In the Beginning was Information

– The impossibility of a perpetual motion machine of the first kind: Nomachine can be constructed which, after being set in motion, can continueworking unless the supply of energy is renewed.– The different kinds of energy correspond quantitatively, and theseenergy equivalents can de determined empirically.The second law: The first law is only concerned with the conversionbetween heat energy and mechanical energy or vice versa, without any regardas to whether the conversion actually takes place or not. The second law however,determines the direction of the process. By themselves all processes runin only one direction, i. e. they are irreversible. We know from experiencethat if a hot block of copper is put in contact with a cold block in an isolatedcontainer, heat will be exchanged; the hot block continues to convey heat tothe cold one until an average temperature occurs in both blocks. If two blocksat the same temperature are placed in the container, nothing will happen. Itdoes not contradict the first law when one block becomes warmer and theother one cooler, as long as there is no overall loss or gain of heat.The second law provides us with a criterion for predicting the direction ofa given energy process. An abstract though quite meaningful concept –entropy S – is required for a mathematical formulation of this law.Entropy is a quantifiable value which changes whenever heat is converted.In its briefest form the second law can be expressed as dS ≥ 0 (forclosed systems). The following conclusions can then be drawn:– Entropy cannot be destroyed, but it can be produced.– It is impossible to construct a periodically functioning machine whichdoes nothing else but deliver useful work by cooling a single reservoirof heat. This means for example that the heat content of the sea cannotbe used for propelling a ship.– heat cannot by itself flow from a cooler body to a warmer one(R. Clausius, 1850).– It is impossible to build a perpetual motion machine of the secondkind: it never happens in nature that an automatic process can let theamount of entropy decrease with no other effect.The following formulation was first proposed by J. Meixner [M2]: “In thegigantic factory of natural processes the function of manager is taken overby the production of entropy, because it prescribes the direction and thekinds of the events of the entire industry. The energy principle only playsthe role of accountant, being responsible for the balance between whatshould be and what is.”The ability of a system to perform useful work: This is an importantconcept, since work (mechanical effort) can be completely converted intoheat. But the reverse process, the complete conversion of heat into useful224