@Magrathea_staff @LIGO Cosmology can be really tricky sometimes, but I can try to clear some things up. We measure luminosity distance from gravitational waves sources, which tells us how far away an object would be based on the brightness (or luminosity) of the detected signal. @Magrathea_staff @LIGO But luminosity distance can be a bit confusing when talking about really far away sources. We can't apply the usual d=vt here to convert the distance to the time in took the gravitational waves to travel.