Dropping from 80K to sea level, no sonic boom?
What this sounds like to me is Electronic Warfare / Electronic Countermeasures...
...it was being spoofed by Electronic countermeasures painting a false target. That may be an explanation.
If we can speculate that Kevin Day's radar targets were all the result of electronic warfare testing, which is a credible hypothesis at this point, what reasoning can be used to dismiss/explain the visual sightings by Fravor, Dietrich, et al?
This isn't a challenge in order to delegitimise the radar spoofing theory. I'm geuinely curious to know what people believe the US military has by way of physical/optical spoofing tech, i.e. assuming Fravor et al are telling the truth about what they saw, how might one fool 4 experienced pilots and WSOs into "seeing" a 40-foot hypersonic flying tic-tac over the open ocean?