[sandworm101]

The various candles are not independent yardsticks, nor are they just assumed to be true. Wherever possible they are compared against each other. And there are people who spend entire careers debating how dust absorbs light in order to best compensate for such things.

If measurements point to some sort of incongruity, questioning the accuracy of one's ruler is a fools trap. Altering the rulers to remove incongruities results in a spiral of compromises, internal debates that don't result in progress. If one suspects that the rulers are wrong, the answer is to build a better ruler. Not to arbitrarily chop bits off until the difficult observations go away.

[netcraft]

I totally agree, hope my comment didnt come off to the contrary. As a layman, I consume most of my information through popsci sources (though I try to go more for the Dr. Beckys than the meatless or sensational stuff), and its generally described as something that we just take for granted - "we just found the oldest galaxy ever observed, only a few hundred million years after the big bang - and its too bright and has way more 'metals' than expected" - but we measured that with redshift, which makes a bunch of assumptions that of course they cant talk about in every video, but we dont talk about anyone questioning them.

I have no doubt that there are great scientist spending their entire careers trying to improve these rulers and measurements, but I also know that there are great scientists spending their entire careers basing everything on the best rulers they have...