“Delta S is always greater than or equal to zero, we call this ‘the second principle of thermodynamics’”.[1] This law developed by Rudolf Clausius in the early 19th century, after he saw Sadi Carnot’s paper of 1824, is the only equation in fundamental physics that represents any difference between past and future.

“In elementary equations of the world, the arrow of time appears only where there is heat. The link between time and heat is therefore fundamental: every time a difference is manifested between the past and the future, heat is involved.”[2] Carnot in trying to understand the theoretical physics of the steam engine identifies that steam engines function because heat passes from hot to cold. It is then that Clausius declares heat cannot pass from a cold body to a hot one. Clausius is saying that heat can only travel in the one direction, and it is from this that he develops the only equation and law of fundamental physic that alludes to a flowing of time.

Expanding on Clausius’s thought through the process of my drawing, I see Entropy being activated at the very tip of my pencil. As the pencil scribes the surface of the paper, the friction that causes heat, enables the passage of time on the surface of the paper. The process within the drawing now becomes both a metaphorical representation of the passage of time and also an actualisation of the passage of time.

[1] Rovelli, Segre, and Carnell, The Order of Time.

[2] Rovelli, Segre, and Carnell. 23