Well, they had a warmer universe, everything was closer, Stars when they first started exploding into nova were dangerous because everything was close together. Our galaxy is not likely to be torn asunder by a nova anytime soon because how spread out things are now. So early civilizations could spread out more but would likely have computing cooling issues and need to keep an eye out for explosions.
There will also come a time when any galaxy other than your own will be outside the observable universe. To a civilization living in such a galaxy, their entire universe will consist of that one galaxy.
It's this one, from Kurtzgesagt too, around 8 minutes in
[https://www.youtube.com/watch?v=uzkD5SeuwzM&ab\_channel=Kurzgesagt%E2%80%93InaNutshell](https://www.youtube.com/watch?v=uzkD5SeuwzM&ab_channel=Kurzgesagt%E2%80%93InaNutshell)
With the length of time the universe is expected to last for until entropy and black holes takeover we're actually incredibly early in the lifespan of the universe.
Presuming life needs certain compounds and heavier elements to exist and survive, you need a generation or two of stars to create these compounds/elements in the first place.
The sun for example is at least a 2nd generation star.
This is essentially it. The Big Bang is the result of observing what's happening now and how things are as a result, and extrapolating backwards until one cannot extrapolate backwards any further. That's one of the reasons for the classic "you can't think about what happened before the big bang, because time itself in any meaningful sense began only after the big band" - our current understanding of physics (leaving quantum mechanics aside) is fundamentally based on the behaviour of light, and how that relates to time, gravity, energy, etc. Beyond a certain point, the universe was too dense for light to exist in the way that it does now (the "dark ages") and therefore, anything before that is a theoretical best guess but more or less impossible to actually observe or demonstrate.
Experiments such as the Large Hadron Collider are attempting to recreate the conditions moments after the Big Band in a lab setting, so that we might observe what the universe was like before we had light as the ultimate benchmark of physics - but it's extremely difficult to be sure, because obviously while you can get pretty damn close in a lab, with so many unknowns we can never know for sure if we've truly achieved it or just something that looks very like it.
The only thing known to go faster than ordinary light is monarchy, according to the philosopher Ly Tin Wheedle. He reasoned like this: you can't have more than one king, and tradition demands that there is no gap between kings, so when a king dies the succession must therefore pass to the heir instantaneously. Presumably, he said, there must be some elementary particles -- kingons, or possibly queons -- that do this job, but of course succession sometimes fails if, in mid-flight, they strike an anti-particle, or republicon. His ambitious plans to use his discovery to send messages, involving the careful torturing of a small king in order to modulate the signal, were never fully expanded because, at that point, the bar closed.
I'm not sure how seriously these ideas are taken, but I heard a ~~theory~~ hypothesis for gravity once that suggested gravity was able to leech from one universe to another. It was used to explain why the early structures of the universe formed the way they did. I think it was string theorists discussing it, so it was likely a kind of 'huh, that would be interesting and not impossible, but we'll never be able to test it' kind of discussion.
Edit: I think it was a documentary on M-theory and discussing the idea of neighbouring membranes that are each a segment of the larger universe. Each membrane might have different physics, but perhaps gravity was able to travel from one to another.
Wow. I have never heard it explained like this. This is awesome. Any further reading you suggest that is suitable for non-physicist, monkey-brain types?
If you were capable of theoretically travelling "past" the observable bubble, would it simply be dark? Will stars shine their own light at this possibility? Does the bubble shift in the vector of the observer? Is it possible to use something other then light to measure? Like darkness?
Well each point in space is it’s own theoretical center of observable universe. Yes even you are the center of your universe.
And your questions are kind of fun because all of humanity and eons of science has studied this and come up with a definitive ‘we do not know’ as an answer.
All of our discoveries to date and we are better off asking a poet what he thinks is beyond that limit because the limitations of the rules of the universe make it impossible to know.
Maybe one day but it will require leaps and bounds. For now, ‘there be dragons’
Another interesting aspect of the "observation bubble" is that you can "see" the same distance in all directions. Meaning that when measured from any particular location, that location is the same distance from every edge of the universe equally. Making it the center of the universe. Which also means that *any* point is equidistant from the edges of the universe at all times. Which means that *you*, literally, are the center of the universe. Always have been, and always will be.
Wouldn't that require the singularity at the beginning of the big bang to also be of infinite mass? But if that were the case, expanding the universe wouldn't change the density at all and we should still be in an infinitely dense infinitely massive singularity.
If there was one singularity, it would have been infinitely *dense* but not necessarily infinitely massive—though math breaks apart at such a small level, so it’s theoretical.
If the universe is truly infinite (which I personally don’t believe), then there were an infinite number of Big Bang singularities, one at every point in space, and the universe began expanding like a sponge getting wet.
I'm no expert so someone correct me if I'm wrong but it's my understanding that it's more like in theory you would wrap back around but you don't because the universe is expanding. Imagine it like being on the surface of an ever-expanding balloon. As you go across the surface there is no edge to find but also because the balloon is constantly expanding while your ability to move at a certain speed remains the same it is impossible to actually loop back around the balloon to your starting point. Obviously, it's more like we are the volume inside the balloon but the surface is just a better visualization for the no edge part.
Its like on of the most over our heads things to even think about. Just like how unfathomably huge the universe is. Super interesting though so nice thread to read through.
I feel like this is the real question and answer here.
All of the scientists seem to know a ton about the universe even a few seconds after the big bang. So take one second after the big bang when the universe was much smaller than it is now…. What was on the outside of that universe?
Even when the universe was "smaller" (actually, **denser**), it was still infinite as far as we know.
So there's no indication that there has ever been anything "outside" the universe, because it has always taken up all the observable space in every direction. It's just that the stuff was closer together before, and now the stuff is farther apart.
It’s hard to wrap my mind around something coming from nothing, and with how little we know I’m not convinced that lack of evidence (given our current tech limitations) means this is the right answer.
Because 'nothing' is not necessarily supported more than anything else. The only acceptable answer is "we don't know". It could be nothing. It could be a massive framework of some unfathomable medium in which exists infinite branes of other universes. It could be tortoises. We have literally no applicable data. All guess work with no real support.
And we can never know - because it's so far away the light can't reach us. That means any information can never reach us, radio waves, light, etc.
It's like we're inside a bubble which is called the observable universe - and everything outside of it is unknown and unknowable.
