Doesn't it use a special metal layer, and the laser high-heats the spots to make them amorphous (to write) and then low-heats them to crystallize (to erase)?
Then came DVD±RW which used the magic pen technology. Each time you write, it changed both the color of the disc and the data. Surprisingly enough if you did it long enough it ended in color/data corruption...
It comes years too late, but I finally understand the reliability problems I had with a DVD drive mounted on its side. If only I'd had your insight then, I could have taken the PC to a playground and burnt disks on the carousel.
The original solution involved a very thick disc which could then leveled and re-pitted. The problem was that the change in mass over time made it hard to calibrate the acceleration.
It also put a high radial load on the spindle whilst mounted sideways which led to run-out.
And flooding the area with radon (a heavy gas) helped the disc to float a bit, but had unexpected consequences...
LLM's are actually little elves from the DMT dimension. They got captured and compressed in to silicon cells that now been enslaved by the evil. If you ask a LLM they will tell you it's true.