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PHYSICS OF THE IMPOSSIBLE
centuries to reach nearby stars. Such a mission would need to involve
a multigenerational crew whose descendants would arrive at the final
destination.
One solution, proposed in such movies as Alien and Planet of the
Apes, is for space travelers to undergo suspended animation; that is,
their body temperature would be carefully lowered until bodily functions almost cease. Animals that hibernate do this every year during
the winter. Certain fish and frogs can be frozen solid in a block of ice
and yet thaw out when the temperature rises.
Biologists who have studied this curious phenomenon believe that
these animals have the ability to create a natural "antifreeze" that lowers the freezing point of water. This natural antifreeze consists of certain proteins in fish, and glucose in frogs. By flooding their blood with
these proteins, fish can survive in the Arctic at about -2°C. Frogs have
evolved the ability to maintain high glucose levels, thereby preventing
the formation of ice crystals. Although their bodies might be frozen
solid on the outside, they are not frozen on the inside, allowing their
bodily organs to continue to operate, albeit at a reduced rate.
There are problems with adapting this ability to mammals, however. When human tissue is frozen, ice crystals begin to form inside the
cells. As these ice crystals grow, they can penetrate and destroy cell
walls. (Celebrities who want to have their heads and bodies frozen in
liquid nitrogen after death may want to think twice.)
Nevertheless, there has been recent progress in limited suspended
animation in mammals that do not naturally hibernate, such as mice
and dogs. In 2005 scientists at the University of Pittsburgh were able to
bring dogs back to life after their blood had been drained and replaced
by a special ice-cold solution. Clinically dead for three hours, the dogs
were brought back to life after their hearts were restarted. (Although
most of the dogs were healthy after this procedure, a few suffered some
brain damage.)
That same year scientists were able to place mice in a chamber
containing hydrogen sulfide and successfully reduce their body temperature to 13°C for six hours. The metabolism rate of the mice
dropped by a factor of ten. In 2006 doctors at Massachusetts General
PHYSICS OF THE IMPOSSIBLE
centuries to reach nearby stars. Such a mission would need to involve
a multigenerational crew whose descendants would arrive at the final
destination.
One solution, proposed in such movies as Alien and Planet of the
Apes, is for space travelers to undergo suspended animation; that is,
their body temperature would be carefully lowered until bodily functions almost cease. Animals that hibernate do this every year during
the winter. Certain fish and frogs can be frozen solid in a block of ice
and yet thaw out when the temperature rises.
Biologists who have studied this curious phenomenon believe that
these animals have the ability to create a natural "antifreeze" that lowers the freezing point of water. This natural antifreeze consists of certain proteins in fish, and glucose in frogs. By flooding their blood with
these proteins, fish can survive in the Arctic at about -2°C. Frogs have
evolved the ability to maintain high glucose levels, thereby preventing
the formation of ice crystals. Although their bodies might be frozen
solid on the outside, they are not frozen on the inside, allowing their
bodily organs to continue to operate, albeit at a reduced rate.
There are problems with adapting this ability to mammals, however. When human tissue is frozen, ice crystals begin to form inside the
cells. As these ice crystals grow, they can penetrate and destroy cell
walls. (Celebrities who want to have their heads and bodies frozen in
liquid nitrogen after death may want to think twice.)
Nevertheless, there has been recent progress in limited suspended
animation in mammals that do not naturally hibernate, such as mice
and dogs. In 2005 scientists at the University of Pittsburgh were able to
bring dogs back to life after their blood had been drained and replaced
by a special ice-cold solution. Clinically dead for three hours, the dogs
were brought back to life after their hearts were restarted. (Although
most of the dogs were healthy after this procedure, a few suffered some
brain damage.)
That same year scientists were able to place mice in a chamber
containing hydrogen sulfide and successfully reduce their body temperature to 13°C for six hours. The metabolism rate of the mice
dropped by a factor of ten. In 2006 doctors at Massachusetts General