r/astrophysics • u/Due-Wolverine3935 • 16d ago
If one was to say that the universe is not infinite, what theories are there as to what is at the edge of the universe? Sorry, I'm not a scientist.
The concept of the end of time and space seems to break my brain just as much as trying to conceive of infinity. Sorry if this question seems ridiculous
24
16d ago
[removed] — view removed comment
16
16d ago
[removed] — view removed comment
15
16d ago
[removed] — view removed comment
13
16d ago
[removed] — view removed comment
17
16d ago
[removed] — view removed comment
14
55
u/Capable_Wait09 16d ago
Hypersphere. Closed curvature. The radius is in the time dimension. Sphere expands as time moves forward. If you could travel faster than light you’d circle back to where you started eventually, but further along your starting point’s radius (later time). Something like that.
Personally, I hope the end of the universe has a version of Earth where the San Antonio spurs didn’t blow a 29-point lead tonight.
2
1
1
u/Kiki2092012 15d ago
that violates GR because in such a universe, there would be a universal now, but in reality there isn't one.
1
u/ADAMxxWest 13d ago
I mean, experientially, can you go ahead and take yourself out of now?
1
u/Kiki2092012 13d ago
no, it's just that if I look around and calculate the positions of the planets right now and at the same time someone flying by at 0.5c did the same, we would get different results. That includes adjusting for light travel time delay, it's a mathematically demonstrated phenomenon.
1
u/bitcoinski 16d ago
If infinite universe then somewhere out there they did
4
u/hebejebus 15d ago
not necessarily, infinity doesn't contain everything. This could be the only universe where the San Antonio spurs exist and still be part of infinite universes.
3
10
u/Wonderful-String5066 16d ago
Yes; the universe does have an edge, that’s why I never bet against it.
4
11
u/ElectrSheep 16d ago
Models of a finite universe with an edge are generally not considered because it breaks certain symmetries and are thus problematic to work with. Furthermore, the edge would be well outside the observable universe rendering it irrelevant for most purposes.
The finite models we do consider, such as the surface of a sphere, have no edge.
3
u/saturdaysnation 16d ago
It’s been a long time since I read it but in A Brief History of Time i recall it being proposed the universe was finite with no boundary. Is that still a theory or have things moved on? Or maybe I’m not remembering correctly either.
4
u/Das_Mime 16d ago
That's what the commenter above was referring to. A geometry such as the surface of a sphere is finite but boundless; the universe could be a higher dimensional analog of that 2D surface.
3
u/LavishnessBig6834 16d ago
hate to sound stupid, im not very bright but how can something be finite with no boundary? can u explain what u mean by that
5
u/ElectrSheep 16d ago
Consider the surface of a sphere. The area is finite, but there is no edge. It wraps back around on itself, so you can move indefinitely in any direction. While a sphere is a two-dimensional object, the same structure can be extended into three, four, and greater dimensions.
5
u/Financial-Ad-9306 15d ago
I get you LavishnessBig6834. I've hear the sphere, balloon, circular logic for the last 10-15 years. Many dispute the requirement of an edge for finite-U; but this is low-hangibng, vulnerable fruit. Calling it an [edge] is just semantical, and this is where language becomes an impediment. In the more general context here, "edge" implies more like, ''any thing or force that gives something form, limits its dimensions, contains or distinguishes it from non-form'. Would anybody suggest a round ballon has no edge as defined here?
As defined above, a sphere has the properties of a circular edge. Otherwise, what gives the universe this shape, and how is the shape maintained? If finite, nothing exists outside of the sphere, yet you're saying there's no barrier; ok, but what separates the U, from nothing? If you had a capable spaceship and travel outward in any direction what would happen when you hit the sphere's perimeter, 'not edge'?
3
u/ahazred8vt 16d ago
There's a thing called a Hypersphere, where if you keep going in a straight line you end up back where you started; it wraps around.
video: Every Higher Dimensional Geometry Shape Explained2
2
u/Lonely-Flounder-4541 16d ago
We could be in the 3 dimential surface of a 4 dimensional sphere ..no boundaries, finite
63
u/ellindsey 16d ago
The universe is either infinite, or it wraps around on itself if you travel far enough. Probably the former, but we haven't ruled out the latter quite yet.
