnetic field
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can influence the outcome.
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Near the equator, they may be more likely to be red-red.
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But near the pole, they may be more likely to be red-green.
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And that's the vital factor that finally tips the balance of
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the Robin's chemical compass.
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Tiny variations in the earth's magnetic field change the way
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electrons in the Robin's eye are entangled,
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and that's just enough to trigger her compass.
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Now, finally, we can see how something as weak as the earth's
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magnetic field can tip that balance one way or the other.
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If the message changes,
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the chemical reaction tips a different way...
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...changing the Robin's compass reading.
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Suddenly it looks like it's a fundamentally quantum mechanical
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phenomenon in birds.
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It would be one of the first, if not the first, in biology.
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Biologists better get used to the weirdness of physics.
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The Robin is navigating by "spooky" quantum entanglement.
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To see subtle quantum effects,
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even in a controlled, austere environment of a physics lab,
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is really difficult.
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And yet here's the Robin doing it with ease.
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These experiments are real and verifiable, and yet even though
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I'm seeing them with my own eyes, I still find it hard to believe.
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Bird navigation has brought physics
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and nature together as the science of quantum biology.
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There's a whole new world to explore.
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But its pioneers have found that it doesn't just affect birds.
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It affects every single one of us.
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Because the latest experiments say
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you're doing quantum physics right now.
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And believe it or not, you're doing it with your nose.
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Hello, jem!
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Hello.
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Hello, little girl! Hello...
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Our sense of smell is remarkable,
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and quite different from our other senses of sight and hearing.
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Among the thousands of scents that we can recognise,
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many of them may well trigger very powerful memories and emotions.
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It's as though our sense of smell is
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wired directly to our inner consciousness.
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It's also different in another way.
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The other senses of sight and hearing rely on us detecting waves -
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light and sound.
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But our sense of smell involves detecting particles -
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chemical molecules.
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Recently, scientists have begun to realise that when it comes to
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our sense of smell, something very mysterious is going on.
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For decades, biologists thought they knew exactly how our noses
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sniffed out different chemicals.
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But physicists like Jenny brookes think there could be a new
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ingredient in the mix.
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And it smells like quantum mechanics.
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A lot of people speak of the sense of smell and olfaction,
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and the science of olfaction as being a problem that's been solved
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and we know all about it - and we do know a lot about it.
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We know about the ingredients,
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we know about the equipment that we use to smell.
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But I would argue that there's a little bit more to understand.
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To understand more, I need someone to help me with a smell test.
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And jem is going to sniff him out.
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Every human being gives off a cocktail of chemicals.
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Jem's nose could detect a single gram of it
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dissolved over an entire city.
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So she has no trouble finding the man I'm looking for.
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Meet Colin the gardener, a man who's used to smelling the flowers.
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Right, then, Colin, I'm going to put your sniffing skills to the test.
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Cool. I've got a selection of chemicals here,
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and I want you to tell me what they remind you of.
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Ok.
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I'll start you off easily.
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Oh, that's...
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...like a minty, minty vapour rub... it is, yeah... sort of thing.
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Yeah, this is... something what you'd rub...
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This is men... menthol. Menthol. Yeah. But it's that essence.
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Right, here's the next one.
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Ah. You should be able to recognise this one.
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That's baking with my daughter.
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Mm-hm. Erm, icing sugar sort of thing...
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Vanilla. Vanilla, yeah.
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When our noses detect a chemical,
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they fire a nerve signal to our brains.
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But different chemicals create different sensations.
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The standard explanation for this is to do with
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the shape of the molecules.
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The conventional theory that goes back to the 1950s
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says that the scent molecule has a particular shape that allows it
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to fit in to the receptor molecules in our nose.
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If it has the right shape, it's like a hand in a glove,
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00:18:16,200 --> 00:18:20,500
or a key in a lock. In fact, it's called the lock and key mechanism.
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00:18:20,500 --> 00:18:23,900
With the wrong shape, it won't fit into the receptor.
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But with the right shape, it fits into the receptor,
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triggering that unique smell sensation.
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Different receptors are wired to different parts of our brains.
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So, when a menthol molecule locks into its specific receptor,
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it triggers that minty fresh sensation.
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But the lock and key theory has always had a problem...
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...and Colin's next test will show you why.
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Ok, how about...
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This one?
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00:19:00,100 --> 00:19:01,800
Quite a strong smell.
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Oh, that's...
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Yeah. What does it remind you of? What does it conjure up?
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What memories?
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I think Christmas.
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Christmas cake. Yeah. Marzipan.
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Marz... marz... yeah, that's it, yeah.
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Almonds. Very, yeah.
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Colin identified the smell of marzipan or almonds.
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In fact, it's due to a scent molecule called benzaldehyde.
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What I didn't give him to smell was this other chemical - cyanide.
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Both benzaldehyde and cyanide have the same smell,
286
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they both smell of almonds,
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but these molecules are both very different shapes,
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so the lock and key mechanism,
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as an explanation for how we smell, can't be the whole story.
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So why would two molecules with different shapes smell the same?
291
00:19:54,100 --> 00:19:57,100
Quantum biology has a head-spinning explanation.
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It says our noses aren't smelling chemical molecules...
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...they're listening to them.
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It's not just the shape of a scent molecule that matters.
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Let's take a closer look at this model of a cyanide molecule.
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The white ball here is a hydrogen atom,
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and the grey sticks are the bonds that hold it together
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with the carbon and nitrogen.
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But the reality isn't as simple as that.
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I can give you a better sense of what's going on
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if we look at this larger white ball.
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00:20:34,900 --> 00:20:37,900
You see, atoms don't just sit still.
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The bonds that hold them together are like vibrating strings,
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and that gives us a whole new way of thinking about smell.
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00:20:49,300 --> 00:20:54,700
The bizarre new quantum theory of smell is all about vibrating bonds.
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Chemical molecules are playing music for our noses.
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Imagine a receptor molecule in my nose is like my guitar.
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Before it can make a sound, a scent molecule has to enter my nose,
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and when that scent molecule is in place, its chemical bonds
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provide the strings, and it's ready to be played.
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The receptor molecules contain quantum particles -
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electrons.
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As they leap from one atom to another, they vibrate the bonds of
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the scent molecule,
315
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like my fingers plucking a guitar string.
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What's remarkable about this theory is that it tells us
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our sense of smell is about the vibrations of molecules,
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or wave-like behaviour,
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and not so much about the shape of a particular scent molecule.
320
00:21:57,100 --> 00:22:00,900
Our sense of smell may be much more like our sense of hearing.
