Paula Muhr: Limits to the Circulation of Epistemic Critique in the Recent Reanalyses of the EHT Images of the M87* Black Hole

In April 2019, the Event Horizon Telescope (EHT) Collaboration that gathered over two hundred international scientists famously revealed the first empirical images of a black hole—a mysterious cosmic object thus far regarded ‘unseeable’. To create these revolutionary images that visualise the immediate surrounding of the black hole at the centre of the galaxy Messier 87, the EHT team used a constellation of seven radio telescopes that spanned the Earth and then spent two years algorithmically reconstructing empirically reliable images from the thus collected non-visual data. To obtain valid imaging results, the EHT team deployed multiple methodologies during the image reconstruction process, which all delivered sufficiently consistent results. Apart from revealing their final images to the public, the team also made their processed data and algorithms accessible to the public.In 2022, five studies authored by scientists who were not members of the EHT team were published. Each study focused on reanalysing the publicly available EHT data, testing if they would obtain sufficiently similar images of the black hole. The stated purpose of these epistemic critiques was to verify the epistemic truth claims of the EHT’s final images of the black hole. The authors of each study thereby deployed different approaches. Some replicated the procedure developed by the EHT team; others developed alternative algorithmic techniques for reconstructing images from the EHT non-visual data. Four of the five critical reanalyses converged on their findings by obtaining images that were sufficiently similar to the initial EHT images published in 2019. One study diverged in their results and was subsequently criticised by the EHT team for its methodology.As my paper will show, this circulation of the epistemic critique in the community of astrophysicists focused on imaging black holes is far more than a contrived academic exercise. Instead, it is of critical importance for the epistemological consolidation of the currently emerging research field of black hole imaging and, with its fine-grained methodological insights, has the potential to inform future EHT analyses and results. However, while the importance of critical replication studies for the community of specialists is difficult to overestimate, this type of discipline-specific epistemic critique remains highly hermetic. Since the implications and import of such a critique remain opaque for non-specialists, its circulation remains constrained to the members of the scientific community.