Dan wrote----------
how does a table "know" to push upwards with exactly the right force
to support a book and not drop it or throw it into the air.
Notice how sometimes if you drop a book on to the table, the table doesn't
"know" exactly what the "right" force is and throws the book a little bit
back into the air. Perhaps it's because it hasn't had time to get
acquainted with the book. Its big cousin, a trampoline net, makes this sort
of mistake all the time.