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00:22:05,200 --> 00:22:08,100
A particular molecule, say that of grass,
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will vibrate at a particular frequency.
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00:22:17,200 --> 00:22:20,100
But a different molecule, say, that of mint,
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00:22:20,100 --> 00:22:22,900
will vibrate at a different frequency.
325
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This would explain why cyanide smells like almonds.
326
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The two molecules have different shapes,
327
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but their chemical bonds just happen to vibrate
328
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at the same frequency.
329
00:22:51,900 --> 00:22:55,100
The constant vibration in the odorant is almost
330
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literally like a particle of sound.
331
00:22:57,500 --> 00:23:00,700
So, yeah, we're saying that the process of smell could be
332
00:23:00,700 --> 00:23:04,000
exactly like an acoustic resonance event,
333
00:23:04,000 --> 00:23:09,100
it could be very analogous to, erm, hearing and seeing, actually.
334
00:23:10,500 --> 00:23:13,300
But can we really be listening with our noses?
335
00:23:15,500 --> 00:23:18,800
A bizarre theory needs a bizarre experiment to test it.
336
00:23:20,800 --> 00:23:22,000
Here's how it works.
337
00:23:24,000 --> 00:23:27,300
This molecule has a musky aroma, like perfume.
338
00:23:29,100 --> 00:23:30,800
But if the theory is right,
339
00:23:30,800 --> 00:23:36,200
then I should be able to change its smell by changing its vibrations.
340
00:23:36,200 --> 00:23:38,500
The musky molecule contains
341
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lots of hydrogen atoms like this
342
00:23:41,400 --> 00:23:45,400
bonded to carbon atoms, but what if I were to replace all these atoms
343
00:23:45,400 --> 00:23:50,000
with a different form of hydrogen called deuterium?
344
00:23:50,000 --> 00:23:52,600
Now, it won't change the shape of the molecule,
345
00:23:52,600 --> 00:23:55,600
but it will change the way it vibrates.
346
00:23:55,600 --> 00:24:00,100
And here's why - deuterium is twice as heavy as normal hydrogen,
347
00:24:00,100 --> 00:24:04,000
and so it vibrates more slowly.
348
00:24:04,000 --> 00:24:07,300
Now, different vibrations mean different smells,
349
00:24:07,300 --> 00:24:10,300
so if I were to make a new form of this chemical,
350
00:24:10,300 --> 00:24:13,900
all packed with deuterium atoms instead of normal hydrogen,
351
00:24:13,900 --> 00:24:15,800
it should smell different.
352
00:24:18,700 --> 00:24:22,800
Quantum biologists found a unique way to carry out this experiment.
353
00:24:26,200 --> 00:24:27,900
A smell comparison,
354
00:24:27,900 --> 00:24:31,700
using the most sensitive noses they could find.
355
00:24:34,000 --> 00:24:35,400
Fruit flies.
356
00:24:36,600 --> 00:24:39,900
First, the flies were trained to avoid the modified version
357
00:24:39,900 --> 00:24:41,700
of the musky molecule.
358
00:24:43,000 --> 00:24:44,100
To be honest,
359
00:24:44,100 --> 00:24:47,900
I haven't got a clue how you go about training a fruit fly,
360
00:24:47,900 --> 00:24:49,600
but apparently you can.
361
00:24:51,700 --> 00:24:56,300
In the laboratory, the flies had to pass through a kind of maze.
362
00:24:59,400 --> 00:25:01,300
They were then given a choice.
363
00:25:05,000 --> 00:25:08,100
Go right for the nice, musky smell,
364
00:25:08,100 --> 00:25:12,300
or left, for the nasty, modified version.
365
00:25:19,500 --> 00:25:21,900
They could definitely smell the difference.
366
00:25:25,500 --> 00:25:29,000
They always preferred the original and turned right.
367
00:25:37,400 --> 00:25:40,600
The fruit fly experiment gives hard evidence
368
00:25:40,600 --> 00:25:43,100
that quantum smell theory really works.
369
00:25:46,000 --> 00:25:50,200
But ultimately, it works in harmony with the lock and key theory.
370
00:25:52,000 --> 00:25:55,800
First, the scent molecule fits into the receptor...
371
00:25:57,100 --> 00:26:00,100
...then those molecular vibrations take over.
372
00:26:03,500 --> 00:26:07,100
Incredible as it seems, flies, humans
373
00:26:07,100 --> 00:26:11,300
and dogs may be smelling the sound of quantum biology.
374
00:26:15,400 --> 00:26:19,100
Our sense of smell is fascinating and mysterious as it is,
375
00:26:19,100 --> 00:26:22,900
but to think that when I encounter a particular scent
376
00:26:22,900 --> 00:26:26,300
and that sets off a whole wave of memories
377
00:26:26,300 --> 00:26:30,200
and emotions in my mind, that it's underpinned,
378
00:26:30,200 --> 00:26:32,600
that it's triggered by quantum mechanics,
379
00:26:32,600 --> 00:26:35,300
I think makes it even more remarkable.
380
00:26:47,200 --> 00:26:51,100
The mysterious influence of quantum physics
381
00:26:51,100 --> 00:26:53,100
reaches into every corner of the natural world.
382
00:26:57,700 --> 00:27:00,300
In fact, it inhabits the walls
383
00:27:00,300 --> 00:27:02,800
of every living cell on earth.
384
00:27:06,500 --> 00:27:10,100
Because the latest experiments suggest a magical solution
385
00:27:10,100 --> 00:27:12,600
to one of the greatest mysteries of nature.
386
00:27:16,900 --> 00:27:19,700
The miracle of metamorphosis.
387
00:27:29,000 --> 00:27:32,500
The transformation of a tadpole into a frog
388
00:27:32,500 --> 00:27:35,300
has never been fully explained.
389
00:27:35,300 --> 00:27:39,200
In little more than six weeks, the tadpole breaks down,
390
00:27:39,200 --> 00:27:42,700
then reassembles in its adult form.
391
00:27:42,700 --> 00:27:47,400
But the big mystery is how it happens so fast.
392
00:27:47,400 --> 00:27:50,200
When you think about it, there's nothing more extraordinary
393
00:27:50,200 --> 00:27:52,800
than a tadpole turning into a frog.
394
00:27:52,800 --> 00:27:55,000
Take its tail, for example.
395
00:27:55,000 --> 00:27:58,900
Over a period of several weeks, it gets reabsorbed into the body
396
00:27:58,900 --> 00:28:02,700
and the proteins and fibres that make up the flesh
397
00:28:02,700 --> 00:28:06,400
get recycled to form the frog's new limbs.
