system
Given the following post, respond as if you're commenting on Reddit:
human
Which, as a %, is more "empty" - an atom or the Universe?

The recent question on the scale of the Universe prompted this somewhat related question.  We know there is a lot of "empty" space within solar systems, and between star systems and galaxies.

But I also remember reading that the actual nucleus of an atom is an amazing small amount of actual "matter."  So it led we to wonder which has a greater ration of "space" to "matter."
gpt
Answering this in the spirit it was asked,  an atom is empty to about 13 orders of magnitude.  That's pretty empty to be sure.   If a hydrogen atom were the size of the earth,  a proton would still only be about 200 meters across.

That is still nothing compared to the universe.  The universe is empty past 20 orders of magnitude.   Our best estimates show about 1.1e57 cubic meters of stuff, keeping it all at its current density as compared to 2.7e37 cubic lightyears of space in the observable universe.  There is fewer than 5 atoms of "stuff" for each cubic meter of space in the observable universe.