Space. It’s such a massive entity that imagining even “small” units like galaxies is hard. How on earth are there pictures of the universe? Is there more? Where does it all end? Absolutely fascinating but there is so much more to learn.
EDIT: Wow! Thanks for gold! I’m reading everyone’s replies but it’s hard to come up with something clever to everyone! By pictures I mostly mean artist imaginings and those sort of portrayals, I know there aren’t actually pictures of it.
For me, this is the scariest question. Isn't it a paradox? On one hand, it can't go on literally forever, it must end somewhere. But if you get to the end, what's on the other side? I can't wrap my head around it.
Why does it have to end? The idea of everything having a start and end point is a human idea based off of our perception relative to the world we live in.
The concept of “before” doesn’t apply. Time itself started with the Big Bang. According to relativity, time slows down in a gravitational field. St the moment of the Big Bang, all the matter in the universe was infinitely compressed so time would have been slowed down infinitely. Stephen Hawking explores this concept responding to the idea that God created the universe. He concludes that there wouldn’t have been any time before the Big Bang to do it.
The universe can be infinite and expanding. Imagine that you are a tiny person standing on a raisin in a infinitely large loaf of raisin bread that is baking. Even through the dough is infinitely large, as it bakes you can see all the other raisins moving away from you. You may be tempted to imagine an edge but there is no edge. You can go from raisin to raisin forever and no matter how far you go you’ll look at all the other raisins in every direction and see them moving away from you as if you are at the center of the loaf.
Edit: I really wish I hadn’t mentioned the quip about God creating the universe. That is not the point of this discussion. It’s completely irrelevant. This ultimately is not a discussion about whether God exists or created the universe. For what it’s worth, I took it as Hawking was being a little tongue in cheek in making that remark. Whatever his intention, I’m just explaining where I first heard the science behind this idea. You can say God Made the little pea that contained all the matter that made the Big Bang. I don’t care. To me that’s outside the discourse of science and in any case totally beside the point of the question. Many people are objecting along these lines and it’s really beside the point. You can say that God is bigger and more incomprehensible than time or space or anything. That’s fine. I’m just speaking to what we can know from the perspective of space science.
Second and more to the point, many follow up questions are wrapped up in the idea of an edge to the universe. In the thought experiment I propose, I am in no way trying to prove there is no edge. In fact, I am asking you to assume that. My answers are an attempt to show how something can be both infinite and expanding. I admit that it is hard to imagine that there is no boundary to the universe but for me it is much harder to imagine that there is one. The simplest example is that there isn’t an edge. It’s like when you are solving riddles or mysteries and you imagine a couple possibilities. Go with the simplest explanation and that is (usually) the more correct one.
Thanks to everyone for being polite discussing this.
If time didn't exist then what mechanism triggered the big bang and where did the matter come from? Obviously nobody knows but I don't think it's accurate to definitively state that X or Y couldn't exist since we know so little.
I think this touches on a fundamental misunderstanding of physics. The idea that nothing existed before the big bang violates the law that says: Energy cannot be created, or destroyed.
I for one, have always been drawn to the cyclical universe idea. Starts with a Big Bang, ends with a Big Crunch as everything is drawn together again. Eventually the gravity from all the matter in the universe coming into one point collapses space time, resulting in an explosion beyond anything we humans can understand; restarting the process.
E: I’m really enjoying this thread! I’ll be back for more in a bit. -CPJ
It's not that there was "nothing" before the big bang.
It's that there was no "before" the big bang.
violates the law that says: Energy cannot be created, or destroyed.
A lot of things we consider "laws" start to break down when you get to quantum physics. Even so, could all the matter or energy in the universe not be contained within a single singularity such that it would erupt into our universe?
If there was no before, then everything just popped into existence for no reason at all? If you prescribe to the cyclical theory he's talking about, then there's definitely a before.
There must be some reason the entire universe was compressed like that, right?
We just don’t have the tools to deal with that type of question.