398
00:28:06,400 --> 00:28:08,300
But for this to happen,
399
00:28:08,300 --> 00:28:11,500
trillions and trillions of chemical reactions work together,
400
00:28:11,500 --> 00:28:16,600
breaking molecules, forming new ones in a carefully orchestrated dance.
401
00:28:16,600 --> 00:28:20,700
But the fibres that hold flesh together are very, very strong.
402
00:28:20,700 --> 00:28:24,400
They're a bit like these ropes holding my raft together.
403
00:28:24,400 --> 00:28:29,500
In order to dismantle the raft, I'd have to undo these very tight knots.
404
00:28:31,000 --> 00:28:32,900
You could think of it like this...
405
00:28:34,300 --> 00:28:38,200
...a tadpole is held together by long robes of proteins
406
00:28:38,200 --> 00:28:40,700
knotted together by chemical bonds.
407
00:28:42,600 --> 00:28:46,500
The bonds are so strong that they should last for years,
408
00:28:46,500 --> 00:28:50,300
much longer than the tadpole's entire life span.
409
00:28:50,300 --> 00:28:55,800
So how can it turn into a frog in just a few weeks?
410
00:28:55,800 --> 00:28:59,700
The explanation involves one of the most important molecules of life.
411
00:29:01,300 --> 00:29:05,900
Tiny widgets in all our cells called enzymes.
412
00:29:05,900 --> 00:29:09,300
The enzymes are the actual machinery of the cell.
413
00:29:09,300 --> 00:29:13,500
They are actually the little machines inside cells
414
00:29:13,500 --> 00:29:17,500
that do the chemical transformations that are involved in everyday life.
415
00:29:17,500 --> 00:29:19,500
They are absolutely crucial.
416
00:29:19,500 --> 00:29:23,000
And the reason they're so crucial is because what they are able to do
417
00:29:23,000 --> 00:29:28,500
is to accelerate chemical reactions by enormous amounts.
418
00:29:28,500 --> 00:29:32,100
Let me show you just how quickly enzymes get to work.
419
00:29:33,800 --> 00:29:37,700
Inside this bottle is a substance called hydrogen peroxide.
420
00:29:37,700 --> 00:29:39,800
You're probably most familiar with it
421
00:29:39,800 --> 00:29:41,400
as the chemical used to bleach hair.
422
00:29:41,400 --> 00:29:43,700
In fact, I obtained this sample
423
00:29:43,700 --> 00:29:45,900
from my local hairdressers.
424
00:29:45,900 --> 00:29:48,600
Hydrogen peroxide is also produced in the body,
425
00:29:48,600 --> 00:29:51,700
and it's the job of the liver to get rid of it.
426
00:29:51,700 --> 00:29:53,900
The way it does that is using an enzyme
427
00:29:53,900 --> 00:29:59,000
which breaks down hydrogen peroxide into water and oxygen.
428
00:29:59,000 --> 00:30:02,200
Now, to show you just how quickly this enzyme works,
429
00:30:02,200 --> 00:30:04,200
I'm going to do a quick demonstration.
430
00:30:04,200 --> 00:30:06,800
I've got some liver here which I've chopped up
431
00:30:06,800 --> 00:30:09,100
in order to release the enzyme.
432
00:30:11,500 --> 00:30:15,100
Now, watch what happens when I add this liver mixture
433
00:30:15,100 --> 00:30:18,500
containing the enzyme to the hydrogen peroxide.
434
00:30:18,500 --> 00:30:21,100
Watch how quickly the oxygen is released.
435
00:30:37,000 --> 00:30:42,000
Just 100 grams of liver fired my rocket nearly 20 feet.
436
00:30:45,700 --> 00:30:48,900
Liver enzymes make the breakdown of hydrogen peroxide
437
00:30:48,900 --> 00:30:50,500
incredibly efficient.
438
00:30:50,500 --> 00:30:53,200
It happens a trillion times faster.
439
00:30:53,200 --> 00:30:56,900
That's a million, million times faster than it would otherwise.
440
00:30:59,100 --> 00:31:01,500
In metamorphosis, it's enzymes
441
00:31:01,500 --> 00:31:04,100
that dismantle the tadpole's tail.
442
00:31:05,500 --> 00:31:07,300
And that means breaking down
443
00:31:07,300 --> 00:31:09,100
an incredibly tough protein
444
00:31:09,100 --> 00:31:10,500
called collagen.
445
00:31:12,200 --> 00:31:16,800
Collagen is one of the most important proteins in the biological world.
446
00:31:16,800 --> 00:31:21,000
It's the protein which actually gives that resilience, that elasticity
447
00:31:21,000 --> 00:31:23,500
to tendons, to cartilage,
448
00:31:23,500 --> 00:31:26,700
and of course to our skin, as well.
449
00:31:26,700 --> 00:31:30,700
And in the tail of the tadpole, it provides the kind of scaffold
450
00:31:30,700 --> 00:31:33,900
that supports that structure.
451
00:31:33,900 --> 00:31:36,900
Now, when the tadpole is transformed into the frog,
452
00:31:36,900 --> 00:31:40,200
what you need to do is to essentially have an enzyme,
453
00:31:40,200 --> 00:31:43,700
collagenase, which will literally snip the collagen down
454
00:31:43,700 --> 00:31:47,500
into small pieces and thereby take that scaffold apart.
455
00:31:51,600 --> 00:31:56,400
But how do enzymes break chemical bonds apart so incredibly fast?
456
00:31:58,600 --> 00:32:03,600
Let me show you why it's a problem only quantum biology can solve.
457
00:32:05,700 --> 00:32:09,700
Think of it this way, all these different parts of the knot
458
00:32:09,700 --> 00:32:13,300
are like subatomic particles - electrons, protons -
459
00:32:13,300 --> 00:32:16,200
that hold the different parts of the molecule together.
460
00:32:16,200 --> 00:32:21,800
Now, to untie the knot, enzymes have to move protons about.
461
00:32:21,800 --> 00:32:25,500
But as you can see, this takes quite a bit of effort
462
00:32:25,500 --> 00:32:29,100
and a lot of time if there are many knots to unpick.
463
00:32:30,300 --> 00:32:32,500
Physicists have a fancy way of saying
464
00:32:32,500 --> 00:32:34,900
"put in effort to get something done".
465
00:32:34,900 --> 00:32:38,200
They say you have to overcome an energy barrier.
