| | Re: Why is putting a hand in the vacuum bad for us?
Your cells receive oxygen from the blood, it is a common misconception that humans need oxygen arounds their skin, for example in the James Bond movie Goldfinger, a small square of skin was left unpainted on the golden womans back so she would not suffocate..... People breathe through their lungs we are not frogs which do however breathe through their skin.
In a vacuum i reckon the severly reduced pressure would have some sort of adverse effect on your hand.
Temperature is related to how quickly particles are moving, the hotter temperature, the faster the particles. At absolute zero no particles are moving what so ever, i think in a vacuum the temperature would be absolute zero (0Kelvin , -273 C) i'm not sure about all the variables but this would kill all the cells in your hand.