First... above all... in today's way of thinking about QFT,  it
should be impossible to make your idea about observing the
universe work... or impossible to find ANY OTHER WAY to image
the future, in effect. It falls out directly from the
mathematics as they use it. Given a huge telescope and
temperature distribution and all... the predicted outcome can be
found by coding up the initial density function, evolving that
forwards in time, and applying measurement operators WHICH DO
NOT ADMIT any dependence on future time events. That is hard-
wired into the measurement operators.  And... more precisely..
The events you are proposing to use, to image the future, are
events in which a photon is connected in the present to this
telescope, and in the future to another region of the universe.
But in today's view, probabilities of photon emission into "free
space" (which includes billion-light-year pathways if it
includes anything!) can be calculated entirely from the local
conditions, using well-established calculati