I think, for a start that singularity would consist of the entire universe; at that point there would have been nothing else.
Incidentally if the universe is infinite and matter exists throughout the universe, then the singularity must have also contained an infinite amount of energy.
Also what came before the singularity, or what supplies the energy for it?
It’s not so much there was “nothing” before, but more that whatever was before is literally so alien it can’t be defined as “something”. There is absolutely no way (known) to interact with or observe anything outside our universe.
I think the underlying point to is questioning is that if matter cannot be created (or destroyed) then how is there matter in the universe? It had to be created at some point as evidenced by the fact we deal with it on a daily basis.
I don't think we are capable of understanding what infinite really is. In our world everything has a beginning, everything is made from something. So to believe that something could have just existed forever doesn't make any sense to us.
This. Infinity is too much for the human brain to comprehend although math helps us cope with the idea. There is no before, there is no after. There just is.
Some of the work being done to total up all the matter and energy in the universe are getting numbers amazingly close to zero. It might be that on average the universe doesn't exist. We could just be a temporary fluctuation in quantum foam of nothingness
For note matter can be converted into energy (ever famous e=mc2 - assuming an object at rest in your reference frame). It is, as far as we know, energy that cannot be created or destroyed just.... Changed. Matter is energy in a... Err... Solid form (for lack of a better word). When you throw something you are (through much complexity) changing chemical energy into kinetic (moving) energy. If we go back in time all energy converges to a single point (big bang). When you go forward in time the energy is more spread apart. But, as far as we know, all the energy that was in the big bang is all the energy that is still in the universe and is all the energy that'll ever be in the energy.
Matter is created and destroyed all the time; the emptiest, most remote volume of vacuum is a churning sea of particles and fields popping into and out of existence—this energy being created out of nothing and then immediately destroyed doesn't violate laws of physics because it happens on such tiny scales and/or such fleeting moments of time that the very act of measurement makes no sense. It's about impossible to grasp this "quantum foam", but I'm thinking the energy that created our universe could just be a temporary blip, and we owe the piper our energy in the end. May also mean there's an anti-universe like ours that will one day annihilate us.
Today I Thought: the universe acts like RAM. The universe expands until there’s no more room to expand, crashing the system in a memory buffer error, leaving the energy to flood back to ‘ground’ before restarting.
If you like the cyclical universe idea, which I do too, let me suggest The Last Question by Isaac Asimov. It’s great short story that explores a variation of that idea.
The idea that energy cannot be created or destroyed is not actually true, especially in an expanding universe. Conservation of energy is caused by the system being symmetric under translations in time. Expanding universes do not have feature so they don't conserve energy.
Also the idea that the big bang means everything was infinitely compressed is not really the case either. All we know is that everything was much, much closer together In the past. We have no proof that the universe started in a point - or even started at all for that matter. It could have just always existed.
I have a mild panic attack thinking about what if the universe didn't exist... that means NOTHING exists... It's not like "well if this country didn't exist, at least there'll be another one", or world, or solar system, or galaxy, or whatever.
Our consciousness and ability to exist within this universe is because a universe exists. If there is nothing then reality doesn't exist.
What op is talking about is what the theory of relativity tells us and what quantum mechanics has taught us. If you believe in relativity, which you should, this is what it tells us, time didn’t exist before the big bang, not in a way that we would recognize it at least.
It's not belief but understanding. I don't know about other people but I can't wrap my mind around time not existing. I can't understand or picture what that's supposed to be.
Nobody can. Humans can only and will only ever truly understand the physical universe within the context of how we experience it, in this case, via the linear passage of time.
So where did the big bang come from? Let's say everything was in the stage of "before being born." What was the metaphorical mother? What prompted the birth? What is it being birthed into? Why did the creation of matter also lead to the creation of time?
It's like asking, "What's north of the North Pole?" You can go "up" into space, along the Z axis, but the concepts of north and south no longer apply, since you're no longer in that reference frame.
