“The Moving Finger writes; and, having writ,
Moves on: nor all thy Piety nor Wit
Shall lure it back to cancel half a Line,
Nor all thy Tears wash out a Word of it.”
― Omar Khayyám
When I was a student of Fuel Technology and Chemical Engineering in 1961 my then girlfriend gave me a copy of the ‘Rubayat’. I then, and now, interpret it to mean that “What has been done has been done. It can never change. We cannot go back to the time before.
Incidently at the same time, I also attended three series of lectures on thermodynamics more or less concurrently. In Physical Thermodynamics, Chemical Thermodynamics and Engineering Dynamics the laws are largely the same. The units were then different in all three courses of lectures, and the laws needed to be extended to clarify equilibrium conditions in some chemical systems.
Since that time I have become interested in computational thermodynamics, which reaches the (albeit disputed) inference that information has mass.
I observe that, whichever system of thermodynamics we use, The second law implies that heat always moves from hotter objects to colder objects, unless energy in some form is supplied to reverse the direction of heat flow. The first person to formulate the 2nd Law was Sadi Carnot in 1824 or perhaps Rudolph Clausius in the 1850s. It applied specifically to heat engines and set an upper limit to the efficiency of any working heat engine like a steam engine, internal combustion engine or gas turbine.
All formulations contain the same definition of entropy as that which was used in the early 19th century:
change in entropy =< (change in heat energy / absolute temperature)
and all formulations agree that the change can never be negative unless energy is supplied from an external source.
Entropy is normally interpreted as ‘the degree of disorder’. The second law implies that things can naturally become less ordered by giving off absorbing heat. Thing can only become more ordered with the supply of heat from outside the system.
All this implies that things tend to become disordered unless energy is supplied to reorganise them.
For something to be predictable it cannot be disordered. Only if the degree of order were maintained could the future be predicted. But as in the pysical world the entropy must increase, the degree of order cannot be mantained, real events cannot be fully predicted.
On the other hand in the the real world forcasts can be made. But for an event to be observable it cannot be in a fully isolated system except for an observer within that fully isolated system.