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I'd like to introduce you
to an emerging area of science,

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one that is still speculative
but hugely exciting,

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and certainly one
that's growing very rapidly.

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Quantum biology
asks a very simple question:

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Does quantum mechanics --

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that weird and wonderful
and powerful theory

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of the subatomic world
of atoms and molecules

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that underpins so much
of modern physics and chemistry --

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also play a role inside the living cell?

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In other words: Are there processes,
mechanisms, phenomena

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in living organisms
that can only be explained

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with a helping hand
from quantum mechanics?

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Now, quantum biology isn't new;

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it's been around since the early 1930s.

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But it's only in the last decade or so
that careful experiments --

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in biochemistry labs,
using spectroscopy --

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have shown very clear, firm evidence
that there are certain specific mechanisms

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that require quantum mechanics
to explain them.

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Quantum biology brings together
quantum physicists, biochemists,

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molecular biologists --
it's a very interdisciplinary field.

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I come from quantum physics,
so I'm a nuclear physicist.

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I've spent more than three decades

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trying to get my head
around quantum mechanics.

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One of the founders
of quantum mechanics, Niels Bohr,

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said, "If you're not astonished by it,
then you haven't understood it."

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So I sort of feel happy
that I'm still astonished by it.

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That's a good thing.

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But it means I study the very
smallest structures in the universe --

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the building blocks of reality.

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If we think about the scale of size,

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start with an everyday object
like the tennis ball,

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and just go down orders
of magnitude in size --

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from the eye of a needle down to a cell,
down to a bacterium, down to an enzyme --

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you eventually reach the nano-world.

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Now, nanotechnology may be
a term you've heard of.

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A nanometer is a billionth of a meter.

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My area is the atomic nucleus,
which is the tiny dot inside an atom.

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It's even smaller in scale.

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This is the domain of quantum mechanics,

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and physicists and chemists
have had a long time

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to try and get used to it.

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Biologists, on the other hand,
have got off lightly, in my view.

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They are very happy with their
balls-and-sticks models of molecules.

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(Laughter)

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The balls are the atoms, the sticks
are the bonds between the atoms.

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And when they can't build them
physically in the lab,

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nowadays, they have
very powerful computers

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that will simulate a huge molecule.

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This is a protein made up
of 100,000 atoms.

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It doesn't really require much in the way
of quantum mechanics to explain it.

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Quantum mechanics
was developed in the 1920s.

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It is a set of beautiful and powerful
mathematical rules and ideas

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that explain the world of the very small.

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And it's a world that's very different
from our everyday world,

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made up of trillions of atoms.

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It's a world built
on probability and chance.

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It's a fuzzy world.

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It's a world of phantoms,

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where particles can also behave
like spread-out waves.

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If we imagine quantum mechanics
or quantum physics, then,

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as the fundamental
foundation of reality itself,

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then it's not surprising that we say

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quantum physics underpins
organic chemistry.

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After all, it gives us
the rules that tell us

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how the atoms fit together
to make organic molecules.

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Organic chemistry,
scaled up in complexity,

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gives us molecular biology,
which of course leads to life itself.

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So in a way, it's sort of not surprising.

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It's almost trivial.

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You say, "Well, of course life ultimately
must depend of quantum mechanics."

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But so does everything else.

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So does all inanimate matter,
made up of trillions of atoms.

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Ultimately, there's a quantum level

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where we have to delve into
this weirdness.

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But in everyday life,
we can forget about it.

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Because once you put together
trillions of atoms,

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that quantum weirdness
just dissolves away.

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Quantum biology isn't about this.

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Quantum biology isn't this obvious.

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Of course quantum mechanics
underpins life at some molecular level.

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Quantum biology is about looking
for the non-trivial --

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the counterintuitive ideas
in quantum mechanics --

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and to see if they do, indeed,
play an important role

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in describing the processes of life.

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Here is my perfect example
of the counterintuitiveness

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of the quantum world.

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This is the quantum skier.

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He seems to be intact,
he seems to be perfectly healthy,

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and yet, he seems to have gone around
both sides of that tree at the same time.

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Well, if you saw tracks like that

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you'd guess it was some
sort of stunt, of course.

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But in the quantum world,
this happens all the time.

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Particles can multitask,
they can be in two places at once.

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They can do more than one thing
at the same time.

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Particles can behave
like spread-out waves.

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It's almost like magic.

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Physicists and chemists have had
nearly a century

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of trying to get used to this weirdness.