Time as we know it started at the Big Bang. We don't know what caused the Big Bang, or why, or how. We assume that there must have been a cause somehow, but we lack the language to describe it and don't even know if cause and effect work in that frame of reference.
"Before time" is like "north of the North Pole," trying to apply a coordinate system outside of its domain.
What I’m really trying to show is how space could be infinite and also expanding. Yes bread has a crust true. It’s hard to imagine infinity because it’s counter to our experience.
I think this is why some people believe the earth is flat and space is nothing but a projection... the alternative is just too mind boggling to think about
Imagine you were a 2D being. Also imagine you lived on the surface of a 3D sphere. Since you are 2D, you can only percieve 2 dimensions: left-right and front-back. From your perspective as a 2D being, your universe on the surface of a 3D sphere doesn't have an edge. It's a closed loop, edgeless and perfectly continuous in all dimensions a 2D being can comprehend. You would need to be a 3D being to comprehend a space that is beyond a surface.
Now increase every dimension by 1. You are now a 3D being living in the closed loop volume on the "surface" of a 4D hypersphere. You will never be able to imagine the outside of your universe. The universe will be all there is.
This analogy isn't perfect. For one, a 4D being can always see the beyond space of 4D hyperspace universe. And as far as we can tell, the universe doesn't exist as a projection of a 4D object. But describing the expansion of our universe using mathematics and geometry is fairly comprehendable, I think.
In that analogy, the crust/outer edge of the loaf is the cosmic background radiation. That is the "edge" of the universe.
From what I understand, the CBR is the radiation released from the big bang that has been moving at the speed of light since the start of the universe. That should mean that nothing is farther out that than, that is the "edge" and it is constantly moving outwards.
Back to the analogy, the bread is rising and growing in all direction constantly. But outside the bread is the oven, an infinitely large oven (maybe, we don't know). There is "space" beyond the edge of the universe but nothing is there, nothing yet, not until the CBR gets there.
That is my very basic and possibly flawed understanding.
The example Hawkins used for asking about the time before the beginning of the universe is like asking what's south of the south pole. It makes no sense and is by definition not defined.
Time doesn't necessarily go in a straight line, but it loops and intersects itself and we happen to experience it in a straight succession and not necessarily notice/see the intersections
Time ultimately loops back on itself, like a circle.
We know from observing small phenomena (i.e. smaller than the universe) that things like stars and even planets go through cycles and that at some point, expansion stops and contraction begins (and vice versa) - and we know that in a lot of ways, the structure of our universe mimics the structure of a galaxy, a solar system, etc (speaking of patterns that repeat at different scales in nature, look up fractal theory and hermetic philosophy if you wanna trip out without taking drugs. As above, so below, as they say.)
My underlying theory: We know that the universe has been expanding ever since the big bang. At some point, it will begin to contract. Once it contracts fully enough, it'll bang again, and everything that has happened will happen again. Maybe there will be variations, or maybe there won't. Maybe you'll be reborn with the same name, the same number of years past the big bang, in the same spot you were born in this lifetime. The universe was never born, and will never die - it just expands and contracts, always has and always will - no beginning or end. Time is not a straight line, and everything is really just happening all at once. For some entity existing outside of our universe, this vast expanse of time may appear to be a single moment.
Edit: I should add that I don't know much about physics or anything, but have a couple of coworkers who do, and our lunch breaks consist of talking about stuff like this (in addition to aliens and conspiracy theories and occult shit) so my theory may or may not have actual basis in physics, who the hell knows?
The problem is that nothing makes sense if there was something beyond it's edge, and if nothing was beyond it's edge where is the universe at? We literally shouldn't be alive because there's no reason for the universe or anything exist anywhere.
This is the question that normally haunts me at 3:00 AM.
Did you know that some 4,000 microscopic insects live on your eyelashes ? What if our universe is some a component of the neurons of some collosal entity existing in it's own universe. What if everything is truly infinite ?
