Here's a little thought experiment for everyone to consider:
You forgot your watch at home and you're walking past an atomic clock that indicates it is exactly 2 o'clock. In fact, at that moment it is 2 o'clock, exactly. There are no tricks in this experiment. Now, do you know that it's two o'clock?
Leave to Mac to throw a knuckle ball like that. Einstein himself considered the possibility of a variable speed of light, but as it stands, the issue is very controversial, Setterfield's arguments notwithstanding.
I made a bad mistake in using an
atomic clock. It could have been any old clock tower with the hands showing 2 o'clock.
To review:
(1) It
really is 2 o'clock
(2) You
believe it is 2 o'clock, because ...
(3) The clock tower
says it is 2 o'clock, and finally
(4) No, you do
not know that it is 2 o'clock.
Why not? Answer next time.