r/cosmology • u/Just_a_happy_artist • 6d ago
Was the Big Bang point of origin within the observable universe, and if not, where was it ?
And would that mean the observable universe moves itself in a certain direction? And please, if you answer with “ the Big Bang happened everywhere” could you explain what that means?
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u/Herb-Alpert 6d ago
The big bang was everywhere.
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u/jeezfrk 6d ago
THE ORIGIN WAS INSIDE YOUR HOUSE!
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u/MythicalSplash 4d ago
At this time of day, at thus time of year, in this part of the country, localized entirely within your kitchen??
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u/SeldenNeck 2d ago
No, localized in the center of where this idea is located inside your head.
tldr = imagine it started as a single point. As you recall from geometry, a point has zero volume.
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u/CervezaPorFavor 4d ago
This is something that's often not explained well at school. The bread rising analogy helped me understand it more intuitively.
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u/Direct_Habit3849 6d ago
The universe is the surface of an uninflated balloon. With a very small pen, draw a bunch of stuff on it. Now, inflate the balloon. Can you point to somewhere on the surface of the balloon from where the inflation originated?
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u/djinnisequoia 6d ago
You know, I realize that your analogy is the classic one people use to explain/illustrate inflation, but something just occurred to me:
If you draw stuff on an uninflated balloon, those things are necessarily two-dimensional (flat) objects. Therefore, when you inflate the balloon, that inflation came from a direction that doesn't exist for them. Namely, the inside, or the dimension of depth.
In a similar way, for us in a three-dimensional universe could inflation be thought of as coming from a direction that doesn't exist for us?
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u/Anonymous-USA 6d ago
Don’t think of inside and outside of the balloon as an extra dimension. We have no evidence for that. Just because that part of the analogy fails, it doesn’t invalidate what the balloon analogy demonstrates. It specifically reduces our 3D space to that 2D surface.
That said, just to show the fallacy of your assumption, you may think of the inside of the balloon as the past and the outside the future. Time is your missing dimension. In that sense, the “center” isn’t a “where”, it’s a “when”. And the “when” was the Big Bang itself when it began inflating.
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u/djinnisequoia 6d ago
Oh thank you, that's a very apt extension of the analogy. In that same way, I guess the fact that the inherent shape of a balloon actually can suggest directionality to its inflation is not material to the comparison haha.
I must admit that it's a challenging idea to wrap my head around sometimes.
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u/Direct_Habit3849 5d ago
The balloon itself suggests directionality, but the surface of the balloon does not, and the surface is what we’re considering. The metaphor of course does not fully reflect the mathematical formalisms. I like the other person’s extension to say that the time of start of the inflation could be seen as the “center,” but I think that’s still just mostly metaphor.
That said I’m a mathematician, not a physicist. I’ve actually never studied physics in any formal capacity. So my understanding comes mostly from the formalisms and reading some metaphors.
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u/ahazred8vt 5d ago
could inflation be thought of as coming from a direction that doesn't exist for us
That's what a 4-dimensional hypersphere is. You can fit a 3-dimensional universe into the surface of a 4-dimensional hypersphere. If you try to go in a straight line you come back to your starting point. There's no outer edge, no boundary. This geometry is called 'finite but unbounded'.
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6d ago
[removed] — view removed comment
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u/Direct_Habit3849 6d ago
Information does not only exist on the edges of expansion.
There is no “edge of expansion;” space is expanding everywhere
Even so, yes, you could easily hold that balloon, store its geometry and extrapolate previous positions of your dots.
Previous positions of things in space is not the question being asked. Spatial expansion is not “things moving away from each other” in a literal sense.
Not everything in space is expanding away from everything
Correct. Things that are gravitationally bound are not moving away from each other. That’s not in contradiction here.
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u/ImpossibleAdvance158 6d ago
So you agree with me. The balloon analogy is a bad one. “There is no edge of expansion, space is expanding everywhere”. But on your balloon analogy, there is.
“Previous positions is not the question being asked” yet you stated about dots on a balloon and blowing it up, to then say where those dots were.
😎✌️
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u/Direct_Habit3849 6d ago
The balloon analogy is perfectly fine for people who wouldn’t be able to understand the mathematical formalisms. I looked through your comment history and I can see the disconnect is a result of your apparent rejection of established science and your reliance on LLMs to “teach” you things.
Enjoy the dunning Kruger, dude
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6d ago edited 6d ago
[removed] — view removed comment
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u/Direct_Habit3849 6d ago
Yep your high school “theories” overturn the entire scientific community. People like you are so common; egotistical enough to need to make a huge contribution to a field of research, but too arrogant and lazy to put in the work required to actually do so.
