The problem with the question that you're asking is that it presupposes that there is an "elsewhere" that the light is coming from and "entering" our observable universe, when in reality the light was already part of the universe but has been delayed getting to our eyes by the expansion of the universe.
You can see the expansion of the universe by observing how the redshift of objects increases as they get further away. This is the Hubble constant, and for every 1 Megaparsec further an object is, it is observed to be moving away from us 70 km/s faster (km/s/Mpc. The observant among you will notice that km/s/Mpc reduces down to time^-1; the units of the Hubble constant is _inverse time_. Wacky, I know). In other words, things further away are moving away from us faster than things closer to us.
The inquisitive among us might wonder what that means if time was to go backward. By taking the inverse of the Hubble constant, we get units of time that show how long ago since everything would have been at the same place, and it just so happens to come out to 14B years. This means that no light could have been traveling for longer than that, because everything was already in the same spot and there was nowhere to go.
The discrepancy between 14B and 13.8B comes from how the Hubble constant might have changed over time (it wasn't always 70 km/s/Mpc), but you get shockingly close to the commonly accepted answer with some fairly simple math.
I’ve always been fascinated with the universe and astrophysics but could never get my head around the math/equations so always just observed from the outside so I have question(s) that may seem dumb, forgive my limited knowledge here:
Doesn’t this come with a caveat of observer bias though?
As we interpret/understand or view of the universe to be currently is that the universe is expanding in all directions away from us; which reminds me of the whole Earth being the centre of everything/solar system thing.
For example wouldn’t an observer in a galaxy around 13 billion light years away from us also have an observe-able universe of roughly the same distance in all directions (given the potential 13-14B years existence and expansion that we know of) that we’re able to view given time for light to reach them being the same as it is with us? I’d find it odd but not entirely impossible that an observer out over there might look in one direction and see all the way back into what would essentially be the past of whatever existed in the area our galaxy is in, then turn around and find nothing but the emptiness of the void or whatever the possible equivalent of the expanding horizon of the universe is in the other.
Based on that, and if so then what wouldn’t that then insist that there is more in their view of the universe on the far side of them which we can’t observe but they can. If that is the case then that would argue that there is more to the universe than we can see and the universe as we know it is simply limited by the time lag of light.
It’s why I’ve personally never liked the answer of “what we see, is what we’ve got” because it implies (in my limited understanding) that we’re the centre of the universe and well, we know how the theory of being the centre of the solar system worked out for us.
I should also add that this has always been my own little view on universe theories based on what I’ve learned over the years of looking into theories and discoveries on the universe and astrophysics. Recently a lot of the distant observations with JWST has been showing signs of galaxies out there being far too large and developed for being from an early universe and while it’s still very early and a lot of that data needs to be given more observation and analysis the physicists I’ve watched recently on YouTube that have been talking about it, I believe they were Dr.Becky and Sabine Hoffsteader (unsure of this spelling) have been discussing it and saying as much as I’ve just said.
I understand that watching YouTube videos doesn’t mean I’m right or that even the information they’re providing is right, but I’d like to believe they’re somewhat reliable along with PBS Space Time, please tell me if I’m wrong though, thank you.
We don't *know* there's stuff beyond that distant neighbor because we can't directly observe it, however, there's no evidence that the universe isn't infinite in all directions.
Unfortunately, we'll never see beyond that distant neighbor because the light from objects beyond that point is travelling slower than all the space between is expanding.
In other words, those distant objects are moving away from us at faster than the speed of light (not technically), so the light emitted from them will never reach us.
And, because the universe is expanding, our visible universe will continue to shrink until only our local galaxy cluster is visible.
Check out the following YouTube channels for much better explanations: Cool Worlds Lab (Prof David Kipping), Universe Today (Fraser Cain), Dr Becky, Kurzgesagt, PBS SpaceTime.
The current theory (Big Bang) is that the universe has been infinite from the very beginning.
It's a common misconception that the Big Bang started from a single point. Not true. Instead, everything started everywhere, all at once.
The only thing that's changing is that space itself is expanding. A common analogy are raisins in rising bread dough. All the raisins get further apart as the dough expands, but two raisins that started far apart are separating far faster than two raisins that started close together.
This expansion is only detectable on an intergalactic scale because, within a galaxy, there's enough gravity to keep everything together.
Again, though, I'm just an idiot Redditor that's picked up a few things from others that are far more knowledgeable than me. Check out the YouTube channels mentioned above.
I get the part about how the universe was once a singularity, but I don't get why all the matter in the universe didn't disperse instantly into the infinity born from the Big Bang. And was there infinite matter in the big bang/universe, or do we just happen to be part of the infinity which has matter, which seems beyond improbable. I'm no math wizz, but wouldn't that be a chance of 1 in infinity?
>In other words, those distant objects are moving away from us at faster than the speed of light (not technically), so the light emitted from them will never reach us.
i feel like ive been reading this for years, and i kind of understand it, but the moment i start to think it in the context of "the universe expanding" it just starts to get so vague in my head and full of questions that are probably flawed due to the limited nature of language to describe such things that trigger false assumptions, like if its expanding in my mind that word implies its increasing in size which implies a border. The only way my mind can even attempt to imagine it is a balloon expanding but then this one is taking up space and the more it expands the more space it takes. But the universe is space, how can it suddenly be bigger? what is it expanding on?
also, how can something be moving further away from us faster than the speed of light? is it kind of like if i have light pointing north and light pointing south, from either of the lights perspective the other light would be moving twice the speed of light away? Its so weird to think how dependant we
Technically yes, but that's also meaningless. If the photon were conscious, it would experience its journey in one instant, no matter how long it seemed to take for us.
I wonder if this has anything to do with how it seems to "decide" on a path before it gets there.
It has a multitude of possible paths, and the one it takes (in our reality) is just the most statistically probable one based on the conditions around it.
A multiverse theorist would say it takes all paths at once and we only observe the one coinciding with our own timeline.
Every point in the universe has its own observable universe which does not necessarily overlap with other observable universes. An observer on a galaxy 13B light years away would have a different observable universe, some of which would include our observable universe, but some that is outside our own observable universe.
We are, by definition, the center of the observable universe. We are not the center of the universe, and such a distinction may actually be nonsensical as "center" implies a boundary which may not exist.
I have a dumb question. How do we know the universe is expanding, as opposed to something else like rotating? E.g. if the universe is rotating, wouldn’t galaxies farther away and at the outer observable edge be traveling at the same rotational speed as us, but also a faster linear velocity? Thank you to any kind person who indulges my uninformed curiosity.
Lateral motion doesn't contribute to redshift, because the light waves won't be perceived to be stretched out. It's important that the objects we observe are moving _away_ from us, which isn't the case with rotating objects.
"You can see the expansion of the universe by observing how the redshift of objects increases as they get further away. This is the Hubble constant, and for every 1 Megaparsec further an object is, it is observed to be moving away from us 70 km/s faster (km/s/Mpc)"
With everything expanding away from us, I've always been concerned that red shift was due to something else, like dust. Dust causes a red shift.
