Q: How much pressure does it take to burst someone's chest open? A: Lots
Around the time of Star Wars Episode VII: The Force Awakens, astrophysicist Neil DeGrasse Tyson decided to spoil everyone’s fun by imposing actual physics on its far-away universe. Would BB-8 actually be able to roll on sand? Would TIE fighters actually make any sound in space? Are Roman Numerals actually a viable counting method in the 21st century? Stuff like that.
Now two Australian scientists have done the same thing with Alien: Covenant, out tomorrow, on Aussie-founded academic site The Conversation. Michael Milford (Associate professor, Queensland University of Technology) and Juxi Leitner (Research Fellow, Robotics & AI, QUT) ask questions like: Can glass withstand insane pressure? Would 20 crewmates want to kill each other after years on a ship? How much force would an alien need to break out of someone’s chest? Here’s what they reckoned.
1. Wouldn’t this glass panel break?
Maybe, maybe not.
Over at The Conversation the science-men did some complex maths that they’re modestly downplaying as ‘back of the envelope calculations’. Ultimately they decided that the pressure exerted on the glass by the alien’s head in the above clip was 18,130 Pascals per square inch, which may or not make the glass break. They explain: “tough tempered glass is known to break at somewhere in the 10,000 to 24,000 PSI range, so it looks like it could be touch and go”.
2. Wouldn’t the crew hate each other?
Yes – unless they were hand-picked first
This question presupposes that the company that sent the Covenant spaceship didn’t handpick its crew – which they probably did – but the maths is still interesting, so let’s take a look.
If you’ve got a group of 20 randomly selected people, chances are there are going to be some major personality clashes, especially over a long trip through space. This is simply because of how probability works: imagine there’s a 5% chance that you really don’t get on with someone – if it’s just you and someone else, the scientists at The Conversation say the probability you get on with them is something like this: ‘chance you like them x chance they like you’. This would be (1 – 0.05) × (1 – 0.05), which is equal to 0.9025, or 90.25%. So 9 times out of 10, you and a random other person will get on great.
That chance rapidly decreases the more people you add to the equation. “Grab any random group of 20 people with those individual characteristics, and there’s only a tiny chance there won’t be some significant conflict potential there”. The figure they come up with is about 0.00000034%. “That’s why there’s so much psychological profiling for missions to Mars,” they say.
3. How does an alien break out of someone’s chest?
Method A: cutting
The ‘elegant’ method
If a newly ‘hatched’ alien only weighs 5kg, it’d have to be very strong to break through the chest of something with 16 times its own body mass. But imagine an alien’s incisors working like a saw to cut open a human chest, like sternum saws might do for open heart surgery. Leitner and Milford imagine that, in relation to its body mass, an alien is four times as strong as a human – so, they say, “if the ‘chestburster’ could apply its incredible power as efficiently to cutting its way out as a cardiac surgeon does with a saw, this approach is feasible.”
Method B: brute force
If at first you don’t succeed…
The human ribcage is very strong – a well-placed blow with a force of 3,300 Newtons will break a rib only one in four times. And that’s the force an Olympic boxer might have – not, perhaps, a newly born alien. So can an alien break out of a chest purely by bashing its way out? Leitner and Milford estimate the alien could only produce about 1,175 Newtons of force, so it would probably take a long time, and a lot of bashing to burst from someone’s chest like it does in the original Alien. Cutting > bashing, says science.