The operation in 4a is perfectly reversible, as shown in Figure (b) by taking the example of author JM Lehn, a chemistry Nobel prize. Proceeding in exactly the same way as in Figure (a), we show that, while JM Lehn remains connected through all these years to "Supramolecular Chemistry" and "Complexes", his coworkers change. So do his main fields of interest, shifting from "Double Helix" or "Ligands" in the 90's to "Self-assembly" in the 2000's.
Both Figures show that the arrow of time is not necessarily linear (which would show as a linear arrangement of the red circles), but is somewhat circular because several items occur throughout the years, building an effective attraction between the first 5-year time slice and the last.
