Answer to Question #83151 in Molecular Physics | Thermodynamics for Lc

Question

Ch. 13.2 Thermal Expansion of Solids and Liquids

CQ 6:) Water expands significantly when it freezes: a volume increase of about 9% occurs. As a result of this expansion and because of the formation and growth of crystals as water freezes, anywhere from 10% to 30% of biological cells are burst when animal or plant material is frozen. Discuss the implications of this cell damage for the prospect of preserving human bodies by freezing so that they can be thawed at some future date when it is hoped that all diseases are curable.

Answer 1

The idea of preserving a person's body at very low temperatures in the hope that it will be restored by future medical technology has been a staple of science fiction.

If a person is cooled below -5 °C the water inside their cells freezes and creates ice crystals. As ice is less dense than liquid water, it takes up more space. So the crystals punch through the cell membranes causing severe damage.

Cryonic preservation facilities attempt to overcome this by employing a process known as vitrification. This replaces some of the body's water with cryoprotectant agents, in an attempt to reduce the amount of ice crystal formation.

As yet there is no proof that we can vitrify human organs. If scientists did one day work out how to successfully cryopreserve a whole human body, there is still the matter of bringing the body back to life.

There are other significant complications, such as the fact that cooling a body to -196 °C makes it incredibly brittle.

The brain, which has as many as 10,000 connections for each of the 100 billion neurones, is particularly sensitive to heating and cooling.