> Recent ideas suggest that little red dots could be black holes cocooned in thick gas, possibly representing a completely new type of object called a black hole star, in which the tight shroud of gas emits light like a stellar atmosphere.
Just be sure to name the members of Soundgarden on the paper.
I thought I read somewhere that many of these little red dots are turning out to be nothing more than bog-standard brown dwarfs in our own galaxy that are confusing the signal. These days we have some pretty powerful agents who can read these things faster than I can, so I went and found the paper: https://arxiv.org/abs/2506.04004
It turns out that brown dwarfs are actually corrected for, so my remembrance is correct but factored in. I’m posting anyway because 1) it’s interesting and mildly relevant and 2) others might have the same “vague but unclear” recollection I had and appreciate the elaboration.
Little red dots are my favorite new concept in astrophysics. This idea that there could be so much matter orbiting a black hole that the matter reaches sun levels of pressure which in turn starts steller fission without there being an star. Mind-blowing
There was a time where Hawking's A brief history of time gave a decent overview of the universe to beginners. Does anyone know how well it holds up today and if anything better exists?
I'll give a shoutout to Feynman's QED. It's approachable for anyone with high school understanding, and gives a reasonable insight into all sorts of phenomena.
I went to a public lecture by Martin Rees at uni. He asked everyone who read it to put up their hand, then put it down if they understood it. He pointed to the professor of astrophysics who had invited the lecture and said "ok, you! The rest of you, no chance!"
Look up introductory college courses, e.g.., in astronomy. Their syllabi have your answers. Maybe it is more extensive than you want, but one or two book might be what you seek.
The very useful Open Syllabus Project collects syllabi and lists the most popular books, etc.: https://www.opensyllabus.org/
A professor's course materials may suit your need.
Have not read it yet, but recently researched this question and came to this book as a readable overview of the latest thinking in cosmology, Battle of the Big Bang: The New Tales of Our Cosmic Origins by Afshordi and Halper [1].
The book assumes a basic knowledge of physics and cosmology so it does not spend half the book reviewing basics like many pop physics books do.
There was never a time when a book gave the public an overview of the universe. ABHOT was so popular for being a book no one actually read, theres even an index named after Hawking due to it: https://en.wikipedia.org/wiki/Hawking_Index
Did _you_ read that book?
There however definitely was a piece of media that captured public minds and educated them about the cosmos. And that was the show Cosmos. The original of course. Not the NDT drivel.
I am pretty certain this "hawking index" meme must be a new-ish thing. I read the book as teenager and know also others who did. It is a fairly easily readable book imo, so I don't think this characterisation is warranted by the qualities of the book itself.
I suspect that a popsci book becoming a bestseller creates a larger-than-the-usual-nerds audience, a big part of which lacks the motivation to actually finish it. I expect that in places like this you will find higher frequency of people who have actually read it.
Moreover, when i read the book i did not have easy access to pop-sci sources as a (practically pre-internet) teenager in a small town of a small country, like i would have had today. I got upon a booklet of a small publishing house with the titles of translated pop-sci books and would order them from a local bookstore. Maybe if I was already familiar enough with the topic through youtube videos etc I would not have finished either.
> this "hawking index" meme must be a new-ish thing
TBF the methodology and hypotheses that it's based on aren't that bad. I'm sure Amazon has better data, but for a "publicly accessible" data (at that time) I can see it. The problem is that while lots of people might abandon the book, that doesn't mean that still loads of people don't read it fully. They are, after all, extremely popular books. Obviously some people will have received / impulse bought / FOMO / new year resolution / etc the books, but from the sales numbers that's still a lot of people that did enjoy them. Marketing aside, the book is pretty approachable, like were Sagan's books and so on.
As an early teen I begged my parents for both A Brief History of Time and The Grand Design. Read both several times. ~15 years later, my parents are still holding on to them and my Dad has read them a couple of times too. It was great reading and played a significant role in my choice of research as a career.
Never heard of the "people don't actually read it" meme.
From that list I've read three books: "A Brief History of Time", "Thinking, Fast and Slow", and "Capital in XXI Century". First two I've read from start to end. The last I didn't read to the end, I think I've read ~50% of it. My numbers correlate with that list, the least "readable" book in the list is the book I didn't read through.
However I still doubt the methodology. It is not obvious for me that if a book was read in full, then highlights from it would be distributed uniformly all over the book.
Interesting. I've been gifted that book at just the right time in my life as a teenager. It captured me. I read it the to end many times. Not understanding everything or course. But it created a spark which laid the groundwork for my entire career.
I did read it and I'm sure a whole generation of people also did, it is a very clear and readable book. Don't underestimate or minimize the impact of Hawking's book when it was released.
I read it in high school in 82. I still have the book.
Fun fact: The very first book ever sold on Amazon was "Fluid Concepts And Creative Analogies: Computer Models Of The Fundamental Mechanisms Of Thought" also by Douglas Hofstadter
A downside to the tech. You never really know if you made it because you enter another universe within.
You make it to the next cycle, but within a new universe rather than the one you aimed for. Your black hole displaces spacetime within the universe whose cycle renewed, but you are no longer an active component of that universe.
Of course, if you didn't deliberately do this, I guess you're a spectator to someone else in their black hole. So, congrats, I guess, but also you need to advance your science a bit faster if you don't want to count on luck next time.
Nancy Grace Roman Telescope is also going to be amazing for raising new questions
and I hope the attempt to lift the Swift telescope to a higher orbit is successful
if you really want to stay on top of what is breaking astrophysics in realtime, I highly recommend following DrBecky on youtube or elsewhere, she is fantastic
So I wonder, where are these giant black holes now? There should be some closer to us than at the edge of the universe, unless something happens to them.
The M87 supermassive blackhole is thousands of times as massive as Sagittarius A*, but since Sagittarius A* is a lot closer their emission rings appear roughly the same size in the sky (42 μas vs 51 μas). Both have already been imaged by the Event Horizon Telescope. https://en.wikipedia.org/wiki/Event_Horizon_Telescope
This is one of my favorite phenomena: again in again, across various fields of study, breakthroughs in discovery allow us to go from relative ignorance to a level of knowledge and understanding that enables clear and clean conceptual models; then, as we learn even more, we realize how much more complex and weird and multifaceted reality really is.
It’s like a Dunning-Kruger effect on a field-wide scale, but in a good way. Rather than an example of hubris, it’s an opportunity for awe.
I think this can be explained by the dictum "big effects get discovered first"
It does present a weird science communication problem. After the first generation, scientists are all focused on "little effects" and don't get excited about talking about the big effects any more. They like talking about what they're working on (little effects). Textbooks drift from fundamentals and new entrants and outsiders get a distorted view of reality.
The most exciting idea to me that JWST has bolstered is primordial black holes. Many models already predict them but JWST has provided the first good indirect evidence in the form of too-early galaxies. The models that predict PBHs predict that.
If they exist, they would not be constrained to stellar mass and above. There could be a population of little black holes floating around. Anything under the mass of a decent size asteroid would have evaporated by now but anything that mass and above would still exist.
They are a dark matter candidate, and one that doesn’t require new physics. But even if they don’t account for a significant amount of dark matter they still probably exist.
The most exciting thing about PBHs is that one or more may exist in our solar system. They might have been captured over billions of years. Finding them would be incredibly challenging, especially if they are low mass, but if we did it means we could directly examine and experiment on a black hole.
It could be something with the mass of a large asteroid but the size of a hydrogen atom. We could only find it by its gravitational effects. It would be utterly invisible otherwise unless it encountered matter and even then there might only be a tiny gamma ray flash, a nano accretion disc that lasts femtoseconds. We might also find smaller objects that appear to be orbiting nothing and find it that way.
Directly accessing one could allow us to test theories of quantum gravity and things like string theory, and maybe more. A black hole could be like a Rosetta Stone of deep fundamental physics.
The film Interstellar involved using plot magic to visit a black hole and solve physics, but this would allow it for real. It would just be an itty bitty one.
Of course if we had a black hole in a lab (or one in a convenient orbit) we could run all sort of experiments, but which experiments exactly? We will start by throwing things at it and watch, obviously, but that's unimaginative. What are the smart experiments?
If you had a small black hole in a lab you could generate power from the hawking radiation, likely enough to power the entire world. A 1,000,000 ton black hole would last over a thousand years without feeding it more mass and produce about 300 TW of energy (increasing over time, so you better keep feeding it). You'd also need some pretty good sunglasses to be able to watch things being thrown into it. Also I'm not sure how you could throw anything into it given the amount of radiation pressure... Maybe a dedicated particle accelerator could do it.
