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Jim Al-Khalili: How quantum biology might explain life’s biggest questions

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How does a robin know to fly south? The answer might be weirder than you think: Quantum physics may be involved. Jim Al-Khalili rounds up the extremely new, extremely strange world of quantum biology, where something Einstein once called “spooky action at a distance” helps birds navigate, and quantum effects might explain the origin of life itself.

- Quantum physicist
Physicist Jim Al-Khalili and co-author Johnjoe McFadden, a biologist, explore the far edges of quantum biology in their book "Life on the Edge." Full bio

I'd like to introduce you
to an emerging area of science,
00:13
one that is still speculative
but hugely exciting,
00:17
and certainly one
that's growing very rapidly.
00:21
Quantum biology
asks a very simple question:
00:25
Does quantum mechanics --
00:29
that weird and wonderful
and powerful theory
00:30
of the subatomic world
of atoms and molecules
00:34
that underpins so much
of modern physics and chemistry --
00:36
also play a role inside the living cell?
00:40
In other words: Are there processes,
mechanisms, phenomena
00:43
in living organisms
that can only be explained
00:47
with a helping hand
from quantum mechanics?
00:51
Now, quantum biology isn't new;
00:55
it's been around since the early 1930s.
00:57
But it's only in the last decade or so
that careful experiments --
00:59
in biochemistry labs,
using spectroscopy --
01:03
have shown very clear, firm evidence
that there are certain specific mechanisms
01:06
that require quantum mechanics
to explain them.
01:13
Quantum biology brings together
quantum physicists, biochemists,
01:17
molecular biologists --
it's a very interdisciplinary field.
01:20
I come from quantum physics,
so I'm a nuclear physicist.
01:24
I've spent more than three decades
01:28
trying to get my head
around quantum mechanics.
01:30
One of the founders
of quantum mechanics, Niels Bohr,
01:33
said, If you're not astonished by it,
then you haven't understood it.
01:36
So I sort of feel happy
that I'm still astonished by it.
01:40
That's a good thing.
01:42
But it means I study the very
smallest structures in the universe --
01:44
the building blocks of reality.
01:51
If we think about the scale of size,
01:53
start with an everyday object
like the tennis ball,
01:56
and just go down orders
of magnitude in size --
01:59
from the eye of a needle down to a cell,
down to a bacterium, down to an enzyme --
02:02
you eventually reach the nano-world.
02:08
Now, nanotechnology may be
a term you've heard of.
02:09
A nanometer is a billionth of a meter.
02:12
My area is the atomic nucleus,
which is the tiny dot inside an atom.
02:16
It's even smaller in scale.
02:20
This is the domain of quantum mechanics,
02:22
and physicists and chemists
have had a long time
02:24
to try and get used to it.
02:27
Biologists, on the other hand,
have got off lightly, in my view.
02:29
They are very happy with their
balls-and-sticks models of molecules.
02:33
(Laughter)
02:38
The balls are the atoms, the sticks
are the bonds between the atoms.
02:39
And when they can't build them
physically in the lab,
02:42
nowadays, they have
very powerful computers
02:45
that will simulate a huge molecule.
02:47
This is a protein made up
of 100,000 atoms.
02:49
It doesn't really require much in the way
of quantum mechanics to explain it.
02:53
Quantum mechanics
was developed in the 1920s.
02:59
It is a set of beautiful and powerful
mathematical rules and ideas
03:02
that explain the world of the very small.
03:09
And it's a world that's very different
from our everyday world,
03:12
made up of trillions of atoms.
03:15
It's a world built
on probability and chance.
03:17
It's a fuzzy world.
03:21
It's a world of phantoms,
03:22
where particles can also behave
like spread-out waves.
03:24
If we imagine quantum mechanics
or quantum physics, then,
03:29
as the fundamental
foundation of reality itself,
03:32
then it's not surprising that we say
03:38
quantum physics underpins
organic chemistry.
03:39
After all, it gives us
the rules that tell us
03:42
how the atoms fit together
to make organic molecules.
03:44
Organic chemistry,
scaled up in complexity,
03:47
gives us molecular biology,
which of course leads to life itself.
03:50
So in a way, it's sort of not surprising.
