Like a mustard seed in Fenway Park

"The pit at the center of each atom, the nucleus, is not only hard but minuscule: a hundred thousand times smaller than the atom as a whole. To use an analogy, if an atom were the size of Fenway Park, the home stadium of the Red Sox in Boston, its dense central nucleus would be the size of a mustard seed, with the electrons gracefully orbiting in the outer bleachers...

This ultra-tiny scale is called the Planck length, named after Max Planck, a pioneer in quantum physics. The Planck length is 10^-33 centimeters, a hundred billion billion times smaller than a quark, which is itself a few hundred thousand times smaller than an atom. Another way to visualize the size we are talking about: the Planck length is smaller than an atom by about the same ratio as an atom is smaller than the sun. It is staggering that we have anything at all to say about such impossibly tiny elements of existence...

Regardless of whether space is indeed grainy at very small scales, physicists are confident that time and space must be chaotic at Planck. Because of the indeterminate, probabilistic character of quantum physics, at the dimensions of the Planck length, space and time churn and seethe, with the distance between any two points wildly fluctuating from moment to moment. Indeed, at the Planck scale, time itself randomly speeds up and slows down, perhaps even going backward as well as forward. In such a situation, time and space no longer exist in a way that has meaning to us. The sensation of smoothness and substantiality that we experience in our large world of houses and trees results only from averaging out this extreme lumpiness and chaos at the Planck length, in the same way that the graininess of a beach disappears when seen from a thousand feet up."

Excerpts from an interesting essay in the March issue of Harper's.  The infinitely small, like the infinitely far (deep space) and infinitely old (deep time) are concepts that I cannot wrap my mind around, but love to ponder.