Comment by coryfklein | Hacker News Reader

Comment by coryfklein | Hacker News Reader

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I'm having a hard time finding more data on the density of matter in interstellar space.

Wikipedia says

> The density of matter in the interstellar medium can vary considerably: the average is around 10^6 particles per m3 but cold molecular clouds can hold 10^8–10^12 per m3 [1]

But I imagine that interstellar gas would be easier to fly through than interstellar sand. Do we know the composition of matter in interstellar space?

[1] https://en.wikipedia.org/wiki/Outer_space#Interstellar_space

It's almost all Hydrogen/Helium gas. Other larger atoms and molecules are known to exist in the interstellar medium, but it's primary gas.

Also, a good way to remember the density is ~1 Hydrogen atom per cm^3.

We could catch it and use as a fuel or recoil mass!

(does napkin math)

Nope :-(

How about intergalactic densities?

Don't know the number off the top of my head, but it should be considerably less. It should also be highly varying as some galaxies live in pretty densely packed environments (galaxy clusters), which some live in very open environments like our own galaxy.

Nothing like a little "look it up yo damn self": Looks like it's about 1 hydrogen per m^3 [1] (via SO [2]), about 1 million times less dense. Damn.

  [1]: http://www.universetoday.com/30280/intergalactic-space/
  [2]: http://physics.stackexchange.com/questions/25378/how-vacuous-is-intergalactic-space/25379#25379

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