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Why is there a normal galaxy sitting at the edge of the Universe?

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Re: Why is there a normal galaxy sitting at the edge of the Universe?

#41

Post by dumbfoundded »

joombaga wrote: post #33
vkou wrote: post #22

Earlier quoted context omitted.

No, 13 billion years is the age of the universe. The observable universe is a sphere with a diameter of ~93 billion light years (And is likely to only be a subset of the entire universe).

Sorry to bikeshed, but I was struck by the word "likely" in your parenthetical. Are there models of the universe that predict our observable universe is _not_ a subset of the entire universe? How would one describe cosmological expansion in such a model?

The Cosmic Microwave Background Radiation is a pretty uniform field that exists over the entirety of the observable universe. It was created in the earliest days in our universe. The fact that it exists everywhere we look with high regularity lets us guess that we're only a subset of a larger universe. There are many theories about the unobservable parts of the universe but these are impossible to test with any foreseeable technology that doesn't fundamentally break our understanding of physics.

Re: Why is there a normal galaxy sitting at the edge of the Universe?

#42

Post by webkike »

komali2 wrote: post #34
excalibur wrote: post #4

> Why is there a normal galaxy sitting at the edge of the universe? To facilitate the restaurant?

This is a reference to Douglas Adams' absurdist Sci Fi series, "Hitchhiker's Guide to the Galaxy," which is amazing and I recommend everyone read! https://www.goodreads.com/book/show/13.The_Ultimate_Hitchhik... (The first book is "Hitchhiker's Guide to the Galaxy," there are 5 books, one of which is titled "The Restaurant at the End of the Universe")

It bugs me that no one realizes that the “end” refers not to the “edge” but at the closing of the universe - the restaurant is in a frozen time bubble that can watch the universe end.

Re: Why is there a normal galaxy sitting at the edge of the Universe?

#43

Post by xwdv »

adventured wrote: post #37

> The thing is, where they found it is not normal: The light we see from it left the galaxy 12.4 billion years ago, meaning we’re seeing it as it was when the Universe itself was only 1.4 billion years old! It's not confusing at all. It's because the long-worshipped, conventional big bang theory is wrong. The universe doesn't have a beginning or end. It's eternal. The original sin of that theory is that it's tainted…

Wouldn’t a universe with no beginning or end begin to exist only when the first sentient being is able to observe it?

Re: Why is there a normal galaxy sitting at the edge of the Universe?

#44

Post by jahnu »

disown wrote: post #20
excalibur wrote: post #4

> Why is there a normal galaxy sitting at the edge of the universe? To facilitate the restaurant?

Not that anyone cares what I say, but the Restaurant is on the other end of the universe.

Give it a rest, Marvin

Re: Why is there a normal galaxy sitting at the edge of the Universe?

#45

Post by jahnu »

komali2 wrote: post #34
excalibur wrote: post #4

> Why is there a normal galaxy sitting at the edge of the universe? To facilitate the restaurant?

This is a reference to Douglas Adams' absurdist Sci Fi series, "Hitchhiker's Guide to the Galaxy," which is amazing and I recommend everyone read! https://www.goodreads.com/book/show/13.The_Ultimate_Hitchhik... (The first book is "Hitchhiker's Guide to the Galaxy," there are 5 books, one of which is titled "The Restaurant at the End of the Universe")

Many people don't know that a radio series preceded the books. I find that the funniest version, personally.

Re: Why is there a normal galaxy sitting at the edge of the Universe?

#47

Post by bhk »

lkbm wrote: post #36
wffurr wrote: post #29

Earlier quoted context omitted.

"Measurements made by NASA's WMAP spacecraft have shown that the universe is 13.7 billion years old, plus or minus about 130,000 years." https://starchild.gsfc.nasa.gov/docs/StarChild/questions/que... .

Whoa, that's crazy precise. They got it down to the tens of thousands? If so, seems like they should write "13.700 billion" for the first part. I'm a little suspicious of this number as-is. Looking for a source for those numbers, I found this[0]: > While previous estimates were 13.7 billion years old, give or take 130,000 years, new predictions hone in with more precision- at around 13.77 billion years, plus or minus…

So NASA said "plus or minus 130,000 years" when they were actually off by about 70 million years?

Re: Why is there a normal galaxy sitting at the edge of the Universe?

#48

Post by sdflhasjd »

joombaga wrote: post #33
vkou wrote: post #22

Earlier quoted context omitted.

No, 13 billion years is the age of the universe. The observable universe is a sphere with a diameter of ~93 billion light years (And is likely to only be a subset of the entire universe).

Sorry to bikeshed, but I was struck by the word "likely" in your parenthetical. Are there models of the universe that predict our observable universe is _not_ a subset of the entire universe? How would one describe cosmological expansion in such a model?

It depends on the size and topology of the entire universe. It's possible the universe is smaller and sort of wraps around: literally, objects that appear far away are just past images of the back of objects that are closer to us.

More boringly, measurements of the curvature of the universe mean this is probably not the case.

Re: Why is there a normal galaxy sitting at the edge of the Universe?

#49

Post by djsumdog »

dumbfoundded wrote: post #41
joombaga wrote: post #33

Earlier quoted context omitted.

Sorry to bikeshed, but I was struck by the word "likely" in your parenthetical. Are there models of the universe that predict our observable universe is _not_ a subset of the entire universe? How would one describe cosmological expansion in such a model?

The Cosmic Microwave Background Radiation is a pretty uniform field that exists over the entirety of the observable universe. It was created in the earliest days in our universe. The fact that it exists everywhere we look with high regularity lets us guess that we're only a subset of a larger universe. There are many theories about the unobservable parts of the universe but these are impossible to test with any fores…

One analogy I've heard: Imagine the big bang split into 4 spheres and they accelerated away from each other. Because they'll all be expanding and accelerating, there could be 4 equally sized spheres of stuff just like our own, but it would be impossible for us to observe them. Change the number 4 to 2 or 1000 or n. We really would have no idea.
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