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I don't blame the biologists

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for not having to or wanting
to learn quantum mechanics.

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You see, this weirdness is very delicate;

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and we physicists work very hard
to maintain it on our labs.

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We cool our system down
to near absolute zero,

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we carry out our experiments in vacuums,

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we try and isolate it
from any external disturbance.

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That's very different from the warm,
messy, noisy environment of a living cell.

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Biology itself, if you think of
molecular biology,

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seems to have done very well
in describing all the processes of life

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in terms of chemistry --
chemical reactions.

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And these are reductionist,
deterministic chemical reactions,

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showing that, essentially, life is made
of the same stuff as everything else,

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and if we can forget about quantum
mechanics in the macro world,

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then we should be able to forget
about it in biology, as well.

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Well, one man begged
to differ with this idea.

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Erwin Schrödinger,
of Schrödinger's Cat fame,

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was an Austrian physicist.

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He was one of the founders
of quantum mechanics in the 1920s.

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In 1944, he wrote a book
called "What is Life?"

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It was tremendously influential.

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It influenced Francis Crick
and James Watson,

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the discoverers of the double-helix
structure of DNA.

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To paraphrase a description
in the book, he says:

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At the molecular level,
living organisms have a certain order,

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a structure to them that's very different

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from the random thermodynamic jostling
of atoms and molecules

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in inanimate matter
of the same complexity.

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In fact, living matter seems to behave
in this order, in a structure,

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just like inanimate matter
cooled down to near absolute zero,

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where quantum effects
play a very important role.

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There's something special
about the structure -- the order --

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inside a living cell.

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So, Schrödinger speculated that maybe
quantum mechanics plays a role in life.

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It's a very speculative,
far-reaching idea,

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and it didn't really go very far.

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But as I mentioned at the start,

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in the last 10 years, there have been
experiments emerging,

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showing where some of these
certain phenomena in biology

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do seem to require quantum mechanics.

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I want to share with you
just a few of the exciting ones.

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This is one of the best-known
phenomena in the quantum world,

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quantum tunneling.

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The box on the left shows
the wavelike, spread-out distribution

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of a quantum entity --
a particle, like an electron,

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which is not a little ball
bouncing off a wall.

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It's a wave that has a certain probability
of being able to permeate

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through a solid wall, like a phantom
leaping through to the other side.

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You can see a faint smudge of light
in the right-hand box.

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Quantum tunneling suggests that a particle
can hit an impenetrable barrier,

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and yet somehow, as though by magic,

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disappear from one side
and reappear on the other.

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The nicest way of explaining it is
if you want to throw a ball over a wall,

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you have to give it enough energy
to get over the top of the wall.

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In the quantum world,
you don't have to throw it over the wall,

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you can throw it at the wall,
and there's a certain non-zero probability

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that it'll disappear on your side,
and reappear on the other.

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This isn't speculation, by the way.

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We're happy -- well, "happy"
is not the right word --

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(Laughter)

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We are familiar with this.

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(Laughter)

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Quantum tunneling
takes place all the time;

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in fact, it's the reason our sun shines.

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The particles fuse together,

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and the Sun turns hydrogen
into helium through quantum tunneling.

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Back in the 70s and 80s, it was discovered
that quantum tunneling also takes place

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inside living cells.

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Enzymes, those workhorses of life,
the catalysts of chemical reactions --

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enzymes are biomolecules that speed up
chemical reactions in living cells,

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by many, many orders of magnitude.

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And it's always been a mystery
how they do this.

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Well, it was discovered

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that one of the tricks that enzymes
have evolved to make use of,

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is by transferring subatomic particles,
like electrons and indeed protons,

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from one part of a molecule
to another via quantum tunneling.

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It's efficient, it's fast,
it can disappear --

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a proton can disappear from one place,
and reappear on the other.

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Enzymes help this take place.

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This is research that's been
carried out back in the 80s,

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particularly by a group
in Berkeley, Judith Klinman.

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Other groups in the UK
have now also confirmed

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that enzymes really do this.

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Research carried out by my group --

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so as I mentioned,
I'm a nuclear physicist,

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but I've realized I've got these tools
of using quantum mechanics

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in atomic nuclei, and so can apply
those tools in other areas as well.

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One question we asked

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is whether quantum tunneling
plays a role in mutations in DNA.

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Again, this is not a new idea;
it goes all the way back to the early 60s.

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The two strands of DNA,
the double-helix structure,

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are held together by rungs;
it's like a twisted ladder.

