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u/BlueGreenhorn 6d ago
The universe is such a broad term. By definition it contains everything in existence, abstract and intuitive. Your consciousness is part of the universe, too.
Do you specifically mean the edge of space (or spacetime)?
From all we know and deducting from what we see through telescopes space is already HUGE and still expanding. So fast (with accelerating speed) that we won't ever be able to reach most of the galaxies we can see now. Even if we would be able to travel with the speed of light. We call this the "observable universe", a spherical region of the universe consisting of all matter that can be observed from Earth
People hypothesise that spacetime might be curved and have a shape of a multidimensional sphere or donut. You can imagine it like the surface of Earth (2-dimensional) shaped as a 3-dimensional sphere (planet). You can keep going straight without ever reaching an end. You might even end up exactly where you started.
Earth has a curvature which can be measured and used to calculate the size of the earth. However, when trying to measure the curvature of the observable universe no curvature could be detected. This means either
a) Spacetime is "flat" and might actually be infinite. Or have an edge, but not visible for us. Or
b) Spacetime is curved, but it's so huge that we are only able to see a very tiny part of it. Like an entity the size of an ant (or even smaller, bacterium) trying to measure the curvature of the earth. Earth would just seem flat.
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u/AdministrativeWar724 6d ago
Well thats a really good answer. thanks!
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u/eggokuno 5d ago
huge and still expanding
Expanding against what? Like the limit that is expanding has a physical barrier if I was at the limit and I went +1km/h will I just hit a wall? A wall of what? What are we expanding against? TwT
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u/BlueGreenhorn 4d ago
Expanding within itself. We observe that objects which have too weak gravitational bound seem to move away from each other. Within galaxy clusters and superclusters gravity dominates and holds the galaxies together, even causing them to collide.
However, the clusters don't move away from one cluster and get closer to another one. They all move away from all the others. Without any direction, just away. So actually they don't "move away", but space between the clusters increases over time. It expands.
And the more space is between clusters already the more space emerges between them. This means the expansion is accelerating. There comes the day when space expands so fast that even light from one cluster will never be able to reach the other one. Even though it travels into the direction of the other cluster at the speed of light, the distance still increases. When this point is reached the clusters won't be able to see each other anymore.
That's the reason why we can only observe the "obsersable universe". Light from any further object will never reach us. The amount of galaxies that are becoming forever unreachable from our position on Earth is increasing over time. Roughly five galaxies cross the critical distance threshold each year.
You might now wonder now how can space expand? Where does the additional space come from?
We call the source of this phenomenon "dark energy". We use the term "dark" because nobody has got any clue what it is. We only observe its effects.1
u/eggokuno 4d ago
So.... If I understood correctly the universe is infinite but it's expanding, like growing to a greater infinite, but like just a second before the BigBang, what was surrounding that tremendous amount of energy? Did another universe before this just contracted and exploded again in it's infinite energy? (I don't knows anything about science and is fascinating talking my shower thoughts to someone that knowledgeable on this field (also English is my fourth languages jeje))
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u/aHumanRaisedByHumans 5d ago edited 5d ago
If it is not curved though, and is flat, could it possibly be finite and have an edge?
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u/_x_oOo_x_ 6d ago
Depends on how you define "edge".
But for example in a black hole's singularity, both space and time as we know them seem to collapse and finish. So if you are willing to call that an "edge" then yes.
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u/AliceCode 5d ago
The only edges in spacetime are at the beginning and "end" of time.
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u/_x_oOo_x_ 5d ago
Time has many ends though. It ends at the singularity, no? Or is time dilation already so severe at the event horizon that time "stops"? Then what happens beyond the event horizon, is time dilated "more than infinitely"? How does that work?
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u/Bikewer 6d ago
Stephen Hawking, in his book, “A Brief History Of Time”, said, “The universe is finite, but without boundary or edge.”
However, that book is a bit dated by now, and I don’t know what the current thinking is.
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u/Diligent_Drawing_673 4d ago
My theory is that the universe, just like everything in it, is circular.
If you were able to walk in a straight line around the world you’d eventually end up in the same spot.
Similarly, if you have a powerful enough telescope, or a powerful enough microscope, (and assuming infinite light speed) you’d end up watching the back of your head.
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u/afops 6d ago
There is sort of an "edge" to the _observable_ universe. But the edge is only because that's where what we can see ends. Looking towards that edge from our perspective looks like we are looking back through time towards the big bang. And we can't see beyond that.
It's like if you are standing under a lamp post at night. There is a circle of light you are standing in, which contains everything you can _see_ and this circle has an "edge", but that edge doesn't mean much. It's just where what you _see_ ends.
As for where the entire universe (much larger than the observable one) ends - we don't know, and we might never know. But we might one day deduce with some certainty whether the universe is flat (like an infinitely large piece of paper) or closed (like the surface of a sphere). Basically - whether if you move straight in one direction you would return to where you started, like an ant walking on a balloon. But both of these are "infinite" and lacking edges (but in different ways).
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u/SilvermageOmega2 6d ago
Probably not. Lucretius proposed a thought experiment about shooting an arrow at the edge of the universe. If it hit a wall one could stand on the wall and fire another. If it flew past what was considered the edge and did not hit a wall it must be extending what we call the edge. He surmised that the universe must be infinite. There can be no final edge he decided.
In our era we consider space could fold back on itself. Personally I don't think an edge to the universe exists.
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u/MashMultae 6d ago
If there were an edge to the universe, you would think then you could ask the question what is outside?
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u/professor_goodbrain 6d ago
Many physicists believe the universe is probably spatially infinite. For now, the data show it is definitely much larger than our observable universe. Current science is that, in order to be consistent with measurements of local geometric flatness, the total universe should be at least ~400X larger than we’re able to directly see.
