  I argue that both digital and analog information are important in the
foundations of quantum physics. If it is possible for information present in
one system to become present in others without being erased in the original
system I will say that this information can be copied. I argue that copying is
important for understanding issues like causality and that all information that
can be copied is digital. I then explain that analog information that cannot be
copied can be understood in terms of decision theoretic probability. Finally, I
argue that these ideas can help explain the second law of thermodynamics. The
arrow of time we experience is the knowledge arrow of time -- the present
contains more knowledge, that is, useful or explanatory information, than the
past. That knowledge is created by evolutionary processes that involve copying,
variation and selection and such processes increase entropy.
