Scales in the Universe

Down

As we shrink down from normal size, details become fuzzy and we encounter atoms, in the realm of the quantum,

Out

On the large scale the Universe is vast, and space is expanding. The galaxies are moving ever further apart.

We live in an intermediate world.. In our day to day life we are little aware of anything much smaller than a millimeter or much larger than a kilometer. The boundaries of the Universe extend far beyond these limits.

Shrink from our own scale by a factor of ten billion and you are down to the size of atoms and the strange world of the quantum. Enlarge your view by ten billion times ten billion and you are on the scale of a galaxy.

At both extremes, the very large and the very small, things are, not surprisingly, different from our familiar world.
It is so unfamiliar that its understanding may well be approached through allegory.

The far Boundaries of our Universe