5 ms·

Does anyone know if JWST has seen stuff far enough for this effect to kick in? [Angular Diameter Turnaround](https://xkcd.com/2622/ https://xkcd.com/2622/)

• jdiff 7mo ago
  Yes, JWST can see as far back as 300 million years after the big bang.
• ben_w 7mo ago
  Yes, as per Wikipedia that happens much closer to us, at redshift 1.5: https://en.wikipedia.org/wiki/Angular_diameter_distance https://en.wikipedia.org/wiki/Angular_diameter_distance (Note: the reason to measure in red shift rather than light years is that when this comes up it suddenly gets very important to be very careful about what exactly you even mean by "how far away is that thing?")
  • jahnu 7mo ago
    Incredible! So if I understand this correctly, the galaxy above in the paper is at Z=14.4 and that means it appears in the sky about as big as if it were a very small Z or roughly 350 megaparsecs away?
• metalliqaz 7mo ago
  I think about that one a lot. It goes all the way back to the CMB, which is so "big" that it is literally everywhere you look and the shapes we see were apparently at the quantum scale.
  • floxy 7mo ago
    >the shapes we see were apparently at the quantum scale I thought that was sound waves? https://duckduckgo.com/?q=baryon+acoustic+oscillations&t=ffab&ia=web https://duckduckgo.com/?q=baryon+acoustic+oscillations&t=ffa... ...unless you are thinking about something else?
    • metalliqaz 7mo ago
      I don't really know, to be honest. Everything I know about it is from pop-sci sources.
  • ElectronCharge 7mo ago
    According to current theory AIUI, cosmic inflation greatly influenced the CMB. It ended approximately 10^-32 seconds after the Big Bang: "Cosmic inflation is believed to have occurred in an incredibly brief, rapid, and exponential expansion phase lasting from approximately 10^-37 to 10^-32 seconds after the Big Bang. During this minute interval, the universe expanded by a factor of at least 10^26, and potentially as much as 10^50." Quite a theory, cosmic inflation...