This is a poorly written article, it almost appears whole paragraphs are missing. For instance the phrase "an impossibly high value when compared to Planck’s measurements" is not explained at all. (Planck was a physicist, but I suspect they're referring to https://en.wikipedia.org/wiki/Planck_(spacecraft)
I think what it's actually saying is that we've confirmed that the Hubble tension is real. Whether or not that means different parts of the universe are accelerating at different speeds is still not clear. If the meaning of the results is deeper than that, it seems to have completely eluded the author who nonetheless wrote a breathless exaggeration of the findings.
EDIT: In 2024 actually I have to wonder if any humans were involved in the making of this article. It certainly doesn't appear to have passed an editor's eyes.
We knew that before. This goes deeper than that. It accelerates in a way that cannot be explained by a constant dark energy density, which is part of our standard model. We have plenty of alternative models that can explain this, but our measurements are not precise enough yet to rule any of them out. Hopefully Euclid will provide data that is.
If expansion at the big bang started with a rate of X. Could the varying densities at different points cause their expansion to deviate from the original rate?
I'm not sure what exactly you mean, but the Hubble tension could also be explained if we live in a particularly large under dense region of the universe. Then the light we observe from the CMB basically has to climb out of a gravitational well which would influence our measurement. IIRC such a substantial under density is considered unlikely though and very hard if not impossible to measure.
The spatial inhomogeneities of matter in the very early universe, which I believe you might be talking about, were extremely tiny.
> I'm not sure what exactly you mean, but the Hubble tension could also be explained if we live in a particularly large under dense region of the universe.
There was an amazing paper on this published on HN a year or three ago that explained at certain discrete points in the future, entire percentages of the known universe will be beyond our reach. It was profoundly beautiful and sad at the same time.
I'll try to dig it up.
Edit: found the post (three years ago) and some of the quotes and figures I pulled from it:
Edit 2: another commenter had made a note about the Big Rip. I was writing a response, but they unfortunately deleted their (good) comment. I'll include my response below:
> wait until you find out about the Big Rip (paraphrasing)
That one's even wilder. To think every atom of every place and loved one you ever touched would vanish infinitely far away. Every atom and then subatomic particle of your own once corporal body, regardless of its final resting place, torn and scattered.
Last Contact is a great short story if you're in the mood [1].
Then there's vacuum collapse and all the other theories.
I wonder what humans or human descendents 500 years from now will figure out about the universe's ultimate fate.
No. The fact that the expansion is accelerating was already established by supernovae measurements alone [0]. The Hubble tension is about the degree of acceleration, not about whether there is an acceleration or not.
Garbage article, clickbait tile; they're talking about the Hubble tension, not any kind of anisotropy in the Hubble constant. The latter would be actual news.
We don’t really know - you are right to ask this question. There are two methods and they disagree with each other. JWST is precise enough to rule out a simple reason like instrument imprecision.
So remaining possibilities are new physics, a deep flaw in our assumptions/methods, or a universe which is not uniform (but in a peculiar way).
Perhaps the small anisotropy that is observed in cosmic microwave background observations imprints to the dark energy that accelerates expansion. I haven't kept up on the modern state of the art.
Becky Smethurst, an astrophysicist, goes through how the cosmic distance ladder works and the recent JWST results here[1].
As you say, measurement errors of Cepheid stars has been something scientists considered a possibility, hence why they're cross-checking by measuring them in different ways.
And, as mentioned in the posted article and the other papers mentioned in the video, it seems that measurement errors are very unlikely to be the culprit.
Preprints to the articles Becky mentions are here[2][3][4].
I've found this interesting and have read up a little on it. I believe there have been a good amount of studies trying to verify the different measurement methods. I believe they have made some progress in verifying the methods but I'm sure there is still more work to do. I think this is mainly in attempts to deal with the "cosmological crisis."
the current thought is that these are measurement errors not actual differences in expansion rate but even if they were actual different expansion rates, they are separated by time not space.
The "cosmic ladder" supposition's underpinnings are a bit shaky anyway. Calculating distance and age by examining ever distant Cepheid variable stars is prone to cumulative error. But it's the best estimate we've got.
If the universe expands at different speeds, is it even possible to determine expansion relative to earth since you don’t have something fixed (since everything is at different speeds) to measure earths local expansion against?
Yes, in fact, because the big bang happened everywhere and not in one central place, pretty much every part of space is moving away from Earth, so movement from earth is a pretty good measurement.
Think of it not as things moving apart, but that space, emptiness, is expanding. Like if you laid the universe out on a sheet of rubber and then pulled at the corners. Everything gets further apart and the expansion is happening everywhere
Confused, are they saying that different parts of the universe are expanding at different rates? Or are they saying two methods give different results for the same parts?
This result confirms that the "hubble tension" is real. In other words, two methods for measuring the expansion of the universe disagree, but we can't figure out why and have new and really strong evidence that the "cosmic ladder" method is correct. (The other method is based on the cosmic microwave background radiation and our best theories of physics, so we're caught between a rock and a hard place here: strong experimental evidence one way, and throwing out a ton of what we think we know about the universe with no obvious replacement the other way.)
given everything we already know about the fabric of spacetime, this makes sense. Every time we expect there to be an even distribution, we find more structure. So if something like dark energy is the driver of the expansion, and there is an unequal distribution of that, then this would be an expected outcome.
But of course, without this new data it would be difficult to believe!
But what is it expanding into? If the universe is expanding like a balloon then there's some sort of "edge". What is that edge expanding into? Imagine we had a craft that could take us to the edge and you could stand on it, the way you place your finger on the outside of a balloon. If you could stand on the outside/edge of the expanding universe, what would you see, that we're expanding into?
