Where does the universe end?

[Riva]

What theories do you have?

Or

What is the theory your religion has given?

 

[Riva]

That question keeps on coming to my mind once every 4 years which makes me travel the stars in my head to go on and on and on and on to imagine all possibilities of an end.

But the end never comes. And then I forget the question for the next 4 to 5 years, for it to come, back haunt and nag me again.

 

[JocktheMotie]

Where does the earth end? It does not. The middle is everywhere!

 

[FDG]

It does not end in a specific place, because outside the bounds of our universe the concept of space as we known it is non-existant. So, it never ends.

 

[Robopop]

If you mean if there is an edge to the universe where you cannot go any further(maybe like a wall or something), then probably not. But space could be finite in size, therefore it could curve in on itself(like the surface of a sphere) so if you were to travel in a straight line eventually you'd arrive at your start point.

 

[King sns]

Not sure. I like to think the rips and holes they have found lead to something else that is important outside of us, but maybe just to the black space. I think about this a lot more than I should, and come up with a lot of funny things. (I feel like a four year old with these funny things, but it's fun for me anyway.) Usually I picture it like a balloon being blown up or pulled open by a vacuum type atmosphere. Other universes. Black space that is surrounded by something else and something else and so on. So in short, not sure. Sometimes reading helps me understand better, and other times it creates more funny thoughts. Maybe I should go for a physics class sometime soon. or I could just keep dreamin'.

 

[guesswho]

The outer lair of the universe is God's beard.

 

[Eric B]

I was always more comfortable with the hyperspherical model (which Jock alludes to, by analogy with the 3spherical earth). So in any direction you travel straight in, you would circle back around to the starting point; only in 3 dimensions, it would actually be a straight line. In hyperspace, you would see the path was really a "great circle".

For some reason, scientists tie the shape of the universe to the rate of expansion. since it's not slowing down, but rather speeding up, they seem to go with a hyperbolic model, where parallel straight lines diverge instead of converging.
(That would almost insinuate that the 4th dimension is time, and they do treat it as such in the equations, but when we speak of 3-space as the surface of a 4D object like a hypersphere, then the 4th dimension is also spatial, and the shape has nothing to do with the rate of expansion, as you could have a closed hypersphere that expands faster).

After reading Brian Greene's treatment of string theory, where he mentions spacetime as itself having strings as its quanta, then it becomes conceivable for there to be an end to space. What would happen, is once you reach a certain point, the strings stop, and you are no longer in space or time. That of course also means your matter (also made of strings, of course) instantly disappears as well. Everything just ceases to exist past this edge. The same thing actually happens if you decrease size to below the Planck length. The strings are embedded in a medium that is not spacetime, so there is actually no space between them. (I've just seen that the theory of this kind of geometry is attributed to mathematician Alain Connes).

In any case, I myself was always uncomfortable with the notion of infinite space. It would have been hard for me to explain why, but as I eventually heard someone else put it; if space is infinite, then everything in it is reduced to zero. Locating a given point in the whole universe, like earth, or even the galaxy, would be like identifying a single point in a line.

One theory is that in an infinite space, eventually, there will be no more possible arrangements of matter, so stuff will only be able to begin repeating itself, until you arrive at an exact copy of our world. The same thing is posited in infinite time as well.
But another point is that if it were uniformly filled with matter and energy, then total matter and energy would be infinite.

 

[Totenkindly]

Where does the earth end? It does not. The middle is everywhere!

IOW, we are in the creamy white filling (instead of the crunchy wafers) of an Oreo cookie?

That's a tasty answer, if true.

 

[stigmatica]

The observable Universe is currently estimated at about Ninety some odd billion light years across, the age around 13 and 3/4 billion years old. (Space expands faster than light).

So the real size of the universe is probably at least 150% of the observable size, but likely even larger. We'll probably never know, considering that, yes, space is expanding faster than light from end to end, and we'll never be able to see further than the age of the universe in light years.

 

[guesswho]

The observable Universe is currently estimated at about Ninety some odd billion light years across, the age around 13 and 3/4 billion years old. (Space expands faster than light).

So the real size of the universe is probably at least 150% of the observable size, but likely even larger. We'll probably never know, considering that, yes, space is expanding faster than light from end to end, and we'll never be able to see further than the age of the universe in light years.