466
00:32:44,900 --> 00:32:47,200
Ok, here's my energy barrier.
467
00:32:49,400 --> 00:32:51,300
And here's my proton.
468
00:32:53,100 --> 00:32:54,700
To break a bond apart,
469
00:32:54,700 --> 00:32:57,800
it needs enough energy to get over the barrier.
470
00:32:59,600 --> 00:33:03,100
The trouble is, when we work out how long this would take,
471
00:33:03,100 --> 00:33:06,000
it's much too slow to break down a tadpole's tale.
472
00:33:09,000 --> 00:33:12,500
But this is where protons turn into ghosts.
473
00:33:15,800 --> 00:33:18,700
I wouldn't blame you for thinking that this is an idea
474
00:33:18,700 --> 00:33:21,300
that a clever theoretician has come up with,
475
00:33:21,300 --> 00:33:26,000
that it's just mere speculation - something that we have no proof of.
476
00:33:26,000 --> 00:33:29,100
But we do. It takes place all the time.
477
00:33:31,200 --> 00:33:33,000
In the quantum world,
478
00:33:33,000 --> 00:33:36,100
protons don't have to go over barriers.
479
00:33:39,300 --> 00:33:41,400
They can tunnel...
480
00:33:41,400 --> 00:33:43,000
Straight through.
481
00:33:45,000 --> 00:33:47,900
Tunnelling strikes at the very heart of what is most strange
482
00:33:47,900 --> 00:33:49,900
about quantum mechanics.
483
00:33:49,900 --> 00:33:52,900
It's like nothing we see in our everyday world.
484
00:33:52,900 --> 00:33:56,500
A quantum particle can tunnel from one place to another
485
00:33:56,500 --> 00:34:00,200
even if it has to pass through an impenetrable barrier.
486
00:34:00,200 --> 00:34:05,800
They are not solid objects like balls in our everyday world.
487
00:34:05,800 --> 00:34:08,600
They have spread out, fuzzy,
488
00:34:08,600 --> 00:34:13,300
wavelike behaviour that allows them to leak through an energy barrier.
489
00:34:13,300 --> 00:34:16,500
A particle can disappear on one side of the barrier
490
00:34:16,500 --> 00:34:19,700
and instantaneously reappear on the other.
491
00:34:21,700 --> 00:34:25,100
In nuclear physics, this effect is a proven fact.
492
00:34:26,800 --> 00:34:30,900
Without quantum tunnelling, the sun simply wouldn't shine.
493
00:34:33,400 --> 00:34:35,600
But I never thought I'd see it...
494
00:34:37,900 --> 00:34:39,800
...in a tadpole.
495
00:34:39,800 --> 00:34:43,600
It's hard to stress just how weird this process is.
496
00:34:43,600 --> 00:34:46,800
It's as though I would approach a solid brick wall and,
497
00:34:46,800 --> 00:34:51,500
like a phantom, disappear from one side and reappear on the other.
498
00:34:55,500 --> 00:34:59,000
The most important advantage of tunnelling is its speed.
499
00:35:01,500 --> 00:35:04,200
It happens incredibly quickly -
500
00:35:04,200 --> 00:35:07,100
much faster than if protons go over the barrier.
501
00:35:09,600 --> 00:35:13,300
As a nuclear physicist, quantum tunnelling is my bread and butter.
502
00:35:13,300 --> 00:35:17,000
Subatomic particles like protons do it all the time.
503
00:35:17,000 --> 00:35:19,700
But what has this got to do with biology?
504
00:35:25,700 --> 00:35:28,800
The answer is that without quantum ghosts,
505
00:35:28,800 --> 00:35:31,900
the metamorphosis of a tadpole would be impossible.
506
00:35:33,700 --> 00:35:36,900
Remember, chemical bonds are basically knots.
507
00:35:39,100 --> 00:35:43,000
Tunnelling unties them - fast.
508
00:35:43,000 --> 00:35:45,400
Have a look at these two knots.
509
00:35:45,400 --> 00:35:48,300
Now, on the face of it they look identical,
510
00:35:48,300 --> 00:35:51,000
but there's a subtle difference.
511
00:35:51,000 --> 00:35:53,500
This knot has the two short ends
512
00:35:53,500 --> 00:35:55,700
of the rope on the same side.
513
00:35:55,700 --> 00:35:57,400
Whereas this one
514
00:35:57,400 --> 00:35:59,600
has the two short ends on opposite sides.
515
00:36:00,700 --> 00:36:05,000
Now, you'd think that wouldn't make a difference, but it does.
516
00:36:05,000 --> 00:36:06,400
You see, this knot...
517
00:36:07,900 --> 00:36:09,700
...is very hard to break,
518
00:36:09,700 --> 00:36:11,100
whereas this one...
519
00:36:12,700 --> 00:36:13,600
...is easy.
520
00:36:15,800 --> 00:36:17,200
Quantum tunnelling...
521
00:36:19,900 --> 00:36:22,900
...turns strong knots into weak ones.
522
00:36:25,400 --> 00:36:27,000
So in a tadpole,
523
00:36:27,000 --> 00:36:31,100
the entire collagen scaffold breaks apart easily.
524
00:36:31,100 --> 00:36:36,500
And finally, other enzymes rebuild it in the shape of a frog.
525
00:36:41,000 --> 00:36:44,600
The quantum tunnelling of particles is one of those weird features
526
00:36:44,600 --> 00:36:46,000
of the subatomic world
527
00:36:46,000 --> 00:36:48,700
that a physicist like me is very familiar with.
528
00:36:48,700 --> 00:36:51,800
After all, it's responsible for radioactive decay
529
00:36:51,800 --> 00:36:53,700
and it goes on inside the sun.
530
00:36:53,700 --> 00:36:57,000
It's the reason why the sun and all stars shine.
531
00:36:57,000 --> 00:37:00,900
But to discover this going on inside every cell of every
532
00:37:00,900 --> 00:37:05,100
living organism on the planet, because every cell contains enzymes,
533
00:37:05,100 --> 00:37:07,800
now, that I find truly amazing.
534
00:37:11,700 --> 00:37:15,700
Quantum biology casts its spell over every living creature.
535
00:37:17,900 --> 00:37:21,300
We've seen that birds, mammals, insects
536
00:37:21,300 --> 00:37:26,500
and amphibians are governed by the strangest laws in science.
537
00:37:28,100 --> 00:37:31,000
But the most dramatic recent breakthrough concerns
538
00:37:31,000 --> 00:37:35,400
the single vital process on which all these forms of life depend.