Anything smaller while also lasting long enough to do an experiment on and you'd likely end up producing too much energy and destroying the planet.
There's a few obvious things. What you've got is an almost "vertical" gravity well near the object. A smaller black hole would actually have a steeper gravity well than a large one.
(1) See how gravity behaves at those strengths and scales by firing lasers and particle beams past it, grazing the event horizon, and use that information to test quantum gravity hypotheses and things like string theory. Classical gravity predicts certain results. Quantum and non-classical theories would make different predictions. For example, you might see direct evidence of gravitational quantization very close to the horizon.
(2) Chuck stuff into it: heavy ions, small masses with a coilgun. Measure the results: spectrum, particles emitted, etc.
(3) Chuck stuff into it in a very precise way and use its extreme near-horizon gravitational well as a particle accelerator to achieve collision energies potentially millions of times greater than the LHC. You would not be able to directly observe these collisions, but you could potentially observe stuff kicked out. Orbit it with an array of sensors and magnetic traps.
Bonus: use its gravity well to yeet small probes at interstellar velocities (a few percent 'c' or higher) for flyby missions to photograph exoplanets? I believe you could use the Oberth effect here and do something like fly very close and fire a single Orion-style nuclear pulse at a sacrificial pusher plate. The impulse would accelerate the payload to insane velocities.
We could probably redirect budget for next gen particle accelerator to building an experimental platform orbiting the black hole, and get better results, right?
I’m still convinced a muon collider is the best bang for the buck for a next-generation collider. It requires new engineering and could probe new physics.
A black hole isn't a magic cosmic vacuum cleaner. It's a dense piece of mass. An asteroid mass black hole the size of a hydrogen atom would be... an object the size of a hydrogen atom with the mass of an asteroid. You could orbit it and the orbital calculations, at a reasonable distance, would be the same as orbiting an asteroid. You just can't get too close or you get into that steep gravity well and "become physics" (spaghettification etc.).
It would have an insanely steep gravity well, but you'd have to get close to actually feel it. It would rarely interact with mass naturally. We could chuck stuff into it or fire lasers and particle beams at it to study it, of course, but to hit it we'd have to fire it at the right angle and velocity to negate the orbit and fall into it. Orbital mechanics still works the same way.
If a black hole this size flew through the Earth at high velocity, it might not even do anything. It'd be like a bullet being fired through a puff of smoke. It might leave some kind of trail if you knew exactly what to look for and where to look, something almost analogous to the trails left by particles in a chamber.
I've given this example multiple times because it illustrates the point well, I think.
If you could magically transform the Moon into a black hole of the same mass, you would now have an object of that mass about the size of a BB or a small marble orbiting the Earth right where the Moon's center of mass orbited. The tides would continue as normal, since its gravitational effects on the Earth would be the same at that distance. Probes and other objects orbiting the Moon would continue to orbit it.
You just wouldn't be able to see it anymore. If you focused a very good telescope on its location, though, you could probably see gravitational lensing of the star field behind it.
The only risk might be if a large object actually hit it, in which case the accretion disc might temporarily emit enough X-rays and gamma rays to be harmful to Earth. Not sure though. It might not be that harmful at that distance.
How certain is the evaporation? Obviously Hawking radiation has never been observed, but is it tied in enough to other known physics that we can be reasonably certain it exists?
It's a very strong consensus among physicists, but has not been observed. My understanding is it pops right out of the math. If it doesn't exist it means some new fundamental physics is in play, like quantum gravitational effects we don't understand at all right now.
If it doesn't exist its also has profound implications for the long term fate of the universe, since it would mean black holes never evaporate.
As observations become too numerous, it seems like it can be summarized as there now being too many possible candidate explanations. As data increases and becomes clearer, more and more things don't fit the existing theories.
What are the current theories explaining the early universe? What happened to the Big Bang? I only studied astronomy up to an undergraduate level, so I don't really know.
I imagine that various non-uniform gases were scattered around, and due to spatial distortions, those uniform gas regions clumped together, forming stars and other structures. Perhaps the expansion of space wasn't uniform either—it expanded unevenly, sometimes bulging, and when space expands or contracts, energy is generated, causing spacetime changes to shake the field, and that shaking might have created matter. Maybe the dynamic interaction between changing spacetime and fields revealed the energy stored in the field in the form of particles.
What do scientists think about this in modern cosmology? My knowledge is far too limited and I lack intuition, but reading science-related articles always excites me. Maybe it's because I still have some childlike curiosity left in me
The evidence for the big bang is generally not that if you look far enough back in a telescope, the universe looks younger, which is somewhat the layperson's confusion.
Evidence for the big bang is about measuring redshift of galaxies throughout universal history, homgeneity and thermal equilibrium of the universe and CMBR, which could only be explained by it all having been in a compressed location where it could reach thermal equilibrium at some point in the distant past.
None of that is challenged by the Webb observations about very young supermassive black holes.
In fact, the existence of supermassive black holes themselves has basically always been an unsolved problem even before Webb. The only known possible explanation (stellar collapse -> accretion -> supermassive black hole) could be ruled out even before Webb on theoretical and experimental grounds, we just have stronger evidence against it now. (To wit: if supermassive black holes form from stellar black holes by growing, you would expect to see lots of intermediate mass black holes. We see almost none. Furthermore, the process of accretion is extremely energetic, so IMBHs would be the most visible objects in the night sky. The fact we see none is doubly damning)
The mainstream position now will be big bang + some kind of primordial black hole formation during the very early stages of the universe. Work of Hawking/Penrose shows that black holes can form under generic conditions in solutions to the EFE equations. We have a general understanding of how they could come about from certain dense matter layouts in a standard GR cosmological model.
I think you're leaving out a major issue there. Homogeneity was not in favor of the big bang. It's actually a major problem - the horizon problem. [1] Parts of the universe (think opposite sides) are not causally connected. Even traveling at the speed of light, there would not be enough time for a particle in one side to reach the other since the birth of the universe. Yet the temperature within these regions is homogeneous - at a thermal equilibrium. That doesn't make any sense.
This led to the development of cosmic inflation [2], which is what largely drove me from a doe eyed young astronomy enthusiast to a highly skeptical old fart. It solves the problem in an ad hoc fashion. Just have the universal expansion go into overdrive for a bit shortly after the big bang, then slow down, then start accelerating again - and then at the end we finally get something that looks like what we see - a homogeneous system in this case.
It made some highly accurate and improbable predictions which led to widespread adoption but then ran into numerous issues requiring further ad-hoc solutions. And this process has been repeated multiple times since its original formulation, to the point that there's a library of different inflation theories now a days, all getting ever more fine-tuned. If non-casually connected regions of space acted like they were non-casually connected then all would be fine, but the homogeneity that we do have is a big problem for the big bang.
Acoustic distortions. The universe was small and dense enough for sound to travel through ‘space’, which was filled with plasma. The theory is that inflation blew up these tiny distortions to the scale of the structure we see in the universe.
Right. When you don't have any breathing room, it's hard to think about anything else. That's why I take about two hours a day to just watch the news and clear my head. I'd probably forget all about it too if I were working 70-hour weeks on a contracted project, haha. Hang in there. Have a good day
With the caveat I'm summarising from what PBS Space Time and Dr Becky* say:
• Big Bang: we can only see back to surface of last scattering, i.e. the CMB, extrapolating backwards goes "???" at much the same point as it did a few decades back because we still have not unified quantum mechanics and general relativity
• CMB should only have isotope distribution of Big Bang nucleosynthesis, that hasn't changed in the last decades, dunno if that's what you meant by "various non-uniform gases were scattered around"?
• Variations in density of CMB do exist, key phrase is "Baryon acoustic oscillations", while they're very small magnitude they're also massive in distance scale, so they're how galactic clusters formed (that scale rather than stars directly): https://en.wikipedia.org/wiki/Baryon_acoustic_oscillations
• Re: "Perhaps the expansion of space wasn't uniform either": I heard about specifically "Timescape Cosmology", but a quick search says that's part of a broader category of inhomogeneous cosmologies: https://en.wikipedia.org/wiki/Inhomogeneous_cosmology#Timesc...
