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Precision was a hallmark of space exploration in the twentieth century.
Precise orbits, precise take-offs, precise landings.
Now, in the twenty-first century
a new kind of precision has enabled an exploration of a fundamentally different kind
Through the phenomenon of self-assembly, we can now design materials with atomic precision.
Materials that may revolutionize practically every technology on Earth
For example...
...the fuel tank.
The problem with fuel tanks today is that they can only store liquid fuels
such as gasoline (also called petrol).
Gaseous fuels like methane are much better for the environment
but because gas molecules tend to spread out as far as they can,
an ordinary fuel tank would contain very little fuel.
At standard pressure a tank of methane contains a little over one thousandth
the energy of a tank of gasoline. Enough to drive about one hundred meters.
If you were to look closely at the walls of the fuel tank containing methane...
...you would notice that the molecules are much less spread out.
This is because methane, like all gases, is attracted to surfaces.
This suggests a simple improvement to our tank design.
Simply extend the walls of the tank inward to increase the surface area,
the freshly exposed surface will attract new methane molecules,
which in turn will allow us to store more methane in our tank than before.
We can visualize the total amount of methane stored on the inner surface of our tank,
by laying out each molecule on an imaginary flat surface.
With our creative wall extension idea, a fifty litre (or twelve gallon) tank would have one square meter of methane stored on the surface.
Not bad, but perhaps we can do better!
A simpler, more effective idea is to simply fill our tank with sand!
Each grain of sand adds a small amount of surface area,
but millions of grains of sand can fit inside the tank.
This simple strategy results in one hundred square meters of internal surface area,
and a significant increase in the amount of stored methane.
Consider the self-assembled crystal "NU-100" designed at Northwestern University
by Omar K. Farha and colleagues.
Unlike sand, each crystal contains trillions of identical pores,
that allow methane to get *inside*
This multiplies the surface area available for methane storage.
Filled with a "NU-100" crystals we obtain in total surface...
... of 50,000,000 square meters! But do better materials exits?
To find a better material, let's examine "NU-100"
It is self-assembled from an organic chemical and metal copper atoms, which is why it's called a "metal-organic framework"
There are many organic chemicals and many metals.
For the small number of chemicals we are showing here, there are already 9,000 possible materials!
Which is the best one?
It would take a chemist many years to try all of these reactions.
Thankfully we don't actually have to make every material to find the best one.
We can computationally simulate them...
The enormous complexity of simulating methane gas,
interacting with trillions of self-assembled molecules,
can be reduced to the problem simulating the smallest repeating element.
We can predict how well the crystal stores methane,
by connecting it to an imaginary methane reservoir. We then fill the crystal with methane until,
the system has reached thermodynamic equilibrium.
Once equilibrium is reached, we generate thousands of random configurations of methane molecules,
each of which contributes to a statistical average of overall methane storage.
This is just one possible material...
...using supercomputers, we can simulate hundreds of thousands of materials simultaneously!
Each material is generated by computer algorithms, developed by Christopher E. Wilmer and peers,
and then simulated to obtain physical properties,
essentially performing millions of computational "experiments,"
in the time a chemist needs to make just one material!
The best materials out of the hundreds of thousands,
are identified by the supercomputer,
and it is left to us to create them in a lab.
We will rely on self-assembly,
so that we create these materials precisely,
with every atom,
in its place.