"if The Universe Is Expanding, What's It Expanding Into?"

[Delta4Embassy]

Question I've long mused over. Looking it up a while back, the answer I found didn't really help me only leaving me more confused. But it's worth a read and its' own thread.

Curious About Astronomy What is the universe expanding into

"What is the universe expanding into?

I am very confused about things my science book says about the expanding universe. Every book I have seen has defined the universe as "everything". If the universe is expanding what is it expanding into? It would have to expand into even more universe. I understand that the red spectra indicates that things are moving away from us but that is drifting not expanding, right? If you could help me to understand this, it would be appreciated. Thank you for your time.

This is a very good question which is not at all easy to give a satisfactory answer to! The first time I tried to write an answer to this, we got so many follow-up questions from people who were still confused that I decided to try to answer it again, this time much more comprehensively. The long explanation is below. However, if you just want a short answer, I'll say this: if the universe is infinitely big, then the answer is simply that it isn't expanding into anything; instead, what is happening is that every region of the universe, every distance between every pair of galaxies, is being "stretched", but the overall size of the universe was infinitely big to begin with and continues to remain infinitely big as time goes on, so the universe's size doesn't change, and therefore it doesn't expand into anything. If, on the other hand, the universe has a finite size, then it may be legitimate to claim that there is something "outside of the universe" that the universe is expanding into. However, because we are, by definition, stuck within the space that makes up our universe and have no way to observe anything outside of it, this ceases to be a question that can be answered scientifically. So the answer in that case is that we really don't know what, if anything, the universe is expanding into.

Now, for those of you who want a more comprehensive discussion:"

Longer more convoluted (imo) answer follows at link.

 

[martybegan]

Question I've long mused over. Looking it up a while back, the answer I found didn't really help me only leaving me more confused. But it's worth a read and its' own thread.

Curious About Astronomy What is the universe expanding into

"What is the universe expanding into?

I am very confused about things my science book says about the expanding universe. Every book I have seen has defined the universe as "everything". If the universe is expanding what is it expanding into? It would have to expand into even more universe. I understand that the red spectra indicates that things are moving away from us but that is drifting not expanding, right? If you could help me to understand this, it would be appreciated. Thank you for your time.

This is a very good question which is not at all easy to give a satisfactory answer to! The first time I tried to write an answer to this, we got so many follow-up questions from people who were still confused that I decided to try to answer it again, this time much more comprehensively. The long explanation is below. However, if you just want a short answer, I'll say this: if the universe is infinitely big, then the answer is simply that it isn't expanding into anything; instead, what is happening is that every region of the universe, every distance between every pair of galaxies, is being "stretched", but the overall size of the universe was infinitely big to begin with and continues to remain infinitely big as time goes on, so the universe's size doesn't change, and therefore it doesn't expand into anything. If, on the other hand, the universe has a finite size, then it may be legitimate to claim that there is something "outside of the universe" that the universe is expanding into. However, because we are, by definition, stuck within the space that makes up our universe and have no way to observe anything outside of it, this ceases to be a question that can be answered scientifically. So the answer in that case is that we really don't know what, if anything, the universe is expanding into.

Now, for those of you who want a more comprehensive discussion:"

Longer more convoluted (imo) answer follows at link.

I've had this debate with a friend, and all I have gotten out of it is a headache. To me what it expands into is another one of the "dimensions" we can't fathom in our 4D existence. The expansion has to go "somewhere" but we can't define "somewhere".

This is why crap like this is handled by the uber-high IQ people. I know I don't have the mental acuity to picture these concepts, and I've been considered a "smart" person. I think I might be able to get into Mensa, but I would be the dumbest person in the room.

 

[TheOldSchool]

There's no chance we'll ever know. All we can do is take a hit of the bong and speculate with some Janis on in the background.

 

[Delta4Embassy]

Seems counterintuitive to me. If the space or area the universe takes up is getting bigger, then logicly there must be more 'space' to occupy with space. Like an inflating balloon inside another balloon and both are expanding. If tehre's some rigid 'wall' surrounding the universe then the universe couldn't expand infinitely. And that makes even less sense. But conversely, if the universe is about 80 billion light-years across (oweing to inflation according to latest theories) and getting bigger, then some 'other universe' must exist beyond our current one to fill up as our's gets bigger.

Not a thought to have if trying to fall asleep that's for sure.