03:53
It's almost trivial.
03:55
You say, "Well, of course life ultimately
must depend of quantum mechanics."
03:57
But so does everything else.
04:01
So does all inanimate matter,
made up of trillions of atoms.
04:04
Ultimately, there's a quantum level
04:08
where we have to delve into
this weirdness.
04:13
But in everyday life,
we can forget about it.
04:15
Because once you put together
trillions of atoms,
04:18
that quantum weirdness
just dissolves away.
04:21
Quantum biology isn't about this.
04:27
Quantum biology isn't this obvious.
04:29
Of course quantum mechanics
underpins life at some molecular level.
04:32
Quantum biology is about looking
for the non-trivial --
04:37
the counterintuitive ideas
in quantum mechanics --
04:43
and to see if they do, indeed,
play an important role
04:47
in describing the processes of life.
04:50
Here is my perfect example
of the counterintuitiveness
04:54
of the quantum world.
04:59
This is the quantum skier.
05:01
He seems to be intact,
he seems to be perfectly healthy,
05:02
and yet, he seems to have gone around
both sides of that tree at the same time.
05:05
Well, if you saw tracks like that
05:09
you'd guess it was some
sort of stunt, of course.
05:10
But in the quantum world,
this happens all the time.
05:13
Particles can multitask,
they can be in two places at once.
05:16
They can do more than one thing
at the same time.
05:19
Particles can behave
like spread-out waves.
05:22
It's almost like magic.
05:25
Physicists and chemists have had
nearly a century
05:27
of trying to get used to this weirdness.
05:30
I don't blame the biologists
05:33
for not having to or wanting
to learn quantum mechanics.
05:34
You see, this weirdness is very delicate;
05:37
and we physicists work very hard
to maintain it in our labs.
05:40
We cool our system down
to near absolute zero,
05:44
we carry out our experiments in vacuums,
05:49
we try and isolate it
from any external disturbance.
05:51
That's very different from the warm,
messy, noisy environment of a living cell.
05:55
Biology itself, if you think of
molecular biology,
06:01
seems to have done very well
in describing all the processes of life
06:04
in terms of chemistry --
chemical reactions.
06:08
And these are reductionist,
deterministic chemical reactions,
06:10
showing that, essentially, life is made
of the same stuff as everything else,
06:15
and if we can forget about quantum
mechanics in the macro world,
06:20
then we should be able to forget
about it in biology, as well.
06:23
Well, one man begged
to differ with this idea.
06:27
Erwin Schrödinger,
of Schrödinger's Cat fame,
06:31
was an Austrian physicist.
06:35
He was one of the founders
of quantum mechanics in the 1920s.
06:36
In 1944, he wrote a book
called "What is Life?"
06:40
It was tremendously influential.
06:43
It influenced Francis Crick
and James Watson,
06:45
the discoverers of the double-helix
structure of DNA.
06:48
To paraphrase a description
in the book, he says:
06:51
At the molecular level,
living organisms have a certain order,
06:54
a structure to them that's very different
07:00
from the random thermodynamic jostling
of atoms and molecules
07:03
in inanimate matter
of the same complexity.
07:08
In fact, living matter seems to behave
in this order, in a structure,
07:13
just like inanimate matter
cooled down to near absolute zero,
07:18
where quantum effects
play a very important role.
07:22
There's something special
about the structure -- the order --
07:26
inside a living cell.
07:30
So, Schrödinger speculated that maybe
quantum mechanics plays a role in life.
07:31
It's a very speculative,
far-reaching idea,
07:37
and it didn't really go very far.
07:41
But as I mentioned at the start,
07:45
in the last 10 years, there have been
experiments emerging,
07:46
showing where some of these
certain phenomena in biology
07:49
do seem to require quantum mechanics.
07:53
I want to share with you
just a few of the exciting ones.
07:55
This is one of the best-known
phenomena in the quantum world,
08:00
quantum tunneling.
08:03
The box on the left shows
the wavelike, spread-out distribution
08:05
of a quantum entity --
a particle, like an electron,
08:09
which is not a little ball
bouncing off a wall.
08:12
It's a wave that has a certain probability
of being able to permeate
08:16
through a solid wall, like a phantom
leaping through to the other side.