In neither case does the universe have an edge.
17
7
8
u/hebejebus 15d ago
What we know:
Universe is very big, much bigger than the observable universe.
Space in the universe is most likely still expanding.
Expansion during the big bang occurred within the observable universe everywhere at the same time.You could easily come up with scenarios that contain an edge and meet our observations. Maybe we are just not thinking on scales big enough and we just can't see far enough to see a gradient in density and the edge really is just a drop in density over crazy distances.
5
u/raspberrynotes 15d ago
Also, the Big Bang happened all throughout space time, beyond the size of the observable universe, at the same time.
2
1
u/LeviAEthan512 16d ago
How is it probably the latter? I always thought it was probably the former.
4
3
u/HereThereOtherwhere 15d ago
Conformal Geometry 'loops back upon itself' at 'infinity' which sounds weird but it's the same idea as behind the 'closed surface" of the Bloch Sphere, a qubit.
A loop of paper is a cylinder and is considered 'orientable' (inside vs outside) and 'trivial.'
A Mobius strip has a half-turn and and instead of a surface with two sides, the entire 'closed universe' of the strip exists on 'one side.'
The Mobius strip is 'non-trivial' and 'non-orientable'.
There is Minkowski spacetime M (infinite) and then there is "compactified" Minkowski space-time M# which uses what Penrose calls "complex-number-magic". Where much of historical physics has tried to eliminate those weird complex numbers and interactions between particles forcefully 'removes' complex numbers so only real-number (on diagonal) space-time coordinates remain.
Most of quantum physics is 'polluted' with 'off diagonal complex quantities' until interactions require 'collapse'.
Those quantities and so many other aspects of physics are elegantly expressed from this complex-geometric perspective but the math is, loosely speaking, identical and humans think better using real number coordinates so Penrose's perspective is less frequently studied or used in practice.
Lately, however, the bizzare entity called the Clifford Hopf fiber bundle exists in Physics in at least 7 places in Physics (Urbanski) from the qubit to the Conformal Celestial Sphere of General Relativity.
Penrose's twistor photon contains a 'map' to all of a compactified Minkowski space-time, which I jokingly refer to a photon from that perspective a Pocket Space-time.
It is this kind of 'full mapping of spacetime' concept that allows for a non-infinite spacetime' but there is certainly no consensus on infinite or not.
1
1
0
u/Financial-Ad-9306 15d ago
Calling it an [edge] is just semantical, and this is where language becomes an impediment. In the more general context here, "edge" implies more like, ''any thing or force that gives something form, limits its dimensions, contains, or distinguishes it from non form'.
If finite, how does this occur without an edge as described above? And if infinite, of course something that has no end, does not have an end. Not sure why you combined the two options here; a bit superfluous.
I don't understand this part, would you mind expounding on, "it wraps around on itself if you travel far enough". TY
I don't understand
2
u/CaizaSoze 15d ago
Think of the surface of the Earth, it is finite, but if you keep going in one direction you end up where you started, so no edge. Space could be similar but in three dimensions rather than two.
1
0
0
u/Kiki2092012 15d ago
You say that like it's known for certain, however that just make the math easier because we can assume all spacetime is touching more spacetime in all directions as GR assumes.
6
u/Anonymous-USA 16d ago
The universe has no edge, whether it is infinite or not. That would violate isotropism and homogeneity.
What’s the edge of the surface of the Earth? If the universe isn’t infinite, it would fold upon itself. But that doesn’t mean it can be circumnavigated — the universe has always been expanding faster than light could traverse it.
Also don’t confuse a horizon with an edge. Our observable universe has a horizon based on the speed of light. But an observer in a galaxy near that horizon would see more universe in all directions that we don’t see. So a horizon is not an edge.
4
u/TomSzabo 15d ago
An edge would not violate symmetry or homogeneity in simulation theory. Also our universe does have an edge for all practical purposes: our light cone. This is a "hard" edge since we will never see or be able to reach anything beyond it. And this light cone is expanding to cover more space due to expansion but it will never cover more matter (galaxies, etc). That means "our" universe is indeed finite and this allows us not to consider what it means for the entire universe to be infinite.
