I have just recently started learning some very basic thermodynamics and there is one question that has been driving me crazy:
Why do we even need the Zeroth law of thermodynamics?
The law states:
If a body A, be in thermal equilibrium with two other bodies, B and C, then B and C are in thermal equilibrium with one another. (Wikipedia)
This seems like the most obvious statement ever. How could B and C not be in thermal equilibrium?
While looking for an answer I came across a Khan Academy video that deals with this exact question. The lecturer in the video says:
"...yeah our universe is like that but think about it a little harder, you could problably think of a universe where it might not be like that." (Video)
This just confused me even more. If we follow that logic wouldn't we have to formulate something like Newtons Zeroth Law or Keplers Zeroth law too?