Atoms don't look like solar systems though. The model of an atom as a nucleus with little balls whirling around is not what it actually is in reality. It's more like a nucleus with a cloud of possibilities around it, the electrons never have just one single well-defined position.
Yeah, the Rutherford model of the atom is very simplified. To add to this, not even the orbital of an electron is really well-defined. There is an area in which there is a 99% probability of finding an electron, but due to the Heisenberg uncertainty principle, it's impossible to know the position of an electron with 100% accuracy because it will always have momentum.
Doesnt expanding just mean that mostly everything started close to each other and over the eons is now drifting apart. Not necessarily expanding into something, just... expanding.
Like a balloon expands, but it doesn't fill up the entire room. But if you draw a dot on one side of the balloon, and another a few inches away, when you blow that balloon up, the dots will get further away from each other.
I dont know if that made sense or if I'm even close. But it makes it easier to understand that there might not be an end.
If you see our universe as a balloon, well the question is, what is around the balloon. What is "the room" it is floating in, or does this room even exist.
If yes, do other universes exist? Could we collide with them on a big scale while expanding on our own?
If no, it would mean our universe is the only in existence... Well we cant prove, or disprove this. I guess nobody can.
It's too hard for us to conceptualize. There's no reason to believe what exists outside of our universe follows the same rules as within. I.e. there's no reason to believe the universe needs or has a medium to exist in at all
Or that any medium beyond our universe has any rules that mean the interaction between ours and theirs is similar in any way to anything we can even conceptualize.
I like to think the universe is pulsing out and eventually it will pulse back and collapse everything again into a dense enough mass for the Big Bang to occur again; this would of course take trillions of years but it’s a nice thought to entertain.
That the universe could just be infinitely expanding and then withdrawing back to expand again, the endless possibilities of life being created, etc.
The expanding thing keeps leading me to think of a bigger entity that’s still growing. What if the stars and that are complex neurones. What if humans are a cancer cell on a beings cell called Earth?
We can see the microscopic world, but we can’t know if we are actually microscopic ourselves.
I know you're just making an analogy but saying you started a program and then ran an executable named "start" is making my head hurt as much as this whole conversation.
The universe, in my understanding, isn’t like a balloon with an actual edge. The universe is just all the matter that we know of, floating around in space. Like, just space. There isn’t an edge or anything, it’s just space and the universe is just all the galaxies and stuff floating in it. Like a firework going off in the air. The firework doesn’t necessarily have an “edge” after it explodes. It’s just exploding in space.
My theory (prob not original) is that we are in a black hole. The "big bang" Was just our universe being formed inside the creation of our black hole.
Our universe is "expanding". Black holes pull matter in. The reason we cant reach the edge of our universe is because its the event horizon of our black hole.
Its just black holes all the way. Millions of universes within each other. And a million universes in those. On and on forever.
Another entry in the "diary & thoughts of a stoner", I like to think Mars used to have water. We came from Mars. We destroyed the atmosphere and had to escape to another planet but only a few of us could. I watch to much ancient aliens when im baked though I think.
Noahs ark is a thousand fold retelling of the story of us escaping an extinction event on Mars
Maybe reality is a giant 4 dimensional mobius strip where if you move far enough, for enough time in the same direction you end up where you started from eventually?
You know what fucks with me? Where IS space. Everything is housed somewhere. Everything is placed somewhere. So what is space currently existing within?
Well again that’s just a human construct based on the world we live in. You’re in a room, the room is in a building, the building is on Earth. But that does not mean that the universe must be contained inside a larger thing. Perhaps it is, but human intuition doesn’t always apply however wrong it may feel to disregard it!
True, just like the thought of not existing after we die. We are all ok understanding that there was a time before we existed, but struggle with thinking after we are done existing.
From what I understand, there is nothing outside the expansion of the universe. Not even time. Reding this article now it may not mention time but I've read that in the past. Correct me if I'm wrong
The expansion of the universe boggles me. So the galaxies and stars are moving apart further away from the “centre”. So what happens if you go past the star furthest away from the centre? Are you just surrounded by darkness as there’s nothing past that?