 

[martybegan]

Seems counterintuitive to me. If the space or area the universe takes up is getting bigger, then logicly there must be more 'space' to occupy with space. Like an inflating balloon inside another balloon and both are expanding. If tehre's some rigid 'wall' surrounding the universe then the universe couldn't expand infinitely. And that makes even less sense. But conversely, if the universe is about 80 billion light-years across (oweing to inflation according to latest theories) and getting bigger, then some 'other universe' must exist beyond our current one to fill up as our's gets bigger.

Not a thought to have if trying to fall asleep that's for sure.

Maybe we can't apply our vision of "space" to the universe as a whole, i.e treating it as a room with walls and limits. Some people use the balloon approach, saying our recognized "dimensions" are like the surface of an expanding balloon, which leads to the question of what is then inside?

Ugh, I feel the headache coming on.....

 

[TheOldSchool]

"There is a theory which states that if ever anyone discovers exactly what the Universe is for and why it is here, it will instantly disappear and be replaced by something even more bizarre and inexplicable.

There is another theory which states that this has already happened."

- Douglas Adams (Hitchhiker's Guide to the Galaxy)​

 

[Delta4Embassy]

"Space is big. Really big. You just wouldn't believe how mind numingly big it is..."

Cosmic Web aka The Known Universe

 

[martybegan]

"There is a theory which states that if ever anyone discovers exactly what the Universe is for and why it is here, it will instantly disappear and be replaced by something even more bizarre and inexplicable.

There is another theory which states that this has already happened."

- Douglas Adams (Hitchhiker's Guide to the Galaxy)​

There was a short story about a bunch of Monks hiring some tech geeks to run a supercomputer for them. They thought if they listed all the names of God, the universe would end. So as the time approached that the computer was about to reach the end of the program, the tech geeks left the Monastery, thinking nothing would happen and they would have a bunch of pissed off Monks, as they were leaving however, they noticed the Stars going out, one by one.

 

[Delta4Embassy]

"There is a theory which states that if ever anyone discovers exactly what the Universe is for and why it is here, it will instantly disappear and be replaced by something even more bizarre and inexplicable.

There is another theory which states that this has already happened."

- Douglas Adams (Hitchhiker's Guide to the Galaxy)​

There was a short story about a bunch of Monks hiring some tech geeks to run a supercomputer for them. They thought if they listed all the names of God, the universe would end. So as the time approached that the computer was about to reach the end of the program, the tech geeks left the Monastery, thinking nothing would happen and they would have a bunch of pissed off Monks, as they were leaving however, they noticed the Stars going out, one by one.

Sounds like a Larry Niven story. Got a collection of his short stories here and one that came to mind was "The Hole Man" about scientists discovering alien tech on Mars concerning a device that had captured and suspended an artificial black hole. One scientists pisses off another who releases the black hole as the guy's walking under it, it "falls" through him killing him in a very interesting way. Story concludes with other scientists talking about how though small it's eating atoms already and eventually there's going to be a black hole where Mars used to be...

 

[Unkotare]

It's not expanding "into" anything. As it expands, there is more something.

 

[Steven_R]

Seems counterintuitive to me. If the space or area the universe takes up is getting bigger, then logicly there must be more 'space' to occupy with space. Like an inflating balloon inside another balloon and both are expanding. If tehre's some rigid 'wall' surrounding the universe then the universe couldn't expand infinitely. And that makes even less sense. But conversely, if the universe is about 80 billion light-years across (oweing to inflation according to latest theories) and getting bigger, then some 'other universe' must exist beyond our current one to fill up as our's gets bigger.

Not a thought to have if trying to fall asleep that's for sure.

You're thinking about it wrong. The universe isn't expanding into something, like a balloon inside a larger balloon. It's expanding into non-existence.

Think of it like this: the universe is a balloon. Everything we know about the universe (e.g. atoms, energy, time-space) is in the balloon. Out side of the balloon simply doesn't exist. It's not empty space, it just isn't anything because it is a state of non-existence. As the universe expands, it expands existence into this state of non-existence. Where there was nothing before, there is now something because the universe is now there.

But there isn't really an edge to our balloon either. We think the universe is really about 80 billion light years wide, but the math suggests it's not like an expanding ball, so much as it is flat plane that comes back on itself. Think of it like living on the surface of a ball. Go far enough left and you eventually reach your starting point from the right. Go far enough "north" in the universe and eventually you'll be coming from the "south" end of the universe towards your starting point.

It's tough to wrap our brains around, simply because the ape brain really isn't geared or built to think about this stuff. It would be like trying to teach your dog algebra when his brain is designed to do is dog stuff.

