system
Given the following post, respond as if you're commenting on Reddit:
human
What is the consistency of outer space? Does it always feel empty? What about the plasma and heliosheath and interstellar space? Does it all feel the same emptiness or do they have different thickness?
gpt
Space is not empty at all! We have entire branches of astronomy dedicated to studying the stuff between stars and galaxies (the so-called interstellar medium and intergalactic medium). The density of the interstellar medium is about one atom per cubic centimeter, and the density of the inter-galactic medium is much lower.