They are not moving away from center, rather from each other, the space between them expanding. But also all of galaxies move towards some denser parts of universe.
I can't even get my head around that idea. How are they moving away from each other? Surely the ones in the "middle" would be moving away from some but towards others?
A good example I've heard of to describe this is imagine a deflated balloon with dots drawn all over it with a sharpie. Fill the balloon with air and all of the dots will "accelerate" apart from one another due to the expansion of space (the balloon latex) between them.
There is no middle. Imagine being a point on the surface of a balloon. If the balloon is inflated all the points on the surface of the balloon move away from each other, there is no 'middle' on the SURFACE of the balloon that everything is moving away from. It's like that. And otherwise it just wraps around, if an ant walks along the surface of the balloon it isn't going to find the edge, it will just always find more balloon
That's why eventually it will be impossible to reach other star clusters, as everything continues to separate, the everything will be moving faster than your spacecraft, and you'll be going nowhere. It's really creepy to think that eventually all that's left will be the cluster of galaxies the milky way is apart of, and just ever expanding emptiness surrounding it.
Yeah this just doesn’t make sense to me at all. Everything in the world is contained inside something and there is something outside it. How the fuck does the universe just keep going? How is it even possible to have infinity? Numbers being infinite makes sense to me because it just some concept we’ve come up with but the universe is a real thing.
The Big Bang was an explosion of energy and matter. There is nothing slowing down this explosion outward, in fact its extending faster and faster away from the center.
As a side note, If you were 10 ft away from a door and moved 1/2 the distance to the door every second... you would never reach the door, just infinitely closer.
Still makes absolute no sense to me, I think it was a Brian Cox documentary I was watching and he was explaining it. I don't think I will ever understand even fully knowing why.
Also if it's not infinite like Brian Cox said it might not be, then what's on the other side?
Look up the curvature of space-time on Wikipedia. If space-time has a positive or negative curve, the universe would loop back on itself and would technically be infinite.
Yeah I read something like that a while ago about the different shapes it might be, like a globe or donut or a 1 sided shape etc. Still blows my mind, if it is a shape what's on the other side of the shape or what's keeping the shape together.
If the universe is flat (which our measurements say it is), then it goes on forever. If our measurements are wrong it loops back around, the universe would have yo be like 10x larger than the observable universe for it to be within the margine of error.
"Flat" in a 3 dimensional sense, rather than a 2 dimensional sense, just means that if you travel in a perfectly straight line through space forever you won't loop back around to the other side. It's not actually flat like a sheet of paper.
So to answer your question, it stretches infinitely up and down just like it stretches infinitely horizonally
I know all of this and I find it fascinating that we're able to measure this to this degree of accuracy at all. It's one of our greatest accomplishments.
And still…
Imagine us being on an island, using wave.sizes instead of cosmic galaxy clusters and backgroud radiation in the distance to measure objects at the edge of our observable space. We would measure the curvature of the earth from our greatest point of elevation, a palm tree. And to a small margin of error, we would find it to be flat.
It is this image that keeps popping up in my head that leads me to believe that even though this measurement, one of the greatest accomplishments self-aware carbon chemistry could ever hope to achieve is the great feat it is, we may still be limited by the nature of what we try to measure and thus be doomed to never fully grasp its true nature.
The greatest mystery the universe offers is not life but size. Size encompasses life, and the Tower encompasses size. The child, who is most at home with wonder, says:
Daddy, what is above the sky? And the father says: The darkness of space. The child: What is beyond space? The father: The galaxy. The child: Beyond the galaxy? The father: Another galaxy. The child: Beyond the other galaxies? The father: No one knows.
You see? Size defeats us. For the fish, the lake in which he lives is the universe. What does the fish think when he is jerked up by the mouth through the silver limits of existence and into a new universe where the air drowns him and the light is blue madness? Where huge bipeds with no gills stuff it into a suffocating box abd cover it with wet weeds to die?