• Re: "and when space expands or contracts, energy is generated": no, general relativity does not in general conserve energy, and it is related to the curvature of spacetime. Simple example is that the photons in the CMB have much less energy to us than they did to the atoms they were emitted from**: https://www.youtube.com/watch?v=04ERSb06dOg
* I assuming I'm correctly judging the level and attention to detail they're providing, given the detail they put in and references to specific research publications. My degree is Software Engineering.
** There's also a Veritasium video about this, but to me Veritasium feels like a BBC 2 evening popular science show, so I'm not as confident about recommending it.
I took a good long look at the CMB picture, including the caption. It basically says the Universe was one big hot apparently uniform ball at one stage.
I don't know what conditions were like before that stage, but like Eric Idle says, nothing can come from nothing.
Dark energy is a horse shit name for a theory that was horse shit to begin with. The Universe is probably just inhomogeneous, like your intuition is saying.
Why do you say "probably"? We can measure and quantify the inhomogeneities very precisely, and they're tiny. This isn't a matter of opinion or intuition.
“Dark” matter and energy are placeholder names. “Dark” means “we don’t know” which either means we can’t see or detect it or there is an alternate explanation for the effect.
It’s like a comment in your code like \\ TODO…
I don’t see why that’s that hard, or why we’d expect to instantly be able to figure everything out.
I think the problem is that it wasn’t just used merely as a placeholder, but to hard shutdown any discussions—often started by lay persons—about possibilities that didn’t involve brand new
particle physics.
I still recall how neutrinos and black holes “couldn’t” be candidates.
To physicists, this means stellar neutrinos and blackholes (and galaxy centers). To lay persons, any category such as cold neutrinos or primordial black holes also qualify.
The sheer amount of vitriol and—I can’t think of a better term than this—“smugness” was off putting.
Before the internet, this was fine when locked away in their labs and classes; but I don’t think you understand the scale of damage neurodivergent scientists and its fans have done to the science community once they started to participate directly.
That’s a beautiful article showcasing our predicament in having access to more information about the universe.
Now i have to be the one to ask the dumb defensive question:
what makes us so certain that we can trust what we see on James Webb?
Can we definitely discard a measurement problem?
JWST has 4 different instruments on it. While they all share the same focusing mirrors, but otherwise are 4 different measurement devices.
For the red dot observations, I believe this things have been measured by at least 3 of the 4 devices on board - NIRCam (near infrared camera, has very limited spectral capabilities through its filter wheel), NIRSpec (near infrared spectrograph) and MIRI (mid infrared instrument).
I cannot pretend to have the actual expertise, but it does seem vanishingly unlikely that all 3 instruments could create consistent artefacts in the same location.
Unless there was a flaw in the mirrors they all use. I’m not saying this is so, but the software developer in me would immediately try to figure out what was wrong with the component they shared.
A flaw in the mirrors wouldn't leave the anomaly in a consistent place, it would keep causing problems no matter where you look.
But I'm pretty sure they thought of all of this and many more objections already. It's not like this is a super advanced thread of skepticism that physicists would have overlooked
Afaik they did that during calibration. Take known close by objects, compare results, make sure they are the same (up to the capabilities of your ground truth).
If you're worried about bad pixels or noise, it seems like there is an easy fix: point it in a direction specified by some angles theta & phi, wait long enough to accumulate light from distant faint objects (high redshift galaxies etc), then shift Webb's orientation by a small amount to theta+delta_1 & phi+delta_2, which will have a significant overlap with the original image, and after taking the 2nd image check to make sure that all the objects have shifted over together by the same amount...
Some of the Hubble results were also raising questions. At the same time, I read one of the papers on the galaxy stuff, and what struck me was they were identifying galaxy shapes by counting the pixels each galaxy had, so there are definitely some question marks over how they do some of this.
astro1234, your account is dead for some reason - you might consider emailing the admins.
I vouched for your two posts in this thread, but that never works, and honestly it gets a little old trying to pick up the slack left by HN's inscrutable, unaccountable, and largely-broken filter. This has been happening a lot lately, unfortunately.
Not a dumb defensive question but you should know the nice thing about these experiments is the incredible amount of work that goes into calibration and understanding all error signals.
Messing up the data analysis has major precedents. If you aren't familiar you should look into BICEP data in 2014, they thought they had observed primordial gravitational waves which would have been earth shattering. Instead they just messed up the dust correction pipeline. I don't envy the day they came to that realization. I was in several conference rooms at Princeton where BICEP people presented their analysis and David Spergel (of WMAP, previous head of the department at princeton) and others were able to walk them through how they thought they had kind of messed things up. This is what routinely happens, ESPECIALLY when something unexpected is observed. Every possible explanation is looked into, and ESPECIALLY in cosmology, you can do that incredibly well. Cosmology is one of the most beautiful sciences in my experience, precisely because we have such good ways to model the observations to probe various models, and you can treat the observations with Bayesian stats with virtually no risk of misspecifying your model, or, if you do find its misspecified, you have discovered something new about the universe.
The process to go from raw observations to physics, correcting for all the crap in between early universe light and us (dust which also rotates light polarization -- this explained the BICEP issue, instrument systematics which are measured to incredible precision on the ground (e.g. point spread function -- what is the detector response to various intensities of light; e.g. you get electrons for bright sources that spill into neighboring pixels)
Everyone everywhere is looking to make a name for themselves by discovering the discrepancy -- be it a screwup of some other team (astro community is generally very supportive and positive but also competitive) or a problem with simulation assumptions, a genuine discrepancy in our understanding of the universe (i.e. the tension in the hubble constant -- you infer rate of expansion from cosmic background radiation / early universe observations, and then try it using an alternative method -- using local variable stars, and you get a statistically significant difference).
So I would say: if there's a screwup it will be found, and a genuine fuckup is possible and does happen, but when it does believe me we will know usually within a few months. You'll have a ton of people trying to reproduce the results, pouring over everything there is that could possibly explain these observations. The wheel of astrophysics grinds slowly but it grinds finely.
Edit: also shoutout to Jenny Greene -- one of the world's foremost experts on galactic astronomy and also a genuinely great person. She rented me her house for a summer for dirt cheap when I was a poor grad student with nowhere to stay. Also hosted the best graduate student parties (our idea of a party is beer and board games and complaining about our advisers)
"Virgil led Dante into the next layer of hell, past the lecherers, the murderers, the thieves... 'And here,' he said 'is where we keep the web designers who break scrolling'"
The institutions, projects and individuals named in the article are, in order of appearance:
--1-- Charlotte Mason (not, so far as I can tell, affiliated with or funded by the Simons Foundation)
of the Cosmic Dawn Center (not, so far as I can tell, affiliated with or funded by the Simons Foundation)
which is associated with the Niels Bohr Institute at the University of Copenhagen (not, so far as I can tell, affiliated with or funded by the Simons Foundation, except that the NBI hosts something called the "Niels Bohr International Academy" that has taken money from the Simons Foundation; it doesn't look to me as if Charlotte Mason has any connection with this)
and also with the National Space Institute at the Technical University of Denmark (not, so far as I can tell, affiliated with or funded by the Simons Foundation)
--2-- The James Webb Space Telescope (not, so far as I can tell, affiliated with or funded by the Simons Foundation)
--3-- Jenny Greene (not, so far as I can tell, affiliated with or funded by the Simons Foundation, though she did once give a talk at the Center For Computational Astrophysics at the Flatiron Institute which is part of the Simons Foundation)
of Princeton University (not, so far as I can tell, affiliated with the Simons Foundation though I expect it's taken some of their money, but in any case no one needs an excuse for reporting on work done at Princeton)
--4-- Unnamed-in-the-article researchers who found that a "little red dot" is likely a supermassive black hole without stars around it; the Simons Foundation is not mentioned anywhere in the paper they published about this; neither the first-named author of that paper nor the one quoted in the linked article has obvious Simons connections, and both are at the University of Cambridge which, again, no one needs an excuse for reporting on the doings of.
--5-- Rachel Sommerville of the Flatiron Institute. Here there really is a Simons connection; the Flatiron Institute is part of the Simons Foundation. It does computational research in scientific fields, astrophysics being one of them.
--6-- "a meeting in April 2026 in Helsingør, Denmark" about the early universe; this was titled "Charting Cosmic Dawn in Copenhagen" and so far as I can tell has no Simons connection other than the fact that two of the 21 people listed as "invited speakers and tutorial leads" are from the Flatiron Institute, which seems innocuous since the F.I. does in fact do scientific research in this area.
