#SpaceVacuum #EdgeOfTheUniverse #CosmicMysteries
Have you ever wondered what lies at the edge of the universe? 🌌 It’s a mind-boggling concept that can leave anyone pondering the mysteries of the cosmos. 🤔 Let’s explore this question and dive into the depths of space exploration to uncover the secrets of the universe.
### The Universe: A Vast Vacuum 🚀
When we think of space, we often imagine it as a vast vacuum with nothing in it. 🌠 But the truth is, space is not completely empty – it is filled with various particles and radiation that make up the fabric of the universe. ✨ So, if space is already a vacuum, what would the edge of the universe even mean? 🌟
#### Outer Space vs. Empty Space 🛰️
Outer space is indeed vast and mostly empty, but it is not devoid of matter and energy. 🪐 The edge of the universe, if it exists, would be a boundary where the known laws of physics may break down, leading to new realms of existence beyond our current understanding. 🌠
### Exploring the Boundaries 🌌
Scientists and astronomers have been studying the universe for centuries, trying to unravel its mysteries and uncover the secrets of its origins. 🔭 Through observation and theoretical models, they have proposed various theories about the edge of the universe and what lies beyond it.
#### Theoretical Concepts 🌠
1. **Multiverse Theory**: Some scientists believe in the existence of multiple universes, each with its unique set of physical laws and properties. 🌌
2. **Big Bang Theory**: The prevailing theory of the origin of the universe suggests that it began from a single point of infinite density, known as the Big Bang. 🌠
3. **Dark Energy and Dark Matter**: These mysterious forces play a crucial role in shaping the structure of the universe and its expansion over time. 🌌
### Final Thoughts 🌠
In conclusion, the edge of the universe remains a tantalizing mystery that continues to captivate scientists and enthusiasts alike. 🚀 While we may never know for sure what lies beyond the boundaries of our universe, the quest for knowledge and understanding drives us to explore the cosmos further. 🌌
So, next time you look up at the night sky, remember that the universe is full of wonders just waiting to be discovered. 🌟 Let your imagination soar beyond the stars and into the infinite possibilities that lie at the edge of the universe. 🔭
…it would be a 'border' between nothing and nothing?
You sort of got why “edge of the universe” doesn’t make sense if you define the universe as “everything there is.” As far as we know, the universe is flat, so it just goes on to infinity with no edge. It’s also possible for the universe to be slightly curved so that it’s closed, but that doesn’t give it an edge either since traveling in a straight line just eventually leads back to where you started.
Since all interactions are limited by the speed of light, we can talk about the _observable_ universe (i.e. the region of space around us with which we theoretically could have interacted with) but even that doesn’t have a real edge, and it’s constantly expanding anyway as older and older light catches up to us.
As far as we know, “edge of the universe” is a nonsense concept.
As you say, it doesn’t even make sense.
I like the explanation that our dimension (3D) is like the surface of a balloon and the ballon itself is so to say in the 4th dimension. If the balloon inflates our universe expands. But there is no edge or border, though it might be interesting if one could hypothetically travel into one direction and come back from another direction one day.
A vacuum is not totally empty. There are still things (virtual particles etc) in a vacuum so we could define the edge of the universe as a place where there is stuff and then there isn’t stuff.
Then there’s the observable edge which just means as far away as w le can see. That’s not really satisfying because there is stuff beyond but we just can’t see it.
Then there is the “actual” edge in the way that we think of edges of boundaries. We haven’t been able to define an edge or even if there is one. The universe is everything.
Space isn’t a vacuum with nothing in it. You’re in it. The Earth you live on is in it. There are planets and stars and comets and all manner of particles pinging about. It’s literally full of stuff. It’s an extremely low pressure environment but it’s not nothing.
Space is not empty, and in the known dimensions of the universe, has no edge. Space is constantly expanding into itself, creating more space. As light is the “speed limit” of the universe, the observable universe is ~13.8 billion years.
But, since that is how we measure “the beginning” everything since then has been expanding, and the farther we look, the faster the universe seems to be moving away. In the idea of cosmic inflation, *space actually moved faster than light.*
The lamba cold dark model presents this idea that “dark energy” (basically a place holder for something not yet understood) is the force behind this expansion, and most of the matter in the universe being “dark matter” that doesn’t interact with light or electromagnetic fields (another place holder for something not understood.)
