The actual journal article (linked in the article) has more info, it actually seems they did something interesting. The calibration was a cool - https://doi.

The actual journal article (linked in the article) has more info, it actually seems they did something interesting. The calibration was a cool - https://doi.org/10.1016/j.cell.2020.04.033 https://doi.org/10.1016/j.cell.2020.04.033