Isn't outer space a perfect vacuum?
I suppose it depends on how you limit "outer space." Are you talking about a cubic meter somewhere in an arbitrary point in the universe or are you speaking of the universe as a whole? If I remember correctly, there's something like 30 Hydrogen atoms in the average cubic meter of space, but that's a horrible statistic, I'm sure.
A relatively small vacuum can be found in a relatively big reference frame. For example, there's probably millions of billions of vacuums the size of a cubic picometer at your fingertip. However, it's impossible to say how long it will remain a vacuum due to particles moving into said region and phenomena such as virtual particles.
