ʻOumuamua's Anomalous Acceleration

The claim

First confirmed interstellar object detected in the solar system showed non-gravitational acceleration without visible outgassing. Mainstream explanation is exotic outgassing (e.g. molecular hydrogen ice); Avi Loeb has argued for engineered origin.

State of the evidence

Pan-STARRS detection data, Spitzer follow-up, Bialy & Loeb 2018 paper, Bergner & Seligman 2023 hydrogen-ice hypothesis