A small thing for SciFi writers.

[bizzybody]

If you have a spacecraft in your story that is somehow going to develop a hole in its hull, please do not write that your characters get sucked into the vacuum of space.

They get blown out into space.

Think of this, a car tire has air inside at a pressure greater than the atmosphere outside it. If you poke a hole in the tire with a nail, would you say the air is getting sucked out of the tire?

NO! You'd say the air is blowing out of the tire. Same thing with wind. It blows from areas of higher atmospheric pressure to areas of lower pressure. "Man, that wind was sure sucking hard this morning!" Nobody ever says that.

So if you're writing the next great SciFi novel, at least get this one thing right while you're typing about impossibly dense asteroid fields and kilometers long space dreadnoughts zipping around like fighter planes.

If you really want to get an earful, use the term "vacuum pressure" in conversation with a person who works with gasses or liquids at pressures above or below ambient. If you absolutely must use the word pressure when talking or writing about less than ambient pressure (ie vacuum) use the term "absolute pressure". That's what engineers and scientists use when the variable of ambient pressure is not relevant or must be calculated in with the relative pressure.

For example, the pressure in your car tires is relative to the current ambient atmospheric pressure. The absolute pressure in them is what the gauge reads PLUS the ambient - or what it would read if you took the wheel off and put it in a vacuum chamber with a 29.92 InHg vacuum.

If your tire gauge reads 30 PSI, the absolute pressure is actually around 44 PSI.

[Gudy]

Originally Posted by bizzybody

If you have a spacecraft in your story that is somehow going to develop a hole in its hull, please do not write that your characters get sucked into the vacuum of space.

They get blown out into space.

Eh, potayto - potahto.

Air movement happens because of pressure differentials. When we consider the high end of the differential "normal", we call it sucking. When we consider the low end normal or completely disregard the cause, as for wind, we call it blowing. So from the inside of the space craft, where the higher atmospheric pressure is the norm, it sure is sucking. For an observer on the outside, it's blowing.

Move on, no nits to pick here.

[crich70]

There are plenty of errors in Sci Fi. I remember in one Star Trek movie they show a bottle of champaign revolving in space til it hits the hull of a star ship whereupon it shatters and liquid splatters. I'd think that a rigid substance like a champaign bottle would shatter in vacuum as there would be no external pressure and plenty of internal. Not to mention the contents should freeze solid at 250 below zero (the temp in orbital space). No doubt hundreds of people worked on that movie and it still slipped through so an individual writer could make errors and not catch them as well.

[Ninjalawyer]

I like to get the basic science right in my writing, but the latest Star Trek movies prove you can get away with pretty much anything.

I think my favourite part was the beginning of Into Darkness when the crew has to use a "cold fusion" device to freeze a volcano (cold fusion has "cold" right in the title, so it must just freeze stuff, right?). Leaving that aside, a volcano with a frozen top would still build up pressure from magma, and the eventual eruption would be even worse.

[HarryT]

Originally Posted by crich70

There are plenty of errors in Sci Fi. I remember in one Star Trek movie they show a bottle of champaign revolving in space til it hits the hull of a star ship whereupon it shatters and liquid splatters. I'd think that a rigid substance like a champaign bottle would shatter in vacuum as there would be no external pressure and plenty of internal.

Nope. A thin glass container will easily withstand a 1 bar+ pressure differential. Glass is pretty strong stuff - it's just susceptible to impacts.

Not to mention the contents should freeze solid at 250 below zero (the temp in orbital space).

It would either freeze or explode depending on whether or not it was in sunlight. Space itself has no "temperature".

[Penforhire]

Put me in the "eh" category and I work with high-vacuum equipment (physical vapor deposition, e-beam evaporation and magnetron sputtering). Now if you start talking Torr versus Bar versus Atmospheres... them's fighting words, lol.

[dwig]

Originally Posted by bizzybody

If you have a spacecraft in your story that is somehow going to develop a hole in its hull, please do not write that your characters get sucked into the vacuum of space....

more like:

1. you are "sucked" by the near vacuum of space.

or

2. your are "blown" by the escaping air.

If you are talking about to where you are translated ( ... sucked into the vacuum...), then either verb works because the active agent isn't defined except by the verb chosen.

[gmw]

Technicalities are exactly that, technicalities. Even non-fiction books often over-simplify in order to make things accessible for their readers.

If in doubt, check the dictionary. From dictionary.com for "suck":

6. to render or bring to a specified condition by or as if by sucking.
8. to draw or be drawn by or as if by suction.

