system
Given the following post, respond as if you're commenting on Reddit:
human
What physically happens to SSD drives that make the memory blocks wear with each write operation?

It's common knowledge that SSD drives have a limited number of writes and it must minimize the amount of times each memory block is rewrited, to make it last more, bla bla bla. 

But, why does it happen? I mean what is the physical reason behind this? What is happening inside the drive that make the memory blocks wear with each use?
gpt
Flash uses a floating gate transistor that permanently stores a charge in a totally electrically insulated floating gate that isn't connected to anything. Hot carrier injection or tunneling is used to force electrons though the insulator and into the floating gate at very high voltages where they are essentially trapped forever (until reprogrammed again) and electrostatically cause the non floating gate to be on or off depending on the content of the charge trapped in the floating gate. Thus representing one or zero.

The high voltage and tunneling of electrons through the insulator breaks down the dielectric insulator with each erase/program cycle as electrons tunnel through the material and change the molecular state and electron composition. Basically the high voltage tunneling poisons the insulator with free electrons (?) until the dielectric starts becoming a conductor and progressively leaking so much that the floating gate can no longer hold a isolated charge. It just conducts and drains instantly through the insulator when you try to fill it and can't ever be a "1" again.