Optimization is important for people, animals and machines.
Everyone wants to maximize expected reward (expected utility),
and minimize the complement (prediction error, expected cost).

Which brings us to the free energy principle.
''The free energy principle describes the behaviour
of a given system by modeling it through a Markov blanket that tries
to minimize the difference between their model of the world and their
sense and associated perception. This difference can be described as surprise''.
And is minimized by continuous correction of the world model of the system.

Now, as Anil Seth explains, in his book ''Beeing you'',
this does not mean that
''A living system can get away with retreating into
a dark and silent room and staying there, staring at the wall.
You might think that this would be an ideal strategy, since
sensory inputs from the external environment will become
highly predictable. But it is far from ideal.
Over time, sensory inputs signalling other things, like levels
of blood sugar and so on, will start to deviate from their
expected values: You are going to get hungry
if you stay in tho dark room for too long. Sensoy entropy
will start to grow, and non-existence will loom''.

Complex living organisms need to ''allow things to change
in order stay the same''. Minimizing sensory prediction error
in the long run means that you have to get out there and
explore the (your) environment in order to keep reward
(expected reward, expected utility) up, and
its complement, surprise (prediction error, expected cost), down.

At least these are the necessary information-theoretic behaviours
of systems that maintain a separation from their environment.
In other words - you die, if you don't play along those lines.

''In brief, for a well-defined agent to exist it must
occupy a limited repertoire of states; for example, a fish in
water...
Agents must avoid surprising states (e.g. a fish out of water)''

''If we change
the environment or our relationship to it, sensory input
changes. Therefore, action can reduce free-energy (i.e.
prediction errors) by changing sensory input, whereas
perception reduces free-energy by changing predictions''.

''In short, we sample the world to ensure our predictions
become a self-fulfilling prophecy and surprises are avoided''.

Anil Seth writes in ''Being You'', that even octupuses are like that
''On this particular day, David had chosen a tank in the left-hand
row, about half way along. When I walked to see
what was going on. I was astonished to see all the octopuses
on the other side of the walkway pressed up against
the glass of their tanks, every one of them staring
intently at David while he repeately lowered his objects
into his chosen tank.
The observing octopuses seemed to be trying to
figure out what was going on for no other reason than the sheer
interest of it''.
Of course.

(You might not be an octopus)
But sure, you also need to know what
could happen out there,
so no suprise that you need to read you daily dose
of science fiction!

:)