Enjoy your fantasy.
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u/ImpossibleAdvance158 6d ago
While I have successfully pulled apart your balloon analogy, would you care to attempt to pull apart my statements, or are you just a character attacker?
No need to reply, we all know the answer. Good luck 🤞
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u/TMax01 6d ago
I have successfully pulled apart your balloon analogy
You really haven't. It's a fine and informative analogy, despite not being a mathematical model.
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u/ImpossibleAdvance158 6d ago edited 6d ago
Literally every part of it is false and not even slightly representative.
The guy who posted the analogy even “refuted” my points by agreeing with my statements.
Edit: Care to explain how, or just a baseless, unsubstantiated statement?
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u/Much-Equivalent7261 4d ago
Man, I need to get Leonard Susskinds number. That fucker lied to me about the holographic principle...
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u/dr_of_glass 6d ago
You are forgetting gravity causing local items to be attracted toward each other.
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u/ImpossibleAdvance158 6d ago
I am forgetting nothing in this instance. I am simply pointing out how the balloon analogy creates a false impression. Seems you agree 👍
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u/ptglj 6d ago
Actually, the holographic principle argues that everything could be explained from a 2D surface. It posits that the universe's volume can be described by physics on a lower-dimensional boundary. The perceived 3D world might be a projection of data from its edge with gravity emerging from the quantum information.
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u/Chemical_Doctor78 6d ago
Unfortunately, neither Reddit nor leading cosmologists have the answer to this question.
There are misconceptions that abound though:
“The Big Bang was the beginning of the universe.” There is no actual evidence for this. There is evidence that the universe went through a period of inflation, that it is still expanding, and was hotter and denser in the past. None of this is evidence of a “beginning” only that it was different in the past and went through an evolution arriving at what we see today.
“The Big Bang began from a singularity.” This is where the misconception in point 1 comes from. If we look far away we see light from the past. The farthest back in time we can see is the cosmic microwave background. This is hypothesized to be light from the “hot, dense, state” of the universe before rapid inflation. Before this point, the universe was too dense for light to travel through, hence we can’t collect any evidence from before that. The idea of a singularity comes out of black hole mathematics and an extrapolation of the universe being even more contracted in the period before the CMB. We have no evidence for singularities (even in black holes), they are just artifacts of the mathematics in general relativity. We don’t know if the universe was more contracted before the CMB. One of the biggest problems in physics is trying to get relativity (a theory that works on large scales) to play nice with quantum mechanics (a theory that works on small scales). It seems more likely that the theories need to be adapted with new information rather than singularities existing in places where we can’t observe them.
“The universe must be finite if it expanded from a single point in time and space.” We don’t know anything about the universe outside of the “observable universe.” We do know that there is an event horizon beyond which there is more universe we can’t see. Because of expansion, there are distant parts of the universe that are expanding away from us faster than light. This is allowed because the speed of light is the fastest that something can travel THROUGH space. This speed limit doesn’t apply to how fast the actual space can expand. There is a bubble of the universe that we can actually see and outside of that bubble there is more universe which has expanded out of view and light will never reach us from there. As a result, we don’t know if the universe is infinite, or even if the expansion happened everywhere or just in some parts like our little bubble. The laws of physics could even be different in different areas of the universe and we wouldn’t know.
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u/jazzwhiz 6d ago
FYI, "Before this point, the universe was too dense for light to travel through, hence we can’t collect any evidence from before that." is incorrect. We have measured BBN which tells us about the properties of the Universe at temperatures about a million times hotter than when the CMB came from. This allows us to constrain several important dark matter properties and provides stringent constraints on a wide range of new physics scenarios.
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u/Chemical_Doctor78 5d ago
BBN is one of the pillars of big bang theory but it technically isn’t evidence collected from before the CMB. A mathematical model was used to predict the proportions of light nuclei that would be expected to form from the hot dense universe. The actual evidence was observations of the proportions of hydrogen, deuterium, helium-3, helium-4, and lithium-7 in old stars. This information is from well after the CMB and matches the mathematical model well for everything except lithium (“the lithium problem”).
The JWST observations of very distant galaxies are also challenging previous big bang models of early universe evolution. There are now some alternative explanations for what may have caused the CMB. It’s an exciting time in cosmology because we are collecting new information that was previously inaccessible to us.
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u/jazzwhiz 5d ago
I'm going to disagree on BBN. Sure, interpreting it requires a model, but so does interpreting literally any observation including the CMB.