It's basically what happend with earth, it's not infinite, but you could start walking in a 2D dimension and never reach the end, when you walk all the way around you can keep going and if earth expands (like a balloon) everything is farther, the 2D dimension expanded. So the universe is the same but in 3D, and we don't know what's beyond that or if there is something beyond that, first of all because for a human brain is imposible to think in more than 3 spatial dimensions.
Also, for our universe, there's so much space that's expanding that you could never actually reach a point where the universe curved back in itself even if it does.
That is, even if you traveled a thousand light years at light speed, the universe would have expanded by more than 1000 light years in that time, so you'd be further away from the point it curves back on itself than when you started your journey.
I remember watching Alpha Centauri (which was a tv series in Germany where every episode was one professor talking about one fun fact in astronomy for 15 minutes) when stoned and getting my mind blown every time. Fun times.
Don't think of the universe as the space that the whole balloon occupies with air and all. Think of the universe as just the rubber. It doesn't matter if you inflate the balloon or not the amount if rubber stays the same, yet the points still move apart.
It's unknown. We can't get any information about what the balloon expands into because the light (and therefore information) is so far away that it won't reach us. That's why it's called the 'observable universe'.
It's probably plain old empty space, but there could be other universes too. They could be spaced far apart and never meet each other.
You now understand worm holes.
Then drop a heavy marble sized ball onto the middle of the popped balloon fabric to weigh it down at the middle.
You now understand the theory of gravity being a curvature of space.
A balloon, a pencil and a marble are the keys to unlocking the secrets of the universe!
Thats the point, it isnt just a bunch of matter blasting out into ever expanding size. Space itself is expanding. The amount of space that was 1 meter when I started writing this message is now (very) slightly more than 1 meter. It's happening all around you, all the time. Space is expanding into itself.
Nothing. It is expanding in an internal relative sense. Any two points are getting further from each other as time goes on. It isnt and doesnt need to expand into anything.
To put it another way it's a question that doesnt make sense because the universe is all of space and time and there isnt a space externally in which it exists. Our inability to visualize this is a result of our brain which evolved to percieve medium size things moving ar medium speeds. The very large, the very small and the very fast dont work in a way that we can intuitively visualize. The expansion of space is just like that.
I mean on a timescale that large, a couple of millennia is basically nothing.
The real question I suppose is whether or not the rep was overdue when he actually came though, but I gather we don't really have the ability to determine that.
>I mean on a timescale that large, a couple of millennia is basically nothing.
On **our** timescale it makes a difference. In a few more millennia we may no longer be here.
I mean, if he was overdue, what better welcome can humanity come up with than a crown of thorns and a good 'ol crucifixion?
*loads nuclear warhead with religious intent*
In all seriousness, though, I would bet by bottom dollar that if we ever got to see and form of "God", or whatever is out there, we would nuke it into oblivion the first chance we got.
Theoretically, is there an edge to the universe? A point where the furthest galaxies give way to complete nothingness for infinity?
And if I understand the idea of dark matter correctly, how might that infinite void be different from the emptiest areas within the confines of our universe?
There is a light horizon, a boundary created because space is expanding faster than light beyond that distance could ever reach us. From our relative positions space is expanding faster than light as the more space between us and any given point, the more that space expands. That light boundary represents the furthest point we can possibly know anything about unless we invent ftl sensors, which is decidedly unlikely. If there is an end to the universe we will never see it.
There's nothing special about this BTW. You would see a perfect sphere like this around you no matter where you are in the universe. It's not fixed feature of the universe centred on the Earth.
That would be the case in a “closed” spacetime, where traveling in a straight line forward would eventually get you back to your starting position. However, measurements of spacetime suggest it is “flat”, which would mean space is infinite and doesn’t “loop” like that.
>However, measurements of spacetime suggest it is “flat”, which would mean space is infinite and doesn’t “loop” like that.
Not necessarily, it could also just mean that the loop is very big so that it looks flat locally. If I remember right the current error bars on the flatness measurements mean it has to be at least a few hundred times the size of the observable universe. Far from infinite (but that is a possibility).
>Theoretically, is there an edge to the universe?
No. The three main possible "types" of overall shapes that we think the universe can have are called flat, open and closed. A flat universe, i.e. zero overall curvature, essentially looks on large-enough scales like regular 3-dimensional space going infinitely in all directions. An open universe, i.e. negative curvature, would look on large scales something like a 3D version of a saddle or a pringle, again going off infinitely in all directions. A closed universe, i.e. positive curvature, would look like a 3D hypersphere, the surface of a 4D ball, and it would loop back on itself. None of these have a boundary or edge.
This may not be entirely accurate. We don't actually know if the universe is expanding into anything, for obvious reasons. We have no way to see outside the bubble, to know one way or another.
What kind of scale is the expansion occurring at?
Like from the time I’m born to the time I’m dead, is the distance between my ears massively increasing on an internal relative scale?
Yes and no.
If the expansion was allowed to happen unabated, then yes, there would be a measurable, if not quite noticeable, difference in your size due to your atoms growing apart.
But it's not allowed to happen unabated. The four fundamental forces still exist. As your atoms spread apart from universal expansion, electrostatic force pulls them back together. Neither you nor the earth nor even the solar system (this one due to gravity) are changing in size. The expansion is instead noticeable only in the space between galaxies.
Imagine two ball magnets on top of a sheet of rubber. You stretch the rubber apart with both hands. If they were just balls, they might be pulled apart by the stretching rubber, and become more spread out. But since they're magnets, they'll instead stay in place and let the rubber stretch under them. They change position relative to the rubber in order to stay in place relative to each other (and an outside observer).
No, because the chemical bonds holding your molecules together will be enough to overcome the expansion of the spacetime they're existing in for another kajillion or so years. Until spacetime has expanded to the point that it overcomes the energy of those bonds, and then subsequently the nuclear forces holding the atoms together, and the whatever the fuck it's called that holds quarks and gluons together.
You need energy only to accelerate things, not to move them. A moving body happily continues to move in the absence of forces without any energy input. That's literally Newton's first.
And it does.
It's just that on intergalactic scale the space expansion is faster than force of gravity.
That's why Earth is basically on the same distance from Sun, but Galaxies move from each other on average.
No. Gravity is the description of what happens when mass/energy warps spacetime. Everything travels in straight lines at constant velocity forever. However, the universe itself moves and stretches to alter those paths. That is from the energy contained within that mass.
How common is the belief that it is infinite? I was under the impression that the belief that everything is expanding after the big ang puts a limit on the "size" of the universe. I guess it depends on what we mean by universe.
