If one carefully reads the papers submitted to ArXiv astrophysics from after 1998, one sees that Saul Perlmutter’s and Adam Riess’s supernova research groups were not independent (as claimed) and that they were in serious communication. Perlmutter and Riess actually wrote a paper together before they could have otherwise come to cooperate.
They say that the data that the two groups got regarding the distances to supernovae type 1a and other bright extremely distant objects was not concordant at first. In order to force the two data sets to conform, they admit that they had to apply a mutual “adjustment”. This artificial factor was used by both groups to bring the data of each set into alignment with the other so that a smooth plot could be made that included all the data points.
The sense of this artiface alone is the sole “evidence” that they both cite for an accelerating rate of expansion of the universe. They might have applied the adjustment factor to the other data set in the opposite sense. Then, the universe expansion rate would have been seen as decelerating.
There was a choice to be made. A cynic might hazard a guess as to why they made the choice that they did. A cynic might also claim that P&R’s colleagues on the Nobel Committee were grossly biased because they were close friends and few in number. When a subcommittee reports to the full committee, though, their recommendation is often taken as Gospel. How often has the Nobel Prize award been found to be, if not unwarranted, uncompelling?
In college, we had to write laboratory reports on the textbook experiments that we did in lab. We were warned against manufacturing data. Our professors all said that this kind of “fudging” is a big “NO NO”. Ethical standards are not just for students. Still, as professionals who certainly are good scientists, Permutter and Riess, no doubt, think that they were perfectly well justified in applying their adjustment factor and did so in all honesty. But, the result is the same.