Time
Time is that process that takes us from the Past through the
Present and into the Future.
The Past is fixed, it does not change; nor can it be
changed. Thus we cannot revisit the past
directly (i.e., travel back into time).
The Future is unknowable.
It includes every possible outcome from the conditions of the Present.
I believe that the evolution of the universe from past to
future is analogous to the formation of a crystal, or a phase change if you
will; in which a completely random future becomes a completely fixed past. In the future, all outcomes are possible;
however, for each individual outcome, only one manifests itself into reality in
the present and is forever locked as such in the past.