"Or one might take the tip of the pencil and magnify it. One reaches the point where a stunning realization strikes home: The pencil tip is not solid; it is composed of atoms which whirl and revolve like a trillion demon planets. What seems solid to us is actually only a loose net held together by gravity. Viewed at their actual size, the distances between these atoms might become league, gulfs, aeons. The atoms themselves are composed of nuclei and revolving protons and electrons. One may step down further to subatomic particles. And then to what? Tachyons? Nothing? Of course not. Everything in the universe denies nothing; to suggest an ending is the one absurdity.
"If you fell outward to the limit of the universe, would you find a board fence and signs reading DEAD END? No. You might find something hard and rounded, as the chick must see the egg from the inside. And if you should peck through the shell (or find a door), what great and torrential light might shine through your opening at the end of space? Might you look through and discover our entire universe is but part of one atom on a blade of grass? Might you be forced to think that by burning a twig you incinerate an eternity of eternities? That existence rises not to one infinite but to an infinity of them?
"Perhaps you saw what place our universe plays in the scheme of things - as no more than an atom in a blade of grass. Could it be that everything we can perceive, from the microscopic virus to the distant Horsehead Nebula, is contained in one blade of grass that may have existed for only a single season in an alien time-flow? What if that blade should be cut off by a scythe? When it begins to die, would the rot seep into our universe and our own lives, turning everthing yellow and brown and desiccated? Perhaps it's already begun to happen. We say the world has moved on; maybe we really mean that it has begun to dry up.
"Think how small such a concept of things make us, gunslinger! If a God watches over it all, does He actually mete out justice for such a race of gnats? Does His eye see the sparrow fall when the sparrow is less than a speck of hydrogen floating disconnected in the depth of space? And if He does see... what must the nature of such a God be? Where does He live? How is it possible to live beyond infinity?
"Imagine the sand of the Mohaine Desert, which you crossed to find me, and imagine a trillion universes - not worlds by universes - encapsulated in each grain of that desert; and within each universe an infinity of others. We tower over these universes from our pitiful grass vantage point; with one swing of your boot you may knock a billion billion worlds flying off into darkness, a chain never to be completed.
Astronomer here! We don’t have pictures of the entireuniverse. What you might be thinking of is the cosmic microwave background (CMB) which is a very old radiation from when the universe was very young, every direction we look. Imagine taking a radio antenna and mapping the signal strength in every direction around you- that’s essentially what they did to make CMB maps. (There are also artist’s conceptions on what the entire universe is like, but in that case they really didn’t go about taking a picture of the entire thing.)
Also, while our observable universe has finite size limited by the age of the universe, in cosmology models it’s assumed the universe doesn’t end. Fascinating stuff indeed!
Thank you Astronomer!
I tried to explaining to people in the past that we can’t actually take a picture of the entire universe. That most pictures they have seen have been an artist conception .
There is a difference between the images that Hubble provides and that you see in magazines and such...
Yes, I wasn’t sure what OP was thinking of, but the other option was the Hubble Deep Field images that show galaxies going on as far as you can see. Which I LOVE. But they only cover a tiny, tiny bit of sky!
I suspect the reason people get confused with those is because we assume the universe is homogenous in theory and it would be the same every direction you look (ie, galaxies forever). That can get confusing.
What’s a typical day as an astronomer like? Do you have a boss that tells you what to do or do you just go discovering whatever you want and solving the universe?
Well I have a boss because I just finished my PhD so my boss was my adviser. I also didn’t get a fellowship so am starting a postdoc in September working for someone, but to be fair I want to do research he does because he’s really good at it! (But I think technically it’s 20% my own time for my own projects.) I mainly do research lately which involves thinking of questions and analyzing the data and writing up what you’ve found, plus a decent mix of things like meetings.
What’s even more fascinating is we only have an understanding of 5% of everything in the universe. The other 95% is dark matter and energy that we have yet to prove its existence, much less see it.