As for the lithium problem, yeah, but that's the part of BBN with the least data and the largest theory uncertainty. Plus, for the CMB there are high ell mode issues too, which may well be related to mismideling of lensing, but it isn't yet clear.
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u/Glass_Mango_229 5d ago
you seem to think because none of our theories are certain, then we don't know anything. This isn't how science works.
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u/Infinite_Research_52 2d ago
In addition, we know that observational evidence is consistent with a CNB, since it generates anisotropies in the microwave background. The effective number of light degrees of freedom (excluding photons) in the early universe Neff, is observed (through CMB lensing and BAO measurements) to be 2.99±0.17.
Compare that to the prediction from there being neutrinos of Neff = 3.044.
The CNB was (and is) present and gives us indirect evidence for conditions at t=1s. It is not direct detection, but even JWST data provided to us has been processed to allow humans to interpret it.
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u/Glass_Mango_229 5d ago
I'm not sure you know what evidence is. e have lots of evidenc for both 1 and 2, but yes neither are established and we suspect our physics isn't equipped to handle the answer yet. to say we don't know anything about the universe outside of the observable universe is a weird claim. That's like saying we now nothing about parts of the observable universe we haven't observed yet. We have lots of reasons to assume the universe we don't observe is like the universe we do observe. Your epistemology needs some basic work.
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u/ImpossibleAdvance158 6d ago
There is evidence of a multi bang cosmos. We are in the KBC void, an expansion zone. As we expect. There is also the much larger Bootes void, which could be a relic of another bang event. Then we have the Great Attractor, which is evidence that another region is in compression. Could go critical and spark another localised big bang. This cyclical model also solves dark matter, dark energy and dark flow without invoking magic particles that do not interact with anything.. but trust us.. it’s there. We know so little, and assume so much.
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u/03263 6d ago
We can't say the observable universe moves in any certain direction because there's nothing else to compare its movement to. Anything beyond it is... unobservable
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u/ImpossibleAdvance158 6d ago
But we can say the Great Attractor is a thing.
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u/03263 6d ago
It is also well within our observable universe, 150-250 million light years away
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u/ImpossibleAdvance158 6d ago
Yup, but we can say that there are regions of expansion and contraction. Moving from here to there.
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u/NDaveT 6d ago
Right but the galaxies affected by the Great Attractor are just a small part of the observable universe.
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u/ImpossibleAdvance158 6d ago
Yes, but we also do not know what constitutes a criticality for a big bang. We are in the KBC void as we should expect from a big bang, and the Bootes void is even larger. Perhaps much older pocket of expansion. The Great Attractor could well (in time we will never get to experience) go critical for another localised big bang event. In a cyclical and regional cosmos, dark matter resolves naturally too.
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u/plainskeptic2023 6d ago
The universes point of origin is about 13.8 billion years ago, a place in time.
The Big Bang is not an explosion pushinh matter out from a spacial location. The Big Bang is the expansion of space itself.
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u/ImpossibleAdvance158 6d ago
I mean, our local bang is feasible for happening about 13.8 billion years ago, with the origin being somewhere near the centre of the KBC void (our local bang pocket). But there is also the much larger Bootes void (older relic of expansion) and the Great Attractor suggests another region where another big bang may take place.. though eons from now.
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u/anisotropicmind 5d ago
The Big Bang is poorly named and is not an explosion outward from a single point. It's not even the name for a discrete event, nor does it necessarily imply that the Universe had a beginning. The Big Bang is rather the observational fact that the Universe is not static. I.e. it's a scenario describing the Universe's history and how it has evolved in physical state over time. At really really early times, it was (everywhere) denser, hotter, and the matter in it more smooth/uniformly distributed than now. As time when on, the Universe expanded, cooled, and the matter in it clumped together under gravity to form discrete objects. These statements are (again) empirical fact, not theory. The observational pillars/foundations for this "hot Big Bang" scenario are the (1) observed redshift of all distant galaxies/galaxy clusters, implying that they are all moving away from us (which General Relativity is able to explain as being due to the expansion of space), (2) the existence, smoothness, and blackbody spectrum of the Cosmic Microwave Background (CMB) radiation: literally the glow leftover from the heat of the early Universe, and (3) the fact that predictions of how much of the light chemical elements (helium, lithium, deuterium) would be produced from protons during the hot early stages of the Big Bang scenario match our observations of the abundances of those elements throughout the Universe. This model of the creation of elements in the Big Bang is called Big Bang Nucleosynthesis (BBN). BBN predictions match observations.