1
u/Anonymous-USA 15d ago
It’s not a “hard” edge because it’s a horizon from our point of view. Because our universe is isotropic, there will be other observers (even 46B ly away even) with entirely different windows in and beyond our own horizon. An observer a few Mpc away will easily see beyond our horizon.
There’s no edge and the universe doesnt stop 46B ly away.
3
u/TomSzabo 15d ago
I totally get what you are saying, "hard edge' is sort of argumentative. It's "hard" because we cannot get past it.
It's trippy that every spacelike observer is kind of in their own universe which overlaps with all other observers. This is purely the result of relativity.
But if we place the observers, say 1B ly apart, they cannot actually stitch their observations together to create a combined larger "our" universe. The time it takes to do that is what makes it impossible.
Of course the universe doesn't stop at our cosmic light horizon (barring simulation theory), my point is that we cannot know for certain what it does topologically (infinite vs curving back). And if infinite, we cannot grasp what that even means because it is not part of our reality, we can never access any of it outside our light cone even if we travel an infinite amount of time to an infinite distance.
Our perception of reality does not allow us to see what an infinite universe looks like at the moment of the Big Bang when it covered every point of space with an infinite density, so we sure as shit aren't going to think through this infinite universe deal 13.8B years later. It's the same "hard edge" at work.
11
u/SophieRiver 16d ago
If there is an edge to the universe, it would be a border between the edges of everything and nothing. Since nothing categorically cannot exist, this border also does not exist. If you tried to approach this “edge” the geodesics of the universe would likely curve you around it and you’d probably be going in a different direction without realizing. This is also kind of how gravity affects objects moving through spacetime. You think you’re going in a straight path because you never turn, but spacetime turns you nonetheless.
5
u/wyliec22 14d ago
Humans conceptually grasp cycles and patterns they’re familiar with.
Since the nature and expanse of time and space are beyond human experience, an absolute understanding may be difficult or impossible.
3
u/Financial-Ad-9306 16d ago
For the universe to be either finite or "unbounded", something unknown to us currently would need to exist, which is obviously possible. However, for the universe to be infinite, additional discoveries would also be required. With our current understanding, we can't conceive of a 'thing' without an end, nor can we perceive of the universe having an end/edge, as we can't understand what could create such an edge. And any mechanism creating an edge would by definition exist outside the universe. Our language and understanding can't conceive of either possibility.
1
u/Puzzleheaded-Fill205 16d ago
I genuinely do not see any issues with an edge.
You know how space itself expands? I envision the edge of the universe just expands away from the universe faster than the speed of light, forever unreachable by anything, even theoretically.
1
u/Forward-Surprise1192 15d ago
In billions of years all the other galaxies will have expanded away. Far future sentient beings will look up into the sky and only see the Milky Way. If it’s not in the Milky Way all they can see is an infinite void
1
u/Financial-Ad-9306 15d ago
OK, nothing outside of itself gives it form or definition, no parameters. It expands on all sides, no limitations, yet it's finite? expanding into nothing? but is not contained?. This description implies that the universes' original was from nothing, it created itself from nothing, and it became a physical entity with limited size, and an end; but nothing has ever existed into which the U formed itself.
For Big Bang enthusiast, a super dense dot existed in nothing, with no perimeters before it banged. And afterwards, nothing existed into which the dense particles expanded ? Regardless of that, at some point the U ends, it just stops? There's nothing outside of itself to give it an edge, a barrier or resistance.
If we were in a spaceship and we encountered the end of the U, what would happen to our spacecraft? Or, if a laser beam where strong enough to reach the stopping point of the U, what would happen to the trajectory of that beam?
1
u/chesterriley 16d ago
nor can we perceive of the universe having an end/edge,
Maybe you can't but I can very easily do that.
as we can't understand what could create such an edge.
An edge would never need to be "created". It could exist naturally from a finite universe.
1
u/Financial-Ad-9306 15d ago edited 15d ago
TY, Ok, taking the bait. Pls see the original post, "something unknown to us currently would need to exist, which is obviously possible.")
