The oldest grains we have were magnetised before the sun finished forming

Remanent magnetization is a good record of exactly one quantity: the field intensity present when a magnetic mineral cooled and locked it in ^[6]. That is why the result sits awkwardly inside the framing around it. The group reports a recorded field stronger than Earth's present-day field and reads that as magnetism helping pull primordial matter into the early sun ^[1]. The measurement supports the first half. The second half is theory, and the account of the work describes only how such a field could have arisen, with a collapsing cloud generating a plasma whose spinning charges produce and sustain it ^[7]. Nothing in it describes the machinery that converted field into inward mass transport. Benjamin Weiss of MIT states it more carefully than the headline does: gravity has long been the assumed cause of the change from spherical cloud to protoplanetary disk, and his measurements show magnetism "likely played a role" ^[5].

Earth's field is also the wrong ruler. It is the one every reader has held a compass in, which is why summaries reach for it, but the nebular question is not how the field compares with a planet's. It is whether the field is strong enough relative to the gas it has to move. The only strength figure on offer here is that comparison with Earth today ^[1], and it cannot be set against nebular gas pressure by anyone outside the paper.

The timing is firmer, and the timing is the argument. The group's earlier 2-million-year record sat comfortably after the sun was in place, with planets beginning to assemble ^[8]. These inclusions formed inside the first 200,000 years ^[4]: ten times closer to time zero, 1.8 million years earlier than the previous mark ^[15], inside a window worth about four thousandths of one percent of solar system history ^[16]. Cauê Borlina, who led the work as an MIT graduate student, is blunt that magnetism during planet formation is settled and the disk before that is not ^[9].

The sample supply is not what changed. DOM 08006 came out of the Dominion Range in 2008 and has been picked over since ^[3][10]. It is among the most primitive meteorites known and has kept its original composition and minerals ^[11], with grains that may predate the sun itself ^[12]. Weiss's contrast is with the ordinary career of a meteorite: formed in the nebula, added to a body with water, destroyed, moved out to the asteroid belt ^[13]. The new claim depends entirely on DOM 08006 having skipped that itinerary. The PNAS paper carries co-authors at Tsinghua, Cambridge, Caltech and UCLA ^[14], which spreads the analytical work across four institutions and one rock.

Until the recorded intensity is expressed against the gas it supposedly herded, the defensible reading is narrower than the press line: a field was present while the sun was still gathering, which is not yet a field that did the gathering.