Friedrich W. Hehl

Physicist and co-founder (with McCrea, Mielke, and Ne'eman) of Metric-Affine Gauge Theory of Gravity, laid out in their 1995 Physics Reports review "Metric-Affine Gauge Theory of Gravity" — the framework underlying the modern "hypermomentum challenge" to the Geometric Trinity. Matters to this vault beyond that one co-authored review: he returned to the same unresolved question three decades later as co-author (with Damianos Iosifidis) of the 2024 Physics Letters B paper credited with first making the challenge's technical content explicit, and is personally thanked by Kartik Tiwari for seeding the 2026 paper's line of inquiry — a single figure spanning the founding framework, its sharpest modern statement, and the philosophical paper reacting to both.

References

• claim-gauge-gravitys-hypermomentum-challenge-conditionally-breaks-geometric-trinity-equivalence

• claim-hypermomentum-challenge-latent-in-mag-since-1995-explicit-2024

• claim-iosifidis-hehl-2024-states-trinity-breaking-priority-while-building-on-prior-lineage

• claim-hehl-1995-already-defines-hypermomentum-current-coupled-to-connection

• Related hubs: entity-metric-affine-gauge-theory-of-gravity · entity-geometric-trinity · entity-hypermomentum · entity-kartik-tiwari

• Primaries not yet independently read in full: Hehl, McCrea, Mielke & Ne'eman 1995 (arXiv:gr-qc/9402012) — only its abstract and Introduction, see note below. Iosifidis & Hehl 2024, Physics Letters B 850:138498, now read in full — see question-verify-hypermomentum-challenge-1995-2024-priority-claim.

• 2026-10-10: Both the 2024 paper and the 1995 review were fetched directly for the first time. The 2024 paper states in its own words it is first to show the Geometric Trinity's equivalence fails for hypermomentum-carrying particles, naming Wolf & Read (2023) as its target (claim-iosifidis-hehl-2024-states-trinity-breaking-priority-while-building-on-prior-lineage); the 1995 review's own Introduction confirms its hypermomentum current was defined to couple to the connection, pointing the mechanism at Chapter 5 — though that chapter itself remains unread, since arXiv's copy is only a 6-page stub (claim-hehl-1995-already-defines-hypermomentum-current-coupled-to-connection).