--7-- Hakim Atek (no Simons connection so far as I can see)
of the Paris Institute of Astrophysics (no Simons connection so far as I can see, though I did find evidence that at least once the Simons Foundation has provided funding for a person working there)
of the Sorbonne University (not affiliated with the Simons Foundation; I'm sure they sometimes take S.F. money but, yet again, this is not an institution that anyone needs excuses to report on the work of)
So, I find one, count 'em, one, instance of a Simons-associated entity in the article. How very sinister of Quanta to mention them and hide their own affiliation. Oh, wait: "Editor’s note: The Flatiron Institute is funded by the Simons Foundation, which also funds this editorially independent magazine. Simons Foundation funding decisions have no influence on our coverage."
You may, of course, choose not to believe that last claim. You might be right. But in this article I don't see any obvious sign of bias; they reported on a whole lot of things most of which have no particular connections with the Simons Foundation, and the one S.F.-affiliated thing they reported on does seem relevant. I can't rule out the possibility that Sommerville's work is actually bad and was reported on here only because of the Simons connection, but e.g. she is one of those invited contributors to that conference in Copenhagen which doesn't seem to have had a Simons connection and does seem to have been run by reputable astrophysicists.
Did my PhD at Princeton, knew Jenny Greene personally (not my adviser though). There is zero conflict of interest in Astronomy generally. No one has anything to gain. Various institutions, Simons included, are just one source of much needed funding. Jim Simons is also a legend in the field, known for Chern-Simons (major result), then founding the medallion fund which netted him billions which he then durned around and used to fund fundemental science. Astrophysics is too low paying for anyone who doesn’t genuinely care about it to do it.
Funding institutions can influence which research gets done, that’s what they do by definition. This can steer people towards and away from various topics or questions, but people will loudly speak their mind if they don’t think something is right. It’s a core tenant of the culture. Go to a colloquia and watch people debate and critique each other.
> Faced with observations of early black holes and galaxies that weren’t expected to exist, scientists have come up with a wealth of new theories to explain them. Now they just need to figure out which ones are true.
This subtitle really bothers me. Science isn't about finding out what is true. Science is about finding out what is false and building models to explain the rest. We can never confidently say we know something to be true because that closes the door for future science to disprove our beliefs and that's exactly the purpose of science.
The best we can do is come up with increasingly more useful models accepting that in the end all models are wrong but different models are useful for different purposes.
I think you are confusing the scientific process, in particular Popper's falsification principle, with science's purpose, which is to find the truth, or at least sort things into true and false. It's a bit like saying the purpose of programming is to have a bunch of unit tests.
He's saying that what is believed to be the truth at one point in time often ends up being false from another point in time. And this is inescapable since we never know as much as we think we do. In the late 19th century it was believed that physics was basically done, and all that remained was refinement to ever more decimal points. Then came along the early 20th century when quantum mechanics and relativity completely revolutionized the field and largely overturned stuff that had been believed to be true for centuries.
Science can do a decent job of disproving a hypothesis because even a single contradiction should be enough to suffice in good science, but it's far less efficient at proving anything true even if it seems to always be true. For instance mathematical relationship describing the gravitational attraction between large bodies seemed to always work, but it turns out it was merely a rough approximation that completely fails in various cases such as when one body has a particularly large gravitational pull, or when very high relative velocities are present. And even modern understanding is, at best, another rough approximation because we can already see endless examples in the cosmos of examples that defy current understanding and require further refinements in a direction that's currently unknown.
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Basically at any point in history if you look at the bleeding edge science from a century before, it looks naive in many ways. In each era people always think they have finally moved beyond this, but we never have and it's entirely possible we never will since it's likely this universe has surprises awaiting us that we can't even yet imagine. Think about how utterly bizarre it is that time itself is a relative variable meaning with tech capable of reaching sufficiently high velocities you can literally travel into the future, relative to people at rest (such as all of Earth for example). It's nonsense, but it's completely real.
I think it's very fair to say that the mechanics of science is about creating and selecting ever more predictive models that explain observations. So that's the how and what.
But what about the why? Why do we seek ever more predictive models? Obviously more predictive models allow us to just... do more and better things. And I think it's fair to say that that's enough justification in itself. But is there no substance behind the idea that we seek ever more predictive models because we believe it to be a (perhaps the only) systemic way towards "the truth"?
Put in other words, do you actually believe that there is no room for truth in science? Just concurrence and agreement with observation?
I guess I'm just nitpicking on your use of the phrase "science is about". I do agree that perhaps a better subtitle (without needing to reach for contortions in language) would be "which ones are more true".
"True" has a connotation of absoluteness and finality. But I doubt humanity can ever know what is "true" about the universe. We can only model its phenomena with better theories, where "better" is always a temporary badge conferred for its prediction power and degree of agreement with known observations. Until an even "better" theory is figured out.
"Now they just need to figure out which ones are _better_"
Hypotheses are made for a reason though. Science is still about finding what's true, and ruling out what's not is part of the process/method for doing so. Sometimes all the alternatives to the truth are ruled out and we know the truth. Scientific revolutions happen sometimes, but they still need to explain everything the old theories explained. The newer theories may still be wrong, but in different and hopefully fewer ways. It's important to keep the scope of what's been demonstrated/tested in mind to not be misled about what truths have been established. Newton's physics is still largely true within the scope of everyday experience, for example.
Oh God do we really have to have the pedantic 5 page navel gazing thread about the philosophy of science that ultimately accomplishes nothing other than slightly increasing the entropy of the universe
Instead of questioning whether the Big Bang assumption is true, astrophysicists prefer to perform endless "gymnastics" to try to make the mounting contrary data fit their theory about how the universe began.
Are you kidding? An astrophysicist that could come up with a new model that explains the current data would win a Nobel prize and earth shattering levels of notoriety.
The data found doesn't contradict the big bang in any shape or form. It does challenge beliefs around black hole formation.
The reason for the big bang model is because based on all our measurements of all the visible universe, it appears that everything is spreading out. Any new model needs to explain why it is the universe appears to be spreading out.
There's not a scientist alive that wouldn't like to discover that "actually a fundamental principle about my field of study is completely wrong". But that takes hard work, evidence, and models which better fit than the previous ones did. You need to find something that can't be explained with the old model and can only be explained with the new model.
> Recent ideas suggest that little red dots could be black holes cocooned in thick gas, possibly representing a completely new type of object called a black hole star, in which the tight shroud of gas emits light like a stellar atmosphere.
Just be sure to name the members of Soundgarden on the paper.
Would you say this research is out of... Cornell?
I thought I read somewhere that many of these little red dots are turning out to be nothing more than bog-standard brown dwarfs in our own galaxy that are confusing the signal. These days we have some pretty powerful agents who can read these things faster than I can, so I went and found the paper: https://arxiv.org/abs/2506.04004
It turns out that brown dwarfs are actually corrected for, so my remembrance is correct but factored in. I’m posting anyway because 1) it’s interesting and mildly relevant and 2) others might have the same “vague but unclear” recollection I had and appreciate the elaboration.
> many of these little red dots are turning out to be nothing more than bog-standard brown dwarfs
Your own paper estimates 5 to 25% may be brown dwarfs, and says nothing about whether they might be in our galaxy or not.
Little red dots are my favorite new concept in astrophysics. This idea that there could be so much matter orbiting a black hole that the matter reaches sun levels of pressure which in turn starts steller fission without there being an star. Mind-blowing
There was a time where Hawking's A brief history of time gave a decent overview of the universe to beginners. Does anyone know how well it holds up today and if anything better exists?
It doesn't answer your question, but I would love to read an updated version of Asimov's guide to science: https://archive.org/details/asimovsguidetosc00unse/mode/2up
Depends on how deep you want to go https://en.wikipedia.org/wiki/The_Biggest_Ideas_in_the_Unive...
I'll give a shoutout to Feynman's QED. It's approachable for anyone with high school understanding, and gives a reasonable insight into all sorts of phenomena.
I went to a public lecture by Martin Rees at uni. He asked everyone who read it to put up their hand, then put it down if they understood it. He pointed to the professor of astrophysics who had invited the lecture and said "ok, you! The rest of you, no chance!"
Look up introductory college courses, e.g.., in astronomy. Their syllabi have your answers. Maybe it is more extensive than you want, but one or two book might be what you seek.
The very useful Open Syllabus Project collects syllabi and lists the most popular books, etc.: https://www.opensyllabus.org/
A professor's course materials may suit your need.
