> "we can be absolutely confident of their fantastic distances"<p>My current layperson's understanding is:<p>1) Redshift-to-distance conversion is a calibration based on the distance ladder.<p>2) And the distance ladder itself seems to have come under some doubt recently due to the "cosmological crisis" [1].<p>Can someone here ELI5 how they can be absolutely confident of these distances?<p>[1] "JWST just made the Crisis in Cosmology WORSE" <a href="https://www.youtube.com/watch?v=hps-HfpL1vc" rel="nofollow">https://www.youtube.com/watch?v=hps-HfpL1vc</a>
One of the things which helps with "how far" is time: if you can wait until something has rotated a bit, then you get sideways distance to do triangulation. (because the path of the earth in orbit defines a wider baseline so two observations at the equinoxes (for instance) give you maximal distance. If you can wait even longer you get other rotational movements but some of those "longers" are very long.)<p>As a student in the amateur astronomy space (I didn't progress far) I was quite purturbed by the main sequence "colour == size" thing and the parallel lanes of "colour == distance" and "colour == age"<p>It felt like cheating to put 3 qualities into play, all of which could undermine the others. I'm not even really sure I think you can have two. Maybe there is some unstated principle that all dull things are old and all red dull things are old and far away, but if you also think all old red dull things are huge but all you got was "it's red" then it's feeling shakey.<p>Pick one.
From the abstract:<p>"Using stellar population modelling, we find the galaxies typically contain a hundred million solar masses in stars, in stellar populations that are less than one hundred million years old. The moderate star formation rates and compact sizes suggest elevated star formation rate surface densities, a key indicator of their formation pathways. Taken together, these measurements show that the first galaxies contributing to cosmic reionisation formed rapidly and with intense internal radiation fields."
> The sliver of sky observed is about the size of the queen’s eye “on a pound coin held at arm’s length,”<p>So it can be seen by the naked eye? Granted, not at full resolution, but still, I'd have guessed several orders of magnitude smaller.
It seems a bit underwhelming to go from 400 million years after the big bang to 350 million years. I hope JWST will deliver us even older galaxies in the near future.