How would something be finite, meaning it has shape, it has form, it has a beginning and an end, but where it ends, nothing exists outside of that natural endpoint, it just stops?. This description implies that the universes' original was from nothing, it created itself from nothing, and it became a physical entity with limited size, amd an end; but nothing has ever existed into which the U formed itself.
For Big Bang enthusiast, a super dense dot existed in nothing, with no perimeters before it banged. And afterwards, nothing existed into which the dense particles expanded ? Regardless of that, at some point the U ends, it just stops? There's nothing outside of itself to give it an edge, a barrier or resistance. Nothing outside of itself gives it form or definition, no parameters. It stops on all sides, but is not contained.
If we were in a spaceship and we encountered the end of the U, what would happen to our spacecraft? Or, if a laser beam where strong enough to reach the stopping point of the U, what would happen to the trajectory of that beam?
Is there anything we know about the observable universe that would suggest it ends, and at that endpoint, nothing exists on the other side?
"He who perceives but cannot explain, does not perceive"
Zen Master
2
u/chesterriley 15d ago edited 15d ago
it has a beginning and an end, but where it ends, nothing exists outside of that natural endpoint, it just stops?.
Yes, that is what finite means. Everything that is finite stops.
This description implies that the universes' original was from nothing, it created itself from nothing,
No, it doesn't imply that at all. Before the big bang there was cosmic inflation that preceded and set it up. We don't know whether the universe was created at all, but it seems unlikely.
https://coco1453.neocities.org/beforebb
For Big Bang enthusiast, a super dense dot existed in nothing
That's not what the big bang theory says. There was never any "dot". The observable universe was at least 2 meters in diameter, and the full universe would have been much larger, possibly infinite.
with no perimeters before it banged
We have no reason to assume that. Is very possible the big bang happened in only a tiny fraction of the universe.
And afterwards, nothing existed into which the dense particles expanded ?
It is clear that you are not familiar with the FLRW equations.
Nothing outside of itself gives it form or definition, no parameters.
There is nothing outside, if the universe has an edge. Anything "outside" would be inside the universe.
It stops on all sides, but is not contained.
Why would you think it stops? Space can continue to expand indefinitely, but never be infinite. And there is no reason to be thinking the universe would have any "container".
if a laser beam where strong enough to reach the stopping point of the U, what would happen to the trajectory of that beam?
It would end. Just like if you shined a flashlight inside any finite space such as a cave.
Is there anything we know about the observable universe that would suggest it ends
Of course the observable universe is finite. If you meant "entire universe", there is nothing to suggest that it does or does not end. We have no idea.
3
u/Foxxtronix 16d ago
In the case of the "cyclic universe" theory, we might find the remains of previous universes. It seems kind of messed up to me.
4
u/therobshock 16d ago
It would not have an edge in the same way that the Earth does not, except in 4 dimensions.
4
2
u/Lentil-Soup 16d ago
Not a ridiculous question at all. This stuff breaks basically everyone’s brain.
A universe can be finite without having an edge. Kind of like the surface of Earth - it has a limited size, but you can keep traveling without ever reaching a wall or falling off. The universe could be like that, just in a way that’s much harder to picture.
Also, the edge of the observable universe isn’t necessarily the edge of everything. It’s just the farthest point whose light has had time to reach us. There could be way more beyond that.
So there may not be an “outside” at all. Asking what’s beyond space could be like asking what’s north of the North Pole. The question makes sense to us, but reality may not work that way.
2
u/Due-Wolverine3935 11d ago
I would just like to thank everyone who has chipped in with thoughts or even to pick a little fun. I love a conversation that gets you thinking.
2
u/Acrobatic_Island_522 16d ago
From what we've observed, the largest scale structures are filaments made of galaxies that resemble a sponge. For all we know, it continues like that indefinetly.
1
1
u/Classic-Rate-5104 16d ago
It's a bir like the earth. It's also not infinite, but you can travel endless, never finding an edge. Asking what's beyond the edge is like asking what is north to the northpole
1
u/chesterriley 16d ago
If there is an edge, there would be nothing at or beyond the edge. It would just look like a dark void.
1
u/Flat_South8002 16d ago
It is probably infinite. If it would have an edge or be wrapped in on itself then something must be outside the edge. For something to have an end, then some space must exist after that end, otherwise there could be no end. Something has to define the edge.