It can't be nothing. Something can't expand into nothing.
It doesn’t expand into anything. It has no edge. It expands within itself, like it’s distorting itself. Alternatively, you can picture it as groups of gravitationally bound objects (= galaxy clusters) moving away from each other everywhere in the universe. It’s a bit like raisins in a cake being carried away from each other by the dough expanding in the oven. Where the cake already fills all space infinitely in all directions, from the very start. Space is the cake dough. There is no “outer” space that space expands into. The geometry of space itself expands.
Still alternatively, imagine an infinitely extended graph paper whose grid size slowly and continuously increases, carrying with it the dots already drawn on it. Since the grid has infinite size from the start, it doesn’t expand into anything. It just expands.
To paraphrase Feynman, I can't explain to you how the universe expands in terms that you are familiar with because I don't understand it in terms that you are familiar with.
It takes effort to understand those fundamental terms, so if you want to understand this, you'll have to meet people halfway instead of rejecting how somebody is trying to explain something to you.
The math from general relativity is crystal clear. It’s just difficult to translate into natural language, because it doesn’t match our intuitions, which are primed by local experiences of non-curved space. You have to question your intuitions, and if you’re serious about it, look into the actual math. It all follows from a few basic assumptions, and is consistent with actual observations to an unmatched degree.
Thinking of this kind of "expansion" using an analogy like a balloon does a disservice. When you get to large enough or small enough distances then our intuition often falls down completely.
In this case it's entirely possible for the topology of space to change such that it takes longer to travel from one point to another over time. If you consider a trip from point A to point B in topology A, and then topology A expands during the trip from point A to point B such that new distance is created, then the "distance" you have to travel to get to B is changing because at each moment along the trip you're at a different point.
If you think about it this way, the universe can be both expanding because it takes progressively longer to get from point A to point B, and it can also not be expanding into some "outer" area because there's nothing other than the universe.
It may make more sense to stop thinking in terms of distance and start thinking in terms of time. In that case, when you think of "expansion" what you're really describing is that at a constant speed, the closer you get to B, the more time it takes you to advance toward B. And if you change direction mid-trip to go to C, the "expansion" means that the amount of time required to reach C also increases as time elapses.
It's hard to say what's causing that expansion, but we can measure it by its effects on light traveling the same distance.
The balloon analogy is a 2 dimensional example. If you are on the surface of the balloon, there is no "edge". You can go forever in any direction. If the balloon is inflated, it doesn't expand into something (remember we're in a 2D space, it's not a 3D balloon), it "expands into itself".
If you drew two dots on the surface of that balloon, those dots would get further apart as it inflated. What did those dots expand into? Well, nothing right? They just got further apart from each other on the balloon.
So, if you translate this into 3D space, that's what's going on. It's hard to visualize. It's not that the universe is expanding into something, it's that the space between every "point" in the universe is getting further apart.
> The balloon analogy is a 2 dimensional example. If you are on the surface of the balloon, there is no "edge". You can go forever in any direction. If the balloon is inflated, it doesn't expand into something (remember we're in a 2D space, it's not a 3D balloon), it "expands into itself".
I'm talking about 3d that we live in. We're currently standing on a ball of dirt, if the earth started to swell up, the surface we're standing on would expand into space. The thing we're standing on that's pushing outward is what I mean by "edge".
What is the universe expanding into? If it's pushing outward in all directions, it's pushing into something, the same way a swelling earth would expand into space
The universe is everything. There's no outside the universe, since whatever that "outside" was would also be part of our universe. It's not empty space, since that too would be part of the universe. There is no edge of the universe since that would imply that there is something beyond that edge. In scientific terms, the universe is homogeneous and isotropic.
We've proved the universe itself is getting bigger, which means that yesterday it was smaller and the realization of that fact was how the big bang theory came to be.
There are lots of resources out there if you want to build an intuition around how a universe that's everything can get larger without needing something to expand into.
You can imagine the balloon’s curved surface geometry without assuming that it is embedded into a 3D space. This is what Riemann discovered in the 19th century. Such a non-embedded space is called a manifold. In the case of the balloon, it’s simply a non-Euclidian two-dimensional space. A third dimension doesn’t enter into the picture in that formulation.
Four-dimensional spacetime is considered such a manifold. Its three-dimensional space “slices” are predicted to expand with time by general relativity (first predicted by Alexander Friedmann in 1922), and actual observations have confirmed those predictions.
Like a lot of language we use when discussing things at the universe scale, the word “expanding” operates as a placeholder with analogs in day to day life but isn’t a perfect representation of what we mean.
The “universe” itself is space and time. When we say “expanding” we simple mean that galaxies are observed to be moving farther away from each other. That does not at all imply some kind of “expansion into another space” - space itself is exhibiting this property and we are observing it. That’s all.
The “balloon” analogy and the usage of the word “expand” in this context are both imperfect metaphors for physical phenomena we are observing.
It is a bit like trying to discuss what happened “before” the Big Bang - there is no “before” - time was created.
There are many phrases you can construct which may seem like they “make sense” but are actually combining a set of word concepts in ways that are self-contradictory.
I don't agree. You're assuming that the universe is a distinct 'something' expanding into a distinct 'nothing'. I disagree, I think that the 'universe' is an arbitrary border we created.
If we were somehow able to accelerate a particle out past the edge of the known universe, now the bubble includes that particle too and essentially we've 'expanded' the universe. In other words, the arbitrary bubble containing things that we know about and consider significant is larger than it was before - because there's something out there we can observe.
> I think that the 'universe' is an arbitrary border
I don't think that the scientific definition of the universe matches this. It's a physical thing, not a construct we made up. It's not an imaginary line between two countries.