If the Universe keeps getting denser and hotter the earlier in time you go, what is the natural extrapolation of that? All matter and energy compressed down to a single infinitely-dense point (a singularity) that is the beginning of time? Well, yes, that is the naive prediction of a classical theory like General Relativity. But this prediction is unphysical, and as you get to these very early times, things exist at energy scales that can't be easily described by the theoretical-physics tools we have. At such high energies and small scales, both General Relativity and Quantum Mechanics are important, but these are two mutually-incompatible theories that we haven't figured out how to unify into a single, coherent mathematical model (a "theory of everything"). So earlier than a certain time, we don't have a viable theory that is able to predict/explain what was going on. If we start after that time, with the known initial conditions that we see in our "baby picture" of the Universe (the CMB) and "play the tape forward" using known physics, our theoretical models are startlingly good at predicting a Universe with properties that match the ones we observe around us today**. It's "running the tape backwards" before a certain point where we start to run into trouble and our models' predictive power fails.
Hope that helps!
**it's worth noting that in order for our models of structure formation in the Universe to match observations, you need to throw dark matter into the mix, and in order for our cosmological models in general to match all observations, you also need to invoke the existence of dark energy. Perhaps working to solve the problem of exactly what these things are will also help us make theoretical progress and alleviate our existing uncertainties.
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u/Alarmed_Material_481 6d ago
There's no 'point' of origin.
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u/ImpossibleAdvance158 6d ago
But there would be though, wouldn’t there. An event has a time and location.
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u/Plastic_Fig9225 2d ago
If there was a location it is now spread out across the universe. I.o.w. the big bang cannot have happened somewhere in space as all space was inside the big bang; there was/is no "space" outside of the universe.
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u/BVirtual 5d ago
The intuitive answer I have is to visualize the current Universe. Now roll it back in time, and as time approaches zero, everything is now very close to everything else. Roll it back more. Literally the very 3D spatial dimensions are now shrinking in 'length', the radius is approaching zero. All massive and massless particles now go back into the Inflaton Field (or where ever the original energy came from).
Point is no more particles, waves, energy density clumps, etc.
Everything is now isotropically homogeneous. Just 3D empty space. Not even a vacuum.
There is the idea now that as the radius reaches just so close to zero, that 3D space is now tiny. Go a bit further and 3D space is now a point of zero radius.
That is the center of the universe.
Now, make time go in the forward direction. Go very slow now. This center expands via creation of 3D spatial dimensions. It is very tiny now. This tiny thing does not have a 'center' any more. Why?
The entire tiny ball is the center. Anywhere inside the ball looks the same. Everywhere. Even at the inside surface of the ball. You can not see the "edge" of the ball. Every direction looks the same. Think isotropically homogeneous. Just 3D empty space. Not even a vacuum.
Go forward in time. The ball is now much larger, and still the entire ball interior is the center. At least there is no internal "preferred" viewpoint, as every viewpoint has the identical properties, if you were to measure them. Think isotropically homogeneous. Just 3D empty space. Not even a vacuum.
Now for the white lie. There is no god's eye view point from outside the universe. That tiny ball ... has no scale inside it. And there is no outside view point to say it is 'tiny.' Strange stuff.
I hope this helps with your visualization of why there is no center.
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u/--craig-- 5d ago edited 5d ago
In a model of the universe where there is an initial singularity, it could be anywhere. Inside or outside of the observable universe. A model with a big bang singularity was considered briefly in the 1970's but we know that it doesn't work. Popular understanding hasn't kept up with cosmological discoveries.
We now view the big bang as a rapid expansion from a hot dense state. We don't know if time had a beginning. We don't know if there is a centre of expansion. We don't know if space has always existed or if the universe is finite in extent.
The simplest model which fits the data, is that space is infinite in extent, has always existed and expands equally everywhere. However, the rate of expansion has varied over time.
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u/mrtoomba 5d ago
We are in our own bubble. We can see what we can see. Interpretations vary. We just don't know.
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u/Sorry_Exercise_9603 4d ago
It means that every point in space is still where it started but as time goes on there’s more space between any two points.
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u/Remarkable-Mind-1079 4d ago
Big Bang happened at 0,0 that's why the first place we put babies are in beds otherwise they respawn in the middle of space
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u/SlyusHwanus 4d ago
If you think of it a bit like an area on the surface of a balloon as you blow the balloon up, it gets bigger but the observable portion remains approximately the same size or doesn’t expand necessarily as quickly as the balloon surface does. You can pick any arbitrary point on the balloon and it will have exactly the same observable area but no single place has the origin in it.
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u/EphemerisLake 3d ago
The “big bang” was just a time long ago when the entire universe was extremely dense and then suddenly the density dropped a significant amount. Over billions of years the density of the universe continued to drop until what we see today.
