CHICAGO, SEPTEMBER 26, 2021 — Correspondence preserved in the MQ knowledge base documents that Geiger communicated a proposed distinction between electromagnetic and macroscopic determinations of the gravitational constant to NIST/CODATA researchers on September 26, 2021. The record provides a dated reference for the history of that proposal.

The communication matters because later MQ commentary compares different operating modes of a torsion-balance experiment. Establishing what was stated before the later measurements is necessary when distinguishing a prior prediction from an interpretation developed after the data became available.

The record supports the existence of an earlier, general measurement-regime distinction. It does not show that every later apparatus-specific assignment had already been specified. The mapping of free-deflection and electrostatic-servo modes to MQ realization regimes was recognized after examination of the BIPM/NIST apparatus and must be identified as retrospective.

Nor does the correspondence establish that NIST adopted the proposal, designed its experiment to test MQ, or endorsed the resulting interpretation. The current MQKB says there is no evidence establishing whether the correspondence influenced the later experiment. Geiger did not design, conduct, or analyze that experimental campaign.

The primary record also resolves a chronology discrepancy. One book passage gave September 21, 2021, while the preserved message records September 26. This archive uses the latter. The correction illustrates why dates attached to original communications are preferable to recollection when the historical sequence is scientifically material.

The news value is documentary rather than experimental. It helps define the scope of a claim that can be tested against later evidence. A journalist should keep three stages distinct: the original theory, the earlier communication of a general distinction, and the later interpretation of specific experimental modes.

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