The universe is full of things which have mass. Those things are rapidly expanding outward. What are those masses expanding into as they "blow up the ballon" and push the boundaries of the universe outward? It can't be nothing, it's physically impossible.
EDIT: might as well quote people smarter than I
> The universe is all of space and time[a] and their contents.[10] It comprises all of existence, any fundamental interaction, physical process and physical constant, and therefore all forms of energy and matter, and the structures they form, from sub-atomic particles to entire galaxies. Space and time, according to the prevailing cosmological theory of the Big Bang, emerged together 13.787±0.020 billion years ago,[11] and the universe has been expanding ever since. Today the universe has expanded into an age and size that is physically only in parts observable as the observable universe, which is approximately 93 billion light-years in diameter at the present day, while the spatial size, if any, of the entire universe is unknown.
The edge of the Mandelbrot set expands out to infinity and yet the area within the edge is finite. Who is to say that the universe isn't a hologram on a higher-dimensional Mandelbrot set-like object?
No. This confirms that the "hubble tension" is real. In other words, two methods for measuring the expansion of the universe disagree, but we can't figure out why and have new and really strong evidence that the "cosmic ladder" method is correct. (The other method is based on the cosmic microwave background radiation and our best theories of physics, so we're caught between a rock and a hard place here: strong experimental evidence one way, and throwing out a ton of what we think we know about the universe with no obvious replacement the other way.)
I get that the universe can be expanding, and that there might be different methods to calculate/measure this that have discrepancies. But that the rate of expansion is accelerating, how in the world is that possible?
I don't think it's not possible, I just find it surprising based on the layman understanding that gravity is a dominant force at long distances, leading me to believe that expansion should be slowing.
I also have the layman awareness of some kind of missing mass sometimes explained by "dark matter." But I did not see the additional explanation that this "dark matter" also acts as a repulsive force to accelerate the expansion. Maybe large scale structures manage to create propulsive forces that happen to point away from the center? Anyhow I would love to know what the mechanism is there.
As far as I understand dark energy/matter is not established, it's just a placeholder as we don't quite know what's missing in our formulas. Isn't it like that?
It's not that there is a shifting boundary where the universe ends, but what is meant with universe expansion is (per my understanding) that objects grow further apart over time without experiencing acceleration or any force acting upon them. It's like drawing a map on grid paper and then increasing the grid size without adjusting the scale: all distances become larger
This stretching includes any photons traveling across the grid, and the stretching causes them to expand. Longer wavelengths are more red, giving us the word redshift for stretched light rays. That's one of the ways we measure the expansion: see how much redder the light is as you look at more and more distant objects
From my understanding, The infinitely large theory relies on the Universe being incredibly complex in terms of dimensions. The best way to describe it is like a balloon Take a deflated balloon and draw two dots next to each other on it. Then blow up the balloon. The dots are further away from each other (universe expansion). And if you "walk" across the balloon, you can make a full circumference so you never run into an edge (infinite).
I'm not sure if we know that the universe is infinitely large.
I do know[1] that:
- it's larger than we will ever be able to know or observe (ie.: the observable universe is smaller than "all of the universe"... although that feels a bit hand-wavy to say)
- it's expanding.
---
[1] I am a scientist, but not a physicist. Everything I said could be wrong.
The [Study] has a better framing in its title "JWST Observations Reject Unrecognized Crowding of Cepheid Photometry as an Explanation for the Hubble Tension at 8σ Confidence".
It rejects the hypothesis that there was a systematic observational problem in observing Cepheid variables (CVs), which are in turn used to estimate distances to Type Ia Supernova (SNs), towards a long-term goal the Study concludes with of "Tying all of these together by observing large samples in common can lead to the calibration of ∼100 [SNs] and a <1% local measurement of [The Hubble Constant, H0], a landmark in our quest to understand the expansion of the Universe."
Notably the paper doesn't provide a new estimate of H0, but it does strengthen the case for CV/SN being at odds with other methods of estimating H0, a problem called the Hubble Tension.
JWST was built primarily to extend the sensitivity range for infrared observations, so we can see fainter sources from further away, or near sources with greater resolution. This study is about the latter.. the study of CVs and SNs in nearby galaxies.
"the significantly greater resolution of JWST over [Hubble Space Telescope] has greatly reduced—in practical terms, almost eliminated—the main source of noise in [Near-Infrared] photometry of [CVs] observed in the hosts of nearby [SNs]. The resolution of JWST provides the ability to cleanly separate these vital standard candles from surrounding photometric "chaff."
CVs and SNs are "standard candles", rungs on the Cosmic Distance Ladder[CDL], the framework we use to compare and contrast different astronomical distance measurements. The term "standard candle" is used for a physical process we think we understand well enough to use its appearance at astronomical distance to infer other properties of its observation, e.g. the candle's color shift towards red the further away it appears to be. ("appears" since we can't directly measure actual distances, but observe that galaxies get smaller/fainter/redder together)
Cepheids are a relatively common kind of star that pulsates regularly during its lifetime, while SuperNovas are much rarer one-time very bright events. SNs are really useful to see them far away bc how bright they are, but since there's so few of them, we calibrate nearby SN distances based on the many CVs in the host galaxy of the SN.
In all, this study starts by looking at CVs in NGC 4258 at 23 Million lightyears away, and then looks for photometric crowding of CVs at successively further steps away in NGC 5643 (41 Mly), NGC 1559 (48 Mly), NGC (1448 56 Mly) and NGC 5468 (140 Mly), but don't find evidence of crowding to account for apparent brightness/closeness of the CVs, so rejects that idea with a high confidence. Those galaxies are actually as far away as they appear to be if CVs are good standard candles.
