NANOTECHNOLOGY—TECHNOLOGY ON A MOLECULAR SCALE - Chemistry: Notable Research and Discoveries - page 37

a human being, waiting for the proper moment to pop out and start
growing. Leeuwenhoek referred to it as a little man.
Th e little man, or homunculus, as it was sometimes called, was
imaginative, of course—the mind sometimes creates such illusions
when examining an object too small or fuzzy to be clearly seen. Th e
notion that the microscopic world consisted of familiar objects reduced
to a small scale was also incorrect. As scientists probed the nature of
particles, they realized that the behavior of small objects does not neces-
sarily mimic larger ones. Th is discovery opened up new vistas in science
as well as technology, including the subject of this chapter—technology
on the scale of atoms and molecules.
InTroduCTIon
People have been thinking about tiny objects for a long time. Th e an-
cient Greek philosopher Democritus (ca. 460-370 b.c.e.) believed that
properties of matter depended on the shapes of small, indivisible bits of
matter called atoms. Although this idea failed to catch on at the time—
no one could see these atoms because they were so small—in 1803, the
British chemist John Dalton (1766-1844) proposed a similar theory.
Dalton's theory was an important advance and helped scientists under-
stand chemical reactions—for example, the reaction of two atoms of
hydrogen (H) and one atom of oxygen (O) to form H 2 O—but atoms
themselves remained cloaked in mystery.
Th e Scottish physicist James Clerk Maxwell (1831-79) imagined in
1867 a little being that was small enough to see and manipulate mol-
ecules. Maxwell used his imaginative creation to think and hypothe-
size about the laws of thermodynamics —a branch of physics that deals
with heat and the motion of molecules—but the fi ctional creature, later
known as Maxwell's demon, also encouraged people to think about how
to control or manipulate atoms, which was an exciting prospect. Peo-
ple began developing processes that involved small particles, although
in an indirect manner. Chemists set up reactions with specifi c atoms
and molecules, but of course these reactions involved matter in bulk
quantities.
An early application of small quantities of matter occurred in pho-
tography. A thin fi lm or glass plate, when coated with tiny particles of