Have not read it yet, but recently researched this question and came to this book as a readable overview of the latest thinking in cosmology, Battle of the Big Bang: The New Tales of Our Cosmic Origins by Afshordi and Halper [1].
The book assumes a basic knowledge of physics and cosmology so it does not spend half the book reviewing basics like many pop physics books do.
[1] https://press.uchicago.edu/ucp/books/book/chicago/B/bo244963...
There was never a time when a book gave the public an overview of the universe. ABHOT was so popular for being a book no one actually read, theres even an index named after Hawking due to it: https://en.wikipedia.org/wiki/Hawking_Index
Did _you_ read that book?
There however definitely was a piece of media that captured public minds and educated them about the cosmos. And that was the show Cosmos. The original of course. Not the NDT drivel.
I am pretty certain this "hawking index" meme must be a new-ish thing. I read the book as teenager and know also others who did. It is a fairly easily readable book imo, so I don't think this characterisation is warranted by the qualities of the book itself.
I suspect that a popsci book becoming a bestseller creates a larger-than-the-usual-nerds audience, a big part of which lacks the motivation to actually finish it. I expect that in places like this you will find higher frequency of people who have actually read it.
Moreover, when i read the book i did not have easy access to pop-sci sources as a (practically pre-internet) teenager in a small town of a small country, like i would have had today. I got upon a booklet of a small publishing house with the titles of translated pop-sci books and would order them from a local bookstore. Maybe if I was already familiar enough with the topic through youtube videos etc I would not have finished either.
> this "hawking index" meme must be a new-ish thing
TBF the methodology and hypotheses that it's based on aren't that bad. I'm sure Amazon has better data, but for a "publicly accessible" data (at that time) I can see it. The problem is that while lots of people might abandon the book, that doesn't mean that still loads of people don't read it fully. They are, after all, extremely popular books. Obviously some people will have received / impulse bought / FOMO / new year resolution / etc the books, but from the sales numbers that's still a lot of people that did enjoy them. Marketing aside, the book is pretty approachable, like were Sagan's books and so on.
I did read the book, and know enough people who did. Now I may have weird interests, but that describes basically half the inhabitants of this site.
BTW, as non-USAian, I never saw Cosmos and never heard of NDT.
As an early teen I begged my parents for both A Brief History of Time and The Grand Design. Read both several times. ~15 years later, my parents are still holding on to them and my Dad has read them a couple of times too. It was great reading and played a significant role in my choice of research as a career.
Never heard of the "people don't actually read it" meme.
From that list I've read three books: "A Brief History of Time", "Thinking, Fast and Slow", and "Capital in XXI Century". First two I've read from start to end. The last I didn't read to the end, I think I've read ~50% of it. My numbers correlate with that list, the least "readable" book in the list is the book I didn't read through.
However I still doubt the methodology. It is not obvious for me that if a book was read in full, then highlights from it would be distributed uniformly all over the book.
Interesting. I've been gifted that book at just the right time in my life as a teenager. It captured me. I read it the to end many times. Not understanding everything or course. But it created a spark which laid the groundwork for my entire career.
I've never seen cosmos.
I did read it and I'm sure a whole generation of people also did, it is a very clear and readable book. Don't underestimate or minimize the impact of Hawking's book when it was released.
i will never forget learning about Eratosthenes when i was very young and should have been playing Excitebike or something
I knew dozens of people in my high school who actually read it.
Maybe godel, escher, bach would be a better "book that people talked about but never read"
I read it in high school in 82. I still have the book.
Fun fact: The very first book ever sold on Amazon was "Fluid Concepts And Creative Analogies: Computer Models Of The Fundamental Mechanisms Of Thought" also by Douglas Hofstadter
You won't make it to the next iteration without wrapping yourself in a black hole and appearing as an anomaly to future observers.
How do we know whether we're already in one?
A downside to the tech. You never really know if you made it because you enter another universe within.
You make it to the next cycle, but within a new universe rather than the one you aimed for. Your black hole displaces spacetime within the universe whose cycle renewed, but you are no longer an active component of that universe.
Of course, if you didn't deliberately do this, I guess you're a spectator to someone else in their black hole. So, congrats, I guess, but also you need to advance your science a bit faster if you don't want to count on luck next time.
Nancy Grace Roman Telescope is also going to be amazing for raising new questions
and I hope the attempt to lift the Swift telescope to a higher orbit is successful
if you really want to stay on top of what is breaking astrophysics in realtime, I highly recommend following DrBecky on youtube or elsewhere, she is fantastic
* https://www.youtube.com/@DrBecky/videos
So I wonder, where are these giant black holes now? There should be some closer to us than at the edge of the universe, unless something happens to them.
The supermassive black hole in the giant elliptical galaxy M87 is merely ~53 million light years away, close enough that we have now imaged it:
https://en.wikipedia.org/wiki/Messier_87#Supermassive_black_...
Sagittarius A* is "merely" 26 thousand light years away (but we probably won't be imaging it, since there's a lot more in the way)
The M87 supermassive blackhole is thousands of times as massive as Sagittarius A*, but since Sagittarius A* is a lot closer their emission rings appear roughly the same size in the sky (42 μas vs 51 μas). Both have already been imaged by the Event Horizon Telescope. https://en.wikipedia.org/wiki/Event_Horizon_Telescope
We’ve already imaged it with the event horizon telescope. https://en.wikipedia.org/wiki/Sagittarius_A*?wprov=sfti1#
This is one of my favorite phenomena: again in again, across various fields of study, breakthroughs in discovery allow us to go from relative ignorance to a level of knowledge and understanding that enables clear and clean conceptual models; then, as we learn even more, we realize how much more complex and weird and multifaceted reality really is.
It’s like a Dunning-Kruger effect on a field-wide scale, but in a good way. Rather than an example of hubris, it’s an opportunity for awe.
I think this can be explained by the dictum "big effects get discovered first"
It does present a weird science communication problem. After the first generation, scientists are all focused on "little effects" and don't get excited about talking about the big effects any more. They like talking about what they're working on (little effects). Textbooks drift from fundamentals and new entrants and outsiders get a distorted view of reality.
The most exciting idea to me that JWST has bolstered is primordial black holes. Many models already predict them but JWST has provided the first good indirect evidence in the form of too-early galaxies. The models that predict PBHs predict that.
If they exist, they would not be constrained to stellar mass and above. There could be a population of little black holes floating around. Anything under the mass of a decent size asteroid would have evaporated by now but anything that mass and above would still exist.
They are a dark matter candidate, and one that doesn’t require new physics. But even if they don’t account for a significant amount of dark matter they still probably exist.
The most exciting thing about PBHs is that one or more may exist in our solar system. They might have been captured over billions of years. Finding them would be incredibly challenging, especially if they are low mass, but if we did it means we could directly examine and experiment on a black hole.
It could be something with the mass of a large asteroid but the size of a hydrogen atom. We could only find it by its gravitational effects. It would be utterly invisible otherwise unless it encountered matter and even then there might only be a tiny gamma ray flash, a nano accretion disc that lasts femtoseconds. We might also find smaller objects that appear to be orbiting nothing and find it that way.
Directly accessing one could allow us to test theories of quantum gravity and things like string theory, and maybe more. A black hole could be like a Rosetta Stone of deep fundamental physics.
The film Interstellar involved using plot magic to visit a black hole and solve physics, but this would allow it for real. It would just be an itty bitty one.
Of course if we had a black hole in a lab (or one in a convenient orbit) we could run all sort of experiments, but which experiments exactly? We will start by throwing things at it and watch, obviously, but that's unimaginative. What are the smart experiments?
If you had a small black hole in a lab you could generate power from the hawking radiation, likely enough to power the entire world. A 1,000,000 ton black hole would last over a thousand years without feeding it more mass and produce about 300 TW of energy (increasing over time, so you better keep feeding it). You'd also need some pretty good sunglasses to be able to watch things being thrown into it. Also I'm not sure how you could throw anything into it given the amount of radiation pressure... Maybe a dedicated particle accelerator could do it.
Anything smaller while also lasting long enough to do an experiment on and you'd likely end up producing too much energy and destroying the planet.
So the hawking radiation is so strong that it impedes matter falling into the hole?
And can you charge the hole with enough of a charge to use electromagnetism to move and contain it?
Yes the event horizon would be smaller than the width of a proton. Good luck getting anything into that with 300 TW of gamma rays coming out of it.
