Thinking about the space between the subatomic particles in atom -- and how small they are relative to their atom's size -- isn't it rather convenient that the strength of those forces that govern the way they dance around... tend to keep us floating about 4,000 miles above the center of the earth? That's a lot of earth and it's a long way down. Imagine YOU trying to hold up all that weight. You'd probably give up in a day. I call it luck.
closed as not a real question by Colin K, Qmechanic♦, David Zaslavsky♦ Jan 31 '12 at 16:10
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You may call luck that the various physical constants for the interactions which lead to forces , (gravitational, electromagnetic, strong, weak) hbar and c have the values they do. Others call it the anthropic principle, as we would not exist as observers except for a narrow range in combination of these constants. Most physicists are pragmatic and accept them as is.
But you should read more about physics, since what is holding us up from the center of the earth is not in particular the strong force, but the electromagnetic. Anything we see, touch, smell, hear, taste ( five senses) depends on the electromagnetic force, not the others. The others are a necessary framework that cradles us, but we see/sense the world through electromagnetism and store the information in our heads through electromagnetic interactions.
It is the electrons on the atoms of the ground that are repelling the electrons in the atoms of our shoes and feet so as not to fall through to the center of the earth. Like those russian babushka dolls which are nested withing each other, the other forces are nested and of course equally necessary for the existence of nuclei and therefore atoms, and the existence of livable planets, but as first in human relevance, it is electromagnetism that reigns supreme.