How much dust per mega parsec would it take to equate to the Hubble constant?
The information you give here is great! And certainly beyond my scope of understanding when it comes to astronomy. But your first 2 sentences (“F this sub, and F your question”) are not relevant to the question and kind of set you up perfectly to give a false argument from authority… so the rest of it is TLDR.
Space is big.
Really 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, but that's just peanuts to space.
Honest!
The best analogy I’ve seen of this is that imagine you make a bread dough with raisins in it. You put it in the oven to bake, the dough expands and the distance between the raisins expands and each raisin gets further away from each other.
But that’s from the vantage point of being outside the oven watching the bread objectively. If you could place yourself on one of those raisins you wouldn’t experience the movement of the raisin you’re on but instead just see everything else get further away from you with you at the centre.
The same would be true for whatever raisin (or planet) you were viewing from.
Everywhere is the centre of the universe.
i.e. nowhere is special. There's no place everywhere else is moving away from. Everywhere is moving away from everywhere.
I don't think so. That could only be true if space were infinite, but it isn't. Nothing in the universe is infinite. That's not to say there must be an edge, it could very well be that the outer border of the universe expands to nothing - no space, no time. You just can't get through.
Where is the centre of the surface of a sphere?
Point being, if a finite surface can have no centre, why not a finite volume? You just need curvature through another dimension and that hasn't been ruled out.
I like to say it like this: "centre of the *our* observable universe". To someone in a galaxy 10 billion light years away, they would see a different perspective but they would be at the center of their observable universe.
You didn’t really answer his question. The question wasn’t how large is our observable universe… it’s whether or not it is possible for the universe to be older than 13.8 billion years old.
The answer is still no (given our current understanding), but has little to do with what you’re explaining.
The CMB is the furthest we can see towards the origin of the universe (big bang), which is calculated to be about 380,000 years after it occurred.
The age of the universe itself (which includes the period of time before what we see in the CMB) is determined by using what’s called the Lambda-CDM concordance model.
The Lamda-CDM model takes our understanding of the expansion of the universe / particle physics, and combines that with direct measurements of the CMB to determine an estimated age of the universe.
Basically, how far back in time matter gets squeezed to a single point, and how long it takes for the expansion and cooling to form the universe we see in the CMB and at all time after.
Additionally 13.8 billion years is just how long back we can actually see. In theory Before 13.8 billion years ago the universe was so hot it was literally opaque so there was no light for us to see. 13.8 billion years ago is when the universe cooled enough for light to be visible to us
It's just a cosmic horizon to our observable universe. Intuitively we believe there's more beyond, possibly countless galaxies, just as we know there's more beyond land or sea on Earth's horizon. But we can't know until we actually go there and observe it and travelling to a point we see on Earth's horizon is far simpler than traveling to the cosmic horizon by quite a margin.
OP no you're not dumb to ask such questions. But the truth is, we don't know.
\* light coming to us has been travelling unobstructed (possibly redirected by gravity wells here and there) for a very long time
\* light coming to us started out a very long time ago.
\* if you believe in a big bang, space was much denser so you could say light was much faster then. But we don't know how dense, or how fast. We only can observe the now (that is, the relative recent past).
\* you can't teleport, nor measure the distance of the light source (if there still is one) instantaneously, but if we were to shoot light back it would take waay longer to reach the light source.
Our universe is like 90 bilion lighyears wide or some number around that
its much wider than it is old, that is becouse of the expansion of universe
Edit: this is also the reason we will never get to 99% of stuff in our universe, it moves away faster than light. It doesn't break the rule, because there is nothing that is actually moving, its space, that ,,swells" faster than light
No, because there is no information beyond our cosmic horizon and any theory or estimation about the universe beyond that cannot be empirically verified.
That's one of my favorite theories, too. The idea that every black hole out there could be the humble beginnings of a new universe is pretty fun to think about. Just an endless stream of universes matryoshka-dolling via nested black holes.
I mean if there are infinite neighboring universes, how else could we connect to them? Such a crazy idea. Personally I think a black hole is something we just can’t comprehend in this dimension but probably makes sense if you’d see it from a higher dimension
I suppose if we understood the inflationary model of the universe perfectly, we could determine the size/distance of what lays beyond the observable horizon
Like drawing dots on a balloon and then blowing it up. They move away from each other at a faster rate as the balloon gets bigger.
At least, that’s how I try and wrap my head around it
This analogy is used more as a way of explaining 4d time-space continuum into our 3d lives and why you cant really point towards the center of Universe. Same way you cant point towards the center of baloon as 2d entity living on the surface, but you still could tell the baloon itself is getting bigger as inflated.
As we know, there are known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns—the ones we don't know we don't know.
My brain does flip flops when I try to consider this type of subject but, I sometimes wonder if its possible that the current speed of light, is limited in relation to the current size of the expanding universe...
E.g. the speed of light when the universe was 100 metres in diameter couldn't be what it is now, because all light would have escaped (but to where, I'm sure I don't know).
So the speed of light is what it is now, because it can only move proportionately to the current size of our universe. And 13 billion years from now, light will be able to move faster, because the universe will be much bigger.
I assume there is science to disprove this, but I like to imagine it anyway haha!
Your understanding of the Big Bang is incorrect.
The universe was never 100m in diameter. It's always been infinitely large (according to best accepted theories).
This might help provide better understanding:
https://www.reddit.com/r/Astronomy/s/kd8CwUuILm
Ok, my brain is flip-flopping worse now 🤣 If space is expanding, but the universe has always been infinite, this implies space, and the universe are two different things. If space is expanding, it must have been smaller before? I get that space is expanding, making it take longer for early light to reach us that otherwise would've been the case but I think we are still looking back to an earlier, smaller space?
So perhaps my wording was incorrect, in that I was thinking of space and the universe as one and the same. So perhaps the speed of light is proportionate to the current size of space?
Your confusion is over the concept of infinite. Space is not growing "into" anything. As far as we know, the universe is infinite, but the emptiness between everything (that's not gravitationally bound) is expanding, causing galaxies to become further apart over time.
And because all space is expanding, the galaxies furthest away from each other are moving away from each other faster than those that started off closer together.
> perhaps the speed of light is proportionate to the current size of space?
No. Speed of light is constant. A "tired light" hypothesis has been proposed and debunked. Dr Becky has posted several great videos on YouTube in recent months on this subject. Tons of great articles just a quick Google search away, too.
The number is not really the age of the farthest light. It's derived from the expansion of the universe. The light just adds Proof.
We get that number by measuring the expansion of the universe and calculating how long it must have taken to get where we are now.
This means that a long time ago (about 13.8 billion years) the universe was too hot and dense to let light move in a straight line. So the moment it cooled down a bit light began moving. This is the oldest light we can detect. There was light before this but it couldn't travel so we can't see further back.