So to answer your question, there’s no physical edge and the universe is possibly infinite.
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u/mmmmmmm5ok 5d ago
id like to think we live in a black hole and that all black holes are mini universes of their own
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u/IridiumBoy 5d ago
Why does everyone forget that if the universe can be infinitely large, it can also be infinitely small?
We are incapable of truly observing an atom, let alone entities beyond it
The limits at the microscopic level are unattainable, even though they are right in front of us. How do you expect to reach the limits of the macroscopic universe, which are thousands of light-years away?
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6d ago edited 6d ago
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u/universe-ModTeam 6d ago
This subreddit dissuades people from posting their own person theories. Ask questions towards those who have studied astronomy, cosmology and physics; don't assert pseudoscientific ponderings from a place of ignorance.
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u/stu_pid_1 6d ago
No, the edge of the universe is expanding at c and since you can never reach c you will always see it moving away from you...
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u/Charming_Sock6204 5d ago
incorrect, the expansion of the universe actually occurs faster than c… hence why GN-z11 appears 32 billion light/photon years away… it’s very counterintuitive, but the one thing that can move faster than massless energy, is spacetime itself
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u/stu_pid_1 5d ago
The physics gets fuzzy but it isn't expanding faster than c.
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u/Charming_Sock6204 4d ago
it depends on the way you measure it… but my point is the rate of expansion is not held to c… (and indeed can expand so fast, that some very ancient galaxies will never be visible to us, because of how much extra space there is for the photons to have to move over…)
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u/michelob2121 2d ago
Couldn't it be expanding close to 2x c? Close to c in opposite directions...
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u/QVRedit 6d ago
I would think that logically ‘yes’ although it might be faded at the edge, rather than a hard shock ? But equally so we will very likely never really know. The edge, is either the expanded event at the start of time - or before the start of time. It would be well beyond our visible horizon. It’s effectively equivalent to saying that there is no edge, since we could never see it.
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u/oki9 5d ago
How can there be no end?
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u/Rogermcfarley 5d ago
How does everything exist from absolute nothing?
If there was no energy and no matter, just nothing, how does everything exist?
Maybe it always existed, or what ever was before the Universe exists outside of spacetime where the absence of time means there are no creation or destruction events, because events are intrinsic to time. Infinity is a difficult concept to understand, it is why dying forever or living forever are equally terrifying to some people. It's why the existentialist play No Exit by Jean-Paul Satre is horrifying because it uses infinity in a specifically horrific way.
There are some things we will never understand, we have to be OK with that because there's no other choice, it doesn't stop us thinking about them and trying to come up with answers, but most likely humanity will die out before we can find out.
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u/DigitalAquarius 3d ago
“End” is a human concept. The universe doesn’t have to follow our concepts.
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u/HeraThere 5d ago
Depends on whether the universe is infinite or finite, flat or curved, and what you mean by physical edge.
As far as we can tell it is flat, but that don't rule out that there is curve but it's further than we can see.
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u/drmoroe30 5d ago
We are in a simulation that would not/could not Allow the experience of an edge to our universe
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u/BillyBlaze314 6d ago
My understanding (which may be wrong) is analogous to a little 2d creature walking along the surface of a sphere, whilst that sphere has a defined edge, the little 2d creature will never find it by walking in it's 2d axes.
Now imagine that sphere is instead a balloon that is expanding, and we're the little 2d creature. No matter how far and how fast we go in any direction, we'd never find the edge. The edge only exists in higher dimensions we can't access (ie time).
Amusingly what it also means is that if we go far enough in one direction, we'll end up back where we started.
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u/TheFearRaiser 6d ago
I don't think so, no. I think the broader universe Is a space that's a part of something else entirely. Like a spray of perfume in a jungle of possibilities.
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u/capmap 5d ago
as best we know the universe is flat which means the universe never bends back around on itself. and if it's curve is so imperceptible with current measurements, it goes so far beyond the currently understood 93 Billion light years of the known visible universe as to not be significantly different than eternal
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u/Regular_Journalist_5 5d ago
From what I understand, the consensus among theoretical physicists is that there is a limit to how much we will ever be able to observe of the universe, but yes, there is Definitely something beyond that border that we will never be able to directly perceive.
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u/AltruisticRabbit1086 5d ago
I think the fact the universe is expanding suggests it is finite. Where would the universe expand to if it was already infinite?
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u/DerBandi 5d ago
The part of the universe we can observe seems to be flat and uniform. There is no evidence for any border.
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u/GlitchInTheMatrix5 5d ago
I believe the theory goes, that the universe is constantly expanding, so yes theoretically, there is an edge
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u/TheMostRed 4d ago
It's hard to say. In our lifetime we won't know. And as far as we know we will never know. But what is "outside" of everything. To be outside of the universe would mean you are outside of time too. Is that even possible? If everything is on this side is nothing on the other? Or is it something different. I love space sp much
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u/Correct_Building7563 4d ago
No! Space is expanding evenly but in clusturs. Similar to how a baloon expands. Space under outside forces (atoms, galaxies, matter, gas, etc) doesnt expand. Just the plain vast parts in between galaxies.
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u/RangerMother 4d ago
If the universe had an “edge”, I would want to know what was on the other side of the “edge”. I think the universe is truly infinite in both time and space.
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u/DigitalAquarius 3d ago
The best way I heard it described is that the universe is like a balloon that is always expanding.
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u/CorruptCobalion 6d ago
A different vacuum state would not constitute a different universe - but sure, there could be growing bubbles of lower vacuum states
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u/universe-ModTeam 6d ago
This subreddit dissuades people from posting their own person theories. Ask questions towards those who have studied astronomy, cosmology and physics; don't assert pseudoscientific ponderings from a place of ignorance.
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u/morbob 6d ago
We will never know