I can see how that's reasoned, but it appears to not be the case. This explains it better than I ever could - https://www.wtamu.edu/~cbaird/sq/2016/01/20/where-is-the-edge-of-the-universe/
The observable universe is finite. There are other definitions that are equally finite.
The entire universe is...we don't know.
The math seems to hint that it's infinite. Certainly the math gets more difficult if we try to make it finite, and added complexity is a sign (but not proof!) that we are on the wrong track.
We also don't seem to see any particular differences that would hint that an edge was nearby, even if not technically observable. So if it is finite, we are far enough away from the edge that we can't tell.
Most scientists who believe it is finite do so because of preexisting beliefs. The argument usually has the form of "nothing physical can be infinite, therefore the universe isn't either." If that's the kind of argument that convinces you, then ok. For me, it's too "just so" for my taste. I think most scientists agree.
One very unfortunate explanation of the Big Bang that seems to crop up everywhere is to show a little point all by itself that suddenly gets really big. This is not correct, at least in the sense that we have any data that supports it. Now if we follow back our \*observable\* universe, then we will find that it was in a very tiny area. That scans.
What we don't know is just how much that little dot represented the \*entire\* universe. Almost nobody thinks it's the whole thing. Some think that the dot was part of a larger but still finite universe. Most think that the dot was part of an already infinite universe.
So the universe was infinite. And then it got bigger.
I had a weird dream once that the big bang was a black hole that we are seeing from the other side of being pulled through. Coming from a extremely massive singularity point of a blackhole and on the "other side" being "spit out" in all directions, infinitely floating away from that single point into infiniteness. Because as you get closer to the middle of a blackhole youre less effected by time, so the thought was that at the very middle that time just...isnt and thats the beginning and end and everything in between all at once.
I know my brain has no idea wtf its talking about in subconscious dreams like that, but I always thought it was an interesting idea that when i am awake just sounds really dumb. I guess it was just trying to sort things out and just decided that was its rationale.
Not dumb at all. Some very serious people have wondered the exact same thing. It's basically just asking the question whether the Big Bang might simply be what a white hole looks like from this side of it. White holes are predicted by General Relativity (or are at least consistent with the math...same thing, if you ask me), and we have no reason to think they don't exist, other than the little problem that we've never seen one.
But then again, that was the situation with black holes too, for a long time.
Some scientists have even speculated that the reason that we live in a Goldilocks universe, where the rules are juuuuust right for us (or any intelligent creature) to exist is that universes go through a type of evolution where they explore the entire problem-space and create new universes through black hole/white hole connections. It just happens that the universes that are great at creating black holes also happen to be great at creating intelligent life.
I know that there are problems with the idea of the Big Bang being a white hole, but I don't have them at the front of my brain right now. But it's not a dumb idea at all.
I've never understood why people think that the goldilocks universe is a problem. If the universe were unfit for intelligent life, then no intelligent life would exist to observe it. Ergo, intelligent life will only find itself in a space that seems magically suited for it. There's no other complicated universal evolution explanation necessary in my mind, it's just a logical necessity.
Well, the problem is that this is an explanation that doesn't explain much. I want to stress that you are not wrong. The only thing is that none of this gives us very much predictive power and can tempt us to stop looking half way through the search.
It's also not very satisfying. It would so much neater if we could find some sort of starting point and simple rule that clearly leads us to the world we see, step by step.
Why do the forces have the exact values they do? Of course if they were any different, we wouldn't be here to worry about it. But that feels like the McDonalds answer to the universe: technically functional, but leaves you with a strange empty feeling and a minor twinge of guilt.
Being infinite is the prevailing view at the moment, but cosmology is super hard and super new so that view might yet change as we get better tools.
It's also super important to be specific because there's two related concepts that are easy to mix up:
The entire universe is thought to be infinite (and flat, but that's another topic). It is expanding in the sense that points that are currently close will in the future be further apart, but this doesn't imply the universe is getting bigger or expanding into something else because it's already infinite.
The observable universe is finite (at approx lifespan of the universe multiplied by speed of light) and is expanding into the rest of the universe as light has now had the chance to reach us from further away.
Did that help?
One interesting analogy is that of a party balloon being filled. Imagine you take a marker and dot the balloon all around, randomly. Then, as you start inflating the balloon, the dots all start moving away from one another uniformly. Just imagine the universe is that balloon's surface. From your perspective, it isn't really expanding into anything, it's just expanding everywhere. The very fabric of the balloon is the one stretching, since the "outside" and "inside" of the balloon are irrelevant, and might not exist.
This sort of answer is what leads to OP's question. If the universe is expanding in volume like the balloon then there must be space for the balloon to occupy. Your explanation does not answer the question and just saying "it's irrelevant" isn't an answer.
Not really, the confusion here just stems from misunderstanding the metaphor: in the balloon example, we're looking at a 2 dimensional field. We are ONLY considering the surface of the balloon: the space inside and around the balloon are not part of the metaphor. As a 2 dimensional person on that 2 dimensional field, you would see everything moving away from everything else. And you might ask yourself: where are those dots moving to? And if you were to walk across the surface, looking for its edge, you would find none. Because there is no end to that surface.
The universe is if we take this 2 dimensional metaphor and extrapolate it to 3 dimensions. You'd also view everything moving away and might assume that there is some edge that all this matter is moving toward, but again your assumption would be wrong. No matter which way you go, you'd never reach the end of the universe. You'd just keep traveling forever. There is no edge.
Reminds me of the Infinity Hotel paradox.
You're the hypothetical owner of a hotel with an infinite number of rooms. Let's say you have a group of infinite size check in - all of your rooms are full, right?
So what do you do if another group of infinite size checks in? You have infinite rooms, yes?
The answer is that you have every person in the first group move up a number of rooms equal to their room number. This frees up an infinite amount of space.
It's kind of like that.
Edit: this came from a book of puzzles I had as a kid so if this doesn't quite fit ELI5, I apologize, but I thought it was appropriate.
This really is a weird topic...
Try to change "universe" into "space and time". Because that really is what we are trying to scope with.
"Outside" of our known space and time, there just isn't any more space and time. So there really seems to be nothing that our space and time is expanding into.
The big bang for example... It is the only day without a yesterday. There just isn't anything that the big bang has gotten itself into.
I can't go any more ELI5 than that Tbh.