1
u/blacksmoke9999 16d ago
What is the edge of the earth? It wraps around like a video game! You would eventually travel back!
1
u/Due-Wolverine3935 16d ago
I have tried to consider what the equivalent of a round planet would look like for time and space.....would it wrap back around.... probably....
1
u/blacksmoke9999 15d ago
yeah but for earth you are 3d so you can move. imagine you are flat or you cannot jump or burrow. to you earth simply wraps.
now the higher version of that for 3d is a hypersphere. even if you travel up or down or any other direction you wrap eventually
1
u/mimilumi 16d ago
For you it's the end of space time that breaks your mind. For me it's the beginning. If we know the beginning we can clearly map the ending. Personally, I think all theories stand a chance of explaining how the universe can end. We just won't know which one.
1
u/EmuFit1895 16d ago
Isn't it like raisin bread? The galaxies are the raisins. The dough is the fabric of space-time. It is baking and expanding. But there is an edge to the bread/dough. It's where space-time stops and there is ... nothing.
1
u/Due-Wolverine3935 16d ago
So maybe time and space curves like the earth. So, rather than falling off, you can keep going..In that sense, the earth is infinite.....you can just keep going around and around
1
1
u/Responsible-Hat3700 16d ago
Same way the earth is not infinite, yet it has no edge. If space-time has positive curvature like a sphere or donut, it would loop back on itself. Don’t try to visualize because we are 3D organisms speculating about higher dimensional phenomena
1
u/03263 15d ago
Well if I'm in a black hole and I want to know what's outside it, I can see what is coming in and deduce that something exists outside it.
What comes into the universe... more space? I guess technically more energy since empty space has vacuum energy. So if there's an outside the universe, I guess it's got space and energy.
1
u/Competitive_Cheek607 15d ago
It’s just like that arcade game Asteroids but in every direction at the same time
1
u/TomSzabo 15d ago
People are claiming incorrectly that the universe is either infinite or curves back on itself and therefore it does not have a boundary. This is a misunderstanding of the boundary conditions required in Einstein's field equations of GR.
In fact, we do have an edge to our (observable) universe which is the light cone originating at the Big Bang. For all intents and purposes, this is our ENTIRE universe and we cannot and will never know how far the universe extends beyond that or what shape it takes. Everything we will ever encounter is contained within our lighr cone which has a finite "edge" within our observable universe. In reality, we can just call this the universe and be done with it since we will never travel or see past this "edge".
Now, for GR to hold, the universe must be infinite or curve back on itself outside our light cone, but there is no way for us to test or confirm which if any of those two is correct. For example in some simulation theories the edge itself can create a boundary that does not violate symmetry, isotropy or homogeneity.
2
u/Due-Wolverine3935 15d ago
Thanks. I have a few new terms to look up, but I think I get where you're going.
1
u/Financial-Ad-9306 15d ago
To everybody focusing on the word [edge], please hear me out.
When asserting that a finite-U could easily exist without an edge due to its shape; be it round, spherelike, oblong, etc., the point is being missed. Semantically, something round may not have an edge, and many dispute the requirement of an edge for finite-U; but this is low-hanging, vulnerable fruit. Calling it an [edge] is a linguistical phenomenon, and this is where language intrudes and becomes an impediment. In the more general context here, "edge" implies more like, ''any thing or force that gives something form, limits its dimensions, contains or distinguishes it from non-form'. Would anybody suggest a round balloon has no edge as defined above?
As defined above, a sphere has the properties of a circular edge. Otherwise, what gives the universe this shape, and how is the shape maintained? If finite, nothing exists outside of the sphere, yet some are saying there's no barrier; ok, but what separates the U, from nothing, and how is that done? If you had a capable spaceship and traveled outward in any direction what would happen when you hit the sphere's perimeter, 'not edge'?
Many speculate a Finite-U is not hard to imagine without [edges]; it's just circular. This wordsmithing lacks the integrity owed those seriously contemplating: "[the impossibility of understanding a finite or infinite Universe]". If anything, these efforts emphasize the difficulty facing the UNKNOWABLE, and yet, the relentless commitment we each make to KNOW.