So, since the universe has always been expanding with the expansion of space, this light has now traveled ~46.5 billion light years. With an euclidean “width” of the universe of around 93 billion light years “edge to edge.”
We don’t know what is at the “edge”, but space as we think of it, isn’t exactly nothing. Laws of physics like gravity and time have an effect on it. Lawrence Krauss talks about the topic and defines nothing as, no space, no time, no physics. Here are 3 videos of 3 lengths, if it holds your interest.
As I understood it from an explanation once:
The universe is defined by objects in it (planets, stars, dust.. whatever), which were created during the Big Bang.
And since the Big Bang had a center, it started to expand. Meaning — objects started going outward from the epicenter of the Big Bang.
So the edge is where objects end, and where the forefront of the expansion is.
Now: this might be an outdated model, I don’t know about that, with the latest advances in science. But your question specifically seems to come from this particular model.
The universe isn’t expanding into anything. It is everything. Space is appearing between matter and pushing it further apart. The only border is the observable universe beyond which any light will never reach us in time for us to observe it.
It’s where the “stuff” meets the “no stuff.”
Filling in some random space now because this sub doesn’t like it when you *actually* explain things like the OP is five years old. Five year olds like simple explanations, btw. For some reason though, this sub insists on long and complex explanations.
Whatever though, I have my explanation which was very succinct. Some of us value succinctness, not this sub tho. Verbosity is the name of the game here.
The edge of the universe is where the expansion of space stops. It’s not a physical boundary, just where the universe ends.
But what was before the Big Bang?
There is no “edge of the universe” as far as we know, but there is an edge of the _observable_ universe. That edge is called an “event horizon”, and it’s like the horizon on Earth: you can’t see past the horizon from where you stand, but that doesn’t mean the Earth ends there. Likewise we have no reason to believe that the universe ends at this cosmic event horizon, even though we can’t see anything past it.
The cosmic event horizon is a bit different, though. It’s not just the limit of how far we can _currently_ see from Earth, it’s the limit of how far we could _ever_ see, at any point in the future, even if we were to travel toward it at the speed of light. The problem is that space itself is expanding, and beyond the event horizon, space is expanding so fast that not even light can ever catch up. This means that we will never be able to go beyond the event horizon or see anything that happens beyond it, nor will anyone beyond the event horizon be able to see anything that happens on Earth, or anyone coming from Earth, now or in the future.
This is what’s meant by the _observable universe_ – it’s the slice of the universe within our cosmic event horizon. The universe probably continues outside that horizon, but we cannot and will never be able to see any of it.
There can be multiple ways to define “edge”. For example if we use time as a fourth dimension then one edge is the Big Bang because there is no time before that.
If we consider that there may be more than 3 spatial dimensions, then one might compare space to the Earth. We can travel as far as we want in a straight line around the earth without ever hitting an edge. But if we somehow manage to move up and down we find that Earth does have an edge because in three dimensions Earth is a sphere. We don’t know what shape the universe has in 4 dimensions.
But what if the universe really does have an edge like people normally think of? What would happen when you reach the edge? Perhaps it would be like trying to reach light speed. The closer you get the harder it becomes to move in that direction so that you would only approach the edge but never reach it. What lies beyond that edge would be as undefined as what happened before the Big Bang.
It’s not going to make sense sadly. When you get to either extreme of size, very big like the universe or q black hole, or very small like quantum particles, our everyday experiences and expectations just no longer work. The universe is infinite. Why? Because it is. Just like there was no time before the big bang, all objects with mass warp space time, all objects without mass travel at the speed of causality, black holes are singularities with infinite density, etc. Things just get weird sometimes.
Space isn’t nothing. There’s gravity, radiation, and molecules/atoms and the base fundamental. In some parts there are heavy concentrations (planets, stars, and solar systems). In other parts there are an extreme lack of those things which is called the interstellar medium (interstellar space or the empty space between solar systems). There’s about 3 to 10 atoms per cubic meter in this ’empty space.’ The edge of the universe is a point where there is no longer the effect of gravity, radiation of any kind, and a true 0 atoms per cubic meter. There is true nothingness not even the fundamental laws of physics apply.
