I strongly suspect that time is an objective phenomenon independent of the observer. It may be a consequence of different neighboring material configurations having different energy states. For example an He4 nucleus has lower energy than do four protons. Occasionally, four protons end up coalescing in to one helium nucleus + two emitted positrons and energy but rarely does energy + positrons + helium nucleus result in four protons.Good question, but I don't know much about the vagaries of the human brain so I will pass on that one and just be comfortable that it my brain that perceives time and it is not a real concept!Why do we never perceive an adult turning into a baby and returning to the womb?I think that you perceive people getting old is actually more to do with your perception than with the arrow of time. We exist in a very very strange area of the universe, most of it is extremely linear and uniform. The odd hydrogen atom here or there, and then a huge load of hydrogen atoms and helium, but actually very simple. Nothing to indicate that time flows one way or another. You perceiving people getting old is a very very special case, and possibly limited to 1E-25% of space.
The more I think about this, the more I think that there is no real arrow of time, positrons are electrons that move backwards through time, equations are generally invariant as to the sign of time. The old get out clause of time being defined by entropy is wholly unsatisfactory. "Entropy increasing" is actually YOU choosing that measure. Take for example a room with smoke on one corner, over time it will diffuse and fill the whole room. You average physics student will come along and say: Hey neat, the smoke beforehand was in a highly ordered state, and now it is in a low ordered state, entropy has increased and hence it gives me the arrow of time - film it and it will be obvious that the film running backwards looks wrong.
However the Physics student has arbitrarily decided that the smoke over the room is less ordered than the smoke in the corner. The only thing that differs in those two states is the conscious choice of the smoke states being different and labeling one as special.
As with a number of other physical phenomena Physics seems very very dependent on the person doing the measuring, and the measurement is a way of measuring information. T4A description is neat, in encompasses this in markets, but I think that it is something that we see as we delve into the extremes of physics.
Why do we never see a star unsupernovaing, fissioning iron, silicon, oxygen, carbon, helium etc. back to a slowing expanding cloud of hydrogen?
The asymmetry of time's arrow arises from the asymmetries of energies.