(Bold mine.) There is a fair bit of wriggle-room in those definitions. So I don't actually see much wrong with: "get sucked into the vacuum of space".

And that's all without getting into the more technical discussion of the difference between suck and blow - which, as already pointed out, is a matter of perspective (and convention) rather than real technical difference.

Yes, there are lots of real errors in sci-fi and in other fiction (people getting thrown around as bullets hit them is always a favourite), but I think a suck vs blow complaint in this context is going beyond picky.

[sl42]

On the fate of the wine bottle:

Though exposed to the vacuum of space, the wine bottle is a rigid
container which will not flex and expand therefore the contents will
experience minimal change in pressure, thus no boiling and out-gassing
from the wine and such. The bottle is a strong container and atmospheric
pressure is only about fourteen pounds per square inch, thus the apparent
increase in pressure when it is lobbed into the vacuum of space would be
the same. The weak point, of course, would be the cork which might be
pushed out, but we’ll assume that it is wired in place securely or that
this is a screw top with a strong cap. Then comes the issue of heat loss.
Space has, as noted above, no real “temperature” since there is no
atmosphere of enough density to matter. Further, there is no liquid or gas
in contact with the bottle to carry heat away by convection. Being in a
near perfect vacuum, the bottle is perfectly insulated though it still
will lose heat via radiation, and this will be a much slower process than
in a cold atmosphere. The wine would probably take longer to freeze lobbed
into the vacuum of space than if it were tossed out into the snow on a
sub-zero winter’s day down here. Probably the only point where things
would suddenly get very interesting would be when the bottle finally
smacked into the ship’s hull and shattered because then the liquid
droplets are exposed to vacuum and should begin rapidly boiling and
consequently dropping in temperature rapidly therefore producing bits of
ice which should survive even as most of the volume boils off.

[Rizla]

Possibly the most useful piece of writing advice I have read in this sub-forum.

Edit: There was a great thread about commas that opened my third-eye. But apart from that...

[sl42]

Oh yea, the cooling by radiation also assumes that the bottle isn't absorbing more heat than it is radiating. If this is a dark red wine exposed to sunlight, it could get pretty toasty pretty fast.

[crich70]

Originally Posted by sl42

On the fate of the wine bottle:

Though exposed to the vacuum of space, the wine bottle is a rigid
container which will not flex and expand therefore the contents will
experience minimal change in pressure, thus no boiling and out-gassing
from the wine and such. The bottle is a strong container and atmospheric
pressure is only about fourteen pounds per square inch, thus the apparent
increase in pressure when it is lobbed into the vacuum of space would be
the same. The weak point, of course, would be the cork which might be
pushed out, but we’ll assume that it is wired in place securely or that
this is a screw top with a strong cap. Then comes the issue of heat loss.
Space has, as noted above, no real “temperature” since there is no
atmosphere of enough density to matter. Further, there is no liquid or gas
in contact with the bottle to carry heat away by convection. Being in a
near perfect vacuum, the bottle is perfectly insulated though it still
will lose heat via radiation, and this will be a much slower process than
in a cold atmosphere. The wine would probably take longer to freeze lobbed
into the vacuum of space than if it were tossed out into the snow on a
sub-zero winter’s day down here. Probably the only point where things
would suddenly get very interesting would be when the bottle finally
smacked into the ship’s hull and shattered because then the liquid
droplets are exposed to vacuum and should begin rapidly boiling and
consequently dropping in temperature rapidly therefore producing bits of
ice which should survive even as most of the volume boils off.

Interesting. I guess it shows that common sense and reality aren't always the same. I don't recall seeing any ice in the scene (I think in Star Trek Generations) but the scene shifted just after the bottle shattered I think so the liquid didn't have time to boil away.

[bizzybody]

Now you have me thinking of the light beers scene in "Star Wreck: The Pirkinning"

[Penforhire]

I've been curious about the real behavior of fires inside a spaceship in zero gravity. We've seen all sorts of variations in movies. Most of those feel bogus to me because there should not be much in the way of flammable substances inside a ship, aside from flammable or toxic gasses in some plumbing.

[crich70]

Originally Posted by Penforhire

I've been curious about the real behavior of fires inside a spaceship in zero gravity. We've seen all sorts of variations in movies. Most of those feel bogus to me because there should not be much in the way of flammable substances inside a ship, aside from flammable or toxic gasses in some plumbing.

Ah, but what should be and what is are often two different things. Apollo 1 is a case in point where there were flammable materials, and wasn't there a Russian Mir that had a fire or almost did due to not being maintained properly or something.