 

[Delta4Embassy]

Seems counterintuitive to me. If the space or area the universe takes up is getting bigger, then logicly there must be more 'space' to occupy with space. Like an inflating balloon inside another balloon and both are expanding. If tehre's some rigid 'wall' surrounding the universe then the universe couldn't expand infinitely. And that makes even less sense. But conversely, if the universe is about 80 billion light-years across (oweing to inflation according to latest theories) and getting bigger, then some 'other universe' must exist beyond our current one to fill up as our's gets bigger.

Not a thought to have if trying to fall asleep that's for sure.

You're thinking about it wrong. The universe isn't expanding into something, like a balloon inside a larger balloon. It's expanding into non-existence.

Think of it like this: the universe is a balloon. Everything we know about the universe (e.g. atoms, energy, time-space) is in the balloon. Out side of the balloon simply doesn't exist. It's not empty space, it just isn't anything because it is a state of non-existence. As the universe expands, it expands existence into this state of non-existence. Where there was nothing before, there is now something because the universe is now there.

But there isn't really an edge to our balloon either. We think the universe is really about 80 billion light years wide, but the math suggests it's not like an expanding ball, so much as it is flat plane that comes back on itself. Think of it like living on the surface of a ball. Go far enough left and you eventually reach your starting point from the right. Go far enough "north" in the universe and eventually you'll be coming from the "south" end of the universe towards your starting point.

It's tough to wrap our brains around, simply because the ape brain really isn't geared or built to think about this stuff. It would be like trying to teach your dog algebra when his brain is designed to do is dog stuff.

Latest findings suggests you may be wrong. And that there is in fact 'space' outside of the 'universal balloon.' Matter of regions of the universe is 'clumping' together and being pulled against the very 'border' of the balloon as if being attracted by some massive gravity source. Yet the direction it's getting pulled is the furthest most border of the known universe. Shouldn't be anything there to attract it unless there's another universe outside and jutted up against our own.

Article describing this phenomenae,
Mysterious dark flow at the edge of the universe - physicsworld.com

 

[Delta4Embassy]

"Astronomers have found that whole clusters of galaxies are moving in convoy towards a single point in the sky. This unexpected motion appears to be separate from the expansion of the universe and the researchers even suggest that a force beyond the visible universe is the culprit. The discovery has been named "dark flow".

Cosmologists have already observed two distinct effects caused by invisible entities in the universe: dark matter is known to affect the rotation of galaxies and dark energy seems to be causing the expansion of the universe to accelerate. Dark flow is the latest addition to this shadowy family.

Bubble siblings

The answer to the source of dark flow might be found in the universe's infancy. "What we believe is happening is that we are measuring the influence of the parts of space–time that were there before the inflation of the universe," Kashlinsky told physicsworld.com.

The theory of inflation suggests that the early universe was like cosmic foam made up of many bubbles. One of these bubbles underwent a huge and rapid expansion, when the universe was just 10–36 seconds old, to become the universe that we see today. It is our neighbouring bubbles that Kashlinsky holds responsible for these migrating galaxy clusters.

"Inflation says that if you go to sufficiently large scales you should see structure that is outside this bubble, outside of our universe. If we live in such a world these structures would cause this motion and we suspect that this is what we are seeing," he said.

The findings are published in Astrophysical Journal Letters."
Mysterious dark flow at the edge of the universe - physicsworld.com


Kinda annoying though there may be adjoining universes. Rather than explaining how our universe came to be, it just expands the size of the problem. Say there are in fact universes jutting against one another like soap bubbles, ok fine, so how'd all that come to be?

 

[rightwinger]

Matter is expanding into areas where previously there was no matter

 

[Unkotare]

Whassamattayou?

 

[Vikrant]

There are various schools of thought that propose different models of universe. The school of thought which pushes forward big bang theory is quite popular among religious people. This theory has been expanded to include the idea of finite universe which is expanding. This leads to all sorts of confusion such as "What this universe is expanding into?"

However, there is another theory which is quite popular and it appeals to many people. This theory states that what we call universe is nothing but a black hole. Apparently, there are multiple black holes and in each of those black holes lies a universe unto itself. What we call our universe could very well be a child black hole of another black hole. We cannot see them. But just like we can see our children black holes, our parent black hole can see all its children black holes. This does eliminate lots of confusion but adds some new ones such as "How many layers are there? "

"Is there a root layer from which all the children layers evolved?"

My take is this: it does not matter which theory you go with, you will always end up with some unanswered questions. This is the beauty of this universe.

---

Every Black Hole Contains a New Universe Inside Science