A cubic meter of space has very little heat energy, that's true, but it's more about having only a few molecules here and there in any cubic meter of space. Tha

A cubic meter of space has very little heat energy, that's true, but it's more about having only a few molecules here and there in any cubic meter of space. That leads directly to the problem though, that if there are no molecule to contact you and steal some kinetic energy and then leave, reducing your heat, the only option is to radiate it away. Radiating heat is exceptionally inefficient at rejecting heat from an object than using a material of some sort to sap away that heat with physical contact.