These are at the nearer end of the CDL.. 140 Mly vs the observable Universe is thought to be at least 13 billion light years radius. But if it in turn makes us more confident about SNs, those go out to a current max of 16Bly[FarthestSN].
Does it even bother to rely on physics? Physical experiments show explosions do not propel all matter at the same rate.
James Webb telescope recently found galaxies that were “too old”, would have formed right after the Big Bang. The prevailing wisdom was all matter spread out evenly due to the Big Bang, then coalesced into galaxies (I emailed various researchers to confirm I understood this was indeed the consensus).
But again, other physics shows that clusters of matter ejected from explosions are never uniformly distributed.
Just more evidence the well educated (I assume if it’s concensus driven even the best educated agree) are just typical people and their expertise should be challenged constantly rather than sit back and assume things are figured out.
As Asimov illustrated in the Foundation, if you aren’t measuring for yourself you’re serving someone else’s interpretation.
Hyper-normalized social society just leads to normalization of outputs, which helps preserve and propagate poor science.
Aggressive dismissal of an entire field with minimal attempt made to understand it is never going to play well and following it up with sarcasm doesn't improve the situation.
Attempting to work backwards to the beginning of the universe from a single tiny point in time and space is fairly obviously going to be a lot harder than understanding the physics of events we can repeat, measure, and examine. This doesn't make them quackery and it does explain why many things remain poorly explained. A century from now its likely that many understandings will be retained and some will have been consigned to the bin.
People do challenge existing theories. Most frequently unsuccessfully. Because most novel hypothesis turn out to be wrong.
Riffing off the science fiction reference this isn't a process we can skip any more than authors can skip brainstorming, first drafts, rewrites and just skip to typing out the final draft.
In brief stop coming off like Agent Mulder. Everyone knows the truth is out there. If it takes a while to coalesce its not because the educated folks working on the problem too stupid to listen to basic physics. It's because the physics that explains the rest of the picture isn't written yet.
That’s exactly my point though; it’s incomplete but academics sell incomplete/wrong work to eat.
They’re just as much avoiding real work of keeping themselves alive as an aristocrat to noodle around something that will only ever be incomplete due to our axiomatic systems being leaky abstraction.
I’m a “Perelmanite.” The ethical and communication standards of academia serve its social influence goals, not science.
We get the gist of natures mechanics and know how to measure generally. Further specialization of the syntax rarely moves the needle, which still points at Einstein, Gödel, and other century old works, rarely the contemporary librarians of scientific texts except to say “yeah this customization still preserves the whole of relativity” or some other core body of work we infer modern research form.
Perelman figured out Riemanns at home, alone. Bailed on university as he found it mired in politics and manipulation of social agency to preserve itself.
See that recent article about institutions becoming road blocks to the progress they were created to resolve. There’s been article after article here about science depts veering into pseudo-science. When a workers salary depends on them ignoring truth… “meat suit needs to eat” wins above honesty and integrity.
What are you drawing an analogy to explosions with in this comment? The Big Bang? Why do you expect the analogy to be as precise as you seem to take it to be?
The fact that you seem to be interested enough to email experts about ancient galaxies, yet still are referencing the big bang as an explosion, leaves me utterly confused about your level of knowledge, but leaning heavily towards "no idea what they are talking about".
Oh I’m sorry on an open forum where I don’t know every reader I use casual language.
This isn’t a forum for PhD defense.
So glad the takeaway is about a single word. While the idea that researchers are failing left and right which reaches into everyone else’s lives is left untouched. Likely because you’re the sort that relies on people buying the con about your efforts.
Reality is not a neatly organized set of decoupled microservices. It’s a monolith and bad science radiates through our lives.
Experts should not have the influence over society they demand.
But the core of your post seemed to be an instance of how all the cosmologists are wrong because their description of the universe as it relates to the big bang is wrong because the big bang is an explosion and explosions don't expand uniformly. Am I misunderstanding your point?
Do you have, like, a list of things they're wrong about maybe?
> Just more evidence the well educated (I assume if it’s concensus driven even the best educated agree) are just typical people and their expertise should be challenged constantly rather than sit back and assume things are figured out.
As someone who worked as a cosmologist, I have trouble putting into words how wrong, out of touch and arrogant this statement is.
In my social scene are people who worked at Fermilab, whose work helped inform where LHC should focus its search for the Higgs. A PhD EE who has designed chips you use. The list is long.
A lot of my insight into academia (since it’s been almost 30 years since I graduated and left it behind me) is influenced by academics tired of and often disgusted by their peers dishonesty about their work. Theory after theory have more in common with religion; they were made up.
Historians in my social scene say there’s solid historical evidence advanced degrees were invented as a payola scheme between landed gentry and the church; money for BS theology degree the illiterate public could not falsify. Over specialization doesn’t really make net new discovery so much as normalize old ones, but we keep up the role-play of history and anoint geniuses and the like.
Give them resources and prestige to do some math. Grigori Perelman would like a word on what’s required resource wise to do math. Out of touch and arrogant westerners.
Similar trend going on these days where the innumerate serve BS they cannot begin to try to falsify. Just so happens much of it isn’t reproducible anyway, but the can’t argue that or the out of touch egos of a minority of the populace that make up academia would crumple in outrage.
Offense at minor slight is so endemic to human nature, so general an emotion it impacts all of us.
Out of touch and arrogant is applies just a neatly to academics being normal humans and all.
