[baudrunner]

Lee Smolin has calculated the smallest unit of space that can be occupied by a volume. He has it pegged at 10^-43 of a cubic meter. It isn't just curious that there should be such a limitation, it is curious enough that there is anything here at all. But once it (creation) begins, there is no holding it back.

Angular momentum is that which prevents an object from hurtling into another object but instead encourages its revolution around it. Evidently the comet Shoemaker-Levy did not possess the angular momentum that prevented it from colliding with Jupiter. There could be more objects revolving around our sun but there aren't, only so many possess the angular momentum, which term describes nothing more than the tendency to defer collision in favor of orbit because the angle of approach is not sufficient to cause collision.

The reason for the above mini-diatribe is to point out the influence that size and mass have on particles and objects (in physics, the terms particle and object are interchangeable). So even at the nano level we have particles that will never directly meet head-on unless coerced into doing so, which makes a little more sense when viewed in the same context as neutron behaviour, in which the neutron will never make contact with another particle in its journey through the earth. It's just so darn small.

It is interesting to note that there are more of those Smolin units in a cubic meter than there are atoms in the observable Universe.