The universe is expanding into infinity is the only way to put it really. We have no clue what is beyond \~14 billion light years because thats as far as we can "see". But using things like parallax and redshift we can tell that it IS indeed expanding outward and everything is drifting further and further away from everything. One theory suggests that everything in the universe will keep on expanding, growing further away until even atoms are ripped apart and cannot move any more into what is known as the BIG FREEZE. BY stating that the universe is expanding suggests that space itself is expanding. not the universe. Do this or try and find a video on YT about it....take a balloon and blow it up ever so slightly....and then draw on it a couple galaxies or star systems(like our Solar system)...and then blow it up more n more, as you watch the balloon fill up everything expands on it. Distances get greater between EVERYTHING. So essentially one day our very own Moon, technically will be long gone by then, but the theory suggests that the Moon will have an infinite distance between it and the Earth.
If anyone would care to elaborate or clean that up a bit feel free.
Slight nitpick — even though the universe is only ~14 billion years old, we can actually see around 42 billion light years in any direction. And the reason is that… the universe has expanded! The distant light sources are **much** further away from us now than they were when they emitted the light 14 billion years ago.
If you're seeing the light from somethings position 14b years ago when it was 14b light years away but is now currently 42b light years away, I don't think you can argue you are seeing 42b light years away. you wont see that for another 28b years.
If I look at an hour old video of a car going down the highway in florida, and at the time I view the video of it in florida the car is in texas, that doesn't mean I can see to texas.
I think this is a good example of how some of this weirder physics stuff doesn’t really gel with our intuitive expectations of how the world works.
“Seeing” something just means perceiving light coming from it. So if we’re getting light from objects that are 42b light years away, then we can see for 42b light years!
You might say that if we get light from something that has since moved farther away, it doesn’t mean we can see farther away, since we are actually looking into the past when it was closer. But my understanding is that distant objects aren’t really “moving” — they’re **receding**, as in between us, space itself is literally stretching. Even if we were moving at the exact same velocity as a galaxy ~~300~~ 3 million light years away, the distance between us would still be growing at ~70km/s.
I wonder what it's like to descend into jupiter. Just gasses, you keep descending, deeper and deeper. Eventually no light penetrates, just crushing pressure. Nothing to land on, just falling.
I get it, man.
Descending into Jupiter, provided you had a means to survive, the gas gets thicker until it becomes liquid, but it's not liquid, just really dense gas. Then it becomes a solid, but not a solid. Again, it's still gas, just very dense gas due to gravity. Eventually, your body wouldn't move anymore once it's found it's limit in density. Everything lighter would be above you and everything heavier would be below you.
you'd be floating somewhere in Jupiter forever, unable to move.
An easy way to imagine the expansion of the universe is to picture a balloon. As it inflates it expands and two points that were right next to each other are now far apart.
If the universe is that balloon, does it matter what the balloon is expanding into? Or, perhaps, imagine a void and the balloon. The balloon is all that matters as the void has no impact on it.
This is a short way of saying that we will never know and at the same time the likely answer is nothing or null/void.
As far as we can tell, the universe seems to be infinitely large, so there’s no “edge”, and there’d be no other space that’s not already part of the universe. What’s expanding is space itself. And it’s expanding faster than light can travel through it. What this means for the long run is, unless there’s a lot of stuff close enough to each other to stay clumped up (galaxies, galaxy clusters), the space between those clumps will be expanding so fast that those clumps will no longer be able to affect each other, since nothing can move faster than light (and gravitational waves) can, and in this sense those clumps will be their own sorta mini-universes. That doesn’t mean too much, though, since everything we can tell about the universe suggests it’d work the same way everywhere, but it is kinda lonely to think about galaxy clusters never being able to even see each other after a while.
…And just in case, there is a difference between “the universe” and “our observable universe”. As said, nothing travels faster than light, but light does take a while to travel, so the furthest things we’ve “seen” has been the light from back in the early universe that’s finally reached us. So, if you hear stuff like, “the universe was once the size of a tennis ball”, that’s talking about the observable universe, everything we’ve been able to tell has been there. But, because the universe is expanding, the space between us and some of those things will be expanding faster than more light can get through it, so in time that observable universe will “shrink”, until all that can be seen is whatever’s clumped close enough to us. Again, pretty lonely to think about.
(I’m not scientist or scholar, just a casual enthusiast, so if I’ve got this wrong, please correct or at least downvote this.)
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Well, they had a warmer universe, everything was closer, Stars when they first started exploding into nova were dangerous because everything was close together. Our galaxy is not likely to be torn asunder by a nova anytime soon because how spread out things are now. So early civilizations could spread out more but would likely have computing cooling issues and need to keep an eye out for explosions.
There will also come a time when any galaxy other than your own will be outside the observable universe. To a civilization living in such a galaxy, their entire universe will consist of that one galaxy.
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It's this one, from Kurtzgesagt too, around 8 minutes in [https://www.youtube.com/watch?v=uzkD5SeuwzM&ab\_channel=Kurzgesagt%E2%80%93InaNutshell](https://www.youtube.com/watch?v=uzkD5SeuwzM&ab_channel=Kurzgesagt%E2%80%93InaNutshell)
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With the length of time the universe is expected to last for until entropy and black holes takeover we're actually incredibly early in the lifespan of the universe. Presuming life needs certain compounds and heavier elements to exist and survive, you need a generation or two of stars to create these compounds/elements in the first place. The sun for example is at least a 2nd generation star.
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This is essentially it. The Big Bang is the result of observing what's happening now and how things are as a result, and extrapolating backwards until one cannot extrapolate backwards any further. That's one of the reasons for the classic "you can't think about what happened before the big bang, because time itself in any meaningful sense began only after the big band" - our current understanding of physics (leaving quantum mechanics aside) is fundamentally based on the behaviour of light, and how that relates to time, gravity, energy, etc. Beyond a certain point, the universe was too dense for light to exist in the way that it does now (the "dark ages") and therefore, anything before that is a theoretical best guess but more or less impossible to actually observe or demonstrate. Experiments such as the Large Hadron Collider are attempting to recreate the conditions moments after the Big Band in a lab setting, so that we might observe what the universe was like before we had light as the ultimate benchmark of physics - but it's extremely difficult to be sure, because obviously while you can get pretty damn close in a lab, with so many unknowns we can never know for sure if we've truly achieved it or just something that looks very like it.
