Suppose that the Space Shuttle had a “window” that allowed me to stick my arm out while in orbit. This window would be specially made so that the difference in pressure between the shuttle and space would not cause me to be pushed through the opening. Kind of like the force field that they used on Star Trek: The Next Generation when launching shuttle craft.
What physical effects would my arm experience?
Hmmm. Serious swelling for one; while exposure to vacuum won’t make you explode, having part of your body at normal pressure and an arm at zero pressure will cause blood and such to be pushed into your arm by the pressure. The skin would dry right out as the water on it’s surface sublimes. At some point I’d expect internal bleeding in the arm; even long term exposure to the kind of low pressure found in high mountains can do that.
Forced into your arm? I’d think that the rapidly expanding gas (formerly dissolved in the blood) would force everything out of the arm, similar to a shaken bottle of pop being opened.
An enormous hickey would form on your arm.
You’d get massive radiation burns if your arm was in sunlight at all and bake at a lovely 225ºF. If it was in complete shade, your skin would start to freeze since it’d be at -243ºF.
May not be specific to your question ,but…
A link from NASA.
You’ll get a lot of damaging radiation, but I don’t know how fast that would go.
But that would take a LONG time, since the only way to lose heat in space is by radiating it away. (I’m not sure but it seems to me you might even overheat in space from your body temperature alone).
As long as blood is still pumping through the arm I doubt it would freeze; as said in vacuum without anything to conduct heat it takes a long time for an object in shadow to get cold, and that assumes that the object isn’t self heating like a human body. How long the blood could keep circulating is the question.