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How quantum biology might explain life’s biggest questions

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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)
Title:
How quantum biology might explain life’s biggest questions
Speaker:
Jim Al-Khalili
Description:

more » « less
Video Language:
English
Team:
closed TED
Project:
TEDTalks
Duration:
16:09

English subtitles

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