20
PHYSICS OF THE IMPOSSIBLE
alcohol, ammonia, acetone, hydrogen peroxide, gasoline, and so forth
are all transparent, as are gases such as oxygen, hydrogen, nitrogen,
carbon dioxide, methane, and so on.
There are some important exceptions to this rule. Many crystals
are both solid and transparent. But the atoms of a crystal are arranged
in a precise lattice structure, stacked in regular rows, with regular
spacing between them. Hence there are many pathways that a light
beam may take through a crystalline lattice. Therefore, although a
crystal is as tightly packed as any solid, light can still work its way
through the crystal.
Under certain circumstances, a solid object may become transparent if the atoms are arranged randomly. This can be done by heating
certain materials to a high temperature and then rapidly cooling them.
Glass, for example, is a solid with many properties of a liquid because
of the random arrangement of its atoms. Certain candies can become
transparent via this method as well.
Clearly, invisibility is a property that arises at the atomic level, via
Maxwell's equations, and hence would be exceedingly difficult, if not
impossible, to duplicate using ordinary means. To make Harry Potter
invisible, one would have to liquefy him, boil him to create steam, crystallize him, heat him again, and then cool him, all of which would be
quite difficult to accomplish, even for a wizard.
The military, unable to create invisible airplanes, has tried to do
the next best thing: create stealth technology, which renders airplanes
invisible to radar. Stealth technology relies on Maxwell's equations to
create a series of tricks. A stealth fighter jet is perfectly visible to the
human eye, but its radar image on an enemy radar screen is only the
size of a large bird. (Stealth technology is actually a hodgepodge of
tricks. By changing the materials within the jet fighter, reducing its
steel content and using plastics and resins instead, changing the angles of its fuselage, rearranging its exhaust pipes, and so on, one can
make enemy radar beams hitting the craft disperse in all directions, so
they never get back to the enemy radar screen. Even with stealth technology, a jet fighter is not totally invisible; rather, it has deflected and
dispersed as much radar as is technically possible.)
PHYSICS OF THE IMPOSSIBLE
alcohol, ammonia, acetone, hydrogen peroxide, gasoline, and so forth
are all transparent, as are gases such as oxygen, hydrogen, nitrogen,
carbon dioxide, methane, and so on.
There are some important exceptions to this rule. Many crystals
are both solid and transparent. But the atoms of a crystal are arranged
in a precise lattice structure, stacked in regular rows, with regular
spacing between them. Hence there are many pathways that a light
beam may take through a crystalline lattice. Therefore, although a
crystal is as tightly packed as any solid, light can still work its way
through the crystal.
Under certain circumstances, a solid object may become transparent if the atoms are arranged randomly. This can be done by heating
certain materials to a high temperature and then rapidly cooling them.
Glass, for example, is a solid with many properties of a liquid because
of the random arrangement of its atoms. Certain candies can become
transparent via this method as well.
Clearly, invisibility is a property that arises at the atomic level, via
Maxwell's equations, and hence would be exceedingly difficult, if not
impossible, to duplicate using ordinary means. To make Harry Potter
invisible, one would have to liquefy him, boil him to create steam, crystallize him, heat him again, and then cool him, all of which would be
quite difficult to accomplish, even for a wizard.
The military, unable to create invisible airplanes, has tried to do
the next best thing: create stealth technology, which renders airplanes
invisible to radar. Stealth technology relies on Maxwell's equations to
create a series of tricks. A stealth fighter jet is perfectly visible to the
human eye, but its radar image on an enemy radar screen is only the
size of a large bird. (Stealth technology is actually a hodgepodge of
tricks. By changing the materials within the jet fighter, reducing its
steel content and using plastics and resins instead, changing the angles of its fuselage, rearranging its exhaust pipes, and so on, one can
make enemy radar beams hitting the craft disperse in all directions, so
they never get back to the enemy radar screen. Even with stealth technology, a jet fighter is not totally invisible; rather, it has deflected and
dispersed as much radar as is technically possible.)