539
00:37:37,200 --> 00:37:40,600
The conversion of air and sunlight
540
00:37:40,600 --> 00:37:41,900
into plants.
541
00:37:47,300 --> 00:37:52,500
This fine specimen is a larix decidua, or European larch.
542
00:37:52,500 --> 00:37:55,600
It's about 100 feet high and right at this moment,
543
00:37:55,600 --> 00:37:58,200
passing just this side of the planet Venus,
544
00:37:58,200 --> 00:38:00,600
is a bullet with this tree's name on it.
545
00:38:03,300 --> 00:38:04,900
The bullet is a photon
546
00:38:04,900 --> 00:38:08,300
nearing the end of its long journey from the sun.
547
00:38:12,300 --> 00:38:15,000
Its ultimate destiny is to kick-start
548
00:38:15,000 --> 00:38:19,800
a series of chemical reactions that underpins all life on earth...
549
00:38:21,000 --> 00:38:23,500
...photosynthesis.
550
00:38:23,500 --> 00:38:25,500
Every second of every day,
551
00:38:25,500 --> 00:38:30,300
16,000 tonnes of new plant life are created on earth.
552
00:38:30,300 --> 00:38:33,100
And for me, it's incredible to think that our existence
553
00:38:33,100 --> 00:38:36,200
on this planet depends on what happens
554
00:38:36,200 --> 00:38:38,800
in the next trillionth of a second.
555
00:38:49,700 --> 00:38:52,600
The crucial first stage of photosynthesis
556
00:38:52,600 --> 00:38:54,600
is the capture of energy from the sun.
557
00:38:56,700 --> 00:38:58,800
It's nearly 100% efficient,
558
00:38:58,800 --> 00:39:01,900
vastly superior to any human technology.
559
00:39:04,900 --> 00:39:08,000
But the way that every plant on earth achieves this
560
00:39:08,000 --> 00:39:10,300
is one of the great puzzles in biology.
561
00:39:11,400 --> 00:39:14,900
When it turned out that quantum weirdness might hold the answer,
562
00:39:14,900 --> 00:39:17,000
physicists could hardly believe it.
563
00:39:19,700 --> 00:39:21,300
It was like a revelation.
564
00:39:21,300 --> 00:39:23,100
It was very exciting, because I was
565
00:39:23,100 --> 00:39:24,900
used to working on problems
566
00:39:24,900 --> 00:39:27,400
that were quite abstract experiments.
567
00:39:27,400 --> 00:39:31,100
I am a theoretician, but I always related my theory
568
00:39:31,100 --> 00:39:33,200
to experiments that were very clean in the lab,
569
00:39:33,200 --> 00:39:34,700
things that you can control.
570
00:39:34,700 --> 00:39:37,700
But now, finding out that the things that I knew can help me
571
00:39:37,700 --> 00:39:40,500
to understand better how nature works,
572
00:39:40,500 --> 00:39:44,600
really, scientifically, it was like a...
573
00:39:44,600 --> 00:39:46,100
A new inspiration to my life,
574
00:39:46,100 --> 00:39:50,600
so I would say I fell in love with this field.
575
00:39:53,900 --> 00:39:57,500
Textbook biology says the colour of green plants
576
00:39:57,500 --> 00:39:59,600
comes from chlorophyll molecules.
577
00:40:00,900 --> 00:40:04,800
Inside the living cells, they absorb light from the sun.
578
00:40:07,500 --> 00:40:10,700
This energy is then transferred incredibly quickly
579
00:40:10,700 --> 00:40:13,600
to the food-making factory at the heart of the cell.
580
00:40:17,300 --> 00:40:19,100
The entire event takes
581
00:40:19,100 --> 00:40:22,300
just a millionth of a millionth of a second.
582
00:40:22,300 --> 00:40:24,700
When the photon hits the cell,
583
00:40:24,700 --> 00:40:28,900
it knocks an electron out of the middle of a chlorophyll molecule.
584
00:40:28,900 --> 00:40:33,100
This creates a tiny packet of energy called an exciton.
585
00:40:33,100 --> 00:40:34,900
The exciton then bounces its way
586
00:40:34,900 --> 00:40:37,700
through a forest of chlorophyll molecules
587
00:40:37,700 --> 00:40:41,200
until it reaches what is called the reaction centre.
588
00:40:41,200 --> 00:40:44,900
Now, that is where its energy is used to drive chemical processes
589
00:40:44,900 --> 00:40:49,100
that create the all-important biomolecules of life.
590
00:40:49,100 --> 00:40:52,700
The problem is, the exciton needs to find its way to the reaction centre
591
00:40:52,700 --> 00:40:54,700
in the first place.
592
00:41:00,500 --> 00:41:04,400
Textbook biology can't explain how the exciton does this.
593
00:41:07,700 --> 00:41:10,700
Because, of course, it doesn't know where it's going.
594
00:41:13,400 --> 00:41:15,800
It just bounces around like a pinball
595
00:41:15,800 --> 00:41:18,400
in a process called a random walk.
596
00:41:22,900 --> 00:41:24,100
Sooner or later,
597
00:41:24,100 --> 00:41:26,900
it will pass through every single part of the cell.
598
00:41:29,900 --> 00:41:33,000
But this isn't the most efficient way to get around.
599
00:41:36,600 --> 00:41:40,200
Because when the exciton eventually does reach the reaction centre...
600
00:41:41,600 --> 00:41:43,100
...it's by pure chance.
601
00:41:48,700 --> 00:41:51,200
If the exciton just blindly and randomly
602
00:41:51,200 --> 00:41:53,700
hops between the chlorophyll molecules,
603
00:41:53,700 --> 00:41:56,700
it would take too long to reach the reaction centre
604
00:41:56,700 --> 00:41:59,900
and would have lost its energy as waste heat.
605
00:41:59,900 --> 00:42:03,300
But it doesn't. Something very different must be going on.
606
00:42:05,200 --> 00:42:08,700
The vital clue comes from recent experiments
607
00:42:08,700 --> 00:42:10,600
that stunned the world of science.
608
00:42:13,500 --> 00:42:16,900
Chemists fired lasers at plant cells
609
00:42:16,900 --> 00:42:19,100
to simulate the capture of light from the sun.
610
00:42:22,000 --> 00:42:25,500
They confirmed the exciton wasn't bouncing along a haphazard route
611
00:42:25,500 --> 00:42:26,800
through the cell.
612
00:42:28,100 --> 00:42:30,700
This original understanding didn't explain what
613
00:42:30,700 --> 00:42:32,300
we were observing in the lab.