We have some pretty good ideas about just how "lumpy" the explosion of the big bang should have been. And yes, the best theories in cosmology disagree with the recent observations highlighted in this article. On the other hand, those cosmological theories are rooted in extremely strong physics which does things like predict various attributes of particles that have been measured extremely precisely and were predicted correctly. So the Hubble tension is real. My money is on the theory needing revising, but how? There are no great candidates for something to replace the standard model and our best theories in cosmology. There are plenty of candidates, but no obvious methods to choose a best one. This is science! Remember, the most exciting words in science are, "huh, that's odd." The Hubble tension is extremely odd!
I like how the primary rebuttal is my use of a non-standard academic term on a public forum non academics read. Hear that unzipping sound? That’s reality itself coming apart because the Jedi Sacred texts were not recited from just so.
Really just proving my point that academia is obsessed with little more than normalizing symbolic logic. Such conservatism and thought policing is en vogue across social contexts these days.
I earned a BSc in EE and bailed on an MSc in elastic structures as such notions about academia seemed pretty obvious to me all the way back in the 90s. It’s all mathematical generalization of how matter coalesces at speeds relative to light, arguing for such specific recitation of truth is the problem: you aren’t owed that. The “human” language aspect is arbitrary to me, but often seems to convince the public some BS is immutable physics only for the BS to be falsified decades later.
Scientists do a whole lot of saying what they promotes them, damn the externalities. Has more in common with our economics in that way; can human scientists coupled to human nature to keep their meat suit alive escape such a bias?
I’m not anti-science, I’m anti-contemporary institutions. Only 14% in the US hold more than a bachelors, yet their influence is wide and deep, and (charitably) forever incomplete. A minority have outsized influence over everyone yet their so-called discovery is often restatement of a well known phenomenon or just wrong, damn the externalities.
Resolving all scientific inquiry (I’m sure someone will take offense such specific an idea can exist; academics like to flip flop between arguing for generalization and specificity like typical humans) would mean knowing all states of all matter and energy. Physically impossible, there will always be “holes”. Outwardly academia is dishonest in that regard, and the incompleteness of their work. IMO out of fear society would turn against them. Probably rightly so.
Science is important. I’m not anti-science. I’m anti-institutions manipulating the actually innumerate into serfs based upon (charitably) incomplete and more often than not, outright wrong conclusions.
Academics want to go on about non-experts being wrong and their egos. Well academics are humans mired in the same human condition. Turn the mirror around.
Interresting, but that analogy implies that there is a force that limits the exxpansion and a force that causes it to contract. I'm not sure that's what happens to this universe, and I'm not sure we can know.
I don't want to discourage question-asking but you're now asking someone to give you a background on a physics phenomena without them knowing your starting level. It's awesome that the poster you're replying to introduced a new concept to us (not something I was thinking about, either) and literally taking the thing you quoted: "time does not flow the same everywhere" into Google will give you a starting point for your quest - you'll see even from the blurbs on the search result page that per relativity, time changes depending on where and how fast you're traveling. You can then dive into what that means you want to as well.
I good followup could be something like "I read about relativity and I still don't understand the connection you're making to this current article or something like that - but it doesn't seem fair to skip a basic Google search before asking for elaboration.
Okay. I am a professional astronomer at the University of Washington, and I don’t see that phrase as holding very much meaning. In particular, “flow” is a messy word to use.
A generous reading of the OP might be that it is a restatement of special relativity, but then it is indeed disconnected to this measurement. An uncharitable reading would be that it is spiritual goop.
Anyway, I prefer to let someone answer in their own terms.
A fun exploration of what it means for time to flow, and how we don't really have observational personal evidence of time flowing (at a constant speed or at all), we just have our memories. Seems relatively unrelated otherwise.
Horrible shit article chock full of video ads about the same issue as link 2
Conclusion: It's ok to ask people what they mean when they say things. It's unreasonable to expect a google search from your listeners after you say something.
I think what it's actually saying is that we've confirmed that the Hubble tension is real. Whether or not that means different parts of the universe are accelerating at different speeds is still not clear. If the meaning of the results is deeper than that, it seems to have completely eluded the author who nonetheless wrote a breathless exaggeration of the findings.
EDIT: In 2024 actually I have to wonder if any humans were involved in the making of this article. It certainly doesn't appear to have passed an editor's eyes.
The Hubble Tension is real. The expansion of universe is accelerating.
We knew that before. This goes deeper than that. It accelerates in a way that cannot be explained by a constant dark energy density, which is part of our standard model. We have plenty of alternative models that can explain this, but our measurements are not precise enough yet to rule any of them out. Hopefully Euclid will provide data that is.
The spatial inhomogeneities of matter in the very early universe, which I believe you might be talking about, were extremely tiny.
That would be the proposed Local Hole.
[1]https://en.wikipedia.org/wiki/KBC_Void
There was an amazing paper on this published on HN a year or three ago that explained at certain discrete points in the future, entire percentages of the known universe will be beyond our reach. It was profoundly beautiful and sad at the same time.
I'll try to dig it up.
Edit: found the post (three years ago) and some of the quotes and figures I pulled from it:
https://news.ycombinator.com/item?id=26734913
Edit 2: another commenter had made a note about the Big Rip. I was writing a response, but they unfortunately deleted their (good) comment. I'll include my response below:
> wait until you find out about the Big Rip (paraphrasing)
That one's even wilder. To think every atom of every place and loved one you ever touched would vanish infinitely far away. Every atom and then subatomic particle of your own once corporal body, regardless of its final resting place, torn and scattered.
Last Contact is a great short story if you're in the mood [1].
Then there's vacuum collapse and all the other theories.
I wonder what humans or human descendents 500 years from now will figure out about the universe's ultimate fate.
[1] https://zestfullyblog.blogspot.com/2011/02/last-contact-by-s...
[0] https://iopscience.iop.org/article/10.3847/2041-8213/ad1ddd
[1] https://en.wikipedia.org/wiki/Hubble%27s_law#Hubble_tension
expansion rate in the early universe << expansion expansion rate.