REMEMBER Y'ALL HEARD THAT FROM AN ENFP.

 

[lunalum]

I don't think it has to have an edge. I picture it as either going on forever or looping back into itself, so that if you keep going in a straight line for ridiculous distances you eventually end up back where you started. It doesn't really make sense for the universe to have an edge because then there would have to be something that exists that is not part of the universe that is making the other side of the edge.

I don't think I'm ever going to find that restaurant....

 

[Zangetshumody]

when we solve every conflict, this world will be over.

 

[Saslou]

Seriously .. Does this come easy to you guys or do you ever feel like your brain is going to explode with data/imagery overload?

I love this subject but have a hard time detaching the infinite details so am unable to reach any conclusion until like Riva, i come back to the subject with a clear mind.

I need to find me some guys who will explain (hopefully) in laymans terms.

 

[Eric B]

I don't think it has to have an edge. I picture it as either going on forever or looping back into itself, so that if you keep going in a straight line for ridiculous distances you eventually end up back where you started. It doesn't really make sense for the universe to have an edge because then there would have to be something that exists that is not part of the universe that is making the other side of the edge.

Actually, no it wouldn't. Reading up further on connes' theory, there would be no "other side", as that [i.e. a "side"] presumes more space. But that is the end of space, remember.
What Connes' theory suggests is called noncommutable space. In space, a distance from one string to another (not individual strings, which would probably be indeterminable especially given the uncertainty principle; but let's say part of an observable object) can be traversed, or commuted between. However, the medium the space strings themselves lie in is not commutable. An analogy I'm trying to develop now, is an active matrix display, whether LCD, LED, etc. An image on the display can be defined by picture elements, but in reality, the bits of the image on those elements are really from electronic information sent to particular addresses in a program code, that are not even arranged that way. There may be a "pixel 1" and "pixel 2" and so on, but there is no "1.5". "Between" the pixels doesn't exist, as far as the image is concerned. The same with the edges of the sign.
So the image is a particular construct in space and time, but it is created in an "entirely different conceptual landscape" as Greene put it.

 

[Salomé]

Which one?

 

[Mole]

The observable Universe is currently estimated at about Ninety some odd billion light years across, the age around 13 and 3/4 billion years old. (Space expands faster than light).

So the real size of the universe is probably at least 150% of the observable size, but likely even larger. We'll probably never know, considering that, yes, space is expanding faster than light from end to end, and we'll never be able to see further than the age of the universe in light years.

Yes, the edge of our universe is our event horizon. And this is the horizen beyond which we cannot see any event and it is about 14 billion light years from here.

And interstingly event horizons are common. And of course every self respecting black hole has an event horizon. And so each black hole is also the edge of the universe.

And we can create event horizons in the laboratory, in swirling liquids.

And consider, we are now sharing an event on Central at the speed of light. And as far as we, homo sapiens, are concerned, time and space have been abolished and we are disembodied. It's as though we are pure spirits, but our minds haven't quite caught up with our luck quite yet.

 

[wildcat]

What theories do you have?

Or

What is the theory your religion has given?

When you look into the high open sea you see the sea end in the horizon.
That it because the sea surface bends under your vision.

What is real, the bend of the sea surface or your vision.?
They are both real.
Terra is finite and has no edge.

When you look up at the skyline the horizon greets you there, too.
You see only a fraction of the skyline.
Universe is finite and has no edge.

 

[wildcat]

Yes, the edge of our universe is our event horizon. And this is the horizen beyond which we cannot see any event and it is about 14 billion light years from here.

And interstingly event horizons are common. And of course every self respecting black hole has an event horizon. And so each black hole is also the edge of the universe.

And we can create event horizons in the laboratory, in swirling liquids.

And consider, we are now sharing an event on Central at the speed of light. And as far as we, homo sapiens, are concerned, time and space have been abolished and we are disembodied. It's as though we are pure spirits, but our minds haven't quite caught up with our luck quite yet.

A horizon does not loci.
Does an edge loci?
No.

What does not loci is a horizon.
It is not there.

 

[wildcat]

A flaw in the doctrine.
"There is nothing beyond the edge."
What edge?
Nothing is not beyond.

Is space ahead of Planck time?
Wrong question.

Does number in the loci zero?