614
00:42:32,300 --> 00:42:34,500
So the mystery lies in, ok,
615
00:42:34,500 --> 00:42:38,200
so then, what is the explanation for what we are observing in the lab?
616
00:42:40,700 --> 00:42:44,200
The solution is that plants obey the most famous law
617
00:42:44,200 --> 00:42:46,600
in all of quantum mechanics...
618
00:42:48,900 --> 00:42:50,900
...the uncertainty principle.
619
00:42:54,300 --> 00:42:56,300
It says it you can never be certain
620
00:42:56,300 --> 00:42:59,800
that the exciton is in one specific place.
621
00:43:02,300 --> 00:43:05,800
Instead, it behaves like a quantum wave,
622
00:43:05,800 --> 00:43:08,400
smearing itself out across the cell.
623
00:43:13,100 --> 00:43:16,500
The exciton doesn't simply move from a to b.
624
00:43:19,000 --> 00:43:21,500
In a bizarre but very real sense,
625
00:43:21,500 --> 00:43:26,400
it's heading in every direction at the same time.
626
00:43:26,400 --> 00:43:28,900
It's spreading itself out as a wave
627
00:43:28,900 --> 00:43:32,700
so that it can explore all possible routes simultaneously.
628
00:43:32,700 --> 00:43:34,300
This strikes at the very heart
629
00:43:34,300 --> 00:43:36,700
of what's so strange about quantum mechanics.
630
00:43:36,700 --> 00:43:40,700
The exciton wave isn't just going this way or that way,
631
00:43:40,700 --> 00:43:44,000
it's following all paths at the same time.
632
00:43:44,000 --> 00:43:46,900
That's what gives it such incredible efficiency.
633
00:44:00,300 --> 00:44:01,400
The beauty of it is...
634
00:44:03,600 --> 00:44:06,000
...if the exciton is trying every route
635
00:44:06,000 --> 00:44:07,900
to the reaction centre at once...
636
00:44:09,700 --> 00:44:13,500
...it's bound to find the fastest possible way to deliver its energy.
637
00:44:17,300 --> 00:44:20,700
It's hard to express how incredible this discovery seems
638
00:44:20,700 --> 00:44:22,300
to physicists like me.
639
00:44:23,500 --> 00:44:26,900
Biological cells are full of the random jiggling
640
00:44:26,900 --> 00:44:29,000
of billions of atoms and molecules.
641
00:44:31,000 --> 00:44:34,200
But somehow, excitons maintain their form
642
00:44:34,200 --> 00:44:38,800
as beautiful, perfect quantum waves,
643
00:44:38,800 --> 00:44:43,500
transporting the energy that guarantees life on earth.
644
00:44:47,400 --> 00:44:51,900
It opened a whole new scientific path for me.
645
00:44:51,900 --> 00:44:53,900
And I really enjoy the fact that
646
00:44:53,900 --> 00:44:57,100
to be able to understand fully what is happening there or in the plants,
647
00:44:57,100 --> 00:44:58,900
you have to interact with scientists
648
00:44:58,900 --> 00:45:01,600
that have completely different approaches
649
00:45:01,600 --> 00:45:04,500
like biologists and chemists.
650
00:45:04,500 --> 00:45:06,700
But we all have to come together
651
00:45:06,700 --> 00:45:09,200
to actually understand what is the relevant of this,
652
00:45:09,200 --> 00:45:10,900
the relevance of this.
653
00:45:10,900 --> 00:45:13,600
So, for me, this is one of the most exciting parts of this field.
654
00:45:16,900 --> 00:45:20,500
Real scientific experiments leave no doubt.
655
00:45:22,300 --> 00:45:25,500
The strange hand of quantum mechanics has shaped
656
00:45:25,500 --> 00:45:27,100
the entire living world.
657
00:45:29,800 --> 00:45:34,000
It's not a surprise that you should find quantum tricks being used
658
00:45:34,000 --> 00:45:36,000
in biological systems.
659
00:45:36,000 --> 00:45:38,000
The reason is, because they're better.
660
00:45:42,800 --> 00:45:45,100
Quantum entanglement is normally seen
661
00:45:45,100 --> 00:45:48,200
in the tightly-controlled conditions of the physics lab.
662
00:45:49,600 --> 00:45:51,700
But now, we know that Robins use it
663
00:45:51,700 --> 00:45:54,100
to navigate with extraordinary precision.
664
00:45:58,700 --> 00:46:02,300
Quantum vibrations mean our noses listen to chemicals...
665
00:46:03,900 --> 00:46:06,500
...enhancing our perception of the world around us.
666
00:46:10,900 --> 00:46:14,200
The living cells of all animals depend on protons
667
00:46:14,200 --> 00:46:17,200
that vanish and reappear like ghosts...
668
00:46:19,700 --> 00:46:22,400
...speeding up the vital processes of life.
669
00:46:28,100 --> 00:46:30,800
And photosynthesis reveals the big picture.
670
00:46:32,900 --> 00:46:34,300
A shimmering world
671
00:46:34,300 --> 00:46:38,400
where quantum waves capture the sun's energy in an instant.
672
00:46:40,400 --> 00:46:42,800
Sometimes, people say, "ah, but physicists have been"
673
00:46:42,800 --> 00:46:45,100
"looking for this for decades".
674
00:46:45,100 --> 00:46:47,900
Well, biology has had millions of years.
675
00:46:49,100 --> 00:46:52,400
The ultramodern science of quantum mechanics
676
00:46:52,400 --> 00:46:54,400
is an ancient fact of life.
677
00:46:56,700 --> 00:46:58,500
For the end of my journey,
678
00:46:58,500 --> 00:47:01,300
I want to take these ideas to their logical conclusion.
679
00:47:01,300 --> 00:47:02,700
Of course, as a scientist,
680
00:47:02,700 --> 00:47:07,300
any speculations I have have to be backed up by careful experiments.
681
00:47:07,300 --> 00:47:10,500
So I want to concoct a thought experiment that helps me
682
00:47:10,500 --> 00:47:14,800
to answer the biggest biological question I can think of.
683
00:47:14,800 --> 00:47:18,000
Does quantum physics play any role
684
00:47:18,000 --> 00:47:20,500
in the mechanism of evolution itself?
685
00:47:26,500 --> 00:47:30,300
In 1859, Charles Darwin stunned the world
686
00:47:30,300 --> 00:47:33,400
with his theory of evolution by natural selection.
