Here’s my entry, from David Lewis’ “Void and Object”:
The void is deadly. If you were cast into a void, it would cause you to die in just a few minutes. It would suck the air from your lungs. It would boil your blood. It would drain the warmth from your body. And it would inflate enclosures in your body until they burst.
What I’ve said is literally true, yet it may be misleading. When the void sucks away the air, it does not exert an attractive force on the air. It is not like a magnet sucking up iron fillings. Rather, the air molecules collide and exert repulsive forces on one another; these forces constitute a pressure that, if unresisted, causes the air to expand and disperse; the void exerts no force to resist the pressure; and that is why the air departs from the lungs.
Likewise, when the void boils the blood, there is no flow of energy from the void into the blood. It isn’t like a stove boiling a kettle of water. The blood is already warm enough to boil, if its vapor pressure is unresisted; the void exerts no counter pressure; and so the boiling goes unprevented.
Likewise, when the void drains your warmth, what happens is that your thermal energy, left to itself, tends to dissipate; and the void exerts no counterpressure. So nothing prevents the outward pressure from doing damage.
In short, you are kept alive by forces and flows of energy that come from the objects that surround you. If, instead of objects, you were surrounded by a void, these life-sustaining forces and flows would cease. Without them, you would soon die. That is how the void causes death. It is deadly not because it exerts forces and supplies energy, but because it doesn’t (“Void and Object”).