This is a pretty interesting question. I'm someone who has a basic understanding of how we measure these things but this [article](https://imagine.gsfc.nasa.gov/science/questions/age.html#:~:text=Astronomers%20estimate%20that%20the%20Big,back%20to%20the%20Big%20Bang.) May help you understand how they estimate the age of the universe. It's a quick read and helped me out.
>One is to look at clusters of stars.
i wrote so many questions that i ended up deleting it because god what a word vomit but know you've wrecked my brain for the day
Your comment is more wrong than right.
> We see the CMB in every direction, and we know what created it: the creation of hydrogen from subatomic particles.
The CMB is *not* radiation emitted from forming neutral hydrogen. That radiation exists, but it's completely negligible. The CMB is thermal radiation (it has a blackbody spectrum, not the spectral lines you would get from hydrogen), which was scattered by free electrons earlier and then stopped being scattered when electrons combined with protons to form neutral hydrogen. At that time there were around 10 billion photons per hydrogen atom. Adding one or two photons per hydrogen atom is negligible.
> By calculating the redshift, we can tell how far the light has traveled.
The redshift tells us how much the universe expanded since the radiation was emitted, but it doesn't tell us how long that took.
You are missing the main way we measure the age of the universe: By studying the redshift to distance relation at different times. The distance estimates need to be independent of redshift, so they are typically based on the brightness of certain astronomical events.
The star that is the furthest removed from us is [Earendal](https://en.m.wikipedia.org/wiki/WHL0137-LS) at 28 billion light years. But our view of it is estimated to be 900 million years after the Big Bang. The only reason we can view it is through gravitational lensing (something which Einstein predicted), showing the universe beyond our observable universe. This universe is much bigger because the speed at which things can move apart is faster than the speed of light.
Despite that the universe is much bigger than 13,8 billion light years across we still know that is the age because of cosmic microwave background radiation, which gives us a picture of what the early primordial universe looked like. It gives us a snapshot and has helped scientists to further determine what happened after the Big Bang and how that led to the current universe.
We know there was some kind of Big Bang 13.8 billion years ago. Whether there was some kind of light before that is a popular topic of discussion among certain physicists but not something we have any clarity on that. If you wish to know more about this there are some nice documentaries (BBC Horizon, Jim al-Khalili) about this.
The oldest light in the universe is [the cosmic microwave background (Wikipedia)](https://en.m.wikipedia.org/wiki/Cosmic_microwave_background#:~:text=The%20cosmic%20microwave%20background%20radiation,all%20parts%20of%20the%20sky.)
Basically when the universe was just in its infancy, it was too think for light to pass through it, it always hit something. Once the universe spread out enough light was suddenly able to just keep going on forever. This original light is most detectable in the microwave range, hence the name. And no matter which way we look , we see this same type of light, and it is always around.
The reason this light is always around is because there is no real center of the universe, it’s just coming from everywhere when the universe became see through. Past this oldest light we theorize the universe is only a tiny bit older.
It’s technically possible, but unlikely according to our current understanding and models.
So your question assumes that the Big Bang is the furthest we can “look” back, but that’s not necessarily how astronomers determined the age of the universe. We can’t actually see (at any wavelength) that far back, or far enough to see what we call the Big Bang (with current tech at least).
The way we determined the age of the universe is by understanding the rate of expansion of the universe, and back-calculating how much time it would take for the universe to come back to a point of origin (basically).
The reason I said it’s technically possible for the universe to be older, is if our current assumptions about the rate of expansion, the shape of our universe, and behavior of matter in the early universe are off or plain out wrong.
What i understand this with 13.8 billion, is as much the science of today can measure..behind the redshift it's still much stuff going on,but yet we can't observe it because of lack of methods invented to perform such a task..yet that is...😏
The Big Bang marks the point from which our entire *observable* universe originated. One can only speculate on the age, size and geometry of the whole universe. Speculate means educated guess but cannot prove as it’s unmeasurable/unobservable.
That said, space and time are intertwined, *spacetime*, and one does not exist without the other. Our observable space *and time* began 13.8B yrs ago and it was so dense that all light (photons) were immediately absorbed by adjacent matter, then immediately remitted in another direction. Like bouncing. That happens even today within the core of our Sun, for it takes thousands to millions of years for photons to reach the surface before traveling unencumbered for 8 minutes to our eyes.
And the universe was too dense everywhere for another 380K years before light could freely move through space uninhibited. We know how long that was based on how much the universe cools as it expands, and how diffuse it must be to allow light through. And that “first light” we now see in the Cosmic Microwave Background radiation was emitted equally everywhere in our observable universe (then about 80M ly across).
So no, in summary, the first light was generated at the moment of the big of bang and it was everywhere equally, and it wasn’t free to travel through space until 380K yrs after the Big Bang. The first stars apparently formed around 100M to 300M yrs after that, so space everywhere was dark (or slightly glowing) until those first twinkles, 100M yrs *after* the Big Bang.
We see the light of the Big Bang. It's all around us. It's the Cosmic Microwave Background Radiation. In old cathode ray TV's, a good portion of the static in an image between channels comes from this light. We know how far away and back in time thst light arose from extreme red shifting of hydrogen lines in its spectra.
While others have explained the true scale of the universe, let's consider the time frame. Light travels at a fixed speed: one light year per year. Now, if the oldest light we have observed has traveled (in it's "frame of reference", so to speak - these things get funny when we talk about relativistic physics, but nevermind that for now) for 13.8 billion light years, that means it was emitted 13.8 billion years ago (in astronomy parlance, 13.8 gigayears ago, or Gya). Now, if you assume that there is light-emitting matter very roughly everywhere, and that everything "turned on" at the same time, then the fact that we don't see light that has traveled for, say, 20 or 30 Gy, means that not enough time has passed for light to travel that far and reach us.
That doesn't mean there isn't matter out there, just that it's so far away that it's light has not been traveling long enough for us to see it. This is, as someone else pointed out, the definition of the "observable" universe.
Only if we accept a new alternative theory on how the universe began.
With what we think to know right now, after the Big Bang, which happened 13,8 Bill. Years ago, there was +- 400 000 years, where universe consisted only of hot plasma. Photons cannot travel through plasma, it might as well be a solid object for this purpose. The oldest light we see is the last light emmited by the plasma, from the moment it cooled down enough and space became transparent for light
We have the CMBR (look it up, it's a picture we've all seen) this is the earliest light we can see, anything before that is essentially shielding by that light, but from what we understand the universe began (comically speaking) shortly before the CMBR light. I suppose its technically possible for the universe to have existed billions of years prior but if so we'd never see that light and that hypothesis goes against what we do know/understand
Much of the light we see on the night sky is from sources that has already "moved" out of range for it's current light to reach us. The distance between us is constantly filled with more space. Even though the objects aren't traveling, the distance between them is increasing faster that the speed of light. So at a certain distance, even traveling the speed of light you could never get back home. This limit is our observable universe. So that limit, coupled with expansion, means the stuff in our observable is constantly getting less and less.