> which experiments exactly?
Put a bunch of charge into it to generate a naked singularity. Then look at it.
More usefully: perfect the Penrose process.
There's a few obvious things. What you've got is an almost "vertical" gravity well near the object. A smaller black hole would actually have a steeper gravity well than a large one.
(1) See how gravity behaves at those strengths and scales by firing lasers and particle beams past it, grazing the event horizon, and use that information to test quantum gravity hypotheses and things like string theory. Classical gravity predicts certain results. Quantum and non-classical theories would make different predictions. For example, you might see direct evidence of gravitational quantization very close to the horizon.
(2) Chuck stuff into it: heavy ions, small masses with a coilgun. Measure the results: spectrum, particles emitted, etc.
(3) Chuck stuff into it in a very precise way and use its extreme near-horizon gravitational well as a particle accelerator to achieve collision energies potentially millions of times greater than the LHC. You would not be able to directly observe these collisions, but you could potentially observe stuff kicked out. Orbit it with an array of sensors and magnetic traps.
Bonus: use its gravity well to yeet small probes at interstellar velocities (a few percent 'c' or higher) for flyby missions to photograph exoplanets? I believe you could use the Oberth effect here and do something like fly very close and fire a single Orion-style nuclear pulse at a sacrificial pusher plate. The impulse would accelerate the payload to insane velocities.
No human passengers though, since the acceleration would probably do this: https://www.youtube.com/watch?v=waG8YYTwpAQ
I'm not sure anything after the event horizon right? Since no light == no information.
Can magnetic fields escape, if their lines intersect the event horizon of a black hole?
We could probably redirect budget for next gen particle accelerator to building an experimental platform orbiting the black hole, and get better results, right?
I’m still convinced a muon collider is the best bang for the buck for a next-generation collider. It requires new engineering and could probe new physics.
What could go wrong?
Not much.
A black hole isn't a magic cosmic vacuum cleaner. It's a dense piece of mass. An asteroid mass black hole the size of a hydrogen atom would be... an object the size of a hydrogen atom with the mass of an asteroid. You could orbit it and the orbital calculations, at a reasonable distance, would be the same as orbiting an asteroid. You just can't get too close or you get into that steep gravity well and "become physics" (spaghettification etc.).
It would have an insanely steep gravity well, but you'd have to get close to actually feel it. It would rarely interact with mass naturally. We could chuck stuff into it or fire lasers and particle beams at it to study it, of course, but to hit it we'd have to fire it at the right angle and velocity to negate the orbit and fall into it. Orbital mechanics still works the same way.
If a black hole this size flew through the Earth at high velocity, it might not even do anything. It'd be like a bullet being fired through a puff of smoke. It might leave some kind of trail if you knew exactly what to look for and where to look, something almost analogous to the trails left by particles in a chamber.
I've given this example multiple times because it illustrates the point well, I think.
If you could magically transform the Moon into a black hole of the same mass, you would now have an object of that mass about the size of a BB or a small marble orbiting the Earth right where the Moon's center of mass orbited. The tides would continue as normal, since its gravitational effects on the Earth would be the same at that distance. Probes and other objects orbiting the Moon would continue to orbit it.
You just wouldn't be able to see it anymore. If you focused a very good telescope on its location, though, you could probably see gravitational lensing of the star field behind it.
The only risk might be if a large object actually hit it, in which case the accretion disc might temporarily emit enough X-rays and gamma rays to be harmful to Earth. Not sure though. It might not be that harmful at that distance.
As is often the case (and I suspect you're already familiar with it) Randall Munroe tackled the moon->black hole question:
https://what-if.xkcd.com/129/
How certain is the evaporation? Obviously Hawking radiation has never been observed, but is it tied in enough to other known physics that we can be reasonably certain it exists?
It's a very strong consensus among physicists, but has not been observed. My understanding is it pops right out of the math. If it doesn't exist it means some new fundamental physics is in play, like quantum gravitational effects we don't understand at all right now.
If it doesn't exist its also has profound implications for the long term fate of the universe, since it would mean black holes never evaporate.
My pet theory is that supermassive black holes are older than the universe and they didn't grew much.
Does PBH theory also predict >1 billion solar mass black holes so early?
I believe it does, due to PBHs forming seeds for early accretion, but ask a non-armchair physicist (or a good LLM).
As observations become too numerous, it seems like it can be summarized as there now being too many possible candidate explanations. As data increases and becomes clearer, more and more things don't fit the existing theories.
What are the current theories explaining the early universe? What happened to the Big Bang? I only studied astronomy up to an undergraduate level, so I don't really know.
I imagine that various non-uniform gases were scattered around, and due to spatial distortions, those uniform gas regions clumped together, forming stars and other structures. Perhaps the expansion of space wasn't uniform either—it expanded unevenly, sometimes bulging, and when space expands or contracts, energy is generated, causing spacetime changes to shake the field, and that shaking might have created matter. Maybe the dynamic interaction between changing spacetime and fields revealed the energy stored in the field in the form of particles.
What do scientists think about this in modern cosmology? My knowledge is far too limited and I lack intuition, but reading science-related articles always excites me. Maybe it's because I still have some childlike curiosity left in me
The evidence for the big bang is generally not that if you look far enough back in a telescope, the universe looks younger, which is somewhat the layperson's confusion.
Evidence for the big bang is about measuring redshift of galaxies throughout universal history, homgeneity and thermal equilibrium of the universe and CMBR, which could only be explained by it all having been in a compressed location where it could reach thermal equilibrium at some point in the distant past.
None of that is challenged by the Webb observations about very young supermassive black holes.
In fact, the existence of supermassive black holes themselves has basically always been an unsolved problem even before Webb. The only known possible explanation (stellar collapse -> accretion -> supermassive black hole) could be ruled out even before Webb on theoretical and experimental grounds, we just have stronger evidence against it now. (To wit: if supermassive black holes form from stellar black holes by growing, you would expect to see lots of intermediate mass black holes. We see almost none. Furthermore, the process of accretion is extremely energetic, so IMBHs would be the most visible objects in the night sky. The fact we see none is doubly damning)
The mainstream position now will be big bang + some kind of primordial black hole formation during the very early stages of the universe. Work of Hawking/Penrose shows that black holes can form under generic conditions in solutions to the EFE equations. We have a general understanding of how they could come about from certain dense matter layouts in a standard GR cosmological model.
I think you're leaving out a major issue there. Homogeneity was not in favor of the big bang. It's actually a major problem - the horizon problem. [1] Parts of the universe (think opposite sides) are not causally connected. Even traveling at the speed of light, there would not be enough time for a particle in one side to reach the other since the birth of the universe. Yet the temperature within these regions is homogeneous - at a thermal equilibrium. That doesn't make any sense.
This led to the development of cosmic inflation [2], which is what largely drove me from a doe eyed young astronomy enthusiast to a highly skeptical old fart. It solves the problem in an ad hoc fashion. Just have the universal expansion go into overdrive for a bit shortly after the big bang, then slow down, then start accelerating again - and then at the end we finally get something that looks like what we see - a homogeneous system in this case.
It made some highly accurate and improbable predictions which led to widespread adoption but then ran into numerous issues requiring further ad-hoc solutions. And this process has been repeated multiple times since its original formulation, to the point that there's a library of different inflation theories now a days, all getting ever more fine-tuned. If non-casually connected regions of space acted like they were non-casually connected then all would be fine, but the homogeneity that we do have is a big problem for the big bang.
[1] - https://en.wikipedia.org/wiki/Horizon_problem
[2] - https://en.wikipedia.org/wiki/Cosmic_inflation
> spatial distortions
Acoustic distortions. The universe was small and dense enough for sound to travel through ‘space’, which was filled with plasma. The theory is that inflation blew up these tiny distortions to the scale of the structure we see in the universe.
I dont think about it because my days are occupied by very specific problems. Theory of Bounded Rationality and its implications apply.
Right. When you don't have any breathing room, it's hard to think about anything else. That's why I take about two hours a day to just watch the news and clear my head. I'd probably forget all about it too if I were working 70-hour weeks on a contracted project, haha. Hang in there. Have a good day
With the caveat I'm summarising from what PBS Space Time and Dr Becky* say:
• Big Bang: we can only see back to surface of last scattering, i.e. the CMB, extrapolating backwards goes "???" at much the same point as it did a few decades back because we still have not unified quantum mechanics and general relativity
• CMB should only have isotope distribution of Big Bang nucleosynthesis, that hasn't changed in the last decades, dunno if that's what you meant by "various non-uniform gases were scattered around"?