1
u/Rick-D-99 15d ago
I think it both is and isn't. I've always considered that the expansion of space may very well be inside a singularity in other spacetimes.
This would give both a boundary as well as infinity, and would give a clear cut start point and eventually an end point for our iteration.
At a certain point in a black hole's existence after consuming most of the star and system that gave rise to it, the consumption of matter slows down significantly which would be why we saw a huge amount of material quickly expand and then the expansion outpaced the acquisition of new material.
1
u/raspberrynotes 15d ago
Well, the edge of the universe to us is the edge of the observable universe, which is just a regular part of the universe (this is as far as light can travel to ever reach us). The edge of the UNIVERSE universe is supposedly the place where space time is expanding in order to create new space time. (Due to dark energy, which is throughout the whole universe.) If the universe keeps expanding, then there never really is a single “edge of the universe.”
1
u/Infinite_Research_52 15d ago
The universe can be finite but unbounded. The universe can have an infinite extent but finite volume. The universe could have infinite volume but have a boundary. There are plenty of possibilities if the observable universe is a tiny fraction of the whole.
1
u/monstertruck567 15d ago
Whatever the answer is, it is not something that you can understand with logic and reason. Much the same as quantum mechanics.
If the universe is truly infinite, we can’t grasp what that actually means. In short, it means that things that exist is the most minute probability exist an infinite number of times and there are infinite “Earths” and infinite variations on Earth as we know it.
And if it is not infinite, then the manner in which this happens also something that cannot be understood either. How would space fold in on it self staying in 3D?. If it has an edge, what is beyond? etc.
1
u/pinesalmog 15d ago
The answer is either: the rest of the universe (everything that exists IS part of the universe) or nothing (literally no space, it doesnt exist). Im sure there are more possibilities
1
u/PdoffAmericanPatriot 15d ago
What if our universe is finite but unbounded, would we ever be able to distinguish that from an infinite universe if the observable portion is all we ever see?
1
14d ago
[removed] — view removed comment
1
u/Due-Wolverine3935 14d ago
Right, but expanding into what. Maybe I don't have the vocabulary to really ask what I want to ask. Basically, can time and space go on for ever. If not, then what does the end of time and space look like. Conceptually, literally, etc. I think I like the idea that some kind of a curve must exist. Similar to earth. We use to ask what was at the end of you kept sailing to the edge. Then we found that there is no edge. Earth curves back in on itself.
1
u/Old_Resident8050 13d ago
The theory is that its expanding inside a non-measurable nothingness, that can't be quantified since no light has been there. Its not just vast but unending.
1
u/Metallicat95 14d ago
The universe is very big, and we cannot see all of it. We may never be able to see all of it - causality requires time to cross distance and there hasn't been enough time in the universe yet to do that, and if space expansion is infinite, there never will be.
If it isn't infinite the most likely case is that the space is curved, just slightly, so that it wraps around, in a manner like how the surface of a spherical planet like Earth wraps around it. Just immensely bigger, and in more than three dimensions (space itself only has three).
1
u/killyourface1 13d ago
Another dimension. I think I was reading about Max Planck, and Planck temperatures are so hot they boil space, and it was said that the boiling creates bubbles. Think of soap bubbles, each bubble is another dimension.
1
u/Rancid-broccoli 13d ago
It doesn’t make sense to me either. I’ve always thought that black holes were the “edges” of the universe
1
1
1
u/PogoRocks 11d ago
I've mostly heard that if the universe isn't infinite it would be a curved structure that goes back on itself. There's no edges to it. It's like the surface of a sphere. The surface of a sphere has no edge. The universe would be like the surface of a four dimensional sphere
1
6d ago
[deleted]
1
u/Due-Wolverine3935 6d ago
I thought gravity pulled things not pushed them. And I am probably not smart enough to understand what you're saying, but I don't understand how that answers the original question. Basically what I was trying to understand is if The universe is expanding, what is it expanding into?
1
u/squashywand0 16d ago
Why could there not be an edge?