687
00:47:34,900 --> 00:47:37,200
He went on to explain the differences
688
00:47:37,200 --> 00:47:39,200
between humans and other apes.
689
00:47:41,100 --> 00:47:44,700
150 years later, there's no doubt that Darwin's theory
690
00:47:44,700 --> 00:47:46,400
accounts for every living organism
691
00:47:46,400 --> 00:47:48,500
on land and sea.
692
00:47:51,100 --> 00:47:53,300
But I'd like to explore the latest,
693
00:47:53,300 --> 00:47:56,700
extraordinary interpretation of his ideas.
694
00:48:01,800 --> 00:48:06,200
Could there be a quantum theory of evolution?
695
00:48:33,100 --> 00:48:37,800
Can quantum evolution explain how the snail got its shell?
696
00:48:41,200 --> 00:48:43,700
The snails I'm used to seeing in my back garden
697
00:48:43,700 --> 00:48:46,700
tend to have rather bland, boring shells.
698
00:48:46,700 --> 00:48:48,700
So have a look at this beauty.
699
00:48:50,200 --> 00:48:53,400
The patterns on its shell very perfectly match
700
00:48:53,400 --> 00:48:55,500
the lines on the stem.
701
00:48:58,100 --> 00:49:01,700
It's called a banded snail. Cepaea nemoralis.
702
00:49:03,000 --> 00:49:05,700
And the pattern isn't there by accident.
703
00:49:09,900 --> 00:49:11,400
Come and have a look at this.
704
00:49:15,200 --> 00:49:17,300
Less well adapted snails
705
00:49:17,300 --> 00:49:19,900
are more likely to be found here.
706
00:49:19,900 --> 00:49:23,300
This stone is called a thrush's anvil.
707
00:49:23,300 --> 00:49:25,900
The song thrush is the snail's main predator.
708
00:49:25,900 --> 00:49:27,200
It catches the snail
709
00:49:27,200 --> 00:49:30,200
and smashes its shell against the stone to get to the snail.
710
00:49:30,200 --> 00:49:31,700
Now, what I can see here
711
00:49:31,700 --> 00:49:34,800
is that there aren't many banded snail shells,
712
00:49:34,800 --> 00:49:38,300
suggesting that its colours camouflage it very well,
713
00:49:38,300 --> 00:49:39,600
hiding it from the bird.
714
00:49:43,400 --> 00:49:45,100
Darwin's theory says
715
00:49:45,100 --> 00:49:49,100
that evolution depends on variation within a species.
716
00:49:51,500 --> 00:49:55,500
Snails with camouflage are more likely to survive and reproduce...
717
00:49:58,100 --> 00:50:00,800
...passing on their shells to the next generation
718
00:50:00,800 --> 00:50:04,700
so that the species as a whole becomes better adapted.
719
00:50:07,500 --> 00:50:11,500
So, variation - the random differences between snails -
720
00:50:11,500 --> 00:50:14,400
is the driving force behind their evolution.
721
00:50:16,500 --> 00:50:20,300
Now, all species evolve and adapt to their environment.
722
00:50:20,300 --> 00:50:22,400
But the question I'd like to explore is
723
00:50:22,400 --> 00:50:25,300
whether quantum mechanics plays a role in this.
724
00:50:29,400 --> 00:50:31,000
The only way to find out
725
00:50:31,000 --> 00:50:33,300
is by scientific experiments.
726
00:50:35,500 --> 00:50:39,400
So, my adventures in quantum biology finally bring me home.
727
00:50:41,500 --> 00:50:43,500
To the university of surrey.
728
00:50:46,100 --> 00:50:47,700
Here, in the laboratories,
729
00:50:47,700 --> 00:50:52,100
I'm planning a new analysis of the most celebrated molecule in science.
730
00:50:55,900 --> 00:50:59,700
Deoxyribonucleic acid, or DNA.
731
00:51:02,800 --> 00:51:07,600
Its double helix holds the genetic code for every living organism.
732
00:51:10,100 --> 00:51:13,800
It's a remarkable fact that Darwin himself had no idea
733
00:51:13,800 --> 00:51:17,000
what created variation in the species.
734
00:51:17,000 --> 00:51:20,500
The structure of DNA wasn't discovered until 1953
735
00:51:20,500 --> 00:51:23,300
by Francis crick and James Watson.
736
00:51:23,300 --> 00:51:26,300
The most famous feature of DNA is of course
737
00:51:26,300 --> 00:51:29,000
its beautiful double helix structure.
738
00:51:29,000 --> 00:51:30,700
But that's just scaffolding.
739
00:51:30,700 --> 00:51:33,600
The real genetic secret lies in between.
740
00:51:36,800 --> 00:51:40,500
The four different-coloured molecules are called bases.
741
00:51:42,100 --> 00:51:46,300
The colour code on one side - say blue, red, blue -
742
00:51:46,300 --> 00:51:50,700
forms a gene that parents pass on to their offspring.
743
00:51:50,700 --> 00:51:53,800
A gene is a bit like a Jigsaw puzzle.
744
00:51:53,800 --> 00:51:55,700
It fits together like this.
745
00:51:57,600 --> 00:52:02,000
A full strand of the double helix forms a coloured pattern.
746
00:52:04,100 --> 00:52:07,200
But the other strand always pairs up the same way.
747
00:52:10,400 --> 00:52:13,100
A blue base always goes with yellow
748
00:52:13,100 --> 00:52:16,500
and green always goes with red.
749
00:52:18,000 --> 00:52:22,500
Because only those colours have the right shape to fit together.
750
00:52:22,500 --> 00:52:25,900
What crick and Watson realised was that this provides
751
00:52:25,900 --> 00:52:28,900
a mechanism for passing on the genetic code.
752
00:52:30,300 --> 00:52:34,400
When cells reproduce, the two strands of DNA separate,
753
00:52:34,400 --> 00:52:35,900
ready to be copied.
754
00:52:38,200 --> 00:52:40,500
But red still goes with green...
755
00:52:42,900 --> 00:52:45,000
...and yellow still goes with blue.
756
00:52:46,600 --> 00:52:48,200
So bit by bit,
757
00:52:48,200 --> 00:52:50,400
the cell creates two new strands.
758
00:52:52,100 --> 00:52:55,800
Two perfect copies of the entire genetic code.
759
00:52:57,200 --> 00:52:59,900
So far, there's no genetic variation.
760
00:52:59,900 --> 00:53:03,500
This new copy is identical to the original.
761
00:53:03,500 --> 00:53:05,300
But here's the interesting bit.