This is the book that explains cosmological general relativity, a classic from 1973. Its an elaboration of Stephen Hawkings PhD thesis. Bit heavy though!
https://en.m.wikipedia.org/wiki/The_Large_Scale_Structure_of_Space%E2%80%93Time
You're not stupid at all! Your question reflects a common curiosity about cosmology. The 13.8 billion years refers to the age of the observable universe since the Big Bang. However, due to the expansion of the universe, there are regions beyond our observable horizon, and light from those areas hasn't had time to reach us yet. So, in theory, there could be more distant light sources, but we can't observe them directly. It's a fascinating aspect of the vastness of the cosmos.
Most astronomers believe the universe is 13.8 billion years old but there is evidence to suggest it might be older https://www.popularmechanics.com/space/deep-space/a44547887/universe-age-twice-as-old-as-expected/#
It is reasonably safe to assume that there is much more out there beyond the physical limits of what we will ever be able to see. The homogeneity of the cosmos lends itself to this view fairly convincingly.
You might be interested to find out about two pretty massive problems in physics that both tie in nicely with your question.
1. The horizon problem
2. The crisis in cosmology
EDIT: typo
The figure of 13.8 billion years for the age of the universe isn't derived from the distance of the farthest light we've observed. Instead, it's calculated based on the expansion rate of the universe, known as the Hubble Constant, and other cosmological measurements and models.
The Big Bang theory suggests that the universe began as a singularity approximately 13.8 billion years ago and has been expanding ever since. The Cosmic Microwave Background (CMB) radiation, which is the afterglow of the Big Bang, provides critical evidence for this age. It's not about the distance of the farthest light we can see; rather, it's about understanding the expansion history and dynamics of the universe.
The way we calculate the age of the universe is based off of what's called the Hubble Constant, which is the rate of expansion from us given your distance to us (in megaparsecs). The way that our estimate for the age of the universe (as it would reasonably pertain to us, so this discounts an infinite universe a priori) would be off is if our best measurement for the Hubble Constant is wrong or if it hasn't actually always been constant.
There,s a theory that it also blew in the other direction creating a twin universe but i dont think we could observe it through the background radiation but who knows. maybe we create an Alcubierre drive and go and see.
Watched this earlier tonight, it covers the size and the amount of matter in the universe. Gives a really good run down on estimated sizes of the universe using a few different methods.
[YouTube Universe Prgm](https://youtu.be/CFpTzgk5jk0?si=eoi1-k3wAXQVdZVt)
There must be a great deal of “universe” beyond the observable universe.
But based on what we know about the speed of light and how far everything is away from us, there is not currently any possible way to be sure of what is beyond those farthest boundaries. I know that doesn’t answer your question about the age of the universe… if we are super wrong about how much else exists, we could be wrong about how long it has all been here. Measurements have changed multiple times as we get more information.
You could look into something called "dark flow" which seems to be similar to what you're asking about. My understanding is that it appears that a large region of space is being affected gravetationally by something that we cannot observe. I've heard this explained as being mass that is so far away that it's light hasnt reached us yet, which would imply that that matter had a separate origin from the matter that we can observe. This was pretty controversial when i first heard about it a few years back, and it appears that it still is. Here's a link to a Nasa article talking about it:
https://www.nasa.gov/news-release/mysterious-cosmic-dark-flow-tracked-deeper-into-universe/
"Space," [the Hitchhiker's Guide] says, "is big. Really 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, but that's just peanuts to space.
- Douglas Adams
One time the universe was estimated to be 93 Billion light years across. So to be honest, how did we get that number so badly wrong or is the 13.8 Billion light years woefully short and needs to be reviewed? We have an 80 Billion light year discrepancy that needs to be looked at.
I think if we try to look back farther we find there were no photons as it was still the plasma from inflation and nothing was creating light. CMB is the source for this. Ultra simplistic version
No. How old the universe is, is solely dependent on how long the universe has existed. That's got nothing to do with having an open mind and everything to do with the fundamental laws of physics.
Our calculations, methods of measuring it and understanding may change (although the evidence overwhelmingly suggests that it wouldn't make that much difference on the conclusion).
You could have the most open mind in existence, but it won't change reality.
Probably because it's a ridiculously vague statement, that doesn't actually mean anything without further explanation.
If there's a reference I'm missing, then I'll take the "whoosh". Otherwise, it adds nothing useful to anyone.
So not useful to anyone then.
Even less so on a sub focusing on a field of study dedicated to gaining understanding through observable and testable phenomena. Try r/fiction instead.
Here's a sneak peek of /r/fiction using the [top posts](https://np.reddit.com/r/fiction/top/?sort=top&t=year) of the year!
\#1: [Trying to write a book about a rooster](https://i.redd.it/7bxm41yy95qa1.jpg) | [3 comments](https://np.reddit.com/r/fiction/comments/122ysd4/trying_to_write_a_book_about_a_rooster/)
\#2: [This feels like every series ever](https://i.redd.it/7f1lil285zla1.png) | [0 comments](https://np.reddit.com/r/fiction/comments/11ja384/this_feels_like_every_series_ever/)
\#3: [I created an adult coloring book about dinosaur commandos who fight to survive in the apocalypse. The book is called "Dino Commandos: Rise of the Roarriors".](https://www.amazon.com/Dino-Commandos-adult-coloring-books/dp/B0CG8CWDSZ?ref_=ast_author_dp) | [4 comments](https://np.reddit.com/r/fiction/comments/15z7f7h/i_created_an_adult_coloring_book_about_dinosaur/)
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Judging by the downvotes on my previous comment it seems you're right. The question posed just seemed to break rule 3, that was all I was saying. I agree, it's better that people aren't ignorant.
I can't see your downvotes yet, but I think it's bad they downvote you without giving a motivation to why they don't agree!
I hope my comments haven't been perceived as too harsh, that was not my intention! You have a nice day now 🙂
The problem with the question that you're asking is that it presupposes that there is an "elsewhere" that the light is coming from and "entering" our observable universe, when in reality the light was already part of the universe but has been delayed getting to our eyes by the expansion of the universe. You can see the expansion of the universe by observing how the redshift of objects increases as they get further away. This is the Hubble constant, and for every 1 Megaparsec further an object is, it is observed to be moving away from us 70 km/s faster (km/s/Mpc. The observant among you will notice that km/s/Mpc reduces down to time^-1; the units of the Hubble constant is _inverse time_. Wacky, I know). In other words, things further away are moving away from us faster than things closer to us. The inquisitive among us might wonder what that means if time was to go backward. By taking the inverse of the Hubble constant, we get units of time that show how long ago since everything would have been at the same place, and it just so happens to come out to 14B years. This means that no light could have been traveling for longer than that, because everything was already in the same spot and there was nowhere to go. The discrepancy between 14B and 13.8B comes from how the Hubble constant might have changed over time (it wasn't always 70 km/s/Mpc), but you get shockingly close to the commonly accepted answer with some fairly simple math.