• Variations in density of CMB do exist, key phrase is "Baryon acoustic oscillations", while they're very small magnitude they're also massive in distance scale, so they're how galactic clusters formed (that scale rather than stars directly): https://en.wikipedia.org/wiki/Baryon_acoustic_oscillations
https://www.youtube.com/watch?v=PPpUxoeooZk
https://www.youtube.com/watch?v=LRUTnoveZs8
• Re: "Perhaps the expansion of space wasn't uniform either": I heard about specifically "Timescape Cosmology", but a quick search says that's part of a broader category of inhomogeneous cosmologies: https://en.wikipedia.org/wiki/Inhomogeneous_cosmology#Timesc...
https://www.youtube.com/watch?v=SXg6YVcdOcA
https://www.youtube.com/watch?v=JlNVZz5D6WE
• Re: "and when space expands or contracts, energy is generated": no, general relativity does not in general conserve energy, and it is related to the curvature of spacetime. Simple example is that the photons in the CMB have much less energy to us than they did to the atoms they were emitted from**: https://www.youtube.com/watch?v=04ERSb06dOg
* I assuming I'm correctly judging the level and attention to detail they're providing, given the detail they put in and references to specific research publications. My degree is Software Engineering.
** There's also a Veritasium video about this, but to me Veritasium feels like a BBC 2 evening popular science show, so I'm not as confident about recommending it.
thanks!!
I took a good long look at the CMB picture, including the caption. It basically says the Universe was one big hot apparently uniform ball at one stage.
I don't know what conditions were like before that stage, but like Eric Idle says, nothing can come from nothing.
Dark energy is a horse shit name for a theory that was horse shit to begin with. The Universe is probably just inhomogeneous, like your intuition is saying.
Why do you say "probably"? We can measure and quantify the inhomogeneities very precisely, and they're tiny. This isn't a matter of opinion or intuition.
Oh, sorry I was referring to the cosmological principle [1]. The wiki page is actually quite a good summary of the whole fiasco.
[1] https://en.wikipedia.org/wiki/Cosmological_principle
I will say that the current and future telescope lineup is amazing and is bound to reveal: even more fascinating insights and mysteries!
“Dark” matter and energy are placeholder names. “Dark” means “we don’t know” which either means we can’t see or detect it or there is an alternate explanation for the effect.
It’s like a comment in your code like \\ TODO…
I don’t see why that’s that hard, or why we’d expect to instantly be able to figure everything out.
I think the problem is that it wasn’t just used merely as a placeholder, but to hard shutdown any discussions—often started by lay persons—about possibilities that didn’t involve brand new particle physics.
I still recall how neutrinos and black holes “couldn’t” be candidates.
To physicists, this means stellar neutrinos and blackholes (and galaxy centers). To lay persons, any category such as cold neutrinos or primordial black holes also qualify.
The sheer amount of vitriol and—I can’t think of a better term than this—“smugness” was off putting.
Before the internet, this was fine when locked away in their labs and classes; but I don’t think you understand the scale of damage neurodivergent scientists and its fans have done to the science community once they started to participate directly.
That’s a beautiful article showcasing our predicament in having access to more information about the universe. Now i have to be the one to ask the dumb defensive question:
what makes us so certain that we can trust what we see on James Webb? Can we definitely discard a measurement problem?
JWST has 4 different instruments on it. While they all share the same focusing mirrors, but otherwise are 4 different measurement devices.
For the red dot observations, I believe this things have been measured by at least 3 of the 4 devices on board - NIRCam (near infrared camera, has very limited spectral capabilities through its filter wheel), NIRSpec (near infrared spectrograph) and MIRI (mid infrared instrument).
I cannot pretend to have the actual expertise, but it does seem vanishingly unlikely that all 3 instruments could create consistent artefacts in the same location.
Unless there was a flaw in the mirrors they all use. I’m not saying this is so, but the software developer in me would immediately try to figure out what was wrong with the component they shared.
A flaw in the mirrors wouldn't leave the anomaly in a consistent place, it would keep causing problems no matter where you look.
But I'm pretty sure they thought of all of this and many more objections already. It's not like this is a super advanced thread of skepticism that physicists would have overlooked
Afaik they did that during calibration. Take known close by objects, compare results, make sure they are the same (up to the capabilities of your ground truth).
If you're worried about bad pixels or noise, it seems like there is an easy fix: point it in a direction specified by some angles theta & phi, wait long enough to accumulate light from distant faint objects (high redshift galaxies etc), then shift Webb's orientation by a small amount to theta+delta_1 & phi+delta_2, which will have a significant overlap with the original image, and after taking the 2nd image check to make sure that all the objects have shifted over together by the same amount...
Some of the Hubble results were also raising questions. At the same time, I read one of the papers on the galaxy stuff, and what struck me was they were identifying galaxy shapes by counting the pixels each galaxy had, so there are definitely some question marks over how they do some of this.
You would expect more background pixel fuzz when centering an image kernel over an artefact.
In Hubble, that fuzz was marked. With Webb, far less so.
I think these are real true positives
> what makes us so certain that we can trust what we see on James Webb?
We can trust what we see. We can't trust there's nothing where we don't see anything.
astro1234, your account is dead for some reason - you might consider emailing the admins.
I vouched for your two posts in this thread, but that never works, and honestly it gets a little old trying to pick up the slack left by HN's inscrutable, unaccountable, and largely-broken filter. This has been happening a lot lately, unfortunately.
Not a dumb defensive question but you should know the nice thing about these experiments is the incredible amount of work that goes into calibration and understanding all error signals.
Messing up the data analysis has major precedents. If you aren't familiar you should look into BICEP data in 2014, they thought they had observed primordial gravitational waves which would have been earth shattering. Instead they just messed up the dust correction pipeline. I don't envy the day they came to that realization. I was in several conference rooms at Princeton where BICEP people presented their analysis and David Spergel (of WMAP, previous head of the department at princeton) and others were able to walk them through how they thought they had kind of messed things up. This is what routinely happens, ESPECIALLY when something unexpected is observed. Every possible explanation is looked into, and ESPECIALLY in cosmology, you can do that incredibly well. Cosmology is one of the most beautiful sciences in my experience, precisely because we have such good ways to model the observations to probe various models, and you can treat the observations with Bayesian stats with virtually no risk of misspecifying your model, or, if you do find its misspecified, you have discovered something new about the universe.
The process to go from raw observations to physics, correcting for all the crap in between early universe light and us (dust which also rotates light polarization -- this explained the BICEP issue, instrument systematics which are measured to incredible precision on the ground (e.g. point spread function -- what is the detector response to various intensities of light; e.g. you get electrons for bright sources that spill into neighboring pixels)
Everyone everywhere is looking to make a name for themselves by discovering the discrepancy -- be it a screwup of some other team (astro community is generally very supportive and positive but also competitive) or a problem with simulation assumptions, a genuine discrepancy in our understanding of the universe (i.e. the tension in the hubble constant -- you infer rate of expansion from cosmic background radiation / early universe observations, and then try it using an alternative method -- using local variable stars, and you get a statistically significant difference).
So I would say: if there's a screwup it will be found, and a genuine fuckup is possible and does happen, but when it does believe me we will know usually within a few months. You'll have a ton of people trying to reproduce the results, pouring over everything there is that could possibly explain these observations. The wheel of astrophysics grinds slowly but it grinds finely.
Edit: also shoutout to Jenny Greene -- one of the world's foremost experts on galactic astronomy and also a genuinely great person. She rented me her house for a summer for dirt cheap when I was a poor grad student with nowhere to stay. Also hosted the best graduate student parties (our idea of a party is beer and board games and complaining about our advisers)
This is one reason to dislike the NASA process of building one huge prestige telescope every few decades.
its the only way to study certain things. Can't make up for it with smaller telescopes or cheaper projects.
Only two things are infinite: the cosmos, and a web designer’s obsession with discovering new ways to break scrolling.
And no one can be sure about the cosmos :-p
And we’re not sure about the cosmos.
"Virgil led Dante into the next layer of hell, past the lecherers, the murderers, the thieves... 'And here,' he said 'is where we keep the web designers who break scrolling'"
Quanta magazine is a glorified university press release and marketing shop for Simons associated institutions.
