Worlds of David Darling > Children's
Encyclopedia of Science > Nanotechnology > 4. How Small Can You Get?
MICROMACHINES AND NANOTECHNOLOGY:
The Amazing New World of the Ultrasmall
a book in the Beyond 2000 series by David Darling
4. How Small Can You Get?
Take a grain of sugar and break it in half. Now take one of these smaller
grains and break it in half again. Suppose you have the means to keep on
splitting the bits of sugar exactly two, again and again, even after they
are much too tiny to be seen. Eventually you will reach a limit. You will
end up with a fragment of sugar so small that if you divide it just one
more time it will no longer be sugar. This smallest possible piece of sugar
is called a molecules.
|Atoms and molecules
Most natural and human-made substances are made of molecules. Molecules,
in turn, are built of even smaller particles called atoms. One molecule
of household sugar (sucrose) consists of 12 atoms of carbon, 22 atoms of
hydrogen, and 11 atoms of oxygen, joined together. A simpler molecule, such
as that of water, contains just 2 atoms of hydrogen and 1 of oxygen.
Some substances, such as the precious metal gold and the lightweight gas
helium, consist of atoms that are not linked together to make molecules.
So, with the right equipment, you could pluck a single atom of gold out
of a gold ring or a single atom of helium out of a helium-filled balloon.
Sizing Up Atoms
It is very hard to visualize how small atoms really are. Ten million of
them placed in a line would fit across the period at the end of this sentence.
Put another way, if everything in the world were blown up in size so that
a single atom were as big as this period, then the smallest letters on this
page would be about 50 miles high!
Even the smallest of ordinary things is made up of unimaginably huge numbers
of atoms. A single pin, for instance, contains roughly a million times as
many atoms as there human beings on Earth.
An ordinary hand-held machine, such as a hair dryer, contains about as many
atoms as there are grains of sand on all the world's beaches. When a machine
like this is built, no one knows or cares where each individual atom inside
is located. It might seem beyond belief that people could eventually learn
how to build anything one atom at a time.
Nature's Building Blocks
Atoms are incredibly small, but we know without a doubt that it is possible
to put them together, one by one, in a very orderly way. We know this because
nature does it all the time. The perfectly flat sides and regular shapes
of crystals are due to the precise arrangement of atoms inside the crystals.
As a crystal forms, individual atoms add on to the growing structure like
people sitting down, one at a time, from front to back, on the neat rows
of evenly spaced seats in a theater.
|The flat faces of this crystal
of quartz are caused by the atoms inside being lined up in a regular
The same orderly growth of structures takes place within living things.
A human being is not a confused heap of atoms and molecules. As a baby grows,
it does so according to a definite pattern. Like all the different kinds
of animals and plants, a human being assembles itself in an organized way
from individual atoms and molecules.
If our bodies can control their growth at the atomic and molecular level,
then perhaps scientists and engineers can learn to do the trick by artificial
means. This suggestion was first made by the brilliant American scientist
Richard Feynman, in a speech in 1959. Feynman said: "Consider the final
question as to whether, ultimately – in the great future – we
can arrange atoms the way we want: the very atoms, all the way
down! What would happen if we could arrange atoms one by one, the way we
Nanotechnology Is Born
If we could find a way to put atoms together, one at a time, exactly as
wanted, we could build almost anything at all. We could make a robot spacecraft
that was smaller than a pollen grain. We could mass-produce a billion of
these tiny explorers and scatter them throughout space, just as real pollen
is blown about on the wind. In the remote future, marvelous things like
these may be possible. But first, researchers will have to become experts
at working with atoms.
Some years after Richard Feynman made his speech about building with atoms,
the author Eric Drexler coined the name nanotechnology. People
have been familiar for a long time with words beginning with MICRO. There
are microscopes, microbes (tiny living things), and microchips,
to name a few. Micro comes from the ancient Greek micros,
which means "small." In science, micro also stands for 1-millionth.
A micrometer, for instance, is 1-millionth of a meter.
For defining even smaller measurements, scientists use the prefix nano.
This comes from the Greek nanos, meaning "dwarf." A NANOMETER is
a thousand times smaller than a micrometer, or 1-billionth of a meter.
Because micro was a term already used to refer to anything microscopic,
nano is a good name to describe the possibility of working at even
smaller scales. Nanotechnology, then, is the technique of building machines
and other structures from individual atoms and molecules.
|Inside the Atom
Given enough energy, atoms themselves can be split apart into even
smaller particles. At the center of an atom is the nucleus –
a cluster of particles made up of protons and neutrons. The proton
has a single positive charge, while the neutron is electrically neutral.
Around the nucleus is a cloud of even smaller particles, called electrons,
each of which has a negative charge that is equal in size and opposite
in sign to the charge on the proton. Because, in every atom, the number
of protons is the same as the number of electrons, atoms have no overall
Electrons are believed to be pointlike specks of matter that cannot
be broken apart any further. Protons and neutrons, however, are each
thought to be a kind of bag containing three smaller particles known
Scientists are now learning how to control the movements of individual
electrons or small groups of electrons. This knowledge may eventually
allow them to create new kinds of computer memories capable of storing
fantastic amounts of information. For the purposes of nanotechnology,
however, the smallest possible building blocks wil be atoms and molecules.