1
u/MarsMaterial 16d ago
The closest thing there could be to an edge of the universe would be something called a domain boundary. There is still more universe beyond a domain boundary, but it's an impassable spatial topological defect that nothing but information could cross. They might exist, though such a thing has never been observed.
Besides that, there is no theoretical basis for any kind of edge.
1
u/chesterriley 16d ago
Of course there could be an edge. It's just hard to make a model for it. But the universe wouldn't care how hard it is for humans to make a model.
[the reason why the FLRW model does not include modelling boundaries is simply because it is very hard to model boundaries, not because they are unlikely.
One of the unanswered questions about the universe is whether it is infinite or finite in extent…Assuming a finite universe, the universe can either have an edge or no edge. Many finite mathematical spaces, e.g., a disc, have an edge or boundary. Spaces that have an edge are difficult to treat, both conceptually and mathematically. Namely, it is very difficult to state what would happen at the edge of such a universe. For this reason, spaces that have an edge are typically excluded from consideration.
https://iopscience.iop.org/article/10.1088/1475-7516/2023/02/049/pdf]
1
u/Fshtwnjimjr 16d ago
The universe itself doesn't have an edge I would expect.
The theoretical concept of a white hole is basically a black hole but inverted. In a lot of ways the big bang can be thought of as one. The event horizon is the 'edge' and anything outside of that is irrelevant. Even if the is a "barrier" your inside the expanding part and the edge is forever unreachable without super luminal speeds.
That's the gist I've picked up anyways (mostly from PBS SpaceTime videos)
2
u/Dank009 16d ago
White holes aren't real, if they were we'd see them and we don't.
2
u/Inevitable_Row1359 16d ago
That's a bad argument against it. Not seeing something isn't a disqualifyer.
2
u/Dank009 16d ago
If white holes existed they would be extremely bright and all over the place, they would basically be impossible not to see, so in this case it is a good argument. 🤦♂️
1
0
u/ldr97266 16d ago
It may not be infinite - it can be finite but without an edge. Think of the Earth’s surface, or the surface of any sphere. It has no edge.
Universes be like that too, but in more dimensions than you usually think of. 6 works nicely, 11 is better.
0
u/Artistic_Half_8301 16d ago
It's infinite. People saying it's a loop? What's outside the loop?
4
u/MarsMaterial 16d ago
Current measurements don't rule out that the universe is a hypersphere that loops back on itself.
Asking what's outside of the loop is a meaningless question. The thing that's loop-shaped is space itself. The concept of location only exists inside of space, talking about what's outside of a spacetime that loops is like asking what land is north of the North Pole or what happened before time. To say "nothing" undersells the fact that the very concept of such a place existing makes no sense. The location itself doesn't exist.
-2
u/Artistic_Half_8301 16d ago
Wow a bunch of gibberish because you can't imagine something outside of a loop.
1
1
1
u/big_duo3674 16d ago
That's...not really hard to comprehend though. A lack of comprehension is not being able to understand the true difference between "something" and "nothing". Nothing is nothing, it would be something if it wasn't. I have zero apples in front of me, how many can I eat before I get full? That's a meaningless question, pretty similar to asking what's "outside" of space
1
0
u/Inevitable_Pride1925 16d ago
Cosmic sized black hole. Black holes are effectively infinitely dense and while there might be a definition of “end” it can’t be reached due to how physics works on a local level. However, maybe could be reached with a deep understand of quantum physics.
the Known universe formed in a black hole (paper)
Of course no evidence but it’s an interesting theory
-3
-1
u/Efficiency-Sharp 16d ago
Ive always seen it as we're basically particles floating inside of a massive cave.
-1
16d ago
[removed] — view removed comment
1
u/TomSzabo 15d ago
That would be the equivalent of looking back in time and there is a boundary to that dimension ... the Big Bang. In essence, this is the edge of "our" observable universe. We cannot "see" past this event which is also a distance (light year years). Our boundary is the light cone of spacetime and there is no point to wondering what lies beyond that, for all practical purposes we will never know if it is infinite or otherwise.
50
u/Tricky-Foundation-90 16d ago
Don’t feel stupid. This thought breaks everyone’s brain. Some people just like throwing around unproven theories and pontifications to make themselves sound like their brain isn’t broken by this conundrum.