Who's Better: Ranking Physicists

A favorite pastime of physicists - like that of sports fans or politics enthusiasts - is comparing prominent figures in their discipline to each other: was Einstein's contribution bigger than Newton's? Was Faraday as important as Maxwell? Are the best mathematicians of today as good as Euler or Lagrange?

As may be expected, the debate is ultimately inconclusive, but the discussion sharpens our knowledge of how knowledge is appraised, how major contributions are made, and what we need to be careful about when delivering judgements on such comparisons. Some thoughts about the matter follow.

Who showed up first is often a crucial ingredient in the discussion. On the one hand the first person to discover or invent something has sometimes little prior art (in the language of patenting) to rely on. For example, when Newton and Leibniz discovered calculus, it was a major step (although Newton said he stood on the shoulders of giants; for example, the analytic geometry of Descartes influenced him greatly). And it is surely true that this advance facilitated many discoveries down the line (e.g. Maxwell's laws of electromagnetism).

At the same time, I think chronological priority makes subsequent discoveries of the same order of magnitude difficult: calculus can only be invented once. Indeed, when Newton discovered the universal law of gravitation, Lagrange famously said that "Newton was the greatest genius that ever existed, and the most fortunate, for we cannot find more than once a system of the world to establish." It took Einstein to find another system. Who was greater? (Einstein gave his own vote to Newton).

From the perspective of experimental discoveries, time again plays an interesting role. For example, there can be no doubt that the discovery of electromagnetic induction by Faraday was a stunning advance, facilitating, among other things, the motors that are now so indispensable to present day technology.

However, it is very hard to make again a discovery of that level, since the laws of physics seem to be so few - there aren't too many of that class remaining to be discovered (at least so it seems). Perhaps the next major step in electromagnetism was the discovery of superconductivity by Kammerlingh Onnes. Should we put him in the same class as Faraday? Maybe not, as Faraday was more prolific and versatile; but then Onnes marshalled much more complex technology (for the liquification of Helium).

The argument can be wound back to Einstein who phrased special relativity using not even calculus, just high school algebra - can anyone make such a fundamental advance today using such a simple theoretical tool?

In fact Newton was a mathematical genius who created new mathematics; Einstein was not a mathematical genius (he described himself modestly as a mathematical ignoramus), but he upended Newton's universe with his physics. Who, then, we ask again, was greater?

The debate is inconclusive, but in the process we learn more about Newton and Lagrange and Faraday and Maxwell and Einstein and Kammerlingh Onnes.

Afterword

At some point I will do a post on current ranking systems such as the h-index, proposed by Jorge Hirsch who has been controversial as a physicist (he was previously banned from the arxiv for using unprofessional language), although the index he proposed has become very popular.