-> accelerated expansion .
[0] https://en.wikipedia.org/wiki/Accelerating_expansion_of_the_...
- On the one hand, the universe can be expanding at different rates.
- On the other hand, is it possible our approach to measuring the expansion (e.g., using Cepheid variable stars) might be the problem?
So remaining possibilities are new physics, a deep flaw in our assumptions/methods, or a universe which is not uniform (but in a peculiar way).
As you say, measurement errors of Cepheid stars has been something scientists considered a possibility, hence why they're cross-checking by measuring them in different ways.
And, as mentioned in the posted article and the other papers mentioned in the video, it seems that measurement errors are very unlikely to be the culprit.
Preprints to the articles Becky mentions are here[2][3][4].
[1]: https://www.youtube.com/watch?v=3NeKR7bqolY&t=1330s
[2]: https://arxiv.org/abs/2401.04773
[3]: https://arxiv.org/abs/2401.04776
[4]: https://arxiv.org/abs/2401.04777
What happens to an object as it moves from a high rate-of-expansion region to a low rate-of-expansion region?
Think of it not as things moving apart, but that space, emptiness, is expanding. Like if you laid the universe out on a sheet of rubber and then pulled at the corners. Everything gets further apart and the expansion is happening everywhere
This result confirms that the "hubble tension" is real. In other words, two methods for measuring the expansion of the universe disagree, but we can't figure out why and have new and really strong evidence that the "cosmic ladder" method is correct. (The other method is based on the cosmic microwave background radiation and our best theories of physics, so we're caught between a rock and a hard place here: strong experimental evidence one way, and throwing out a ton of what we think we know about the universe with no obvious replacement the other way.)
It can't be nothing. Something can't expand into nothing.
Still alternatively, imagine an infinitely extended graph paper whose grid size slowly and continuously increases, carrying with it the dots already drawn on it. Since the grid has infinite size from the start, it doesn’t expand into anything. It just expands.
That's not an explanation, that's incoherent ramblings that make zero logical sense
https://www.youtube.com/watch?v=MO0r930Sn_8
It takes effort to understand those fundamental terms, so if you want to understand this, you'll have to meet people halfway instead of rejecting how somebody is trying to explain something to you.
In this case it's entirely possible for the topology of space to change such that it takes longer to travel from one point to another over time. If you consider a trip from point A to point B in topology A, and then topology A expands during the trip from point A to point B such that new distance is created, then the "distance" you have to travel to get to B is changing because at each moment along the trip you're at a different point.
If you think about it this way, the universe can be both expanding because it takes progressively longer to get from point A to point B, and it can also not be expanding into some "outer" area because there's nothing other than the universe.
It may make more sense to stop thinking in terms of distance and start thinking in terms of time. In that case, when you think of "expansion" what you're really describing is that at a constant speed, the closer you get to B, the more time it takes you to advance toward B. And if you change direction mid-trip to go to C, the "expansion" means that the amount of time required to reach C also increases as time elapses.
It's hard to say what's causing that expansion, but we can measure it by its effects on light traveling the same distance.
If you drew two dots on the surface of that balloon, those dots would get further apart as it inflated. What did those dots expand into? Well, nothing right? They just got further apart from each other on the balloon.
So, if you translate this into 3D space, that's what's going on. It's hard to visualize. It's not that the universe is expanding into something, it's that the space between every "point" in the universe is getting further apart.
https://bigthink.com/starts-with-a-bang/what-universe-expand...
I'm talking about 3d that we live in. We're currently standing on a ball of dirt, if the earth started to swell up, the surface we're standing on would expand into space. The thing we're standing on that's pushing outward is what I mean by "edge".
What is the universe expanding into? If it's pushing outward in all directions, it's pushing into something, the same way a swelling earth would expand into space
We've proved the universe itself is getting bigger, which means that yesterday it was smaller and the realization of that fact was how the big bang theory came to be.
There are lots of resources out there if you want to build an intuition around how a universe that's everything can get larger without needing something to expand into.
Four-dimensional spacetime is considered such a manifold. Its three-dimensional space “slices” are predicted to expand with time by general relativity (first predicted by Alexander Friedmann in 1922), and actual observations have confirmed those predictions.
The “universe” itself is space and time. When we say “expanding” we simple mean that galaxies are observed to be moving farther away from each other. That does not at all imply some kind of “expansion into another space” - space itself is exhibiting this property and we are observing it. That’s all.
The “balloon” analogy and the usage of the word “expand” in this context are both imperfect metaphors for physical phenomena we are observing.
It is a bit like trying to discuss what happened “before” the Big Bang - there is no “before” - time was created.
There are many phrases you can construct which may seem like they “make sense” but are actually combining a set of word concepts in ways that are self-contradictory.
“What is space expanding into?”
“What happened before time was created?”
Etc.
If we were somehow able to accelerate a particle out past the edge of the known universe, now the bubble includes that particle too and essentially we've 'expanded' the universe. In other words, the arbitrary bubble containing things that we know about and consider significant is larger than it was before - because there's something out there we can observe.
I don't think that the scientific definition of the universe matches this. It's a physical thing, not a construct we made up. It's not an imaginary line between two countries.
The universe is full of things which have mass. Those things are rapidly expanding outward. What are those masses expanding into as they "blow up the ballon" and push the boundaries of the universe outward? It can't be nothing, it's physically impossible.
