Quantum biology
Quantum biology.
Quantum biology is still a speculative science, but is very exciting, and growing very rapidly.
It addresses a very simple question.
Does quantum mechanics, the weird and powerful theory of the subatomic world of atoms,
and molecules, that underpins so much of modern physics and chemistry,
also play a role inside the living cell?
Are there processes, mechanisms, phenomena in living organisms,
that can be explained only by quantum mechanics?
Quantum biology has been there since 1930’s.
It is only in the last decade, that experiments in biochemistry labs, using spectroscopy,
has shown very clear and firm evidence, that there are certain specific mechanisms,
that require quantum mechanics to explain it.
Quantum biology, brings together quantum physicists, biochemists and molecular biologists.
It is a very interdisciplinary field.
One of the founders of quantum mechanics, Neil Bohr said, if you are not astonished by it,
then you haven’t understood it.
Nano technology operates on the scale of nano meters.
A nano meter is one billionth of a meter.
Biologists use the ball and stick model of molecules.
The balls are the atoms, the sticks are the balls between the atoms.
Nowadays, very powerful computers can simulate a huge molecule,
like a protein which could have 100,000 atoms.
It does not require quantum mechanics to explain it.
Quantum mechanics was developed in the 1920’s.
It is a set of beautiful and powerful mathematical rules and ideas,
that explain the nano world.
It is a world that is very different from our everyday world, made up of trillions of atoms.
It is a world built on probability and chance.
It is a fuzzy world, where particles also behave like spread out waves.
Quantum mechanics or quantum physics, is a fundamental foundation of reality.
We can say that quantum physics underpins organic chemistry.
It gives us the rules that tell us, how the atoms fit together to make organic molecules.
Organic chemistry, scaled up in complexity, gives us molecular biology,
which leads to life itself.
Life ultimately must depend on quantum mechanics, like everything else.
Ultimately there is a quantum level, where we have to delve into this weirdness.
In everyday life we can forget about it.
Because once you put together trillions of atoms, the quantum weirdness just dissolves away.
Quantum biology isn’t about this.
Quantum biology is about looking for the non-trivial,
counterintuitive ideas in quantum mechanics, to see if they play an important role,
in describing the processes of life.
We can look at an example of the counter intuitiveness of the quantum world,
of a quantum skier.
He seems to go around both sides of a tree at the same time.
In the quantum world this happens all the time.
Particles can multitask.
They can be in two places at once.
They can do more than one thing at the same time.
Particles can behave like spread out waves.
It is almost like magic.
Scientists for nearly a century are trying to get used to this weirdness.
The weirdness of quantum mechanics is very delicate.
Scientists cool down there systems, to near absolute zero,
in their labs to carryout experiments, in vacuums,
and try to isolate it from any external disturbance .
That’s very different from the warm, messy environment of a living cell.
Molecular biology has done very well in describing the process of life,
in terms of chemical reactions.
It shows that life is made up of the same stuff like everything else.
If we can forget about quantum mechanics in the macro world,
you should be able to forget about it in biology as well.
The Austrian scientist, Erwin Schrodinger who was one of the founders of quantum mechanics,
had a different view.
In 1944, he wrote a book called ‘What is life?’.
It was tremendously influential, and it influenced Francis Crick and James Watson,
the discoverers of the double helix structure of DNA.
He says at the molecular level, living organisms have a certain order,
a structure to then many different from the random thermodynamic jostling of atoms and
molecules in inanimate matter of the same complexity.
In fact living matter seems to behave in this order, in a structure,
just like inanimate matter cool down to near absolute zero,
where quantum effects play a very important role.
There is something very special about the structure, the order, inside a living cell.
Schrodinger speculated that, may be quantum mechanics plays a role in life.
Recent experiment are showing that there are certain phenomena in biology,
do seem to require quantum mechanics.
One of the best known phenomena in the quantum world, is quantum tunnelling.
A particle like a electron is a wave, that has certain probability,
of being able to permeate through a solid wall, like a phantom.
Quantum tunnelling suggests that a particle can hit an impenetrable barrier,
and yet as though by magic, disappear from one side and reappear on the other side.
Quantum tunnelling takes place all the time.
In fact it is the reason the Sun shines.
The particles fuse together, and the Sun turns hydrogen into helium,
through quantum tunnelling.
Quantum tunnelling also takes place inside living cells.
Enzymes are bio molecules that speed up chemical reactions in living cells,
by many, many orders of magnitude.
It is always being a mystery how they do this.
It was discovered that one of the tricks that enzymes has evolved to make use of,
is by transferring subatomic particles, like electrons and protons,
from one part of a molecule to another via quantum tunnelling.
A proton can disappear from one place, and reappear on the other.
Enzymes help this to take place.
Scientists are researching whether quantum tunnelling plays a role in mutations in DNA.
Two strands of DNA, in the double helix structure, are held together by rungs.
It is like a twisted ladder.
The rungs of the ladder are hydrogen balls, protons,
that act as the glue between the two rungs.
They hold together the large molecules, the nucleotides together.
The bond is a double hydrogen bond.
One prefers to sit on one side, the other on the other side of the two strands.
It can happen that these two protons can hop over.
If the two strands of DNA separate, leading to the process of replication,
and the two protons are in the wrong position, it can lead to a mutation.
The question is how likely are they to do that, and if they do, how do they do it.
Can they quantum tunnel across, even if they do not have enough energy?.
Early indications suggest that quantum tunnelling can play a role here.
We do not know for sure, it is still speculative.
If quantum mechanics play a role in mutations, it will have big implications.
It will help us understand certain type of mutations,
possibly even those that lead to turning a cell cancerous.
Another example of quantum mechanics in biology is quantum coherence.
One of the most important processes in biology, is photosynthesis,
where plants and bacteria takes sunlight, and use that energy to create biomass.
Quantum coherence is the idea of quantum entities multitasking.
An object behaves like a wave.
It does not just move in one direction or the other,
but can follow multiple pathways at the same time.
Scientist have published experimental evidence,
that quantum coherence takes place inside bacteria, carrying out photosynthesis.
The idea is that the photon, particle of light in sunlight,
the quantum of light captured by a chlorophyll molecule,
is then delivered to what’s called the reaction centre,
where it can be turned into chemical energy.
In getting there it does not just follow one route.
It follows multiple pathways at once,
to optimise the most efficient way of reaching the reaction centre,
without dissipating as waste heat.
This is quantum coherence taking place inside a living cell.
More and more evidence is coming out, confirming that this does indeed takes place.
The European robin migrates from Scandinavia, down to the Mediterranean, every autumn.
Like a lot of other marine animals, and even insects,
navigate by sensing the Earth’s magnetic field.
The Earth’s magnetic field is very, very weak.
It is 100 times weaker than a fridge magnet.
Yet it somehow affects the chemistry within a living organism.
Scientists have confirmed that the robin somehow uses the Earth’s magnetic field,
like a compass, to give it directional information.
The puzzle is, how does it do it?.
One theory is, it does it via quantum entanglement inside the robin’s retina.
Inside the robin’s retina there is a protein called cryptochrome, which is light sensitive.
Within the cryptochrome, a pair of electrons are quantum entangled.
Quantum entanglement are when two particles are far apart,
and yet somehow remain in contact with each other.
Even Einstein called it ’spooky action at a distance’.
Two quantum entangled electrons within a single molecule, dance a delicate dance,
that is very sensitive to the direction the bird flies in the Earth’s magnetic field.
Quantum biology is still in infancy.
It is still speculative.
In the coming years, we may start to see, that it actually pervades all of life.