If we agree with the universe starting from a Big Bang, 13.8 billion years ago, expanding at different rates governed by the Hubble constant of 67.4 km/s/Mpec, somewhere about 13.4 billion light years away a galaxy called GN-Z11 should be traveling at near the speed of light .924c and has been for about 13.8 billion years, relative to us. Applying relativity time dilation, the age of that galaxy, should, concurrent to us, be quite young, maybe 4 billion years, since its always (since the big bang) been traveling at relativistic speeds. So, in GN-Z11, is the time, since the big bang, and current state of evolution of the universe, truly much less than the time here?

More significantly is its future when its 13.8 billion, after 9.8 billion years, still unknown? I think it would be unknown because I truly think only 4 billion years could have passed there at the maximum, but the principle "that the universe has no center" tends to imply that it could be 13.8 billion years old there, and everywhere in the universe, like it is here. Which is it? Is it a fair question?

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    $\begingroup$ This is similar to questions you've asked in the past like this one and this one. GN-z11 has a worldline spanning billions of years, and an intelligent civilization could exist anywhere on that worldline; it would see a universe as old as however old the universe is at that point. There isn't such a thing as the age of GN-z11 "concurrent to us". $\endgroup$
    – benrg
    Jan 3, 2021 at 8:28
  • $\begingroup$ Also, GN-z11 doesn’t recede at 0.924c, but at ~2.2c. $\endgroup$
    – pela
    Jan 3, 2021 at 23:22
  • $\begingroup$ is the 2.2c it easy to calculate? you can't just multiply 13.4 billion light years * 67.4 km/s/Mpec and convert units? $\endgroup$ Jan 8, 2021 at 5:05
  • $\begingroup$ Late answer, but: The velocity $v$ is easy to calculate if you know the distance $d$, as this is just Hubble's law: $v = H_0 d$. The distance is less easy though; here you have to integrate the Friedmann equation, assuming values not only for $H_0$ but also for the various density parameters. Btw, if you add a name in a comment, like "@pela", that person will receive a notification so you don't have to wait half a year for an answer :) $\endgroup$
    – pela
    Aug 4, 2021 at 11:54
  • $\begingroup$ "GN-Z11 should be traveling at near the speed of light .924c" This isn't strictly correct. The galaxy isn't moving that fast - it hasn't accelerated. The space between us and it expanding causes that redshift. $\endgroup$
    – John
    Oct 15, 2022 at 19:11


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