Running in a vacuum

[mrk]

Completely not the content I was expecting from the title!

 

[Django x2]

What a complete load of ****. Does an athlete run 100m much faster with a 30mph tailwind? No.

Err....fail. TBF, much faster, no. Faster, yes?

Also, where do you run into 70mph winds on a daily basis? The last time we had 70mph winds in a uniform direction, was, well, never.....

 

[Zefan]

Err....fail. TBF, much faster, no. Faster, yes?

Also, where do you run into 70mph winds on a daily basis? The last time we had 70mph winds in a uniform direction, was, well, never.....

So you agree that it's not much faster, like I said? Intelligent arguement, not even once.

Oh you don't run in to that sort of wind ever? Apologies, that must mean I don't either. You win! Can you imagine if that's how debate actually worked?! I know you're probably a little bit bitter about not being as interesting or handsome as I am, but there's no need to get all upset about it. I currently live on a mountain on a small island in the south atlantic.

 

[PermaChanged]

I read somewhere that the brain uses 400 calories a day which is like 1/6th of the daily amount, so a small of the energy will go into that regardless of the activity.

Is this why stupid people are fat / fat people are stupid?

Their brains aren't burning as many calories as the rest of us!

 

[Zogger]

Surely this could be roughly tested on a treadmill?

Unfortunately not, because as has been well established in previous threads, he would take off.

 

[D.P.]

I wouldn't suggest trying that, though. It's not the instadeath explosion that it's sometimes made out to be, but it's not safe either. Especially if you hold your breath - having your lungs full of air would strongly increase your risk.

It's survivable, but it isn't "just fine". You'll pass out in much less than a minute (an astronaut was exposured to close to a vacuum in a training accident - he passed out in 14 seconds) because your body can't do gas exchange at all in a vacuum. It's not like holding your breath under normal pressure. You'll be totally oxygen deprived immediately, even though there will be some oxygen remaining in your blood. Fluids not contained by your body will boil quite quickly. Sweat wouldn't be a problem, but fluid boiling on the surface of your eyeballs would be. You'd also be at severe risk of the bends, very quickly.

If you take some deep breaths, breath out, close your eyes, jump towards a safe location and have someone there to bring you into a pressurised environment and apply relevant medical help...then you could probably survive a minute's exposure without permanent injury. Probably. That guy I mentioned above was exposed to near vacuum for 15 seconds. He lost his sense of taste for a few days (he said he could feel the water boiling off the surface of his tongue, which must have been rather unpleasant), but that was it. Give it a little more than 15s, or keep your eyes open, and you'll probably be blinded, probably temporarily, by damage to the surface of your eyes.

Of course, you could die immediately of a heart attack.

Survivable? Probably, if you know what you're doing and someone is there to take your unconscious body into a safe, pressurised location and give you medical treatment. Just fine? No.

EDIT: Also, spacesuits aren't mainly for temperature control. If you're in a vacuum, temperature control is the least of your worries because conduction and convection don't happen in a vacuum and heat loss by radiation is very slow for a human body. You'll be dead very quickly, but your corpse will take a very long time to freeze. You'd feel cold due to the fluid boiling on your exposed surfaces (I know that sounds wrong - "cold" and "boiling" don't usually go together but in this context they do), but you wouldn't actually be losing much heat.

I think I remember reading there have reported cases of people being in a vacuum for over 1 minute and just spent the rest for the day in the hospital before being released.

For sure there can be issues and yes I was wrong in holding your breath (I more meant it in the way that obviously you wont be breathing at that point). My main point being the pressure difference between earth and space posses no risk - lack of oxygen does and being in an absolute vacuum does.


I know what you are saying about heat loss in a vacum but you have to realize that in the shade in space leads to fairly rapid cool down to very low temperatures, the opposite occurs in the sun. Some space suits have complex heating and cooling systems that pump heated or cooled water around the body. Straight form wiki: "This space suit is capable of protecting the astronaut from temperatures ranging from −156 °C (−249 °F) to 121 °C (250 °F).". Most most space suits have a pressure lower than 1 atmosphere for a variety of reasons - simpler suit design with less pressure differential, increased mobility, and simply there is no real health risk at low pressures if oxygen is supplied to the lungs. If breathing doesn't use dedicated apparatus (mask like a diver) then the pressure needs to be higher. TO put it another way, people don't die on top of Everest due to lower pressure (30% of surface pressure) they die form oxygen deprivation.
The Armstrong Limit is recognized at about the limit of what a human could survive long term without a pressure suit but assuming oxygen form masks - that pressure is at around 5% of surface pressure (at human body temperature or 37C).

 

[Nick1881]

I didn't read the other replies but there's no need to run in your vacuum cleaner, just start using it as normal, i.e. give it to the wife.

Did I get this right?

 

[Angilion]

I think I remember reading there have reported cases of people being in a vacuum for over 1 minute and just spent the rest for the day in the hospital before being released.

Can you provide any references to that?

In the past, experiments were done in which animals were deliberately exposed to vacuum. The results were not nice. Some died immediately. None retained consciousness for more than seconds. Some chimpanzees did recover from 90s of exposure, but it's clearly far from being "just fine".

For sure there can be issues and yes I was wrong in holding your breath (I more meant it in the way that obviously you wont be breathing at that point).

Now I'm curious...would you have to hold your breath or would you simply be unable to inhale regardless of what you did?

My main point being the pressure difference between earth and space posses no risk - lack of oxygen does and being in an absolute vacuum does.

The difference in pressure isn't an issue people are talking about. The lack of pressure is the main risk in that it's the one that will kill you first. The lack of pressure makes gas exchange in your body impossible, so you will die of oxygen deprivation even though your blood will still have oxygen in it. That's why you faint in seconds in a vacuum, which you won't do if you stop breathing in more normal pressure. The lack of pressure also results in a risk of blindness and damage to other parts of your body that have a high liquid content near the skin and which aren't well sealed, as a result of that liquid boiling at under body temperature (hence, for example, the astronaut exposed to vacuum for 15 seconds losing his sense of taste for a few days).

I know what you are saying about heat loss in a vacum but you have to realize that in the shade in space leads to fairly rapid cool down to very low temperatures, the opposite occurs in the sun. [..]

If you're in a bona fide vacuum, it's debateable whether the concept of temperature applies - there's no matter to have a temperature. If there's anything around, that's a different kettle of fish entirely (surface of the moon, solar wind, etc) but unless you're really close to a star you'll be dead well before temperature is an issue and if you're in deep space your corpse will stay warm for ages.

 

[box]

I know it's not running, but for anyone interested in what is achievable with a lack of drag ... this makes for an interesting watch:

http://vimeo.com/70921986

 

[satanicguardian]

1) Build Giant Vaccum Cleaner
2) Profit

Are you going to use it to steal underpants?

Also, with regards to the posts above; is it true then that a vacuum is kind of a warped mixed of underwater physics but with different pressures? This sort of stuff really intrigues me - I say we vote an OCUK forum member to try it!