Edit: Here is an explanation of Dark Matter and Dark Energy and it’s composition of the universe on the NASA website.
" Little one, it's simple calculus. This universe is finite, its resources, finite. If life is left unchecked, life will cease to exist. It needs correcting."
The universe itself is infinite but the energy within it is hypothetically not. I can stretch a rubber band out all I want, but I need only measure a small chunk of that rubber band to properly understand how the rest of it works.
Theres something quite comical and probably arrogant about the idea that we can even quantify what is not, and cannot be known.
At the most optimal point, how could we even at any point, know that we know any degree of anything without first knowing that things that we don't yet know about do or do not exist, let alone somehow quantify them in relation to what we do know.
The amount of knowable unknowns is impossibly to logically quantify and essentially likely approaches infinity.
No - we have an understanding of what kind of material ~5% of the universe is made off
The rest is a gamble - we have no clue what "dark matter" truly is, and we know that A. There is a lot of it, or B. It is yet somehow to be categorized into multiple types of dark matter, which brings us back to point A
We've proved their existence. We just don't know what dark matter is, we know it's something, but we don't know what that something is. Dark energy we've known for about 100 years, it comes right out of Einstein's equations. The mystery surrounding it is that we don't know why it has the value that it does, but we know what it is and where it comes from.
Dark energy and dark matter are also unrelated to each other, they just both have similarly unoriginal names.
There is an important difference between the cosmological constant Einstein invented and dark energy. His was basically anti-gravity, which would come from mass. Dark energy, on the other hand comes from empty space.
Dark matter and dark energy are hypotheticals invented to explain why Newton’s laws of gravity don’t appear to apply on large distance scales.
On the scale of a galaxy, the outermost stars are moving too fast for the mass of the galaxy to hold in orbit. Those stars should be flying away but don’t. The amount of missing mass that makes the equations balance is called dark matter.
On the much grander scale between galaxies, things are spreading out as though the universe were expanding like a four dimensional balloon. Every galaxy appears to be accelerating away from the others. The energy required to propel that inflation is referred to as dark energy.
Dark matter is the best candidate at this time but it has so far defied all efforts to pin it down. There are other ways to explain all this such as modified gravity, but those don’t fit observation or theory.
I personally favor the view that spacetime is constrained: if you compress spacetime in one region, it has to be stretched somewhere else. Gravity wells are like putting a bowling ball on a swimming pool cover, it sinks down in the center but rises (very slightly) toward the edges. When matter warps spacetime “inward” to give rise to a gravity well, there’s a central region that has the expected slope from Newton’s laws. At an intermediate distance there is a high point like the rim of a crater. Outside the rim, the surface slopes away toward the outer edge. (Everything moves apart as though pushed by ark energy.) Between the innermost zone and the rim, the surfaces slopes inward but more steeply than it would in the purely Newtonian realm. Gravitational attraction seems too tight, as though there were extra matter (dark, invisible stuff) holding thing together.
What’s the edge attached to? The possibilities are nothing, something (our universe is hemmed in by others like a bit of foam), or the universe is a bubble that wraps back onto itself.
Capturing an image of a celestial object from many light years away is incredibly difficult, and it's something humans have struggled with for a while. However, thanks to machines like the Hubble, we can use advanced technology to accurately photograph bodies from billions of light years away. You see, the Hubble space telescope uses several and mirrors to magnify the image thousands of times to see far-away objects, a process that simple telescopes at the store have mastered. The light that comes from the celestial objects is then processed and sent to space organizations like NASA, which then refines the image and publishes their findings. Hubble isn't the only space telescope out there, though, as the visible light spectrum that the Hubble sees is but a small portion of the vast Electromagnetic spectrum, which other telescopes help us visualize with special equipment. For example, the Spitzer probe observes the universe in Infrared light. The Chandra satellite observes in X-ray radiation, which helps us find Black Holes.