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And those rungs of the ladder
are hydrogen bonds --

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protons, that act as the glue
between the two strands.

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So if you zoom in, what they're doing
is holding these large molecules --

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nucleotides -- together.

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Zoom in a bit more.

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So, this a computer simulation.

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The two white balls
in the middle are protons,

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and you can see that
it's a double hydrogen bond.

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One prefers to sit on one side;
the other, on the other side

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of the two strands of the vertical lines
going down, which you can't see.

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It can happen that
these two protons can hop over.

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Watch the two white balls.

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They can jump over to the other side.

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If the two strands of DNA then separate,
leading to the process of replication,

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and the two protons
are in the wrong positions,

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this can lead to a mutation.

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This has been known for half a century.

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The question is: How likely
are they to do that,

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and if they do, how do they do it?

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Do they jump across,
like the ball going over the wall?

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Or can they quantum-tunnel across,
even if they don't have enough energy?

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Early indications suggest that
quantum tunneling can play a role here.

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We still don't know yet
how important it is;

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this is still an open question.

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It's speculative,

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but it's one of those questions
that is so important

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that if quantum mechanics
plays a role in mutations,

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surely this must have big implications,

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to understand certain types of mutations,

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possibly even those that lead
to turning a cell cancerous.

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Another example of quantum mechanics
in biology is quantum coherence,

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in one of the most
important processes in biology,

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photosynthesis: plants
and bacteria taking sunlight,

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and using that energy to create biomass.

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Quantum coherence is the idea
of quantum entities multitasking.

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It's the quantum skier.

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It's an object that behaves like a wave,

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so that it doesn't just move
in one direction or the other,

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but can follow multiple pathways
at the same time.

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Some years ago,
the world of science was shocked

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when a paper was published
showing experimental evidence

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that quantum coherence
takes place inside bacteria,

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carrying out photosynthesis.

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The idea is that the photon,
the particle of light, the sunlight,

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the quantum of light
captured by a chlorophyll molecule,

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is then delivered to what's called
the reaction center,

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where it can be turned into
chemical energy.

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And in getting there,
it doesn't just follow one route;

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it follows multiple pathways at once,

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to optimize the most efficient way
of reaching the reaction center

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without dissipating as waste heat.

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Quantum coherence taking place
inside a living cell.

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A remarkable idea,

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and yet evidence is growing almost weekly,
with new papers coming out,

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confirming that this
does indeed take place.

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My third and final example
is the most beautiful, wonderful idea.

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It's also still very speculative,
but I have to share it with you.

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The European robin
migrates from Scandinavia

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down to the Mediterranean, every autumn,

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and like a lot of other
marine animals and even insects,

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they navigate by sensing
the Earth's magnetic field.

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Now, the Earth's magnetic field
is very, very weak;

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it's 100 times weaker
than a fridge magnet,

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and yet it affects the chemistry --
somehow -- within a living organism.

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That's not in doubt --
a German couple of ornithologists,

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Wolfgang and Roswitha Wiltschko,
in the 1970s, confirmed that indeed,

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the robin does find its way by somehow
sensing the Earth's magnetic field,

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to give it directional information --
a built-in compass.

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The puzzle, the mystery was:
How does it do it?

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Well, the only theory in town --

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we don't know if it's the correct theory,
but the only theory in town --

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is that it does it via something
called quantum entanglement.

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Inside the robin's retina --

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I kid you not -- inside the robin's retina
is a protein called cryptochrome,

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which is light-sensitive.

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Within cryptochrome, a pair of electrons
are quantum-entangled.

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Now, quantum entanglement
is when two particles are far apart,

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and yet somehow remain
in contact with each other.

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Even Einstein hated this idea;

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he called it "spooky action
at a distance."

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(Laughter)

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So if Einstein doesn't like it,
then we can all be uncomfortable with it.

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Two quantum-entangled electrons
within a single molecule

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dance a delicate dance

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that is very sensitive
to the direction the bird flies

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in the Earth's magnetic field.

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We don't know if it's
the correct explanation,

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but wow, wouldn't it be exciting
if quantum mechanics helps birds navigate?

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Quantum biology is still in it infancy.

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It's still speculative.

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But I believe it's built on solid science.

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I also think that
in the coming decade or so,

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we're going to start to see
that actually, it pervades life --

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that life has evolved tricks
that utilize the quantum world.

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Watch this space.

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Thank you.

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(Applause)