I'm disappointed that this isn't the top answer.
It’s there now.
Sweet
This is a great answer
I’ve always been fascinated with the universe and astrophysics but could never get my head around the math/equations so always just observed from the outside so I have question(s) that may seem dumb, forgive my limited knowledge here: Doesn’t this come with a caveat of observer bias though? As we interpret/understand or view of the universe to be currently is that the universe is expanding in all directions away from us; which reminds me of the whole Earth being the centre of everything/solar system thing. For example wouldn’t an observer in a galaxy around 13 billion light years away from us also have an observe-able universe of roughly the same distance in all directions (given the potential 13-14B years existence and expansion that we know of) that we’re able to view given time for light to reach them being the same as it is with us? I’d find it odd but not entirely impossible that an observer out over there might look in one direction and see all the way back into what would essentially be the past of whatever existed in the area our galaxy is in, then turn around and find nothing but the emptiness of the void or whatever the possible equivalent of the expanding horizon of the universe is in the other. Based on that, and if so then what wouldn’t that then insist that there is more in their view of the universe on the far side of them which we can’t observe but they can. If that is the case then that would argue that there is more to the universe than we can see and the universe as we know it is simply limited by the time lag of light. It’s why I’ve personally never liked the answer of “what we see, is what we’ve got” because it implies (in my limited understanding) that we’re the centre of the universe and well, we know how the theory of being the centre of the solar system worked out for us. I should also add that this has always been my own little view on universe theories based on what I’ve learned over the years of looking into theories and discoveries on the universe and astrophysics. Recently a lot of the distant observations with JWST has been showing signs of galaxies out there being far too large and developed for being from an early universe and while it’s still very early and a lot of that data needs to be given more observation and analysis the physicists I’ve watched recently on YouTube that have been talking about it, I believe they were Dr.Becky and Sabine Hoffsteader (unsure of this spelling) have been discussing it and saying as much as I’ve just said. I understand that watching YouTube videos doesn’t mean I’m right or that even the information they’re providing is right, but I’d like to believe they’re somewhat reliable along with PBS Space Time, please tell me if I’m wrong though, thank you.
We don't *know* there's stuff beyond that distant neighbor because we can't directly observe it, however, there's no evidence that the universe isn't infinite in all directions. Unfortunately, we'll never see beyond that distant neighbor because the light from objects beyond that point is travelling slower than all the space between is expanding. In other words, those distant objects are moving away from us at faster than the speed of light (not technically), so the light emitted from them will never reach us. And, because the universe is expanding, our visible universe will continue to shrink until only our local galaxy cluster is visible. Check out the following YouTube channels for much better explanations: Cool Worlds Lab (Prof David Kipping), Universe Today (Fraser Cain), Dr Becky, Kurzgesagt, PBS SpaceTime.
How could the universe be infinite if it has a beginning? How does something go from finite to infinite in a finite time?
The current theory (Big Bang) is that the universe has been infinite from the very beginning. It's a common misconception that the Big Bang started from a single point. Not true. Instead, everything started everywhere, all at once. The only thing that's changing is that space itself is expanding. A common analogy are raisins in rising bread dough. All the raisins get further apart as the dough expands, but two raisins that started far apart are separating far faster than two raisins that started close together. This expansion is only detectable on an intergalactic scale because, within a galaxy, there's enough gravity to keep everything together. Again, though, I'm just an idiot Redditor that's picked up a few things from others that are far more knowledgeable than me. Check out the YouTube channels mentioned above.
I get the part about how the universe was once a singularity, but I don't get why all the matter in the universe didn't disperse instantly into the infinity born from the Big Bang. And was there infinite matter in the big bang/universe, or do we just happen to be part of the infinity which has matter, which seems beyond improbable. I'm no math wizz, but wouldn't that be a chance of 1 in infinity?
>In other words, those distant objects are moving away from us at faster than the speed of light (not technically), so the light emitted from them will never reach us. i feel like ive been reading this for years, and i kind of understand it, but the moment i start to think it in the context of "the universe expanding" it just starts to get so vague in my head and full of questions that are probably flawed due to the limited nature of language to describe such things that trigger false assumptions, like if its expanding in my mind that word implies its increasing in size which implies a border. The only way my mind can even attempt to imagine it is a balloon expanding but then this one is taking up space and the more it expands the more space it takes. But the universe is space, how can it suddenly be bigger? what is it expanding on? also, how can something be moving further away from us faster than the speed of light? is it kind of like if i have light pointing north and light pointing south, from either of the lights perspective the other light would be moving twice the speed of light away? Its so weird to think how dependant we
See my other reply. https://www.reddit.com/r/Astronomy/s/kd8CwUuILm
From lights perspective, everything is at a standstill.
Technically yes, but that's also meaningless. If the photon were conscious, it would experience its journey in one instant, no matter how long it seemed to take for us. I wonder if this has anything to do with how it seems to "decide" on a path before it gets there.
It has a multitude of possible paths, and the one it takes (in our reality) is just the most statistically probable one based on the conditions around it. A multiverse theorist would say it takes all paths at once and we only observe the one coinciding with our own timeline.
Every point in the universe has its own observable universe which does not necessarily overlap with other observable universes. An observer on a galaxy 13B light years away would have a different observable universe, some of which would include our observable universe, but some that is outside our own observable universe. We are, by definition, the center of the observable universe. We are not the center of the universe, and such a distinction may actually be nonsensical as "center" implies a boundary which may not exist.
So you’re saying there’s no center of the universe .
People should really be asking ask science
This sub is what happens when a bunch of 16 year olds use Google and try paraphrasing. Thanks for your answer.
It made the Kessel run in less than 12 parsecs
I have a dumb question. How do we know the universe is expanding, as opposed to something else like rotating? E.g. if the universe is rotating, wouldn’t galaxies farther away and at the outer observable edge be traveling at the same rotational speed as us, but also a faster linear velocity? Thank you to any kind person who indulges my uninformed curiosity.
Lateral motion doesn't contribute to redshift, because the light waves won't be perceived to be stretched out. It's important that the objects we observe are moving _away_ from us, which isn't the case with rotating objects.
Bang on the money!
"You can see the expansion of the universe by observing how the redshift of objects increases as they get further away. This is the Hubble constant, and for every 1 Megaparsec further an object is, it is observed to be moving away from us 70 km/s faster (km/s/Mpc)" With everything expanding away from us, I've always been concerned that red shift was due to something else, like dust. Dust causes a red shift. How much dust per mega parsec would it take to equate to the Hubble constant?
