Space
Periodic table showing origins
The most abundant known entity are small packets of energy we call photons that are considered to be massless.
There is no known way yet to be able to measure the size of a photon(their very very small).
Thoughts on the Universe
Current theories on Dark Energy and Dark Matter that apparently is over 95% of the Universe with just over 4% of matter and light.
Despite there being 100s of billions of know galaxies each containing on average 100s of billions of stars the universe is almost totally empty, so "Space" is a very apt description.All the stars, planets and galaxies that can be seen today make up just 4 percent of the visible universe(not the SPACE inbetween). The other 96 percent is made of stuff astronomers can't see, detect or even comprehend.
The nearest Distance to space from Earth is called the Kármán line.
Atoms
Almost everything inside what we call the atom is completely empty space
The total number of atoms of each element is talked about as relative abundance.
Number of Atoms
Number of atoms for a typical human of 70 kg, there are almost 7*1027 atoms (that's a 7 followed by 27 zeros!) Another way of saying this is "seven billion billion billion." Of this, almost 2/3 is hydrogen, 1/4 is oxygen, and about 1/10 is carbon. These three atoms add up to 99% of the total!
Atoms in the known Univese
The number of atoms in the observable universe is estimated to be between 4×1079 and 4×1081.
The accelerating Universe
The accelerating Universe: Nobel Laureate Brian Schmidt