08:21
You can see a faint smudge of light
in the right-hand box.
08:24
Quantum tunneling suggests that a particle
can hit an impenetrable barrier,
08:29
and yet somehow, as though by magic,
08:34
disappear from one side
and reappear on the other.
08:36
The nicest way of explaining it is
if you want to throw a ball over a wall,
08:39
you have to give it enough energy
to get over the top of the wall.
08:43
In the quantum world,
you don't have to throw it over the wall,
08:47
you can throw it at the wall,
and there's a certain non-zero probability
08:50
that it'll disappear on your side,
and reappear on the other.
08:53
This isn't speculation, by the way.
08:57
We're happy -- well, "happy"
is not the right word --
08:58
(Laughter)
09:02
we are familiar with this.
09:04
(Laughter)
09:06
Quantum tunneling
takes place all the time;
09:08
in fact, it's the reason our Sun shines.
09:11
The particles fuse together,
09:14
and the Sun turns hydrogen
into helium through quantum tunneling.
09:16
Back in the 70s and 80s, it was discovered
that quantum tunneling also takes place
09:21
inside living cells.
09:26
Enzymes, those workhorses of life,
the catalysts of chemical reactions --
09:28
enzymes are biomolecules that speed up
chemical reactions in living cells,
09:34
by many, many orders of magnitude.
09:38
And it's always been a mystery
how they do this.
09:40
Well, it was discovered
09:43
that one of the tricks that enzymes
have evolved to make use of,
09:44
is by transferring subatomic particles,
like electrons and indeed protons,
09:49
from one part of a molecule
to another via quantum tunneling.
09:54
It's efficient, it's fast,
it can disappear --
10:00
a proton can disappear from one place,
and reappear on the other.
10:03
Enzymes help this take place.
10:06
This is research that's been
carried out back in the 80s,
10:08
particularly by a group
in Berkeley, Judith Klinman.
10:11
Other groups in the UK
have now also confirmed
10:15
that enzymes really do this.
10:17
Research carried out by my group --
10:20
so as I mentioned,
I'm a nuclear physicist,
10:23
but I've realized I've got these tools
of using quantum mechanics
10:25
in atomic nuclei, and so can apply
those tools in other areas as well.
10:28
One question we asked
10:35
is whether quantum tunneling
plays a role in mutations in DNA.
10:37
Again, this is not a new idea;
it goes all the way back to the early 60s.
10:41
The two strands of DNA,
the double-helix structure,
10:45
are held together by rungs;
it's like a twisted ladder.
10:48
And those rungs of the ladder
are hydrogen bonds --
10:51
protons, that act as the glue
between the two strands.
10:54
So if you zoom in, what they're doing
is holding these large molecules --
10:58
nucleotides -- together.
11:03
Zoom in a bit more.
11:05
So, this a computer simulation.
11:07
The two white balls
in the middle are protons,
11:09
and you can see that
it's a double hydrogen bond.
11:13
One prefers to sit on one side;
the other, on the other side
11:15
of the two strands of the vertical lines
going down, which you can't see.
11:18
It can happen that
these two protons can hop over.
11:24
Watch the two white balls.
11:27
They can jump over to the other side.
11:29
If the two strands of DNA then separate,
leading to the process of replication,
11:32
and the two protons
are in the wrong positions,
11:37
this can lead to a mutation.
11:40
This has been known for half a century.
11:43
The question is: How likely
are they to do that,
11:44
and if they do, how do they do it?
11:47
Do they jump across,
like the ball going over the wall?
11:49
Or can they quantum-tunnel across,
even if they don't have enough energy?
11:52
Early indications suggest that
quantum tunneling can play a role here.
11:56
We still don't know yet
how important it is;
12:01
this is still an open question.
12:03
It's speculative,
12:06
but it's one of those questions
that is so important
12:07
that if quantum mechanics
plays a role in mutations,
12:09
surely this must have big implications,
12:12
to understand certain types of mutations,
12:14
possibly even those that lead
to turning a cell cancerous.
12:17
Another example of quantum mechanics
in biology is quantum coherence,
12:22
in one of the most
important processes in biology,
12:27
photosynthesis: plants
and bacteria taking sunlight,
12:30
and using that energy to create biomass.