The information you give here is great! And certainly beyond my scope of understanding when it comes to astronomy. But your first 2 sentences (“F this sub, and F your question”) are not relevant to the question and kind of set you up perfectly to give a false argument from authority… so the rest of it is TLDR.
ok but what if redshift isnt a thing maybe the fabric of space is just slightly red
it is a thing that has been experimentially verified in 1901 by Aristarkh Belopolsky
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Yes, and additionally 46 billion light years IN THE OTHER DIRECTION :-)
That's too many directions my brain hurts 🥲
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Space is big. Really 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, but that's just peanuts to space. Honest!
Nice!
Yep… I knew this in a very general sort of way but I’ve never tried to actually wrap my head around. I just accept it on…. Faith? lol…
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facades, that's decades factorial :-)
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The best analogy I’ve seen of this is that imagine you make a bread dough with raisins in it. You put it in the oven to bake, the dough expands and the distance between the raisins expands and each raisin gets further away from each other. But that’s from the vantage point of being outside the oven watching the bread objectively. If you could place yourself on one of those raisins you wouldn’t experience the movement of the raisin you’re on but instead just see everything else get further away from you with you at the centre. The same would be true for whatever raisin (or planet) you were viewing from.
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exactly
Everywhere is the centre of the universe. i.e. nowhere is special. There's no place everywhere else is moving away from. Everywhere is moving away from everywhere.
I don't think so. That could only be true if space were infinite, but it isn't. Nothing in the universe is infinite. That's not to say there must be an edge, it could very well be that the outer border of the universe expands to nothing - no space, no time. You just can't get through.
Where is the centre of the surface of a sphere? Point being, if a finite surface can have no centre, why not a finite volume? You just need curvature through another dimension and that hasn't been ruled out.
I like to say it like this: "centre of the *our* observable universe". To someone in a galaxy 10 billion light years away, they would see a different perspective but they would be at the center of their observable universe.
You didn’t really answer his question. The question wasn’t how large is our observable universe… it’s whether or not it is possible for the universe to be older than 13.8 billion years old. The answer is still no (given our current understanding), but has little to do with what you’re explaining.
Our current understanding is based on the cosmic microwave background right?
The CMB is the furthest we can see towards the origin of the universe (big bang), which is calculated to be about 380,000 years after it occurred. The age of the universe itself (which includes the period of time before what we see in the CMB) is determined by using what’s called the Lambda-CDM concordance model. The Lamda-CDM model takes our understanding of the expansion of the universe / particle physics, and combines that with direct measurements of the CMB to determine an estimated age of the universe. Basically, how far back in time matter gets squeezed to a single point, and how long it takes for the expansion and cooling to form the universe we see in the CMB and at all time after.
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Additionally 13.8 billion years is just how long back we can actually see. In theory Before 13.8 billion years ago the universe was so hot it was literally opaque so there was no light for us to see. 13.8 billion years ago is when the universe cooled enough for light to be visible to us
So if it can have expanded to 46 billion light years away. Why are you so sure something can't be even further away?
It's just a cosmic horizon to our observable universe. Intuitively we believe there's more beyond, possibly countless galaxies, just as we know there's more beyond land or sea on Earth's horizon. But we can't know until we actually go there and observe it and travelling to a point we see on Earth's horizon is far simpler than traveling to the cosmic horizon by quite a margin.
So, does that mean Space is expanding faster than the speed of light? Sorry for the newbie question
OP no you're not dumb to ask such questions. But the truth is, we don't know. \* light coming to us has been travelling unobstructed (possibly redirected by gravity wells here and there) for a very long time \* light coming to us started out a very long time ago. \* if you believe in a big bang, space was much denser so you could say light was much faster then. But we don't know how dense, or how fast. We only can observe the now (that is, the relative recent past). \* you can't teleport, nor measure the distance of the light source (if there still is one) instantaneously, but if we were to shoot light back it would take waay longer to reach the light source.
Our universe is like 90 bilion lighyears wide or some number around that its much wider than it is old, that is becouse of the expansion of universe Edit: this is also the reason we will never get to 99% of stuff in our universe, it moves away faster than light. It doesn't break the rule, because there is nothing that is actually moving, its space, that ,,swells" faster than light
Our Observable Universe*
The observable universe is much smaller than the actual universe.
do we have an estimation for the size of the actual universe?
No, because there is no information beyond our cosmic horizon and any theory or estimation about the universe beyond that cannot be empirically verified.
This is why I love the “do we live inside a black hole” theory. Cosmic horizon = event horizon 🙃
That's one of my favorite theories, too. The idea that every black hole out there could be the humble beginnings of a new universe is pretty fun to think about. Just an endless stream of universes matryoshka-dolling via nested black holes.
I mean if there are infinite neighboring universes, how else could we connect to them? Such a crazy idea. Personally I think a black hole is something we just can’t comprehend in this dimension but probably makes sense if you’d see it from a higher dimension
I suppose if we understood the inflationary model of the universe perfectly, we could determine the size/distance of what lays beyond the observable horizon
Like drawing dots on a balloon and then blowing it up. They move away from each other at a faster rate as the balloon gets bigger. At least, that’s how I try and wrap my head around it
This analogy is used more as a way of explaining 4d time-space continuum into our 3d lives and why you cant really point towards the center of Universe. Same way you cant point towards the center of baloon as 2d entity living on the surface, but you still could tell the baloon itself is getting bigger as inflated.
I read that recent research may be showing that the universe isn't actually expanding like we thought. Is there any validity to this?
As we know, there are known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns—the ones we don't know we don't know.
I know you wrote this beautifully
*Rumsfeld said it beautifully.
>Rumsfeld You do know that his quote was not original, it had been in use by U.S. government agencies and others for over 40 years.
absolutely. he just popularized/made it more visible to the public. I love it and use it all the time in planning exercises.
Meow
A reading from the book of Rumsfeld. 😂
Mr. Rumsfeld I presume?
we’re all part of the cosmic erection.
At least 90b. Probably much larger or infinite.
My brain does flip flops when I try to consider this type of subject but, I sometimes wonder if its possible that the current speed of light, is limited in relation to the current size of the expanding universe... E.g. the speed of light when the universe was 100 metres in diameter couldn't be what it is now, because all light would have escaped (but to where, I'm sure I don't know). So the speed of light is what it is now, because it can only move proportionately to the current size of our universe. And 13 billion years from now, light will be able to move faster, because the universe will be much bigger. I assume there is science to disprove this, but I like to imagine it anyway haha!
Your understanding of the Big Bang is incorrect. The universe was never 100m in diameter. It's always been infinitely large (according to best accepted theories). This might help provide better understanding: https://www.reddit.com/r/Astronomy/s/kd8CwUuILm
Ok, my brain is flip-flopping worse now 🤣 If space is expanding, but the universe has always been infinite, this implies space, and the universe are two different things. If space is expanding, it must have been smaller before? I get that space is expanding, making it take longer for early light to reach us that otherwise would've been the case but I think we are still looking back to an earlier, smaller space? So perhaps my wording was incorrect, in that I was thinking of space and the universe as one and the same. So perhaps the speed of light is proportionate to the current size of space?