So there’s quite a lot to unpack with your question.
First when someone says edge, it’s usually or should be followed by “observable universe”. This is the edge at which light has been able to travel to reach us. So from our point of view, the furthest it’s possible to “look” and see something.
Space being a vacuum is another loaded piece of your question. A vacuum is measured in how little stuff there is to cause pressure. This doesn’t mean there’s no stuff. But just that it’s very spread out. On earth at sea level we will have 1 atmosphere. In space it’s something like 1×10^-20 atmospheres depending where you are. There will still be stuff and in star systems there’s more stuff than the space between galaxies.
Space is not the same thing as the universe. Space is just… the space between the stuff that’s in the universe and there is a lot of space in the universe.
Finally there’s the “border” part. If you were inside a donut (or torus) you could keep travelling around and around without coming to an edge. Now you might say that the donut has an outside. If you take the concept of this donut or edgeless shape into 4 dimensions, then there’s no edge as defined by the 3 coordinates of x,y and z. Outside our universe will be a different dimension that we couldn’t see and so the universe (not to be confused with the observable universe) is infinite in all directions.
The “edge” of the universe is the edge of what we can see. This is an oversimplification, but because the Big Bang happened about 14 billion years ago, we can only see things that are closer than 14 billion light years away. Because for anything further out, the light hasn’t had time to reach us yet.
The edge is just the border of what’s observable. What’s beyond the edge? There’s no way to know. But it’s almost certainly just more stars and galaxies and stuff. Maybe it goes on infinitely in every direction; maybe it doesn’t. We cannot make claims about unobservable phenomena.
I like to think about a black hole. From outside of a black hole, there is clearly an “edge,” or Schwarzschild radius, where everything inside it part of the black hole, but everything outside of it is not. So, to you and me, a black hole is a sphere of finite size and occupies a location within our universe. In theory, you can enter this black hole by crossing the event horizon.
Now think about inside the black hole. From inside the black hole, nothing is restricting you from moving in any direction. However, no matter what you do, you can’t get closer to the edge, only farther away. No matter what you do, how fast you go, whichever direction you go, your future is toward the middle of the black hole. As far as you’re concerned, there is no edge, just an infinite space where directions don’t necessarily make sense the way we think of our space as being a 3d grid, what with all of the spacetime being stretched and pulled by the mass contained within.
Now, back to our universe. We can’t travel to the edge of the universe. Not ever. No matter how fast, how far, for how long, and in what direction we go, the limits of our universe will always be moving farther away from us. It’s a fundamental property of our space. But… we do know that there is a point in time in our reference frame in our distant past where the universe existed in one point, a singularity, and then expanded faster than things within our universe are able to move.
Long story short, I’ve only got an undergrad education in physics, but I firmly believe this universe is the interior of an ubermassive black hole, and that the big bang itself is the white hole that is the time/space reversed black hole that’s been theorized. I hope the people smarter than me can work out if it makes any sense.
I’ve struggled with this concept of reconciling the limited mass of the universe, its spread and the conception of space that contains all of this to be an endless envelope. My understanding is the “edge” of this universe is just the arbitrarily defined “border” where most of the density of the universe tapers off significantly outward into the envelope compared to the volumes behind it.
It’s like imagining a sneeze cloud in a room with no walls (and so, with infinite space)…
Just as fish are locked in an aquarium with us on the outside looking in, the fish are both observers and the observable.
Just like humans are locked in a universe, there may be something on the outside looking in, we’re both the observers and the observable.
there are no edge.
space is infinite.
what we call the “edge” is just how far we can see because even light doesnt come to us fast enough to see further. and the further we watch, the older that light is, therefore now up to date.
the universe is so vast, that even with the speed of light, we cant see far enough.
My understanding has always been that when we say the edge of the universe we’re not talking about the edge of the vacuum but the edge of universe material, which is why the universe can expand.
Like pumping helium into an infinitely large balloon but we’re only measuring where the helium is instead of the volume of the balloon.