12:34
Quantum coherence is the idea
of quantum entities multitasking.
12:38
It's the quantum skier.
12:42
It's an object that behaves like a wave,
12:44
so that it doesn't just move
in one direction or the other,
12:47
but can follow multiple pathways
at the same time.
12:50
Some years ago,
the world of science was shocked
12:54
when a paper was published
showing experimental evidence
12:58
that quantum coherence
takes place inside bacteria,
13:02
carrying out photosynthesis.
13:05
The idea is that the photon,
the particle of light, the sunlight,
13:07
the quantum of light
captured by a chlorophyll molecule,
13:10
is then delivered to what's called
the reaction center,
13:14
where it can be turned into
chemical energy.
13:16
And in getting there,
it doesn't just follow one route;
13:18
it follows multiple pathways at once,
13:21
to optimize the most efficient way
of reaching the reaction center
13:23
without dissipating as waste heat.
13:28
Quantum coherence taking place
inside a living cell.
13:31
A remarkable idea,
13:34
and yet evidence is growing almost weekly,
with new papers coming out,
13:36
confirming that this
does indeed take place.
13:42
My third and final example
is the most beautiful, wonderful idea.
13:45
It's also still very speculative,
but I have to share it with you.
13:50
The European robin
migrates from Scandinavia
13:54
down to the Mediterranean, every autumn,
13:58
and like a lot of other
marine animals and even insects,
14:01
they navigate by sensing
the Earth's magnetic field.
14:04
Now, the Earth's magnetic field
is very, very weak;
14:10
it's 100 times weaker
than a fridge magnet,
14:13
and yet it affects the chemistry --
somehow -- within a living organism.
14:15
That's not in doubt --
a German couple of ornithologists,
14:21
Wolfgang and Roswitha Wiltschko,
in the 1970s, confirmed that indeed,
14:25
the robin does find its way by somehow
sensing the Earth's magnetic field,
14:29
to give it directional information --
a built-in compass.
14:33
The puzzle, the mystery was:
How does it do it?
14:37
Well, the only theory in town --
14:40
we don't know if it's the correct theory,
but the only theory in town --
14:43
is that it does it via something
called quantum entanglement.
14:46
Inside the robin's retina --
14:50
I kid you not -- inside the robin's retina
is a protein called cryptochrome,
14:52
which is light-sensitive.
14:57
Within cryptochrome, a pair of electrons
are quantum-entangled.
14:58
Now, quantum entanglement
is when two particles are far apart,
15:02
and yet somehow remain
in contact with each other.
15:05
Even Einstein hated this idea;
15:08
he called it "spooky action
at a distance."
15:10
(Laughter)
15:12
So if Einstein doesn't like it,
then we can all be uncomfortable with it.
15:14
Two quantum-entangled electrons
within a single molecule
15:17
dance a delicate dance
15:20
that is very sensitive
to the direction the bird flies
15:22
in the Earth's magnetic field.
15:24
We don't know if it's
the correct explanation,
15:26
but wow, wouldn't it be exciting
if quantum mechanics helps birds navigate?
15:29
Quantum biology is still in it infancy.
15:34
It's still speculative.
15:37
But I believe it's built on solid science.
15:41
I also think that
in the coming decade or so,
15:45
we're going to start to see
that actually, it pervades life --
15:49
that life has evolved tricks
that utilize the quantum world.
15:54
Watch this space.
15:59
Thank you.
16:01
(Applause)
16:02

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About the Speaker:

Jim Al-Khalili - Quantum physicist
Physicist Jim Al-Khalili and co-author Johnjoe McFadden, a biologist, explore the far edges of quantum biology in their book "Life on the Edge."

Why you should listen
A professor of physics at the University of Surrey, Jim Al-Khalili doubles as a science communicator and broadcaster. He’s the co-author with Johnjoe McFadden of Life on the Edge: The Coming of Age of Quantum Biology. The book explores this emerging -- and still largely speculative -- area of science suggesting that quantum mechanics may play a role in biology. If so, it may help us understand what drives genetic mutations that lead to cancer, or how robins fly from Scandinavia to the Mediterranean.