Questioning Understanding of the cosmos

Regarding :

Somewhere out in the void — 13.2 billion light years, give or take — is a magnificent red blob, recently discovered by the Hubble Space Telescope. It's a galaxy — or it was; it's long since flashed out of existence — but far less beautiful or dramatic than nearly any galaxy the Hubble has spotted before. Its magnificence, instead, comes from its age.

See the full article here:
www.time.com...

There must be some reasonable explanation as to how they know this.... but...
Here is my question:

If we are only seeing the light that is 13.2 billion light years old.... how is it that we can know that this galaxy does not still exist?
Hopefully someone out there knows...

reply to post by VocalHero


Excellent question.

For starters, since it is an article in a non-scientific journal, you've got to wonder if the writer wasn't just using poetic licence.

That said, the matter isn't exactly cut and dried. As the article pointed out, the first stars were hot, massive and didn't live very long. That means that all of the stars that we see in the Hubble image are long-gone (just like you can bet that every single person in this picture is dead).

The question is, what happened next? Did the gas & debris from the exploding stars get dispersed irretrievably in intergalactic space? If so, then the galaxy is truly gone. Alternatively, if the debris had enough mass to stay in the general area, it would have lead to further star formation, leading to smaller, longer-lived stars like our sun (this is what happens in modern galaxies). So that galaxy would have gone on...

But what happened next? The more we look, the more we find galaxies colliding and interacting. When this happens, some galaxies get torn apart, some get absorbed into others, and some combine in an orgy of star formation and form supergalaxies that, in turn, feed on its smaller neighbors. Since the more time passes, the more likely it is that one or more of these events will befall that far collection of stars.

Thus, we cannot know for certain what became of this particular orange blob, we can be reasonably certain that, if any part of it still exists, it has changed beyond recognition.

That's the fun of this sort of exploration. We create new instruments and find new things that raise more questions, which inspires us to look further and learn more.

What happens next?

reply to post by Saint Exupery


Thank you! You basically confirmed to me that it is simply a guess that it doesn't exist anymore, but most likely does not.

reply to post by VocalHero


Yeah. A phrase like "flashed out of existence" is so unscientific that it it should automatically raise a red flag. The MSM is abysmally bad at reporting scientific discoveries and/or translating them into language the public may understand.

In reality, you may call it a "guess", but it is a well-founded one.

Mmm, the phrase "out of existence" is misleading...
In fact, probably most of the mass in that primeval proto-galaxy was spread and then coalesced with other lumps in the second-generation galaxies...

About *how* do they know, i think they've probably studied thousands of galaxies of diferent ages (regarding their life-cycle, that may be measured by the proportion of Old stars/New stars in the gal.) and established an aproximated "timeline"...
I know, it's a bit vague...

Drakus

reply to post by drakus


That's quite accurate.