Infinitesimal and Heat Sink/Bath
Infinitesimal Arguments
Infinitesimal arguments are well suited to many forms of calculus.
However they can lend themselves to mental hardship when irrationally applied to thermodynamics especially when they are
not given proper context.
Certainly infinitesimal changes can be reversible, but such infinitesimal changes are NOT
necessarily measureable i.e. too small. Moreover they are often meaningless because true reversibility generally only occurs
when the infinitesimal change is zero! Or if prefer reversibility appears realistic when infinitesimal change approaches
zero, hence is NOT a real process.
Moreover, if there were a sufficient/massive number (approaching infinite)
number of infinitesimal changes then the change can become real. And if this change involved work. or thermal energy transfer
between systems, then this becomes real change i.e. a measureable change. And processes whereby energy/work change
is measureable are generally irreversible processes.
Heat Sink/Bath
Similar voids in
logic often applies to heat sink or heat baths. Herein real change often does not affect the heat sink/baths measureable
parameters. In other words real energy change tends to be NOT measureable inside of heat sinks/baths. This is not to say that the
change was infinitesimal although the principles are very much the same.
Again, if you had a sufficient/massive number (approaching infinite) number of real changes then the energy change to the heat sink/bath will become measureable.
And
the mother of all heat baths/sinks that we deal with on a daily basis (experimentally and otherwise) is the Earth’s atmosphere
and/or atmosphere plus planet.
Never Forget
