Anna Damens, age 9, of Philadelphia, Pennsylvania, for her question:
What is the science of cryogenics?
If you were to cry over it, your salty tears just might freeze to solid ice. It so happens that the word cryogenics means "super cold", much colder than ordinary freezing cold. Ages ago we learned what high temperatures can do. A hot oven bakes bread, a super hot furnace makes steel. Cryogenics shows what very low temperatures can do. It is a rather new science, but already it has given us a few miracles.
lie tend to shudder on a frosty morning and chances are the word "freezing" makes us think of an ice cube. If we explain these everyday notions of coldness to a cryo¬genics scientist he might say, "Pooh!"
An ice cube is 32 degrees Fahrenheit. This is the temperature at which liquid water freezes solid. It is, says the expert in cryogenics, on the warmish side. In his lab, he aims to chill things down to a couple of hundred degrees below zero and even colder.
One of the coldest everyday things we come across is dry ice. Actually it is carbon dioxide gas, chilled a bit colder than minus 109 degrees Fahrenheit. Its solid crystals burn bare flesh, somewhat like a red hot poker.
A cryogenics scientist thinks that dry ice is coolish, but not nearly as chilly as his sort of super coldness. One of his favorite items is liquid air. He creates it by chilling ordinary gaseous air way down to about minus 318 degrees Fahrenheit. At this super cold temperature, air becomes a pale blue watery liquid. Beware, it can swiftly freeze a finger beyond repair:
When liquid air is left in a warmish room, it boils and changes back into gases. Some of its gases boil sooner than others. This is how the science of cryogenics made it possible to separate different gases from the air. It also chilled liquid oxygen to make fuel for our space ships.
When nitrogen gas is chilled a little colder than minus 320 degrees, it becomes a liquid. And liquid nitrogen can quick freeze living cells without harming them. When warmed, they start living again. This idea belongs in a newer than new branch of cryogenics. It is called cryobiology. Experts in this science, study what low low temperatures do to living cells. They also use super coldness to preserve living tissues.
Maybe you have heard a chilly story about freezing human bodies for the future. At present, cryobiology scientists are not ready to perform such miracles. However, they can freeze whole blood, skin and body organs for future emergencies. Cryogenic skills also axe used in surgery. Sometimes a touch of super coldness is used to remove decayed or damaged cells from the healthy tissue around a wound.