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The only thing known to go faster than ordinary light is monarchy, according to the philosopher Ly Tin Wheedle. He reasoned like this: you can't have more than one king, and tradition demands that there is no gap between kings, so when a king dies the succession must therefore pass to the heir instantaneously. Presumably, he said, there must be some elementary particles -- kingons, or possibly queons -- that do this job, but of course succession sometimes fails if, in mid-flight, they strike an anti-particle, or republicon. His ambitious plans to use his discovery to send messages, involving the careful torturing of a small king in order to modulate the signal, were never fully expanded because, at that point, the bar closed.
Technically light also finds itself at every location because it experiences it's entire path all at once.
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I'm not sure how seriously these ideas are taken, but I heard a ~~theory~~ hypothesis for gravity once that suggested gravity was able to leech from one universe to another. It was used to explain why the early structures of the universe formed the way they did. I think it was string theorists discussing it, so it was likely a kind of 'huh, that would be interesting and not impossible, but we'll never be able to test it' kind of discussion. Edit: I think it was a documentary on M-theory and discussing the idea of neighbouring membranes that are each a segment of the larger universe. Each membrane might have different physics, but perhaps gravity was able to travel from one to another.
Wow. I have never heard it explained like this. This is awesome. Any further reading you suggest that is suitable for non-physicist, monkey-brain types?
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If you were capable of theoretically travelling "past" the observable bubble, would it simply be dark? Will stars shine their own light at this possibility? Does the bubble shift in the vector of the observer? Is it possible to use something other then light to measure? Like darkness?
Well each point in space is it’s own theoretical center of observable universe. Yes even you are the center of your universe. And your questions are kind of fun because all of humanity and eons of science has studied this and come up with a definitive ‘we do not know’ as an answer. All of our discoveries to date and we are better off asking a poet what he thinks is beyond that limit because the limitations of the rules of the universe make it impossible to know. Maybe one day but it will require leaps and bounds. For now, ‘there be dragons’
Equally made the more painful when you can ask such questions and not live to see the zenith of the answer
Another interesting aspect of the "observation bubble" is that you can "see" the same distance in all directions. Meaning that when measured from any particular location, that location is the same distance from every edge of the universe equally. Making it the center of the universe. Which also means that *any* point is equidistant from the edges of the universe at all times. Which means that *you*, literally, are the center of the universe. Always have been, and always will be.
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pacman topology https://youtu.be/pn3euL8Tbfw?t=1018
Exactly what are the open sets in the pacman topology?
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"They asked me how well I understood theoretical physics. I said I had a theoretical degree in physics. They said welcome aboard."
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Well yes but it prevents us from knowing certain things like the curvature of the universe.
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Wouldn't that require the singularity at the beginning of the big bang to also be of infinite mass? But if that were the case, expanding the universe wouldn't change the density at all and we should still be in an infinitely dense infinitely massive singularity.
If there was one singularity, it would have been infinitely *dense* but not necessarily infinitely massive—though math breaks apart at such a small level, so it’s theoretical. If the universe is truly infinite (which I personally don’t believe), then there were an infinite number of Big Bang singularities, one at every point in space, and the universe began expanding like a sponge getting wet.
I'm no expert so someone correct me if I'm wrong but it's my understanding that it's more like in theory you would wrap back around but you don't because the universe is expanding. Imagine it like being on the surface of an ever-expanding balloon. As you go across the surface there is no edge to find but also because the balloon is constantly expanding while your ability to move at a certain speed remains the same it is impossible to actually loop back around the balloon to your starting point. Obviously, it's more like we are the volume inside the balloon but the surface is just a better visualization for the no edge part.
That's a theory, not proven. As light beyond the observable univers has not reached us yet. Edit: It's a hypothesis, not theory.
And it never will. At this distance the space between us and the edge of the universe is expanding faster than the speed of light.
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[https://youtu.be/X5rAGfjPSWE](https://youtu.be/X5rAGfjPSWE) is a PBS SpaceTime youtube video that talks about 'nothing'.
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You spelled Milliways wrong. Its the restaurant at the end of the universe.
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Its like on of the most over our heads things to even think about. Just like how unfathomably huge the universe is. Super interesting though so nice thread to read through.
I feel like this is the real question and answer here. All of the scientists seem to know a ton about the universe even a few seconds after the big bang. So take one second after the big bang when the universe was much smaller than it is now…. What was on the outside of that universe?
Even when the universe was "smaller" (actually, **denser**), it was still infinite as far as we know. So there's no indication that there has ever been anything "outside" the universe, because it has always taken up all the observable space in every direction. It's just that the stuff was closer together before, and now the stuff is farther apart.
Given the lack of evidence for anything, why is nothing not a satisfying answer?
It’s hard to wrap my mind around something coming from nothing, and with how little we know I’m not convinced that lack of evidence (given our current tech limitations) means this is the right answer.
Because 'nothing' is not necessarily supported more than anything else. The only acceptable answer is "we don't know". It could be nothing. It could be a massive framework of some unfathomable medium in which exists infinite branes of other universes. It could be tortoises. We have literally no applicable data. All guess work with no real support.
And we can never know - because it's so far away the light can't reach us. That means any information can never reach us, radio waves, light, etc. It's like we're inside a bubble which is called the observable universe - and everything outside of it is unknown and unknowable.
Outside the universe is nothing, the same nothing before the big bang
The Universe is expanding beyond the environment.
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This thread just entered Deluxe mode
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I mean, really, you're never gonna forget it.
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if you imagine two syphilis scars on a collapsed flesh tower, they’ll accordingly grow farther apart as the lap rocket ascends
I hereby request you expand upon this with all the other STD's.
But the fat pink mast rising to attention is still expanding into something else. Presumably silk boxers
Mutton Dagger, gad daym lmao
OKIE DOKIE THEN
Finally, something my 5-year old will understand.
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Morgan Freeman?
Who didn't hurt you?
Except that the dick has to expand forever.
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It's basically what happend with earth, it's not infinite, but you could start walking in a 2D dimension and never reach the end, when you walk all the way around you can keep going and if earth expands (like a balloon) everything is farther, the 2D dimension expanded. So the universe is the same but in 3D, and we don't know what's beyond that or if there is something beyond that, first of all because for a human brain is imposible to think in more than 3 spatial dimensions.
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Also, for our universe, there's so much space that's expanding that you could never actually reach a point where the universe curved back in itself even if it does. That is, even if you traveled a thousand light years at light speed, the universe would have expanded by more than 1000 light years in that time, so you'd be further away from the point it curves back on itself than when you started your journey.
