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Hunter Parasite wrote:Is it true that, when a human goes into the vacuum of space, they will blow up because there is no air pressure holding them together. I just wanna know because me and my dad got into the argument after watching the scene in The Hitchhikers guide to the galaxy, where Arthur and Ford are thrown into space.

I think that your Bones and muscles and tendons and such will hold you together.

Well, you will look rather nasty after a very brief exposure to the vacuum.

The crucial aspect is the pressure /difference/ arising between /certain/ inner parts of your body and the outside vacuum.

Crucial parts will be your lungs that are essentially air-filled "vessels" at atmospheric pressure. Other parts in your head as well. So your chest will essentially explode due to 4-6 litres of air in the lungs. Hence, I am afraid you will become kind of a "suicide bomber"...

Bye Fridger

The way I understood it, a person wouldn't literally explode - they would rupture internally, swell up and freeze. And short term exposure (like the scene from 2001 A Space Odyssey where he blasts himself out of one airlock, across a few meters of open space and into another airlock and then shuts the door) can be survived with no long term health effects (unlike the famous scene from the movie Outland).

Below is a quote from the Bioastronautics Data Book, Second edition, NASA SP-3006 from the chapter on the effects of Barometric pressure.

"Some degree of consciousness will probably be retained for 9 to 11 seconds (see chapter 2 under Hypoxia). In rapid sequence thereafter, paralysis will be followed by generalized convulsions and paralysis once again. During this time, water vapor will form rapidly in the soft tissues and somewhat less rapidly in the venous blood. This evolution of water vapor will cause marked swelling of the body to perhaps twice its normal volume unless it is restrained by a pressure suit. (It has been demonstrated that a properly fitted elastic garment can entirely prevent ebullism at pressures as low as 15 mm Hg absolute [Webb, 1969, 1970].) Heart rate may rise initially, but will fall rapidly thereafter. Arterial blood pressure will also fall over a period of 30 to 60 seconds, while venous pressure rises due to distention of the venous system by gas and vapor. Venous pressure will meet or exceed arterial pressure within one minute. There will be virtually no effective circulation of blood. After an initial rush of gas from the lungs during decompression, gas and water vapor will continue to flow outward through the airways. This continual evaporation of water will cool the mouth and nose to near-freezing temperatures; the remainder of the body will also become cooled, but more slowly."

There are cases of people being exposed to vacuum for up to 30 seconds and making a full recovery. See http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/970603.html for more details. So the Hitch Hikers Guide to the Galaxy was almost correct.

The one thing you don't do in space is hold your breath. That just keeps the air inside you, which causes more damage as it expands. You should actually EXhale before you hit vacuum.

The scifi/horror movie "Event Horizon" has what I think is a pretty good rendition of the effects of vacuum on an unprotected human. Though from the sounds of it you're probably too young to watch it, it's pretty gruesome and scary (it's an R certificate, IIRC).

How exactly, do we know there is a vacuum in space?

Hunter Parasite wrote:How exactly, do we know there is a vacuum in space?

If there was something extensive there we'd notice it affecting our observations. While there is some gas and dust (usually localised in interstellar clouds or nebulae), most of space has no effect on the light or radiation reaching us from afar, so we can assume it's just empty (apart from the odd atom per cubic metre).

Plus, having been up there, we know there's nothing in it .

If there were a molecular medium (e.g. 'air' or some other gas mixture) friction would be so high with the relative motions of objects in space (for instance planets) that all would start to 'burn' (like a meteor when it enters earths' atmosphere) and have to slow down to eventually tumble into the sun. Even if this medium would be say around 1/10.000 of te density of our atmospehere.

As most things in the real world, the vacuum in outer space is relative. It's generally much more empty than any vacuum we can make in a lab, but it's by far completely empty.

Actually, there is not absolute vacuum even in space. The closest you get is the vast emptyness between galaxy clusters. http://en.wikipedia.org/wiki/Vacuum

As for the first question, one of the first injuries that occur with people or animals subjected to vaccum is that the nose freezes (!) This is because the rapid expansion of the air that comes out of the mouth makes it very cool

Hi every body.

Well this is my first post and what a way to start of.

Regarding the bit about how we know there is vacuum in space. Well to be pedantic (something I'm good at) we can't really say space is empty because it has planets and other physical objects within it.

Yes, ArneB and I did already mention that specific fact, Thurlor.

Welcome, by the way :)

Although there are more extremes such as the cold, in a psyiological sense what would happen to the body is a very exagerated version of 'the bends', something divers experience if they have been at depth for a long time and come to the surface without allowing the increased pressure of gas in their body to release gradually at each depth as they ascend.

The degree of injury and permanent damage is dependant on how deep you were, and how quickly you ascended.

As you (stupidly) exit the space craft you could liken it to a diver surfacing from great depth to the surface in an instant!

Obviously you will die very quickly.

But soft tissue damage in the brain and other areas makes it very unlikely that you would be 'the same' after even a short exposure to *real* space. Scenes from all movies to date are very very innacurate. With the suprising exception of the scene at the end of 'Total Recall' which is, how should I put it, *interesting*!

The freezing as air rushes out of your lungs would also, as others have said cool and eventually (in a very short period) freeze you from the inside out in your airways. This would be very hard to reverse even if you 'shot straight back into another air lock'!

Also, if you were stupid enough to hold your breath you would rupture, and potentially (I guess) explode in a very small organic sort of way. More like a silent pop in space. By that time you would be pretty much flash frozen anyway.. So you might sort of crack and pop at the same time.

The holding your breath thing can happen in diving as well, actually very easilly in the top couple of meters (as that is where the biggest change in pressure is) if you hold your breath while ascending.

So, what to do?

Hold your breath - Rupture.

Don't hold your breath - Freeze your airways.

Either way - You will freeze and suffocate.

How about.. Stay in the spaceship!