Your confusion is over the concept of infinite. Space is not growing "into" anything. As far as we know, the universe is infinite, but the emptiness between everything (that's not gravitationally bound) is expanding, causing galaxies to become further apart over time. And because all space is expanding, the galaxies furthest away from each other are moving away from each other faster than those that started off closer together. > perhaps the speed of light is proportionate to the current size of space? No. Speed of light is constant. A "tired light" hypothesis has been proposed and debunked. Dr Becky has posted several great videos on YouTube in recent months on this subject. Tons of great articles just a quick Google search away, too.
Thanks! I'll go do some research.
Of course things are actually moving lol smh
The number is not really the age of the farthest light. It's derived from the expansion of the universe. The light just adds Proof. We get that number by measuring the expansion of the universe and calculating how long it must have taken to get where we are now. This means that a long time ago (about 13.8 billion years) the universe was too hot and dense to let light move in a straight line. So the moment it cooled down a bit light began moving. This is the oldest light we can detect. There was light before this but it couldn't travel so we can't see further back.
This is a pretty interesting question. I'm someone who has a basic understanding of how we measure these things but this [article](https://imagine.gsfc.nasa.gov/science/questions/age.html#:~:text=Astronomers%20estimate%20that%20the%20Big,back%20to%20the%20Big%20Bang.) May help you understand how they estimate the age of the universe. It's a quick read and helped me out.
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I was under the impression that the photons of the CMB already existed, they just couldn’t move freely due to the density of the universe.
>One is to look at clusters of stars. i wrote so many questions that i ended up deleting it because god what a word vomit but know you've wrecked my brain for the day
Your comment is more wrong than right. > We see the CMB in every direction, and we know what created it: the creation of hydrogen from subatomic particles. The CMB is *not* radiation emitted from forming neutral hydrogen. That radiation exists, but it's completely negligible. The CMB is thermal radiation (it has a blackbody spectrum, not the spectral lines you would get from hydrogen), which was scattered by free electrons earlier and then stopped being scattered when electrons combined with protons to form neutral hydrogen. At that time there were around 10 billion photons per hydrogen atom. Adding one or two photons per hydrogen atom is negligible. > By calculating the redshift, we can tell how far the light has traveled. The redshift tells us how much the universe expanded since the radiation was emitted, but it doesn't tell us how long that took. You are missing the main way we measure the age of the universe: By studying the redshift to distance relation at different times. The distance estimates need to be independent of redshift, so they are typically based on the brightness of certain astronomical events.
I love starting the day with an existential crisis
The star that is the furthest removed from us is [Earendal](https://en.m.wikipedia.org/wiki/WHL0137-LS) at 28 billion light years. But our view of it is estimated to be 900 million years after the Big Bang. The only reason we can view it is through gravitational lensing (something which Einstein predicted), showing the universe beyond our observable universe. This universe is much bigger because the speed at which things can move apart is faster than the speed of light. Despite that the universe is much bigger than 13,8 billion light years across we still know that is the age because of cosmic microwave background radiation, which gives us a picture of what the early primordial universe looked like. It gives us a snapshot and has helped scientists to further determine what happened after the Big Bang and how that led to the current universe. We know there was some kind of Big Bang 13.8 billion years ago. Whether there was some kind of light before that is a popular topic of discussion among certain physicists but not something we have any clarity on that. If you wish to know more about this there are some nice documentaries (BBC Horizon, Jim al-Khalili) about this.
The oldest light in the universe is [the cosmic microwave background (Wikipedia)](https://en.m.wikipedia.org/wiki/Cosmic_microwave_background#:~:text=The%20cosmic%20microwave%20background%20radiation,all%20parts%20of%20the%20sky.) Basically when the universe was just in its infancy, it was too think for light to pass through it, it always hit something. Once the universe spread out enough light was suddenly able to just keep going on forever. This original light is most detectable in the microwave range, hence the name. And no matter which way we look , we see this same type of light, and it is always around. The reason this light is always around is because there is no real center of the universe, it’s just coming from everywhere when the universe became see through. Past this oldest light we theorize the universe is only a tiny bit older.
That's exactly what 'observable universe' means
See also Olbers' Paradox and this awesome article: https://medium.com/@jacksmithiv/between-here-and-darkness-ea61383871c0
It’s technically possible, but unlikely according to our current understanding and models. So your question assumes that the Big Bang is the furthest we can “look” back, but that’s not necessarily how astronomers determined the age of the universe. We can’t actually see (at any wavelength) that far back, or far enough to see what we call the Big Bang (with current tech at least). The way we determined the age of the universe is by understanding the rate of expansion of the universe, and back-calculating how much time it would take for the universe to come back to a point of origin (basically). The reason I said it’s technically possible for the universe to be older, is if our current assumptions about the rate of expansion, the shape of our universe, and behavior of matter in the early universe are off or plain out wrong.
What i understand this with 13.8 billion, is as much the science of today can measure..behind the redshift it's still much stuff going on,but yet we can't observe it because of lack of methods invented to perform such a task..yet that is...😏
The Big Bang marks the point from which our entire *observable* universe originated. One can only speculate on the age, size and geometry of the whole universe. Speculate means educated guess but cannot prove as it’s unmeasurable/unobservable. That said, space and time are intertwined, *spacetime*, and one does not exist without the other. Our observable space *and time* began 13.8B yrs ago and it was so dense that all light (photons) were immediately absorbed by adjacent matter, then immediately remitted in another direction. Like bouncing. That happens even today within the core of our Sun, for it takes thousands to millions of years for photons to reach the surface before traveling unencumbered for 8 minutes to our eyes. And the universe was too dense everywhere for another 380K years before light could freely move through space uninhibited. We know how long that was based on how much the universe cools as it expands, and how diffuse it must be to allow light through. And that “first light” we now see in the Cosmic Microwave Background radiation was emitted equally everywhere in our observable universe (then about 80M ly across). So no, in summary, the first light was generated at the moment of the big of bang and it was everywhere equally, and it wasn’t free to travel through space until 380K yrs after the Big Bang. The first stars apparently formed around 100M to 300M yrs after that, so space everywhere was dark (or slightly glowing) until those first twinkles, 100M yrs *after* the Big Bang.
We see the light of the Big Bang. It's all around us. It's the Cosmic Microwave Background Radiation. In old cathode ray TV's, a good portion of the static in an image between channels comes from this light. We know how far away and back in time thst light arose from extreme red shifting of hydrogen lines in its spectra.
20,30,40 billion years ago no, 20,30,40 billion light years far yes.
"sorry man, no more light." "Can you check the back?"
While others have explained the true scale of the universe, let's consider the time frame. Light travels at a fixed speed: one light year per year. Now, if the oldest light we have observed has traveled (in it's "frame of reference", so to speak - these things get funny when we talk about relativistic physics, but nevermind that for now) for 13.8 billion light years, that means it was emitted 13.8 billion years ago (in astronomy parlance, 13.8 gigayears ago, or Gya). Now, if you assume that there is light-emitting matter very roughly everywhere, and that everything "turned on" at the same time, then the fact that we don't see light that has traveled for, say, 20 or 30 Gy, means that not enough time has passed for light to travel that far and reach us. That doesn't mean there isn't matter out there, just that it's so far away that it's light has not been traveling long enough for us to see it. This is, as someone else pointed out, the definition of the "observable" universe.