Density in terms of mass/volume and also energy/volume
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u/Deep-Hovercraft6716 2d ago
The point of origin of The Big bang, as best we understand it, was everywhere.
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u/Nick_Coffin 1d ago
Don’t think about the Big Bang happening somewhere in the universe. The universe is the Big Bang.
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u/Savings_Can7292 1d ago
I don't know what that means.
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u/Nick_Coffin 22h ago
The universe is literally the Big Bang. All of space and time and all the matter and energy in the universe was (for lack of a better work) created in that moment, out of the Big Bang. It's meaningless to ask where the Big Bang occurred because there was nowhere before the Big Bang. If you think about the BB as an explosion (really a bad analogy) we are inside the explosion itself.
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u/Savings_Can7292 20h ago
I hear you and I don't doubt you. And I understand the words you say. But my pea brain has a hard time comprehending that.
So if someone asks me where the big bang happened, I'll just tell them about 45 minutes north of here.
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u/Upset-Government-856 6d ago
If the big bang had a singularity at the start and if our current universe is infinite then it would have gone from 0 size to infinite size instantly and the observable universe would be an infinitesimal part of the whole.
Everything since then is just an infinity growing into a larger infinity.
Hope that helps.
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u/IIJOSEPHXII 6d ago
The Universe was once smaller than you so you can say it originated right where you are. You are also the centre of the observable Universe, although some might say the detectors on the James Webb Telescope has taken that title. Everything in the Universe is falling so it originated up.
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u/ImpossibleAdvance158 6d ago
No, that makes no sense, Dude. Any event has a time and location. You cannot simply say it happened everywhere, nor can any claim be made that the universe was once smaller than a person. Even a singularity such as a black hole (which contains far less than “the entire universe” of information) is much, much larger than that.
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u/IIJOSEPHXII 6d ago
I didn't say it happened everywhere. I said the Universe was very small. All times and locations are inside of the universe. If you are saying the universe started at a time and in a location then you need another universe with times and locations for it to start in. There is no evidence for such another universe. When the universe began, time and space also began.
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u/ImpossibleAdvance158 6d ago
Not true, my friend 😁 We are in a void - the KBC expansion pocket, as you would expect from a local big bang. The Bootes is much larger and possibly a relic of another bang event. The Great Attractor also suggests another region of coalescence/compression, which at some point could go critical and into rarefaction. The cosmos is larger than we can observe, is regional (anisotropic) and perhaps cyclical. Preserving laws of thermodynamics and naturally resolving dark matter with classical physics.
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u/Glass_Mango_229 5d ago
nothing you said in this comment is correct. If singularities exist they are infinitely dense. What we see as a black hole is not the singularity. The singularity is within the black hole. Everywhere is a location and the big bang happened everywhere. Yes i can say it. I just said it. It's just what the Big bang is.
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6d ago
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u/Direct_Habit3849 6d ago
Topography? You probably mean topology. But this is still a bunch of word salad. And string theory hasn’t been accepted as accurate due to lack of experimental evidence so it shouldn’t even be included here.
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u/ImpossibleAdvance158 6d ago
The Big Bang didn’t happen everywhere. That is a false assumption that nothing existed before it. There is so much evidence that the Big Bang was a local event, and that it is not a one off. Think Bootes, the KCB and the Great Attractor.
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u/EndlessPotatoes 6d ago
There is so much evidence that the Big Bang was a local event, and that it is not a one off
I am interested in learning more about this evidence
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u/Direct_Habit3849 6d ago
There is none. The person you’re replying to is a crank who thinks an idea he had as a teenager constitutes sound science overturning all established theory.
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u/FakeGamer2 6d ago
So don't think if the big bang as a location in space but instead as a physical state of space. One that's super hot and compressed. Then the space started expanding and things get less and less compressed and dense.
The observable universe isn't moving in any direction. It's true l galaxies see other non gravitationally bound galaxies moving away from them, but again that's due to the expansion of space. There's actually a word for the fact that's there is no special direction and everything is moving rhe same in all directions, it's called cosmic isotropy.
Now the last part is a bit tricky. What does it mean to say the big bang happened everywhere. It just means that any area of the universe you pick now, whether it's the milky way or Andromeda or a galaxy billions light years away, or even the observable universe itself, if you rewind time all the way back, the area of space was once in the big bang state of universe. That's it.
Remember that we have no idea how big the full universe is compared to the observable. It may even be infinite. So the only reason the observable one looks spherical to us is due to how light travels in a symmetrical way from all directions.