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Old 08-06-2014, 04:20 AM   #1
bizzybody
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A small thing for SciFi writers.

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.
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