I was told that a person would vaporize if exposed to 0psia such as in space without protection, such as a spacesuit. But how, specifically, does a spacesuit provide pressure to prevent this?
Also, what is physically happening at 0psia? Is it only true for the liquids within our cells?
Stupid question, I guess, because the need for a spacesuit is accepted by the layman as standard equipment. But what physically happens at 0psia has always bugged me… - Jinx 
VAPORIZE!! Seriously, who told you that? Human bodies (any animal) are pretty sturdy, and 1 atmosphere of pressure isn’t that much.
As I understand it, largely the function of air pressure is to provide something to breathe. Also, our eyes would quickly dry out if we had them open in a vacuum, which would be very bad for the cornea.
this link seems to have some interesting information, or at least educated guesses: Explosive Decompression and Vacuum Exposure
Interesting that breathing from a tube would be apparently unwise or impossible in a vacuum… something about lung rupture??
Ah ! I see what you’re talking about: zero pounds per square inch a[something] - I thought Opsia was a place 
Furthermore, there is no reason why said astronaut MUST be at 1 atm when exposed to vacuum. Typically, the space capsule is at minimum pressure to supply sufficient oxygen, maybe less than 5 psi and possibly as low as 2.5 psi. We’re easily sturdy enough to handle that. The biggest problem is the lung avioli which can rupture as low as 2psi differential, leading to a quick death by embolism.
For more reading:
Damn Interesting had an article on this topic not too long ago.
Also, one of my favorite short stories is the near-futuristic “The Vacuum-Breathers Club” by Arthur C. Clarke. The only requirement for membership is to go without spacesuit in space. The club founder was the subject of a space station rescue where a spacesuit was not available. Clarke, in his usual way, goes into some technical description of how it’s not immediately lethal.
The Master speaks:
If you were thrown into the vacuum of space with no space suit, would you explode?
I once saw a spacesuit design that looked more like long underwear than a conventional space suit. It was not air-tight. It provided mechanical pressure via the elasticity of the porous fabric. See space activity suit.
This is strictly for short-term use, I hope.
The article mentions passive cooling by allowing sweat to pass through the fabric. With the temperature extremes you meet in space (with ranges in the triple digits fahrenheit), I’d be concerned about regulating temperature using just a the human body (which is accustomed to cooling down a body by only about 20-30 degrees F before completely freaking out.) Also, you’d need some kind of active heating system to prevent said sweat from freezing and binding up the joints. If you’re going to go through the effort of actively heating a suit, then why not include an active cooling system?
I’m also a little concerned about the assertion that the spacesuit works because skin is basically airtight. While this may be true in an atmosphere, and to a smaller degree when augmented by mechanical pressure in space, skin will allow fluids to pass. And pass and pass and pass. I’d worry a lot about dessicating my hide for the convenience of a skintight spacesuit.
Then again, with leather for skin, maybe you’d be more resitant to the melanomas that would result from the increased UV exposure…
I love how 2001: A Space Odyssey can almost be used for scientific cites.
Carry on.
IIRC, and my only cite here is a copy of Boys Life I remember reading in 1993 or so, most of the bulk of a space suit is cooling equipment to keep the wearer from dying of heat stroke. Ditto for much of the internals of the space shuttle, designed to keep everything cool enough to work properly in the blistering heat of space.
The main problem with keeping everything cooled in a vacuum is that the two easiest methods of transfering heat, conduction and convection, are not practically possible in space (though a lifeline could probably be designed to facilitate either or both method, and I wouldn’t be suprised if the ones used by NASA already do this). Thus, the only way you have to get heat away from the space suit (or vehicle, or whatever) is radiation, which doesn’t work nearly as well as the first two methods. So you have lots of layers of stuff designed to move heat around and away from the body of the wearer, as well as numerous layers of stuff designed to actively keep him WARM (cause space, while being blisteringly hot, is also ass-chapping cold, depending on where you’re standing).
On top of all the body heat you’re producing, if you’re not in the shade, you’re also standing in front of the world’s largest microwave oven without the protection of Earth’s atmosphere.
Also, I know that you can survive a space walk without a suit because, as Red Barchetta said, Arthur C. Clarke totally said so in “A Space Odessy” (and “Oddessy Two”, but that’s not important)
Pressure is commonly measured as either “gauge” pressure: the pressure above the current surrounding environment, or “absolute” pressure: the pressure above a perfect vacuum.
When measuring in pounds per square inch, these two are abbreviated as psig or psia.
So 0 psia would be, in theory at least, a perfect vacuum. 0 psig just means there is no extra pressure above the environment.
My high school advanced chemistry teacher told us this. Apparently, air rpessure plays a role in keeping our atoms where we want them despite Brownian motion, for one. To be precise, she said one would boil at 0psia. Not sure is a minimum of 1psia is a threshold at which boiling would begin.
This would be indubitably true if we were droplets of water. Since we have quite a bit of solid mass, and since solids appear to stay solid at 0psia, I don’t think this reasoning works.
I understand it’s also the largest microwave oven in the solar system. Guiness is probably late in updating their book. 
I don’t doubt that it’s the largest one in the Solar System, but dammit, it’s OURS. 
Was that Opsia High or Opsia Prep?
Because it’s filled with air like a tire (less than sea-level pressure IIRC otherwise it would be too stiff to move). The suit (and the tire) are strong enough to resist the stresses caused by the difference in pressure.
Your teacher is talking about vapor pressure, and not very well. The boiling point of water (or any liquid) is not constant. It depends on pressure (pv=nRT). The lower the air pressure, the lower the boiling point. For example, mountain-climbers have a harder time cooking at higher elevation because the water boils at a lower temp.
Your blood and other fluids, however are in your circulatory system, surrounded by skin and muscle and whatnot. It’s pretty sturdy stuff
Arthur C. Clarke liked the idea of people going out into space without any suits. He used it in The Other Side of the Sky and Earthlight, both written in the 1950s. He used it in 2001: A Space Odyssey, of course (as noted above), and it showed up again as a suggestion in The Fountains of Paradise.
Knowing he would catch flak over this when 2001 was released, he wrote a defense of the practice, citing work by NASA. IIRC, it’s reprinted in his anthology The View from Serendip.
Of course, other writers and filmmakers screw it up. I can understand the filmmakers – they’re looking for a snazzy special effect. So people Blow Up Good in Outland, License to Kill and Total Recall. Don’t take it seriously.
They alsi explode in vacuum in Pierre Boulle’s Garden on the Moon and in Martin Caidin’s Four Came Back. Caidin, who’d been a pilot, shoulda known better.
Other SF writers, although they don’t generally send people out into space suitless. still sent them out in suits that don’t have much to them. Heinlein did this at the end of Have Space Suit, Will Travel, Dan Simmons does it in one of the Endymion novels, and I’ve read other examples. Heck, Larry Niven has Brennan taken out into space in Protector in just an inflated plastic bag.
One of the Star Trek books, Federation, features a sequence where Data, Picard, Wesley Crusher, and I think LaForge end up inside a shuttle inside of a depressurized shuttlebay, and they have to make their way from the shuttle to the hatch to the interior of the ship. The only one of them who suffered any injury for the effort (Wesley, IIRC), was Wesley, who tried to hold his breath and ended up with a hella nasty sore throat. As we all know, if it’s in a Star Trek book, it’s solid hard truth. 
When you get to about 55,000 feet, your blood will boil. Sorta. the point is that we need positive air pressure in our lungs to prevent that. I suppose you could hold your breath and squeeze and you might last a bit but …