There are several laws of thermodynamics, all of which have applications across the various scientific fields. These laws also have deep philosophical implications, with the second law leading the charge in this regard. I have already written two articles describing the first law (energy balance). I will soon cover the depths of the second law, but I feel the need to discuss the most fundamental law beforehand. Strangely enough, there is a law that comes before the first law.
The zeroth law of thermodynamics states that if two systems are in thermal equilibrium with an external system, then they are also in thermal equilibrium with one another. Thermal equilibrium means that heat is not being exchanged between two systems. When two systems having different temperatures come into contact with one another, they will inevitably experience heat transfer. Once thermal conduction is complete, the collective system will arrive in thermal equilibrium.