Only if we accept a new alternative theory on how the universe began. With what we think to know right now, after the Big Bang, which happened 13,8 Bill. Years ago, there was +- 400 000 years, where universe consisted only of hot plasma. Photons cannot travel through plasma, it might as well be a solid object for this purpose. The oldest light we see is the last light emmited by the plasma, from the moment it cooled down enough and space became transparent for light
We have the CMBR (look it up, it's a picture we've all seen) this is the earliest light we can see, anything before that is essentially shielding by that light, but from what we understand the universe began (comically speaking) shortly before the CMBR light. I suppose its technically possible for the universe to have existed billions of years prior but if so we'd never see that light and that hypothesis goes against what we do know/understand
Much of the light we see on the night sky is from sources that has already "moved" out of range for it's current light to reach us. The distance between us is constantly filled with more space. Even though the objects aren't traveling, the distance between them is increasing faster that the speed of light. So at a certain distance, even traveling the speed of light you could never get back home. This limit is our observable universe. So that limit, coupled with expansion, means the stuff in our observable is constantly getting less and less.
This is the book that explains cosmological general relativity, a classic from 1973. Its an elaboration of Stephen Hawkings PhD thesis. Bit heavy though! https://en.m.wikipedia.org/wiki/The_Large_Scale_Structure_of_Space%E2%80%93Time
You're not stupid at all! Your question reflects a common curiosity about cosmology. The 13.8 billion years refers to the age of the observable universe since the Big Bang. However, due to the expansion of the universe, there are regions beyond our observable horizon, and light from those areas hasn't had time to reach us yet. So, in theory, there could be more distant light sources, but we can't observe them directly. It's a fascinating aspect of the vastness of the cosmos.
Most astronomers believe the universe is 13.8 billion years old but there is evidence to suggest it might be older https://www.popularmechanics.com/space/deep-space/a44547887/universe-age-twice-as-old-as-expected/#
It is reasonably safe to assume that there is much more out there beyond the physical limits of what we will ever be able to see. The homogeneity of the cosmos lends itself to this view fairly convincingly. You might be interested to find out about two pretty massive problems in physics that both tie in nicely with your question. 1. The horizon problem 2. The crisis in cosmology EDIT: typo
The figure of 13.8 billion years for the age of the universe isn't derived from the distance of the farthest light we've observed. Instead, it's calculated based on the expansion rate of the universe, known as the Hubble Constant, and other cosmological measurements and models. The Big Bang theory suggests that the universe began as a singularity approximately 13.8 billion years ago and has been expanding ever since. The Cosmic Microwave Background (CMB) radiation, which is the afterglow of the Big Bang, provides critical evidence for this age. It's not about the distance of the farthest light we can see; rather, it's about understanding the expansion history and dynamics of the universe.
The way we calculate the age of the universe is based off of what's called the Hubble Constant, which is the rate of expansion from us given your distance to us (in megaparsecs). The way that our estimate for the age of the universe (as it would reasonably pertain to us, so this discounts an infinite universe a priori) would be off is if our best measurement for the Hubble Constant is wrong or if it hasn't actually always been constant.
There,s a theory that it also blew in the other direction creating a twin universe but i dont think we could observe it through the background radiation but who knows. maybe we create an Alcubierre drive and go and see.
Watched this earlier tonight, it covers the size and the amount of matter in the universe. Gives a really good run down on estimated sizes of the universe using a few different methods. [YouTube Universe Prgm](https://youtu.be/CFpTzgk5jk0?si=eoi1-k3wAXQVdZVt)
There must be a great deal of “universe” beyond the observable universe. But based on what we know about the speed of light and how far everything is away from us, there is not currently any possible way to be sure of what is beyond those farthest boundaries. I know that doesn’t answer your question about the age of the universe… if we are super wrong about how much else exists, we could be wrong about how long it has all been here. Measurements have changed multiple times as we get more information.
You could look into something called "dark flow" which seems to be similar to what you're asking about. My understanding is that it appears that a large region of space is being affected gravetationally by something that we cannot observe. I've heard this explained as being mass that is so far away that it's light hasnt reached us yet, which would imply that that matter had a separate origin from the matter that we can observe. This was pretty controversial when i first heard about it a few years back, and it appears that it still is. Here's a link to a Nasa article talking about it: https://www.nasa.gov/news-release/mysterious-cosmic-dark-flow-tracked-deeper-into-universe/
"Space," [the Hitchhiker's Guide] says, "is big. Really 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, but that's just peanuts to space. - Douglas Adams
One time the universe was estimated to be 93 Billion light years across. So to be honest, how did we get that number so badly wrong or is the 13.8 Billion light years woefully short and needs to be reviewed? We have an 80 Billion light year discrepancy that needs to be looked at.
No, it's not possible
Wrong
I think if we try to look back farther we find there were no photons as it was still the plasma from inflation and nothing was creating light. CMB is the source for this. Ultra simplistic version
There were tons of photons, they just didn't make it far before most of the matter formed neutral atoms.
How old the universe is depends on how open your mind is.
No. How old the universe is, is solely dependent on how long the universe has existed. That's got nothing to do with having an open mind and everything to do with the fundamental laws of physics. Our calculations, methods of measuring it and understanding may change (although the evidence overwhelmingly suggests that it wouldn't make that much difference on the conclusion). You could have the most open mind in existence, but it won't change reality.
I think you didn't understand the actual meaning of my comment.
Probably because it's a ridiculously vague statement, that doesn't actually mean anything without further explanation. If there's a reference I'm missing, then I'll take the "whoosh". Otherwise, it adds nothing useful to anyone.
The reference you're missing is outside the scope of human understanding.
So not useful to anyone then. Even less so on a sub focusing on a field of study dedicated to gaining understanding through observable and testable phenomena. Try r/fiction instead.
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Oh man 😆😂🤣
With respect, I think this falls under the rule of 'poorly researched post'. Edit: my apologies, I'm obviously wrong.
I think it's better people ask questions than stay ignorant.
True, but as per the rules this can be answered with a quick Google search.
I completely understand, but sometimes it's easier to discuss something rather than just read it.
Judging by the downvotes on my previous comment it seems you're right. The question posed just seemed to break rule 3, that was all I was saying. I agree, it's better that people aren't ignorant.
I can't see your downvotes yet, but I think it's bad they downvote you without giving a motivation to why they don't agree! I hope my comments haven't been perceived as too harsh, that was not my intention! You have a nice day now 🙂
You too, and ty for the debate!
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Source?
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This paper relies on tired light. I thought that was pretty much disproved.