There is a 31 minutes time difference between two items, which are in the
same place, and not moving.
If one of them were still moving, I would think of relativity.
But if they are in the same place, and none of them are moving, this
reminds
me of the Twin paradox.
http://en.wikipedia.org/wiki/Twin_paradox
When I looked for it, I found a Minkoski diagram, a name which reminds me
of
something.
