>So intergalactic space is “crowded” compared to, say, the vacuums at CERN I vaguely recall Sam's Laser FAQ claimed that terrestrial vacuum pumps couldn't do a

>So intergalactic space is “crowded” compared to, say, the vacuums at CERN I vaguely recall Sam's Laser FAQ claimed that terrestrial vacuum pumps couldn't do as well as outer space, due to outgassing of materials and diffusion through vacuum chamber walls. The CERN page on the LHC vacuum system says it gets down to 10^-13 atmospheres. https://home.cern/science/engineering/vacuum-empty-interstellar-space https://home.cern/science/engineering/vacuum-empty-interstel... The wikipedia article on vacuum gives a range for "deep space" from 10^-10 to 10^-20. Interstellar, but maybe not intergalactic.