EDIT: might as well quote people smarter than I
> The universe is all of space and time[a] and their contents.[10] It comprises all of existence, any fundamental interaction, physical process and physical constant, and therefore all forms of energy and matter, and the structures they form, from sub-atomic particles to entire galaxies. Space and time, according to the prevailing cosmological theory of the Big Bang, emerged together 13.787±0.020 billion years ago,[11] and the universe has been expanding ever since. Today the universe has expanded into an age and size that is physically only in parts observable as the observable universe, which is approximately 93 billion light-years in diameter at the present day, while the spatial size, if any, of the entire universe is unknown.
https://en.wikipedia.org/wiki/Universe
It's a pretty well accepted fact.
I also have the layman awareness of some kind of missing mass sometimes explained by "dark matter." But I did not see the additional explanation that this "dark matter" also acts as a repulsive force to accelerate the expansion. Maybe large scale structures manage to create propulsive forces that happen to point away from the center? Anyhow I would love to know what the mechanism is there.
This stretching includes any photons traveling across the grid, and the stretching causes them to expand. Longer wavelengths are more red, giving us the word redshift for stretched light rays. That's one of the ways we measure the expansion: see how much redder the light is as you look at more and more distant objects
I do know[1] that:
- it's larger than we will ever be able to know or observe (ie.: the observable universe is smaller than "all of the universe"... although that feels a bit hand-wavy to say)
- it's expanding.
---
[1] I am a scientist, but not a physicist. Everything I said could be wrong.
It rejects the hypothesis that there was a systematic observational problem in observing Cepheid variables (CVs), which are in turn used to estimate distances to Type Ia Supernova (SNs), towards a long-term goal the Study concludes with of "Tying all of these together by observing large samples in common can lead to the calibration of ∼100 [SNs] and a <1% local measurement of [The Hubble Constant, H0], a landmark in our quest to understand the expansion of the Universe."
Notably the paper doesn't provide a new estimate of H0, but it does strengthen the case for CV/SN being at odds with other methods of estimating H0, a problem called the Hubble Tension.
JWST was built primarily to extend the sensitivity range for infrared observations, so we can see fainter sources from further away, or near sources with greater resolution. This study is about the latter.. the study of CVs and SNs in nearby galaxies.
"the significantly greater resolution of JWST over [Hubble Space Telescope] has greatly reduced—in practical terms, almost eliminated—the main source of noise in [Near-Infrared] photometry of [CVs] observed in the hosts of nearby [SNs]. The resolution of JWST provides the ability to cleanly separate these vital standard candles from surrounding photometric "chaff."
CVs and SNs are "standard candles", rungs on the Cosmic Distance Ladder[CDL], the framework we use to compare and contrast different astronomical distance measurements. The term "standard candle" is used for a physical process we think we understand well enough to use its appearance at astronomical distance to infer other properties of its observation, e.g. the candle's color shift towards red the further away it appears to be. ("appears" since we can't directly measure actual distances, but observe that galaxies get smaller/fainter/redder together)
Cepheids are a relatively common kind of star that pulsates regularly during its lifetime, while SuperNovas are much rarer one-time very bright events. SNs are really useful to see them far away bc how bright they are, but since there's so few of them, we calibrate nearby SN distances based on the many CVs in the host galaxy of the SN.
In all, this study starts by looking at CVs in NGC 4258 at 23 Million lightyears away, and then looks for photometric crowding of CVs at successively further steps away in NGC 5643 (41 Mly), NGC 1559 (48 Mly), NGC (1448 56 Mly) and NGC 5468 (140 Mly), but don't find evidence of crowding to account for apparent brightness/closeness of the CVs, so rejects that idea with a high confidence. Those galaxies are actually as far away as they appear to be if CVs are good standard candles.
These are at the nearer end of the CDL.. 140 Mly vs the observable Universe is thought to be at least 13 billion light years radius. But if it in turn makes us more confident about SNs, those go out to a current max of 16Bly[FarthestSN].
[Study] https://iopscience.iop.org/article/10.3847/2041-8213/ad1ddd
[CDL] https://en.wikipedia.org/wiki/Cosmic_distance_ladder
[HT] https://xkcd.com/2516/
[FarthestSN] https://en.wikipedia.org/wiki/SN_UDS10Wil
Does it even bother to rely on physics? Physical experiments show explosions do not propel all matter at the same rate.
James Webb telescope recently found galaxies that were “too old”, would have formed right after the Big Bang. The prevailing wisdom was all matter spread out evenly due to the Big Bang, then coalesced into galaxies (I emailed various researchers to confirm I understood this was indeed the consensus).
But again, other physics shows that clusters of matter ejected from explosions are never uniformly distributed.
Just more evidence the well educated (I assume if it’s concensus driven even the best educated agree) are just typical people and their expertise should be challenged constantly rather than sit back and assume things are figured out.
As Asimov illustrated in the Foundation, if you aren’t measuring for yourself you’re serving someone else’s interpretation.
Hyper-normalized social society just leads to normalization of outputs, which helps preserve and propagate poor science.
Attempting to work backwards to the beginning of the universe from a single tiny point in time and space is fairly obviously going to be a lot harder than understanding the physics of events we can repeat, measure, and examine. This doesn't make them quackery and it does explain why many things remain poorly explained. A century from now its likely that many understandings will be retained and some will have been consigned to the bin.
People do challenge existing theories. Most frequently unsuccessfully. Because most novel hypothesis turn out to be wrong.
Riffing off the science fiction reference this isn't a process we can skip any more than authors can skip brainstorming, first drafts, rewrites and just skip to typing out the final draft.
In brief stop coming off like Agent Mulder. Everyone knows the truth is out there. If it takes a while to coalesce its not because the educated folks working on the problem too stupid to listen to basic physics. It's because the physics that explains the rest of the picture isn't written yet.