Take it with a grain of salt, and know for sure its leaving out a huge range of scientists views.
The institutions, projects and individuals named in the article are, in order of appearance:
--1-- Charlotte Mason (not, so far as I can tell, affiliated with or funded by the Simons Foundation)
of the Cosmic Dawn Center (not, so far as I can tell, affiliated with or funded by the Simons Foundation)
which is associated with the Niels Bohr Institute at the University of Copenhagen (not, so far as I can tell, affiliated with or funded by the Simons Foundation, except that the NBI hosts something called the "Niels Bohr International Academy" that has taken money from the Simons Foundation; it doesn't look to me as if Charlotte Mason has any connection with this)
and also with the National Space Institute at the Technical University of Denmark (not, so far as I can tell, affiliated with or funded by the Simons Foundation)
--2-- The James Webb Space Telescope (not, so far as I can tell, affiliated with or funded by the Simons Foundation)
--3-- Jenny Greene (not, so far as I can tell, affiliated with or funded by the Simons Foundation, though she did once give a talk at the Center For Computational Astrophysics at the Flatiron Institute which is part of the Simons Foundation)
of Princeton University (not, so far as I can tell, affiliated with the Simons Foundation though I expect it's taken some of their money, but in any case no one needs an excuse for reporting on work done at Princeton)
--4-- Unnamed-in-the-article researchers who found that a "little red dot" is likely a supermassive black hole without stars around it; the Simons Foundation is not mentioned anywhere in the paper they published about this; neither the first-named author of that paper nor the one quoted in the linked article has obvious Simons connections, and both are at the University of Cambridge which, again, no one needs an excuse for reporting on the doings of.
--5-- Rachel Sommerville of the Flatiron Institute. Here there really is a Simons connection; the Flatiron Institute is part of the Simons Foundation. It does computational research in scientific fields, astrophysics being one of them.
--6-- "a meeting in April 2026 in Helsingør, Denmark" about the early universe; this was titled "Charting Cosmic Dawn in Copenhagen" and so far as I can tell has no Simons connection other than the fact that two of the 21 people listed as "invited speakers and tutorial leads" are from the Flatiron Institute, which seems innocuous since the F.I. does in fact do scientific research in this area.
--7-- Hakim Atek (no Simons connection so far as I can see)
of the Paris Institute of Astrophysics (no Simons connection so far as I can see, though I did find evidence that at least once the Simons Foundation has provided funding for a person working there)
of the Sorbonne University (not affiliated with the Simons Foundation; I'm sure they sometimes take S.F. money but, yet again, this is not an institution that anyone needs excuses to report on the work of)
So, I find one, count 'em, one, instance of a Simons-associated entity in the article. How very sinister of Quanta to mention them and hide their own affiliation. Oh, wait: "Editor’s note: The Flatiron Institute is funded by the Simons Foundation, which also funds this editorially independent magazine. Simons Foundation funding decisions have no influence on our coverage."
You may, of course, choose not to believe that last claim. You might be right. But in this article I don't see any obvious sign of bias; they reported on a whole lot of things most of which have no particular connections with the Simons Foundation, and the one S.F.-affiliated thing they reported on does seem relevant. I can't rule out the possibility that Sommerville's work is actually bad and was reported on here only because of the Simons connection, but e.g. she is one of those invited contributors to that conference in Copenhagen which doesn't seem to have had a Simons connection and does seem to have been run by reputable astrophysicists.
Did my PhD at Princeton, knew Jenny Greene personally (not my adviser though). There is zero conflict of interest in Astronomy generally. No one has anything to gain. Various institutions, Simons included, are just one source of much needed funding. Jim Simons is also a legend in the field, known for Chern-Simons (major result), then founding the medallion fund which netted him billions which he then durned around and used to fund fundemental science. Astrophysics is too low paying for anyone who doesn’t genuinely care about it to do it.
Funding institutions can influence which research gets done, that’s what they do by definition. This can steer people towards and away from various topics or questions, but people will loudly speak their mind if they don’t think something is right. It’s a core tenant of the culture. Go to a colloquia and watch people debate and critique each other.
> Faced with observations of early black holes and galaxies that weren’t expected to exist, scientists have come up with a wealth of new theories to explain them. Now they just need to figure out which ones are true.
This subtitle really bothers me. Science isn't about finding out what is true. Science is about finding out what is false and building models to explain the rest. We can never confidently say we know something to be true because that closes the door for future science to disprove our beliefs and that's exactly the purpose of science.
The best we can do is come up with increasingly more useful models accepting that in the end all models are wrong but different models are useful for different purposes.
I think you are confusing the scientific process, in particular Popper's falsification principle, with science's purpose, which is to find the truth, or at least sort things into true and false. It's a bit like saying the purpose of programming is to have a bunch of unit tests.
He's saying that what is believed to be the truth at one point in time often ends up being false from another point in time. And this is inescapable since we never know as much as we think we do. In the late 19th century it was believed that physics was basically done, and all that remained was refinement to ever more decimal points. Then came along the early 20th century when quantum mechanics and relativity completely revolutionized the field and largely overturned stuff that had been believed to be true for centuries.
Science can do a decent job of disproving a hypothesis because even a single contradiction should be enough to suffice in good science, but it's far less efficient at proving anything true even if it seems to always be true. For instance mathematical relationship describing the gravitational attraction between large bodies seemed to always work, but it turns out it was merely a rough approximation that completely fails in various cases such as when one body has a particularly large gravitational pull, or when very high relative velocities are present. And even modern understanding is, at best, another rough approximation because we can already see endless examples in the cosmos of examples that defy current understanding and require further refinements in a direction that's currently unknown.
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Basically at any point in history if you look at the bleeding edge science from a century before, it looks naive in many ways. In each era people always think they have finally moved beyond this, but we never have and it's entirely possible we never will since it's likely this universe has surprises awaiting us that we can't even yet imagine. Think about how utterly bizarre it is that time itself is a relative variable meaning with tech capable of reaching sufficiently high velocities you can literally travel into the future, relative to people at rest (such as all of Earth for example). It's nonsense, but it's completely real.
Exactly
I think it's very fair to say that the mechanics of science is about creating and selecting ever more predictive models that explain observations. So that's the how and what.
But what about the why? Why do we seek ever more predictive models? Obviously more predictive models allow us to just... do more and better things. And I think it's fair to say that that's enough justification in itself. But is there no substance behind the idea that we seek ever more predictive models because we believe it to be a (perhaps the only) systemic way towards "the truth"?
Put in other words, do you actually believe that there is no room for truth in science? Just concurrence and agreement with observation?
I guess I'm just nitpicking on your use of the phrase "science is about". I do agree that perhaps a better subtitle (without needing to reach for contortions in language) would be "which ones are more true".
I agree with you.
"True" has a connotation of absoluteness and finality. But I doubt humanity can ever know what is "true" about the universe. We can only model its phenomena with better theories, where "better" is always a temporary badge conferred for its prediction power and degree of agreement with known observations. Until an even "better" theory is figured out.
"Now they just need to figure out which ones are _better_"
Hypotheses are made for a reason though. Science is still about finding what's true, and ruling out what's not is part of the process/method for doing so. Sometimes all the alternatives to the truth are ruled out and we know the truth. Scientific revolutions happen sometimes, but they still need to explain everything the old theories explained. The newer theories may still be wrong, but in different and hopefully fewer ways. It's important to keep the scope of what's been demonstrated/tested in mind to not be misled about what truths have been established. Newton's physics is still largely true within the scope of everyday experience, for example.
Oh God do we really have to have the pedantic 5 page navel gazing thread about the philosophy of science that ultimately accomplishes nothing other than slightly increasing the entropy of the universe
Instead of questioning whether the Big Bang assumption is true, astrophysicists prefer to perform endless "gymnastics" to try to make the mounting contrary data fit their theory about how the universe began.
Are you kidding? An astrophysicist that could come up with a new model that explains the current data would win a Nobel prize and earth shattering levels of notoriety.
The data found doesn't contradict the big bang in any shape or form. It does challenge beliefs around black hole formation.
The reason for the big bang model is because based on all our measurements of all the visible universe, it appears that everything is spreading out. Any new model needs to explain why it is the universe appears to be spreading out.
There's not a scientist alive that wouldn't like to discover that "actually a fundamental principle about my field of study is completely wrong". But that takes hard work, evidence, and models which better fit than the previous ones did. You need to find something that can't be explained with the old model and can only be explained with the new model.