Topic 5: Cryogenics
The word "cryogenics" has a futuristic feel to many people because science fiction movies sometimes show deep-frozen human bodies, which are later brought back to life -- but that's not really what cryogenics is about. "Cryogenics" simply describes any kind of technology that requires extremely low temperatures. You might be surprised at how many modern technologies require such extreme cold: the flash freezing of vegetables, high-temperature superconductors in cell phone towers, MRIs and storage of liquefied natural gas for energy -- just to name a few.
The coldest temperature ever recorded on Earth was -128.6 F (-89 C) 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 [link to states of matter activity], 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.
Additional liquid nitrogen hands on activities:
More information on cryogenics
- Topic 1: Measuring the Cold - Thermometers
- Topic 2: Understanding Heat and Energy
- Topic 3: States of Matter
- Topic 4: Refrigeration
- Topic 5: Cryogenics
- Topic 6: The Quest for Absolute Zero
- Topic 7: How Animals Survive the Cold
- Topic 8: Superconductivity
- Topic 9: Astronomy
- Topic 10: Spaceflight
- Topic 11: Agriculture
- Topic 12: Cold Medicine