Topic 5 Cryogenics

 

Cryogenics" is a broad term that covers any kind of technology that requires extremely low temperatures. You might be surprised at how many modern technologies require such extreme cold: flash freezing vegetables, high-temperature superconductors in cell phone towers, MRIs, storing liquified natural gas for energy -- just to name a few. (Most of the hands-on activities throughout this section come under the rubric of “cryogenics” as it happens. . .)

The coldest temperature ever recorded on earth was 128.6I F (in Antarctica, measured in 1983), but cryogenics routinely requires temperatures hundreds of degrees below that. To get to temperatures so much colder than those of Mother Nature, these technologies rely on techniques learned over the last century to liquefy gases like hydrogen, helium, nitrogen, and oxygen. These are all things that are a gas at room temperature, but scientists like Heike Kamerlingh Onnes and James Dewar, learned in the late 1800s and the early 1900s how to change their state, and turn them into liquids -- which makes them much colder.

It is these liquids that are used to keep different technologies so mind-bogglingly cold. Liquid helium keeps the superconductors in MRIs cold. Liquid nitrogen is used to flash freeze food, as well as to store seeds and medical samples indefinitely. Liquid oxygen is much easier to store than the gaseous version, and is how hospitals store oxygen for their patients.

 

 

 Cold Bodies

Deep freezing is a great way to preserve something. Archaeologists have found incredible specimens of ancient animals and humans frozen into the ice -- the cold has maintained the integrity of the bodies for millennia. There are also many stories of people who fall into ice water for up to 30 minutes. The cold temperature slows down their bodies so much that instead of drowning, they can survive until rescued. (Don't try this at home!) It's easy to see why one might think you could harness the power of the cold to keep a body in suspended animation -- say, for a long trip to a far away planet, as is seen in sci-fi movies. Or maybe even freeze a dead body to keep it pristine in the hopes of one day bringing it back to life. There are certainly scientists who are trying to figure out how to do this, but the road ahead is unclear. The fact is that freezing human cells can dehydrate and destroy them beyond repair -- and no matter how well a body is preserved, no one has ever succeeded in bringing someone back to life from the dead.

Find some books, movies, Internet stories, or TV shows in which there are examples of humans being put into cryogenic suspension. Examine the stories closely – do they describe the futuristic mechanism for how the suspension works? Does the science make sense? What parts seem factual and what parts seem like science fiction?

 

See topic 13

Building in the Cold and Building materials  - for information on building in the cold.