OK, another thing my angel PT explained to me...
I've been through two diskectomies (L5/S1) and always pictured them as this: the "jelly doughnut" that was my disk had herniated and the jelly had squished out into the spine and was pressing on the nerve. So the doc went in and removed the jelly that was floating around in there.
In thinking of it like this, I thought there was a big hole in the disk and that's why it has reherniated every two years.
The PT explained that the annulus (the outer part of the disk) is made up of many many layers of ligaments and is super tough. More like a steel belted radial tire! So my herniation wasn't like there was disk nucleus floating around. It was that the disk was squished out past the vertibrae and pressing on the nerve. The doc then shaved off some of the annulus.
So this made me believe that it is technically possible for a disk to "go back in".
I just thought I'd share this. I consider myself fairly intelligent and well educated on my back, so this was a big revelation and has provided me with some comfort.