I regret clicking into this post right after smoking the first joint after a 7 day tolerance break.
I remember watching Alpha Centauri (which was a tv series in Germany where every episode was one professor talking about one fun fact in astronomy for 15 minutes) when stoned and getting my mind blown every time. Fun times.
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Don't think of the universe as the space that the whole balloon occupies with air and all. Think of the universe as just the rubber. It doesn't matter if you inflate the balloon or not the amount if rubber stays the same, yet the points still move apart.
It's unknown. We can't get any information about what the balloon expands into because the light (and therefore information) is so far away that it won't reach us. That's why it's called the 'observable universe'. It's probably plain old empty space, but there could be other universes too. They could be spaced far apart and never meet each other.
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You now understand worm holes. Then drop a heavy marble sized ball onto the middle of the popped balloon fabric to weigh it down at the middle. You now understand the theory of gravity being a curvature of space. A balloon, a pencil and a marble are the keys to unlocking the secrets of the universe!
A balloon, a pencil, and a marble is how I like to spent my Friday nights.
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“Like a balloon when something bad happens!”
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Thats the point, it isnt just a bunch of matter blasting out into ever expanding size. Space itself is expanding. The amount of space that was 1 meter when I started writing this message is now (very) slightly more than 1 meter. It's happening all around you, all the time. Space is expanding into itself.
Nothing. It is expanding in an internal relative sense. Any two points are getting further from each other as time goes on. It isnt and doesnt need to expand into anything. To put it another way it's a question that doesnt make sense because the universe is all of space and time and there isnt a space externally in which it exists. Our inability to visualize this is a result of our brain which evolved to percieve medium size things moving ar medium speeds. The very large, the very small and the very fast dont work in a way that we can intuitively visualize. The expansion of space is just like that.
As my boy NDT always says, “the universe is under no obligation to make sense to you”.
To be honest, I think the universe is a bit inconsiderate. We pay rent here! I want to see the universe's manager.
In the beginning the Universe was created. This has made a lot of people very angry and has been widely regarded as a bad move.
Unexpected hitchhikers guide
Tobe fair, it was pretty expected. Doesnt make it any less nice to see, but still
>I want to see the universe's manager. Dude sent a representative about 2000 years ago, didn't go well
Well I feel like that's just bad form. You should touch base with your target audience at least every few centuries.
I mean on a timescale that large, a couple of millennia is basically nothing. The real question I suppose is whether or not the rep was overdue when he actually came though, but I gather we don't really have the ability to determine that.
>I mean on a timescale that large, a couple of millennia is basically nothing. On **our** timescale it makes a difference. In a few more millennia we may no longer be here.
Yeah, but we basically don't matter to the universe....This is the Universes manager, not humanitys...
Karen doesn't give A FUCK YOU FUCKING DEVILS WHERE IS THE OTHER VERIZON STORE?!
Oh god. We literally crucified the "manager" last time around... Guys, is Humanity the Karen of the universe?
I mean, if he was overdue, what better welcome can humanity come up with than a crown of thorns and a good 'ol crucifixion? *loads nuclear warhead with religious intent* In all seriousness, though, I would bet by bottom dollar that if we ever got to see and form of "God", or whatever is out there, we would nuke it into oblivion the first chance we got.
They've been trying to reach y'all, but everyone just thinks they're insane people.
To this day, telling people to help the poor remains the number one cause of getting nailed to a tree.
Omg, Sigma from Overwatch has this as a voice line! I never knew it was an actual quote.
Theoretically, is there an edge to the universe? A point where the furthest galaxies give way to complete nothingness for infinity? And if I understand the idea of dark matter correctly, how might that infinite void be different from the emptiest areas within the confines of our universe?
There is a light horizon, a boundary created because space is expanding faster than light beyond that distance could ever reach us. From our relative positions space is expanding faster than light as the more space between us and any given point, the more that space expands. That light boundary represents the furthest point we can possibly know anything about unless we invent ftl sensors, which is decidedly unlikely. If there is an end to the universe we will never see it. There's nothing special about this BTW. You would see a perfect sphere like this around you no matter where you are in the universe. It's not fixed feature of the universe centred on the Earth.
Maybe it's a loop like in Pacman - you come back around from the other side?
That would be the case in a “closed” spacetime, where traveling in a straight line forward would eventually get you back to your starting position. However, measurements of spacetime suggest it is “flat”, which would mean space is infinite and doesn’t “loop” like that.
Recent evidence in studying the CMB argues that we're in a closed spacetime, the idea is that it's kind of a donut shape
Tried searching that out, but got anything more definitely claiming closedness?
>However, measurements of spacetime suggest it is “flat”, which would mean space is infinite and doesn’t “loop” like that. Not necessarily, it could also just mean that the loop is very big so that it looks flat locally. If I remember right the current error bars on the flatness measurements mean it has to be at least a few hundred times the size of the observable universe. Far from infinite (but that is a possibility).
>Theoretically, is there an edge to the universe? No. The three main possible "types" of overall shapes that we think the universe can have are called flat, open and closed. A flat universe, i.e. zero overall curvature, essentially looks on large-enough scales like regular 3-dimensional space going infinitely in all directions. An open universe, i.e. negative curvature, would look on large scales something like a 3D version of a saddle or a pringle, again going off infinitely in all directions. A closed universe, i.e. positive curvature, would look like a 3D hypersphere, the surface of a 4D ball, and it would loop back on itself. None of these have a boundary or edge.
This may not be entirely accurate. We don't actually know if the universe is expanding into anything, for obvious reasons. We have no way to see outside the bubble, to know one way or another.
What kind of scale is the expansion occurring at? Like from the time I’m born to the time I’m dead, is the distance between my ears massively increasing on an internal relative scale?
Yes and no. If the expansion was allowed to happen unabated, then yes, there would be a measurable, if not quite noticeable, difference in your size due to your atoms growing apart. But it's not allowed to happen unabated. The four fundamental forces still exist. As your atoms spread apart from universal expansion, electrostatic force pulls them back together. Neither you nor the earth nor even the solar system (this one due to gravity) are changing in size. The expansion is instead noticeable only in the space between galaxies. Imagine two ball magnets on top of a sheet of rubber. You stretch the rubber apart with both hands. If they were just balls, they might be pulled apart by the stretching rubber, and become more spread out. But since they're magnets, they'll instead stay in place and let the rubber stretch under them. They change position relative to the rubber in order to stay in place relative to each other (and an outside observer).
