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You're using faulty definitions there. Even outer space is not a 'true' vacuum. Any pressure lower than atmospheric pressure is considered a partial vacuum. 10
by stephen_g 10y ago
You're using faulty definitions there. Even outer space is not a 'true' vacuum. Any pressure lower than atmospheric pressure is considered a partial vacuum.
100 Pascals in a lab would be considered a 'medium' vacuum. And in a tube the size of an actual full-size hyperloop, even that will probably be extremely difficult and expensive to achieve.
I think the hyperloop will end up being technologically unviable mostly because of the cost and the limitations of technology (like the expansion joints that will be required on a decently long track), but I hope I'm wrong on that. It may lead to new innovations which will be good.
- bjterry 10y agoA true vacuum is literally impossible. It's not a category that can exist in nature, because particles aren't actually little balls that bounce around. Every volume has some probability of a particle being in it in the great universal configuration space. It can have an expected number of particles < 1, but never zero.
- rmccue 10y agoYou're right, I'm using vacuum as a layman's term, and shorthand for "hard vacuum" as mentioned in the paper. [0] The paper refers to the Hyperloop system as a "a low pressure (vs. almost no pressure) system". [0]: http://www.spacex.com/sites/spacex/files/hyperloop_alpha.pdf http://www.spacex.com/sites/spacex/files/hyperloop_alpha.pdf (p3)