30
PHVSICS OF THE IMPOSSIBLE
nipulation of individual atoms. In fact, the letters "IBM" were spelled
out via individual atoms, creating quite a stir in the scientific world.
Scientists were no longer blind when manipulating individual atoms,
but could actually see and play with them.
The scanning tunneling microscope is deceptively simple. Like a
phonograph needle scanning a disk, a sharp probe is passed slowly
over the material to be analyzed. (The tip is so sharp that it consists of
only a single atom.) A small electrical charge is placed on the probe,
and a current flows from the probe, through the material, and to the
surface below. As the probe passes over an individual atom, the
amount of current flowing through the probe varies, and the variations
are recorded. The current rises and falls as the needle passes over an
atom, thereby tracing its outline in remarkable detail. After many
passes, by plotting the fluctuations in the current flows, one is able to
obtain beautiful pictures of the individual atoms making up a lattice.
(The scanning tunneling microscope is made possible by a strange
law of quantum physics. Normally electrons do not have enough energy to pass from the probe, through the substance, to the underlying
surface. But because of the uncertainty principle, there is a small probability that the electrons in the current will "tunnel" or penetrate
through the barrier, even though this is forbidden by Newtonian theory. Thus the current that flows through the probe is sensitive to tiny
quantum effects in the material. I will discuss the effects of the quantum theory later in more detail.)
The probe is also sensitive enough to move individual atoms
around, to create simple "machines" out of individual atoms. The technology is so advanced now that a cluster of atoms can be displayed on
a computer screen and then, by simply moving the cursor of the computer, the atoms can be moved around any way you want. You can manipulate scores of atoms at will as if playing with Lego blocks. Besides
spelling out the letters of the alphabet using individual atoms, one can
also create atomic toys, such as an abacus made out of individual
atoms. The atoms are arrayed on a surface, with vertical slots. Inside
these vertical slots one can insert carbon Buckyballs (shaped like a
soccer ball, but made of individual carbon atoms). These carbon balls
PHVSICS OF THE IMPOSSIBLE
nipulation of individual atoms. In fact, the letters "IBM" were spelled
out via individual atoms, creating quite a stir in the scientific world.
Scientists were no longer blind when manipulating individual atoms,
but could actually see and play with them.
The scanning tunneling microscope is deceptively simple. Like a
phonograph needle scanning a disk, a sharp probe is passed slowly
over the material to be analyzed. (The tip is so sharp that it consists of
only a single atom.) A small electrical charge is placed on the probe,
and a current flows from the probe, through the material, and to the
surface below. As the probe passes over an individual atom, the
amount of current flowing through the probe varies, and the variations
are recorded. The current rises and falls as the needle passes over an
atom, thereby tracing its outline in remarkable detail. After many
passes, by plotting the fluctuations in the current flows, one is able to
obtain beautiful pictures of the individual atoms making up a lattice.
(The scanning tunneling microscope is made possible by a strange
law of quantum physics. Normally electrons do not have enough energy to pass from the probe, through the substance, to the underlying
surface. But because of the uncertainty principle, there is a small probability that the electrons in the current will "tunnel" or penetrate
through the barrier, even though this is forbidden by Newtonian theory. Thus the current that flows through the probe is sensitive to tiny
quantum effects in the material. I will discuss the effects of the quantum theory later in more detail.)
The probe is also sensitive enough to move individual atoms
around, to create simple "machines" out of individual atoms. The technology is so advanced now that a cluster of atoms can be displayed on
a computer screen and then, by simply moving the cursor of the computer, the atoms can be moved around any way you want. You can manipulate scores of atoms at will as if playing with Lego blocks. Besides
spelling out the letters of the alphabet using individual atoms, one can
also create atomic toys, such as an abacus made out of individual
atoms. The atoms are arrayed on a surface, with vertical slots. Inside
these vertical slots one can insert carbon Buckyballs (shaped like a
soccer ball, but made of individual carbon atoms). These carbon balls