So in the NYTimes today is an Associated Press report that astronomers believe the Hubble Space Telescope has detected the earliest galaxy yet — one from 13.1 billion years ago,  when the universe was only about 600 million years old.

Now stick with me here; I'm a fantasist, which means my knowledge base is primarily human psychology, history, myth and narrative theory. This is an Actual Hard Science thing, but I don't know Actual Hard Scientists. There's a question I've been meaning to ask a Real Astronomer, but I never seem to meet one.

So I want to lay this out for you, because somewhere among you all out there must be somebody who is one, or knows one, or knows somebody who knows one.

This all comes from one of Isaac Asimov's Cool Science For Yokels essays that I read, if memory serves, sometime in the early-to-mid 70s, when I was in what was then called junior high. The essay was on cosmogony, which was a hot topic, as the Big Bang theory was in those days decisively overtaking Continuous Creation and the other various versions of Where All This Stuff Came From (though the essay may have been written years earlier).

Asimov pointed out that we knew the gravitational constant and suchlike parameters to state with authority This Much Mass in This Much Space Becomes a Singularity Enveloped in an Event Horizon, otherwise known as a black hole. Now, in those days, Asimov reported that astrophysicists generally adhered to the Law of Cosmic Modesty, which was  "There shall be no such thing as a naked singularity," which was evidence that he was writing  before Stephen Hawking came along and told everybody, "Umm . . . we don't actually know as much as we think we know."

So okay. This is where it gets a little weird.

Asimov, in his usual Asimovian Let's Blow Your Little Geek Mind way, mentioned that all the hard SF writers speculating about what might exist inside a black hole were missing the point. Everyone knows what's inside a black hole, because we are.

Yes, we are.

He did a back-of-the-napkin calculation that clearly demonstrated (given what was then accepted as the mass of the universe and the size of what was then called "the cosmic egg") the universe must be enclosed within an event horizon. Which might be, he theorized, why the velocity of light is God's Own Speed Limit — "C. It's not just a good idea. It's the Law."– because anything going faster than c would have enough energy to burst out through our black-hole universe's event horizon . . . into nobody knows what.

This was all in the way of explaining how an infinite universe can still have boundaries. Reading at the time, it struck me this implies (as a thought experiment) that if you stood and stared into a Perfect Telescope long enough — about 13.7 billion years, give or take — you might find yourself looking at the back of your own head.

Now, I'm not hip to the current thinking on the curvature of space, except for some passing mention somewhere that Hawking thinks it might be a regular ovoid, like a flattened sphere, so I don't know if any of this has any meaning in the state of the art as it stands now.

But . . .

This was all brought back to me this morning, when I read the AP report I mentioned above. One of the astronomers was quoted pointing out how that galaxy has almost certainly by now merged with other galaxies etc etc (not to mention fundamentally changing its major components from supermassive blue stars to the more standard distribution). And we also know that the universe (or, at least, the ordinary matter part of it) was a lot smaller back then.

So here's my Size of the Universe for Dummies question:

Given what we know of how galaxies age — how various elements are gradually created, changing the spectrum profile, and how galaxies collide and trade stars and all that stuff — how do we know that this 13.1 billion years-ago galaxy (or some of its stars, elements, or whatever) is a new and unique find? How do we know that we haven't seen it or its descendants already?

In other words, what if the universe is smaller than we think?

How do we know that high-red-shift smear (or its descendants) isn't part of a cluster we've observed only 10 billion light years away? And what we assume is a completely different one at 7 billion lightyears, and one at 3 billion, and a relatively nearby one at a few hundred million . . .?

(Numbers are chosen entirely at random, only for purposes of illustration.)

Do we know what the primordial cluster that would eventually become the Milky Way looked like, 13.1 billion years ago?

In other words, how do we know that unimaginably distant ancient galaxy isn't going to grow up to be us?

Enquiring minds want to know.