New galaxy 'most distant' yet discovered

[D Gary Grady]

20. It depends on which distance scale one uses

As you note, the universe is expanding, so when we see light from a galaxy outside the local group, we're seeing it as it was when it was closer to us. The estimated actual separation today -- the "comoving" distance -- is of course greater. But usually it's the former distance that's given in reports of new galaxy discoveries. Apparently the comoving distance is given here, which makes it difficult to compare different reports, but since galaxies from the very early universe have already been observed, this one can be only marginally farther away.

Incidentally, not only are there almost certainly galaxies too distant for us to observe. it's likely that only an infinitesimal fraction of galaxies are in the part of the universe we can see. Space appears to be "flat" (euclidean) on a large scale, or at least very nearly so, which likely implies that it's far vaster than we can see and quite possibly infinite. (It's still common to refer to the observable universe as "the universe," in part since it's the only part whose existence we can verify empirically.)

Eventually expansion will carry galaxies outside the local group beyond the light horizon, so to astronomers of the remote future, the observable universe will consist of a one big elliptical galaxy (formerly our galaxy, the Andromeda galaxy, and other neighbors) surrounded by an immense lonely emptiness. The only evidence of the gazillions of other galaxies will be in whatever records survive from earlier epochs, such as ours.