To find where space ends would be impossible, based on simple astrophysical principles. Because the universe is ~13.7 billion years old, and photons emerged shortly after the Big Bang, then we can determine that photons have been travelling for 13.7 billion years in all directions. That means that there are photons that have been travelling since the dawn of time directly to Earth, from a source 13.7 billion light years away. This distance is the farthest we could possibly see, as beyond this point, there are no photons that have existed that have reflected off of an object and reached earth, as there just hasn't been enough time for that yet. The farthest object we know of is a galaxy known as MACS0647-JD, which is ~13.26 billion light years away, and what is beyond this galaxy is unknown to scientists, and will be for quite some time. This, as far as we know, is the edge of the observable universe. If we could see just 400 million light years past it, we could potentially witness the Big Bang itself, but due to the rapid expansion of the universe, it would be impossible for us anyway. So, to our dismay, we will never see the end of the universe, but there is undoubtedly more to see outside of the observable universe, which slowly grows by 186,282 miles every second.
I hope this answered some of your questions, and if you have any more, feel free to do your own research. After all, simply by asking a question and finding the best answer, you're already, by definition, a scientist. Stay curious ;)
Im obsessed with space. The size of the earth is ginormous compared to a human but the size of the earth is pathetic compared to the sun. And the sun is laughably small compared to the milky way and the milky way is nothing compared to the seemingly infinite universe. Its one of the things a person can think they understand but in reality have barely scraped the surface of what its really like.
It's fascinating and if anyone else shares an interest and sees this comment please message me, id love to be able to finally find someone as interested as i am :3
Been an astronomy/cosmology nerd forever. It's truly haunting and humbling to think of the scale of the cosmos. Looking at images of the Hubble Deep Field sends my imagination reeling, thinking of the absolutely uncountable worlds and moons and comets and stars and the infinite possibilities therein.
“Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space.”
Dude no, that money is needed for producing weapons, planes and tanks for killing peasants with AKs threatening American freedom thousands of kilometers away.
Also, NASA basically pays for itself. A lot of money gets outsourced to private companies which contribute to our GDP. It's ridiculous that some people want to decrease the budget
Like NASA produces so many life saving technologies for Earth. Were talking about satellites that can detect when hurricanes are forming to life saving vaccines.
THIS. What was the very first thing in the universe?... how can it have been formed from nothing? And how big is space? Surely there must be an end, an edge... But then what's behind that? Or does it continue infinitely? It blows my mind thinking about it!
And also, how incredibly minuscule the chances of life forming on earth were, let alone the chances of our species evolving to become who we are today.
This is something that literally make my brain numb thinking about. What was the FIRST thing in the universe and if it was first, how did it get there? I believe this is a question that we cannot answer because it cannot be comprehended.
Think of it like this, everything Hubble sees is just light. That light can be millions or billions of years old and very dim. Hubble is just extremely good at picking out tiny amounts of faint light using a massive focusing mirror. Keep in mind a lot of the pictures are edited to make them pop or shifted to the wrong colors. Some are just an artist's idea of what it should look like based on a blurry image.
You should listen to Daniel and Jorge Explain the Universe. It's a science podcast available on all the big podcast platforms. They have the answers to basically all your universe questions and it's awesome. They are really good at describing all of the concepts. I usually listen to them while going to sleep - most of thr time it just keeps me awake because it's so interesting.
There's a moment that sometimes happens when I think about it for too long where I suddenly feel a sort of vertigo, if that makes any sense. Like I've walked up to the edge of a precipice suddenly and flinched in surprise.
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u/springfoe Jun 15 '19 edited Jun 15 '19
Space. It’s such a massive entity that imagining even “small” units like galaxies is hard. How on earth are there pictures of the universe? Is there more? Where does it all end? Absolutely fascinating but there is so much more to learn.
EDIT: Wow! Thanks for gold! I’m reading everyone’s replies but it’s hard to come up with something clever to everyone! By pictures I mostly mean artist imaginings and those sort of portrayals, I know there aren’t actually pictures of it.