They’re just as much avoiding real work of keeping themselves alive as an aristocrat to noodle around something that will only ever be incomplete due to our axiomatic systems being leaky abstraction.
I’m a “Perelmanite.” The ethical and communication standards of academia serve its social influence goals, not science.
We get the gist of natures mechanics and know how to measure generally. Further specialization of the syntax rarely moves the needle, which still points at Einstein, Gödel, and other century old works, rarely the contemporary librarians of scientific texts except to say “yeah this customization still preserves the whole of relativity” or some other core body of work we infer modern research form.
Perelman figured out Riemanns at home, alone. Bailed on university as he found it mired in politics and manipulation of social agency to preserve itself.
See that recent article about institutions becoming road blocks to the progress they were created to resolve. There’s been article after article here about science depts veering into pseudo-science. When a workers salary depends on them ignoring truth… “meat suit needs to eat” wins above honesty and integrity.
What are you drawing an analogy to explosions with in this comment? The Big Bang? Why do you expect the analogy to be as precise as you seem to take it to be?
Let’s not pretend the replication crisis isn’t real and endemic within academia these days.
The big bang was not an explosion.
Okay, then lets hear your interpretation of what it was.
This isn’t a forum for PhD defense.
So glad the takeaway is about a single word. While the idea that researchers are failing left and right which reaches into everyone else’s lives is left untouched. Likely because you’re the sort that relies on people buying the con about your efforts.
Reality is not a neatly organized set of decoupled microservices. It’s a monolith and bad science radiates through our lives.
Experts should not have the influence over society they demand.
Do you have, like, a list of things they're wrong about maybe?
As someone who worked as a cosmologist, I have trouble putting into words how wrong, out of touch and arrogant this statement is.
A lot of my insight into academia (since it’s been almost 30 years since I graduated and left it behind me) is influenced by academics tired of and often disgusted by their peers dishonesty about their work. Theory after theory have more in common with religion; they were made up.
Historians in my social scene say there’s solid historical evidence advanced degrees were invented as a payola scheme between landed gentry and the church; money for BS theology degree the illiterate public could not falsify. Over specialization doesn’t really make net new discovery so much as normalize old ones, but we keep up the role-play of history and anoint geniuses and the like.
Give them resources and prestige to do some math. Grigori Perelman would like a word on what’s required resource wise to do math. Out of touch and arrogant westerners.
Similar trend going on these days where the innumerate serve BS they cannot begin to try to falsify. Just so happens much of it isn’t reproducible anyway, but the can’t argue that or the out of touch egos of a minority of the populace that make up academia would crumple in outrage.
Offense at minor slight is so endemic to human nature, so general an emotion it impacts all of us.
Out of touch and arrogant is applies just a neatly to academics being normal humans and all.
Not that you really deserve help, with that attitude...
Or even to type "is the big bang an explosion" into your search bar?
Really just proving my point that academia is obsessed with little more than normalizing symbolic logic. Such conservatism and thought policing is en vogue across social contexts these days.
I earned a BSc in EE and bailed on an MSc in elastic structures as such notions about academia seemed pretty obvious to me all the way back in the 90s. It’s all mathematical generalization of how matter coalesces at speeds relative to light, arguing for such specific recitation of truth is the problem: you aren’t owed that. The “human” language aspect is arbitrary to me, but often seems to convince the public some BS is immutable physics only for the BS to be falsified decades later.
Scientists do a whole lot of saying what they promotes them, damn the externalities. Has more in common with our economics in that way; can human scientists coupled to human nature to keep their meat suit alive escape such a bias?
I’m not anti-science, I’m anti-contemporary institutions. Only 14% in the US hold more than a bachelors, yet their influence is wide and deep, and (charitably) forever incomplete. A minority have outsized influence over everyone yet their so-called discovery is often restatement of a well known phenomenon or just wrong, damn the externalities.
Resolving all scientific inquiry (I’m sure someone will take offense such specific an idea can exist; academics like to flip flop between arguing for generalization and specificity like typical humans) would mean knowing all states of all matter and energy. Physically impossible, there will always be “holes”. Outwardly academia is dishonest in that regard, and the incompleteness of their work. IMO out of fear society would turn against them. Probably rightly so.
Science is important. I’m not anti-science. I’m anti-institutions manipulating the actually innumerate into serfs based upon (charitably) incomplete and more often than not, outright wrong conclusions.
Academics want to go on about non-experts being wrong and their egos. Well academics are humans mired in the same human condition. Turn the mirror around.
I good followup could be something like "I read about relativity and I still don't understand the connection you're making to this current article or something like that - but it doesn't seem fair to skip a basic Google search before asking for elaboration.
A generous reading of the OP might be that it is a restatement of special relativity, but then it is indeed disconnected to this measurement. An uncharitable reading would be that it is spiritual goop.
Anyway, I prefer to let someone answer in their own terms.
https://www.quora.com/Does-time-flow-at-the-same-rate-everyw...
Quora side-paths:
> no, gravity
> no, speed and gravity
> no, gravity and velocity, look up time dilation
> yes, time is constant, however it is relative for observers
Second:
https://www.scientificamerican.com/blog/observations/do-we-a...
A fun exploration of what it means for time to flow, and how we don't really have observational personal evidence of time flowing (at a constant speed or at all), we just have our memories. Seems relatively unrelated otherwise.
Third:
https://medium.com/la-mia-biblioteca/does-time-flow-cafaf084...
Appears to be someone advertising a book.
Fourth: (i don't recommend this link)
https://www.express.co.uk/news/science/738387/Time-NOT-real-...
Horrible shit article chock full of video ads about the same issue as link 2
Conclusion: It's ok to ask people what they mean when they say things. It's unreasonable to expect a google search from your listeners after you say something.