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Question Edgeless universe?

May 26, 2020
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First post, so let me know if I should be in a different forum. Also, I’m not astrophysicist smart, so please forgive my lack of understanding.
I wanted to know what the universe is expanding into. I read a space.com article stating the universe has no edge so it’s not expanding into anything. If I were to travel across the universe eventually I’d end up where I started. I guess that’s the same for light?
if a galaxy is moving away from us, isn’t it also moving closer to us from the opposite direction?
 
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You will probably get a lot of variety in replies.
I don't think you will meet yourself coming back.

I will kick off with one idea I had long ago. If you got to the edge of the Universe (whatever that may mean) there is nothing beyond. If you set off away from the Universe you would become the edge of the Universe. In other words you need a frame of reference. The 'edge' of the Universe must be defined by something. A star ? ? ? whatever. When you set off beyond, you become the new defining point.

You will get more sophisticated replies (maybe including one from me) but I thought I would kick off with a simple one.

Enjoy your visits here. Look through the topics.

Cat :)
 
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May 26, 2020
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Something to consider:
Thank you for the article. It helps to balance the arguments for a closed universe. However, I’m not looking for confirmation of the shape of the universe. Whatever shape it is, I have questions about how it works. Since I titled this post ‘Edgeless’, I’ll just ask closed questions and do flat questions in a separate post.
If a galaxy is moving away from us, is it moving towards us from the opposite direction?
 
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Apr 5, 2020
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Thank you for the article. It helps to balance the arguments for a closed universe. However, I’m not looking for confirmation of the shape of the universe. Whatever shape it is, I have questions about how it works. Since I titled this post ‘Edgeless’, I’ll just ask closed questions and do flat questions in a separate post.
If a galaxy is moving away from us, is it moving towards us from the opposite direction?
Er, actually, we do not it yet. According to Hubble, everything is moving away from us in the speed of the Hubble Constant. And, today's scientist have got to know what's moving that away: Dark Energy. The energy that makes up the most of the Universe (e=mc^2). That is why the universe is expanding and expanding and the amount of Dark Energy seems to be constant. And, that's why the universe is not as large as it's age, it's more large than that.

I just read this: https://www.sciencealert.com/stephen-hawking-s-last-physics-paper-theory-on-eternal-inflation-multiverses
 
May 26, 2020
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That article also covers the shape, and also a bit on the definition of universe, which I want to come back to later (winks at Catstrophe). Right now I’m looking for an answer to my question. If I travel towards a galaxy faster than it is moving away from me I will eventually get there. If I keep going I will pass it. In a closed universe if I keep going I will eventually catch it again. If I start out in the opposite direction eventually I will also get to the galaxy. Since I’m arriving at the same galaxy, it seems in one direction it’s moving away from me, but in the other direction it’s moving toward me. Right?
 
" Right now I’m looking for an answer to my question. If I travel towards a galaxy faster than it is moving away from me I will eventually get there."

The answer is, like a car, you will overtake it unless you are getting close to c.

You will have the problem that your premise may be invalid. If you and your chosen galaxy are moving apart proportionally to the distance you had better pull your socks up (Hubble).

I bet you haven't even got your spacesuit ready?
 
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If I start out in the opposite direction eventually I will also get to the galaxy.
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To put it politely. this is "blowing in the wind".

The Universe is a large place. You don't have a compass. You don't have a spacesuit. You don't have FLT. You are not immortal.

Your premise is leaking badly.
 
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Edgeless Universe?

To be serious, if we are going to posit totally impossible questions, involving such as travelling FLT, non-defined positions., and lack of PPE, we are entering total imagination of the worst anthropomorphic kind.

If you treat exiting the Universe like going to the bathroom you might find that you cannot flush away any galaxies in your way
 
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I am sorry you feel like that. Ask anyone and you will find that I have the reputation of being a kind and helpful person, I have more 'likes' than anyone else. Likes are not only for content. An arrogant person even with good content is not so favoured. I have not attacked you. That is not my nature. What upset me was your dismissive attitude taking over the thread and telling people they could not post until if and when you remembered. There are no personal attacks here. I offer my digital hand to shake (it is covid free) but please don't tell people what to do. I don't know if you intended to be facetious or comical but IMHO that is how some aspects of your post appear. How do you recognise the edge of the Universe? How would anyone get there? I appreciate you are theorising but you should not stop this being pointed out. If there is no practical way of going around the Universe and meeting yourself, it is blowing in the wind to discuss it. Anyway, you have your style and I have mine. I am not unpopular here so perhaps you should examine your attitude. I wish you every success and, even more, I wish you every popularity here.
 
