Oh great. Can you explain how entropy favors this? Why is the Earth so much bigger than the sun and moon in FET?
The earth is not subject to the same physical processes which shapes the smaller celestial bodies above it. They exist at different scales and so it stands to reason that different physics would apply. Why don't we see rocks shaped to the same shape as a mountain? That is because those two things, at different scales, are subjected to different physical processes to shape them.
Let's go one more... Have you ever seen a sun the same size as a moon?
Yes. See the OP.
Actually, everything does not come in various sizes. Do the atoms of the ocean come in various sizes?
Are you suggesting that hydrogen atoms are the same size as oxygen atoms?
All protons are the same size. All electrons are the same size. Hydrogen atoms and Oxygen atoms are merely different configurations of protons and electrons. A hydrogen atom has one proton and an oxygen atom has eight. When they combine they form a water molecule, which is universally the same size. All of these things exist, at similar sizes, at an orderly and predictable atomic scale. Atoms and molecules do not simply come in "various sizes".
"Pebble" and "boulder" are names for the relative sizes of rocks, not rocks themselves.
A pebble is defined by its smooth features. A boulder with smooth features like that wouldn't be found in nature because the physical processes which shape a pebble do not apply to rocks the size of boulders. Thus, pebbles do not come in boulder size.
I would contend that mouse embryos and elephant embryos start out about the same size.
I thought you were supposed to be arguing that things came in wildly different sizes?
Embryos being the same size in their mother's wombs goes to show that things are of suitable sizes in their environments.
Yes, I get that you completely miss my point. Mice and elephants are mammals that are vastly different in size. Pebbles and boulders are rocks that are vastly different in size.
I could go on, but you get my drift.
A mouse would not be the size of an elephant and a elephant would not be the size of a mouse because evolution would not shape a creature in those ways, at those scales. Pebbles and boulders have different features, which can only exist at their different scales. Your argument that "just about everything in nature comes in various sizes" is simply incorrect. There is a certain template which things fall in. Volcanoes are always going to be huge, and atoms and molecules are always going to be small, and never vice versa. There are physical laws which shapes matter into their respective places.