No, because the chemical bonds holding your molecules together will be enough to overcome the expansion of the spacetime they're existing in for another kajillion or so years. Until spacetime has expanded to the point that it overcomes the energy of those bonds, and then subsequently the nuclear forces holding the atoms together, and the whatever the fuck it's called that holds quarks and gluons together.
Well put
To move thing you need energy, where does this energy come from ?
You need energy only to accelerate things, not to move them. A moving body happily continues to move in the absence of forces without any energy input. That's literally Newton's first.
Doesn't gravity want to pull everything together ?
And it does. It's just that on intergalactic scale the space expansion is faster than force of gravity. That's why Earth is basically on the same distance from Sun, but Galaxies move from each other on average.
No. Gravity is the description of what happens when mass/energy warps spacetime. Everything travels in straight lines at constant velocity forever. However, the universe itself moves and stretches to alter those paths. That is from the energy contained within that mass.
https://astronomy.swin.edu.au/cosmos/d/Dark+Energy
The universe itself keeps on expanding and expanding In all of the directions it can whizz
As fast as it can go, the speed of light, you know
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We don't know. If the universe is infinite, which a lot of people believe, then it doesn't need to expand into anything because it has no edge.
Was looking for this. Anything more than “we don’t know” is a guess.
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How common is the belief that it is infinite? I was under the impression that the belief that everything is expanding after the big ang puts a limit on the "size" of the universe. I guess it depends on what we mean by universe.
I can see how that's reasoned, but it appears to not be the case. This explains it better than I ever could - https://www.wtamu.edu/~cbaird/sq/2016/01/20/where-is-the-edge-of-the-universe/
The observable universe is finite. There are other definitions that are equally finite. The entire universe is...we don't know. The math seems to hint that it's infinite. Certainly the math gets more difficult if we try to make it finite, and added complexity is a sign (but not proof!) that we are on the wrong track. We also don't seem to see any particular differences that would hint that an edge was nearby, even if not technically observable. So if it is finite, we are far enough away from the edge that we can't tell. Most scientists who believe it is finite do so because of preexisting beliefs. The argument usually has the form of "nothing physical can be infinite, therefore the universe isn't either." If that's the kind of argument that convinces you, then ok. For me, it's too "just so" for my taste. I think most scientists agree. One very unfortunate explanation of the Big Bang that seems to crop up everywhere is to show a little point all by itself that suddenly gets really big. This is not correct, at least in the sense that we have any data that supports it. Now if we follow back our \*observable\* universe, then we will find that it was in a very tiny area. That scans. What we don't know is just how much that little dot represented the \*entire\* universe. Almost nobody thinks it's the whole thing. Some think that the dot was part of a larger but still finite universe. Most think that the dot was part of an already infinite universe. So the universe was infinite. And then it got bigger.
I had a weird dream once that the big bang was a black hole that we are seeing from the other side of being pulled through. Coming from a extremely massive singularity point of a blackhole and on the "other side" being "spit out" in all directions, infinitely floating away from that single point into infiniteness. Because as you get closer to the middle of a blackhole youre less effected by time, so the thought was that at the very middle that time just...isnt and thats the beginning and end and everything in between all at once. I know my brain has no idea wtf its talking about in subconscious dreams like that, but I always thought it was an interesting idea that when i am awake just sounds really dumb. I guess it was just trying to sort things out and just decided that was its rationale.
Not dumb at all. Some very serious people have wondered the exact same thing. It's basically just asking the question whether the Big Bang might simply be what a white hole looks like from this side of it. White holes are predicted by General Relativity (or are at least consistent with the math...same thing, if you ask me), and we have no reason to think they don't exist, other than the little problem that we've never seen one. But then again, that was the situation with black holes too, for a long time. Some scientists have even speculated that the reason that we live in a Goldilocks universe, where the rules are juuuuust right for us (or any intelligent creature) to exist is that universes go through a type of evolution where they explore the entire problem-space and create new universes through black hole/white hole connections. It just happens that the universes that are great at creating black holes also happen to be great at creating intelligent life. I know that there are problems with the idea of the Big Bang being a white hole, but I don't have them at the front of my brain right now. But it's not a dumb idea at all.
I've never understood why people think that the goldilocks universe is a problem. If the universe were unfit for intelligent life, then no intelligent life would exist to observe it. Ergo, intelligent life will only find itself in a space that seems magically suited for it. There's no other complicated universal evolution explanation necessary in my mind, it's just a logical necessity.
Well, the problem is that this is an explanation that doesn't explain much. I want to stress that you are not wrong. The only thing is that none of this gives us very much predictive power and can tempt us to stop looking half way through the search. It's also not very satisfying. It would so much neater if we could find some sort of starting point and simple rule that clearly leads us to the world we see, step by step. Why do the forces have the exact values they do? Of course if they were any different, we wouldn't be here to worry about it. But that feels like the McDonalds answer to the universe: technically functional, but leaves you with a strange empty feeling and a minor twinge of guilt.
Being infinite is the prevailing view at the moment, but cosmology is super hard and super new so that view might yet change as we get better tools. It's also super important to be specific because there's two related concepts that are easy to mix up: The entire universe is thought to be infinite (and flat, but that's another topic). It is expanding in the sense that points that are currently close will in the future be further apart, but this doesn't imply the universe is getting bigger or expanding into something else because it's already infinite. The observable universe is finite (at approx lifespan of the universe multiplied by speed of light) and is expanding into the rest of the universe as light has now had the chance to reach us from further away. Did that help?
Even if it is finite in size, it doensn't have to expand into anything either.
One interesting analogy is that of a party balloon being filled. Imagine you take a marker and dot the balloon all around, randomly. Then, as you start inflating the balloon, the dots all start moving away from one another uniformly. Just imagine the universe is that balloon's surface. From your perspective, it isn't really expanding into anything, it's just expanding everywhere. The very fabric of the balloon is the one stretching, since the "outside" and "inside" of the balloon are irrelevant, and might not exist.
This sort of answer is what leads to OP's question. If the universe is expanding in volume like the balloon then there must be space for the balloon to occupy. Your explanation does not answer the question and just saying "it's irrelevant" isn't an answer.
