It is interesting to compare two books: Martin Rees’ “Just Six Numbers” and Michael Rowan Robinson’s “Nine Numbers of the Universe”. I will do this in tabular form.
| Nine Numbers | Six Numbers |
| Anisotropy of microwave background | Ripples in microwave Background (Q) |
| Hubble Constant H | - |
| Age of the Universe | - |
| Temperature of Microwave Background | - |
| Density of Cold Dark Matter | Total Matter in Universe |
| Density of Hot Dark Matter | |
| Cosmological Constant | Cosmological Constant |
| Rate of Star Formation | - |
| - | Ratio of gravity to electro-magnetic force |
| - | Mass deficit H to He |
| - | Dimensionality (3) |
Comments: There is some overlap in the numbers which each author considers important. This is because of the different aim: Robinson aims at a complete description of the universe; hence he picks numbers which are not derived from each other – the independent constants. Reese emphasizes only numbers which are “finely tuned” to make life possible. But his six are also mutually independent.