And Abraham took another wife, and her name was Keturah (Genesis 25:1)
Keturah: This is Hagar. She was called Keturah because her deeds were as pleasant as keturah (incense). (Genesis Rabba 61:5)
Ketura is Hagar (Zohar 133).
As we discussed earlier, Abraham had a concubine, Hagar. Later in life, after the passing of Sarah, Abraham took another wife whose name was Keturah. Midrash, Zohar, Rashi, and other commentators state that Keturah is Hagar.
To distill this situation to its essence, we have here two seemingly distinct individuals who, in view of at least some Biblical commentators, are one and the same person. To any physicist, this narrative bespeaks of a unification. Indeed, this situation is analogous to the unification tendency in theoretical physics, where different fundamental interactions are being unified into one.
It all started in the second half of the nineteenth century when Faraday and Maxwell successfully unified heretofore distinct physical phenomena—electric and magnetic forces—into one electromagnetic field governed by the theory of electrodynamics. That was the first unification in history—two distinct phenomena turned out to be two guises of one phenomenon, not unlike two names of the same person.
After publishing his papers on the general theory of relativity in 1916, Albert Einstein spent most of his life in unsuccessful attempts at unifying gravity with electromagnetism. The next success in the quest for unification in physics came in the 1964-1967 period when Steven Weinberg and Abdus Salam independently succeeded in unifying electromagnetic forces with weak forces, also known as beta decay. Although these forces behave quite differently at low energy, they merge into one force at the unification energy of 246 GeV. In 1979, Sheldon Glashow, Abdus Salam, and Steven Weinberg shared the Nobel Prize in Physics for their contributions to the development of electroweak theory.
The standard model goes a step further and provides a common platform for three out of four fundamental forces—bringing together electroweak forces and strong nuclear forces. Gravity still remains an oddball awaiting its unification with other fundamental forces.
It would be downright silly to suggest that Rashi or the Midrash somehow foresaw unification of fundamental forces in suggesting that Keturah is the same person as Hagar, and no such claim is made or implied—far from it. What is interesting, however, is the common sense of parsimony—in a number of distinct characters in the Biblical narrative or in a number of distinct physical phenomena—and a shared drive to unification that is shared by some of the classical Biblical commentators writing many centuries ago and theoretical physicists of today.
 GeV—Gigaelectronvolt, that is a billion electronvolt (1GeV=1,000,000,000 eV). One electronvolt (1 eV) equals 1.602×10−19 J (joules). 1 electronvolt (1 eV) is the amount of kinetic energy gained or lost by an electron accelerating from rest through an electric potential difference of one volt.
 One might speculate that in the Keturah-Hagar analogy with electroweak unification, Keturah is parallel to the weak force, whereas Hagar is parallel to the electromagnetic force. To support this analogy, let us recall that Hagar means a “stranger” or an “outsider.” Keturah is related to ketoret (“incense”). Ketoret are burned in the Holy of Holies—the innermost chamber of the Temple (Bet HaMikdash)—one day a year, on Yom Kippur, by the High Priest. Thus, Keturah is the ultimate insider in stark contrast to Hagar who is an outsider. Electromagnetic forces have infinite range and primarily play a role outside atoms forming chemical bonds that bind atoms together in molecules. Week force is a nuclear force that acts at very short distances inside the atom nucleus. Thus Keturah-Hagar inside-outside dichotomy holds true for week forces and electromagnetic forces respectively, supporting the parallel. Furthermore, Rashi says that Keturah was given this name her deeds were as sweet as incense (ketoret) burnt in the Holy of Holies in the Temple. Coincidentally, the theory of week interactions used to be called “flavordynamics.” However, this parallel is pure speculation and, true or false, adds little to the main point that equating two different people as one is a metaphor for the unification of two different forces.
Originally Published on QuantumTorah.com.