It’s that time of the year again: around October, the Nobel prize winners are announced,
and a few scientists around the world are specially honored for their discoveries.
Olivia talked about the Physiology or Medicine Prize last week, and now it’s Chemistry
and Physics’ turn.
This year’s Chemistry prize was shared between three researchers, who all used molecules
to make tiny machines.
Over billions of years of evolution, nature has come up with lots of molecular machines,
from whip-like flagella that help cells move, to enzymes that catalyze chemical reactions.
These researchers haven’t had that kind of time, but their microscopic tools could
still have a big impact on the future.
First up is the chemist Jean-Pierre Sauvage, who wanted to see if molecules could be mechanically
connected.
Normally, different molecules are connected by covalent chemical bonds between their atoms.
But Sauvage and his team used copper ions to coax molecules into interlocking like links
in a chain, which they call a catenane.
This new way of linking molecules could be used as part of a bigger microscopic machine,
like a switch or a motor.
The researchers even created a simple mechanical system, where adding a bit of energy made
one ring revolve around the other.
The second winner, J. Fraser Stoddart, synthesized two different molecules that can be links
together as one machine: axles and rings.
The axle was basically a rod with bulky ends and two middle bits packed full of electrons,
while the slightly-open ring didn’t have many electrons.
Opposites attract, so the electron-poor rings threaded onto the electron-rich rods when
they were mixed.
Then, the team sealed up the rings with a chemical reaction to mechanically lock them
onto the axles, creating these structures called rotaxanes.
By adding some heat, the team could shuttle the rings along the rods, and make tiny machines
that worked like elevators, muscles, and even computer chips.
Lastly, the third scientist, Ben Feringa, built a tiny molecular motor.
Free molecules are always getting jostled around, so they tend to spin left and right
randomly.
But Feringa’s team built a molecule out of two flat structures that locks together,
so when they added UV light and heat, it only spun in one direction.
The group’s first attempts in 1999 weren’t all that speedy, but by 2014 they had a molecular
motor that spun at 12 million revolutions per second.
They even built a nanocar with four motors for wheels, which zipped forward across a
surface!
So, all these basic machines are neat ways to make molecules spin and slide, but they’re
still just the beginning.
As scientists work to combine them, or build entirely new structures, who knows what microscopic
technologies we’ll be building the future?
Now, the Physics prize this year went to three theoretical physicists who are studying how
more extreme materials behave and change forms.
This involved lots of weird quantum phenomena, plus a branch of math called topology, which
looks at how objects can be arranged and manipulated.
Phase transitions describe how one state of matter becomes another, thanks to changing
conditions like temperature.
You’ve heard of things melting, boiling, freezing, and condensing… but there are
other kinds of phase transitions, too.
If a magnetic substance gets hot enough, for example, the magnetic orientations of the
atoms get all randomized, and its overall magnetism is disrupted.
Two of the Nobel prize winners, Michael Kosterlitz and David Thouless, studied phase transitions
in stuff that’s really cold, and really thin – just a few atoms thick.
Here, things start getting weird… because quantum!
Quantum effects can be hard to study, since they’re tiny and hard to pick out from all
the normal atomic wiggling.
But if you lower the temperature enough, there’s a lot less energy making the atoms move around,
and quantum effects can be seen throughout whole materials.
Take quantum vortices, which are basically whirlpools of angular momentum in materials
like superconductors and superfluids, giving them strange properties.
Turns out, quantum vortices also involved in an entirely new topological phase transition
discovered by these two physicists!
Near absolute zero, the quantum vortices in ultra-cold, ultra-thin superconductor materials
were arranged in pairs.
But with a little bit of heat, the vortices spread apart over the surface.
This shift is now called the Kosterlitz-Thouless transition, and it’s turned out to be important
in other fields of physics too.
Thouless and the final winner, Duncan Haldane, are both also using topology to pave the way
for a new kind of material: topological insulators.
In a conductor like copper metal, electrons flow through the entire material.
And in an insulator, like rubber, electrons can’t really flow at all.
A topological insulator acts like both at the same time, which we used to think was
impossible!
Most of the material is an insulator, but its surface can carry an electric current.
Nowadays, scientists are working to develop topological insulators, and some think they
could be as important for future technologies as semiconductors are today.
So this year’s Nobel Laureates have pioneered some important research into molecular machines
and topological materials, and it looks like there’s a lot more on the horizon!
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