Regarding an edgeless Universe, I believe it is necessary to realise that you need to define your ideas of edge and so on. If I have overstated my view then I hereby publicly apologise. Perhaps I will leave this thread alone now and let those who wish to enjoy whatever their ideas may be. I mean this as it is. It is not intended to be sarcastic. Please continue and enjoy. :)
 
May 26, 2020
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If my words have offended you I apologize as it was never my intent. You brought up a good point; I acknowledged it. I want to talk more about it, but I prefer to tackle one discussion at a time. I didn't come up with this theory. I was doing research on what the universe is expanding into. I got the edgeless universe theory from several sources including wikipedia and space.com. All of these stated that if you started out in a straight line eventually you would end up where you started.
My original question is part of a longer journey. The answer to which will determine the next path to take. Along that journey I expect to come to the definition of the universe. I don't know where the journey will end, but I hope it's not where I started.
 
Good. I can be my nice friendly self :)

Sorry, but I still have the same problem. An edgeless Universe is directly analogous to the seamless surface on a sphere. As you say, if you accept this analogy, you start at a point, say Quito which is virtually on the Equator. Set off in a straight line, which is actually the curved Equator, and you get back to Quito. A "straight" line from Quito can now be to the Moon, but this would be an extra dimension for the flatlander confined to the surface of the sphere. Do not be confused by my analogy of the Earth. I assume we can agree all that?
Now if the Universe is the sphere in the analogy, as the Universe expands the surface of the sphere expands. We, as flatlanders, cannot get off the surface of the sphere = Universe. The distance between us increases but we are still on the "surface".
The problem is we are trying to relate mere humans to the whole Universe, about which we know next to nothing. What the Universe is expanding into, is a non-question. The big problem I have with the Expanding Universe" is that we (objects) are not expanding with it. If ALL were expanding we would not know it, since our rulers would be expanding too. That, I believe, is a flaw in the Expansion theory. By analogy, the surface of the sphere = galaxy and the "into" bit relates to the expansion of the surface. No, you will say, it is expanding "outwards". You are correct, but that is a different dimension unknown to the flatlander. That dimension is unknown to us and it is not the "into" in your question: "Into what is the Universe expanding. Your answer is: "The Universe, as a surface, is expanding. Expansion perpendicular to that surface is in a dimension we cannot detect. It is not in a space dimension familiar to us. Any attempt o make it so is anthropomorphic.

I hope that helps. I am very happy to continue the discussion :)
 
You posted " I read a space.com article stating the universe has no edge so it’s not expanding into anything."
That article is right if the "anything" is the dimension I wrote about. Because it is a dimension unappreciable to us.
Do you have the ref please to that article?

Having done a quick search, is it this one?
"The new study was published today (April 25) in The Astrophysical Journal. You can read it for free at the online preprint site arXiv.org."



;
 
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Apr 5, 2020
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And also, according to the present accepted theories, the Universe is a sphere. And, I don't think a sphere has an "edge" if you mean it. A sphere has no vertex.
 
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I had read somewhere, maybe in the Brief History of Time, that there is a theory that the universe is infinite. And as far as I know infinity + anything is infinity.
 
Nov 20, 2019
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First post, so let me know if I should be in a different forum. Also, I’m not astrophysicist smart, so please forgive my lack of understanding.
I wanted to know what the universe is expanding into. I read a space.com article stating the universe has no edge so it’s not expanding into anything. If I were to travel across the universe eventually I’d end up where I started. I guess that’s the same for light?
if a galaxy is moving away from us, isn’t it also moving closer to us from the opposite direction?
Welcome from me also.

First of all, I would like to suggest that the dictionary definition of the universe, ie "it is everything there is", is out of date, I suggest it was thought of well before the big bang model. This definition doesn't allow for multiple or infinite other universes or multiverse theories etc. So, I would like to add to this thread with some of my own personal ideas.

Our universe started with a finite size, it has a finite rate of expansion and a finite age, so it must now have a finite size. I now treat the universe as an object. Objects exist in a space, they don't create all of space. I think the space our universe is in must be infinite, I call this space 'The Infinite'. So, I now see 'The Infinite' as 'everything there is'.

I also believe nature does not allow one-off processes, if it's possible once then it's always possible. The big bang was a natural process, so, given an infinite space as in 'The Infinite', there must be an infinite number of universes.

So, my answer to your question is that the universe is expanding into the space of 'The Infinite'. Space is a tangible 'something' such as quantum field/foam/fluctuations, vacuum energy, dark energy etc, it's not a void. So as well as expanding into space, space also came out of the big bang along with its matter and energy:)
 

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