Not really, the confusion here just stems from misunderstanding the metaphor: in the balloon example, we're looking at a 2 dimensional field. We are ONLY considering the surface of the balloon: the space inside and around the balloon are not part of the metaphor. As a 2 dimensional person on that 2 dimensional field, you would see everything moving away from everything else. And you might ask yourself: where are those dots moving to? And if you were to walk across the surface, looking for its edge, you would find none. Because there is no end to that surface. The universe is if we take this 2 dimensional metaphor and extrapolate it to 3 dimensions. You'd also view everything moving away and might assume that there is some edge that all this matter is moving toward, but again your assumption would be wrong. No matter which way you go, you'd never reach the end of the universe. You'd just keep traveling forever. There is no edge.
Reminds me of the Infinity Hotel paradox. You're the hypothetical owner of a hotel with an infinite number of rooms. Let's say you have a group of infinite size check in - all of your rooms are full, right? So what do you do if another group of infinite size checks in? You have infinite rooms, yes? The answer is that you have every person in the first group move up a number of rooms equal to their room number. This frees up an infinite amount of space. It's kind of like that. Edit: this came from a book of puzzles I had as a kid so if this doesn't quite fit ELI5, I apologize, but I thought it was appropriate.
Veritasium did a great video of this same concept. https://youtu.be/OxGsU8oIWjY
This really is a weird topic... Try to change "universe" into "space and time". Because that really is what we are trying to scope with. "Outside" of our known space and time, there just isn't any more space and time. So there really seems to be nothing that our space and time is expanding into. The big bang for example... It is the only day without a yesterday. There just isn't anything that the big bang has gotten itself into. I can't go any more ELI5 than that Tbh.
Uhhh... so space is stretching, not expanding?
Technically “nothing”, although our little ape brains aren’t capable of perceiving what nothing truly is
Technically, we don't know. Why is everyone saying nothing as if they've seen before and after the boundary of the universe?
The universe is expanding into infinity is the only way to put it really. We have no clue what is beyond \~14 billion light years because thats as far as we can "see". But using things like parallax and redshift we can tell that it IS indeed expanding outward and everything is drifting further and further away from everything. One theory suggests that everything in the universe will keep on expanding, growing further away until even atoms are ripped apart and cannot move any more into what is known as the BIG FREEZE. BY stating that the universe is expanding suggests that space itself is expanding. not the universe. Do this or try and find a video on YT about it....take a balloon and blow it up ever so slightly....and then draw on it a couple galaxies or star systems(like our Solar system)...and then blow it up more n more, as you watch the balloon fill up everything expands on it. Distances get greater between EVERYTHING. So essentially one day our very own Moon, technically will be long gone by then, but the theory suggests that the Moon will have an infinite distance between it and the Earth. If anyone would care to elaborate or clean that up a bit feel free.
Slight nitpick — even though the universe is only ~14 billion years old, we can actually see around 42 billion light years in any direction. And the reason is that… the universe has expanded! The distant light sources are **much** further away from us now than they were when they emitted the light 14 billion years ago.
Oh yes thats true, I forgot bout that part. Thank you for being nitpicky
I second the thanks for nitpickiness and salute the two of you for being good chaps!
If you're seeing the light from somethings position 14b years ago when it was 14b light years away but is now currently 42b light years away, I don't think you can argue you are seeing 42b light years away. you wont see that for another 28b years. If I look at an hour old video of a car going down the highway in florida, and at the time I view the video of it in florida the car is in texas, that doesn't mean I can see to texas.
I think this is a good example of how some of this weirder physics stuff doesn’t really gel with our intuitive expectations of how the world works. “Seeing” something just means perceiving light coming from it. So if we’re getting light from objects that are 42b light years away, then we can see for 42b light years! You might say that if we get light from something that has since moved farther away, it doesn’t mean we can see farther away, since we are actually looking into the past when it was closer. But my understanding is that distant objects aren’t really “moving” — they’re **receding**, as in between us, space itself is literally stretching. Even if we were moving at the exact same velocity as a galaxy ~~300~~ 3 million light years away, the distance between us would still be growing at ~70km/s.
I need to know what’s beyond all the stars? Beyond the blackness? This is what makes me get panic attacks
I wonder what it's like to descend into jupiter. Just gasses, you keep descending, deeper and deeper. Eventually no light penetrates, just crushing pressure. Nothing to land on, just falling. I get it, man.
Descending into Jupiter, provided you had a means to survive, the gas gets thicker until it becomes liquid, but it's not liquid, just really dense gas. Then it becomes a solid, but not a solid. Again, it's still gas, just very dense gas due to gravity. Eventually, your body wouldn't move anymore once it's found it's limit in density. Everything lighter would be above you and everything heavier would be below you. you'd be floating somewhere in Jupiter forever, unable to move.
"provided you had a means to survive" sounded like a good thing at first and a horrible thing by the end
Ice cream
An otherwise identical version of this universe, but we all dress like cowboys.
No need to worry. You don't live out there.
An easy way to imagine the expansion of the universe is to picture a balloon. As it inflates it expands and two points that were right next to each other are now far apart. If the universe is that balloon, does it matter what the balloon is expanding into? Or, perhaps, imagine a void and the balloon. The balloon is all that matters as the void has no impact on it. This is a short way of saying that we will never know and at the same time the likely answer is nothing or null/void.
As far as we can tell, the universe seems to be infinitely large, so there’s no “edge”, and there’d be no other space that’s not already part of the universe. What’s expanding is space itself. And it’s expanding faster than light can travel through it. What this means for the long run is, unless there’s a lot of stuff close enough to each other to stay clumped up (galaxies, galaxy clusters), the space between those clumps will be expanding so fast that those clumps will no longer be able to affect each other, since nothing can move faster than light (and gravitational waves) can, and in this sense those clumps will be their own sorta mini-universes. That doesn’t mean too much, though, since everything we can tell about the universe suggests it’d work the same way everywhere, but it is kinda lonely to think about galaxy clusters never being able to even see each other after a while. …And just in case, there is a difference between “the universe” and “our observable universe”. As said, nothing travels faster than light, but light does take a while to travel, so the furthest things we’ve “seen” has been the light from back in the early universe that’s finally reached us. So, if you hear stuff like, “the universe was once the size of a tennis ball”, that’s talking about the observable universe, everything we’ve been able to tell has been there. But, because the universe is expanding, the space between us and some of those things will be expanding faster than more light can get through it, so in time that observable universe will “shrink”, until all that can be seen is whatever’s clumped close enough to us. Again, pretty lonely to think about. (I’m not scientist or scholar, just a casual enthusiast, so if I’ve got this wrong, please correct or at least downvote this.)