762
00:53:05,300 --> 00:53:09,500
During the copying process, something very important can happen.
763
00:53:09,500 --> 00:53:11,400
Sometimes, mistakes creep in.
764
00:53:14,500 --> 00:53:16,500
They're called mutations.
765
00:53:17,900 --> 00:53:21,200
Let's have a look at these two bases here.
766
00:53:22,900 --> 00:53:27,600
The two prongs that hold them together are subatomic particles.
767
00:53:27,600 --> 00:53:29,100
They're protons.
768
00:53:29,100 --> 00:53:32,900
They're basically the bonds between the strands of DNA.
769
00:53:32,900 --> 00:53:36,500
These protons can jump across to the other side.
770
00:53:38,500 --> 00:53:42,500
If the strands split when the protons have jumped across,
771
00:53:42,500 --> 00:53:45,200
they find themselves in the wrong position.
772
00:53:47,300 --> 00:53:52,800
Now, this red base will no longer bind to a green base.
773
00:53:52,800 --> 00:53:57,300
Instead, it has to bond to a yellow base.
774
00:53:58,500 --> 00:54:00,200
Slotting this back in,
775
00:54:01,400 --> 00:54:05,100
we see that now this copy is no longer identical to the original
776
00:54:05,100 --> 00:54:09,100
because I have a yellow base here instead of a green one.
777
00:54:09,100 --> 00:54:11,900
We've brought in a genetic mutation.
778
00:54:13,600 --> 00:54:16,800
Jumping protons would change the snail's DNA.
779
00:54:18,500 --> 00:54:21,300
It could make a new gene for camouflaged shells.
780
00:54:22,900 --> 00:54:25,700
The question is, how do protons jump?
781
00:54:28,600 --> 00:54:32,000
It's my belief that quantum's spookiness can take over.
782
00:54:33,700 --> 00:54:36,100
Now, for these mutations to take place,
783
00:54:36,100 --> 00:54:39,900
the protons have to overcome an energy barrier.
784
00:54:39,900 --> 00:54:42,300
And if you remember what happened with enzymes,
785
00:54:42,300 --> 00:54:45,500
well, you can probably guess what's coming next.
786
00:54:49,000 --> 00:54:52,500
Protons can behave as if barriers don't exist.
787
00:54:54,600 --> 00:54:57,200
They tunnel straight through.
788
00:54:58,600 --> 00:55:01,300
But does this ghostly effect really happen?
789
00:55:05,700 --> 00:55:08,400
My colleagues in biology are already looking
790
00:55:08,400 --> 00:55:11,500
for the very first evidence of quantum mutations.
791
00:55:14,500 --> 00:55:17,400
Biologists didn't really even know about quantum mechanics,
792
00:55:17,400 --> 00:55:21,200
so when you tell them that particles can be in two places at once,
793
00:55:21,200 --> 00:55:23,500
they kind of say, "well, not in my cells, they can't!"
794
00:55:25,000 --> 00:55:28,000
Our experiment involves samples of bacteria.
795
00:55:29,400 --> 00:55:32,200
The first sample is prepared in normal water,
796
00:55:32,200 --> 00:55:35,300
containing hydrogen nuclei, or protons.
797
00:55:37,100 --> 00:55:41,500
When the bacteria reproduce, we simply count the mutations.
798
00:55:42,900 --> 00:55:44,700
But if our theory is correct,
799
00:55:44,700 --> 00:55:48,400
then we should be able to change the rate at which mutations occur.
800
00:55:50,000 --> 00:55:53,500
Remember how we tested the quantum theory of smell?
801
00:55:53,500 --> 00:55:58,100
What if I replaced the proton with its big brother, the deuteron?
802
00:55:58,100 --> 00:56:01,200
This is the nucleus of an atom of deuterium.
803
00:56:01,200 --> 00:56:05,000
Now, crucially, a deuteron is twice as heavy as a proton
804
00:56:05,000 --> 00:56:07,900
and this should influence how easy it is for
805
00:56:07,900 --> 00:56:09,700
the deuteron to quantum tunnel.
806
00:56:10,800 --> 00:56:13,200
Quantum mechanics is full of surprises.
807
00:56:14,600 --> 00:56:16,400
Protons tunnel easily.
808
00:56:18,600 --> 00:56:20,900
Deuterons... don't.
809
00:56:26,500 --> 00:56:30,400
These heavier particles are much more likely to bounce straight back.
810
00:56:33,700 --> 00:56:37,900
So the second sample of bacteria is prepared in heavy water,
811
00:56:37,900 --> 00:56:39,700
which is full of deuterons.
812
00:56:41,500 --> 00:56:45,000
Our theory says you should get far fewer mutations.
813
00:56:46,700 --> 00:56:50,400
And, so far, the results are extremely encouraging.
814
00:56:50,400 --> 00:56:54,500
The preliminary experiments that we've done gives us a hint
815
00:56:54,500 --> 00:56:58,000
that the mutation rate is indeed depressed in deuterated water.
816
00:56:58,000 --> 00:57:02,700
We find that it is lower. So my hunch is that we're right,
817
00:57:02,700 --> 00:57:06,600
but we'll have to wait a little while before we're sure.
818
00:57:09,000 --> 00:57:10,700
Final proof lies in the future.
819
00:57:12,300 --> 00:57:13,800
Even if we're right,
820
00:57:13,800 --> 00:57:16,700
quantum tunnelling is a rare form of mutation.
821
00:57:19,000 --> 00:57:21,700
But our results promise hard evidence
822
00:57:21,700 --> 00:57:25,900
for a new explanation of one of the most fundamental processes of life.
823
00:57:28,000 --> 00:57:31,700
Even the merest possibility of a new quantum mechanism
824
00:57:31,700 --> 00:57:35,100
for evolution itself is tremendously exciting.
825
00:57:35,100 --> 00:57:39,600
In fact, the story of quantum biology is only just beginning.
826
00:57:39,600 --> 00:57:43,800
What the frog, the Robin, the fruit fly and the tree have shown us
827
00:57:43,800 --> 00:57:48,500
is that real quantum effects are going on in nature all the time.
828
00:57:48,500 --> 00:57:50,400
And if there's anything we've learnt
829
00:57:50,400 --> 00:57:53,000
from the history of quantum mechanics, it's this -
830
00:57:53,000 --> 00:57:57,100
we can never be certain where new discoveries will take us next.
831
00:58:06,400 --> 00:58:09,900
Quantum biology is a revolution in science.
832
00:58:11,100 --> 00:58:13,900
But it's time I got back to the physics department.
66328
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