This is fairly sensationalized, I think. "The researchers still need more data to confirm that these galaxies are as large, and date as far back in time, as they appear... 'Another possibility is that these things are a different kind of weird object, such as faint quasars'."
And quasars are, if I remember correctly, just galaxies whose central black holes are ingesting large amounts of gas. The accretion disks that form in orbit are simply massive and form giant light years long jets that shoot out from both poles. Active galactic nucleus.
Original title had "massive" as an adjective to galaxies which explains the comma, HN sometimes removes these "superlative" words from the title creating this kind of nonsense.
Hah, but galaxies are one of the few things where "massive" in the original sense of the word is appropriate. The article is about galaxies that are more massive than expected.
Hands down my least favorite feature of Hacker News. Maybe I'd change my mind if it wasn't on and I had to endure all of the clickbaity and superlative ridden headlines but right now I feel like the confusion this creates is much more annoying than the nasty original headlines it is protecting us from.
I think it's overall a good feature, but I'd prefer that it were voluntary. Have HN show you the original headline and the proposed modifications, and let the submitter adjust as necessary.
Because the universe did not originated in a Big Bang, that's just a theory that is becoming more and more disproved. The universe is infinite and eternal, in constant change? sure, but in no way it started 13500 million years ago.
In fact it makes little sense to talk about time before the big bang, because inside a singularity time moves infinitely slow. So the point is that, yes, the universe never really started because time didn't exist before the singularity. The universe only evolved to a different dimension, so to speak, and time as we know started to exist when the big bang occurred.
The question about existence of time before singularity does not have an answer, rather than affirmative no.
A singularity means that all timelines goes through it, but it is impossible to make continues extension of the timelines past the singularity in the current physical models. That literally means that anything is possible with the timeline prior that. The timeline can jump, be replaced by a set of random points, became a multidimensional surface, go back etc. It may even indeed disappear, but we do not know.
Some thing can't become more disproved, either it's disproved or it isn't.
The timeline is certainly up for grabs, there are uncertainties in the various ways we measure or infer distances and the age of objects, but so far nothing that invalidates the overall scheme. Roger Penrose's idea of conformal cyclic cosmology is a plausible alternative, but even that still has an event in our past that looks an awful lot like a big bang. There are just too many observations any alternative theory needs to explain, like galactic red shift and the cosmic background radiation. If stars are infinitely old, how come they still have any hydrogen left?
It's always a good idea to keep an open mind though. What are the alternatives you think have legs?
I like to think that the Big Bang is the ultimate Great Filter. When civilization gets too advanced, they start building galaxy-sized colliders and smash charged supermassive black holes together to see what makes 'em tick...
But as a non-physicist I recognize that my "theories" are just for funsies and have less value than bellybutton lint.
This is similar to the plot of Greg Egan's Schild's Ladder. Fantastic book.
> Twenty-thousand years in the future, Cass, a humanoid physicist from Earth, travels to an orbital station in the vicinity of the star Mimosa, and begins a series of experiments to test the extremities of the fictitious Sarumpaet rules – a set of fundamental equations in "Quantum Graph Theory", which holds that physical existence is a manifestation of complex constructions of mathematical graphs. However, the experiments unexpectedly create a bubble of something more stable than ordinary vacuum, dubbed "novo-vacuum", that expands outward at half the speed of light as ordinary vacuum collapses to this new state at the border, hinting at more general laws beyond the Sarumpaet rules. The local population is forced to flee to ever more distant star systems to escape the steadily approaching border, but since the expansion never slows, it is just a matter of time before the novo-vacuum encompasses any given region within the Local Group.
Do you have any citations for any of what you just said?
Also, the Big Bang "theory" is a theory in the technical sense, in that the overwhelming majority of evidence ever collected is at least neutral towards the Big Bang, to say nothing of the virtually incontrovertible evidence in support (esp. the cosmic microwave background radiation, redshift correlated with distance to virtually all extra-galactic objects, low metalicity in ultra-distant (read early) objects, etc etc etc). It could still be wrong, but we'd need some other theory that adequately explains all the available evidence, and makes several new, testable predictions that are also observed to be correct. The term "theory" is not used colloquially here as a fancy way to say "guess" or "idea" (those are, in the same technical sense, best called "conjectures" or (generously) "hypotheses"). It has a very narrow meaning here, and dismissing the Big Bang theory as "just" a theory really reveals your ignorance on the subject here.
At the risk of engaging in a thread started by a likely troll: the Big Bang hypothesis has a few inconsistencies. For example, different distance candles disagree on the Hubble constant. Now JWST is finding unusually old galaxies. Etc…
I still lean towards the Big Bang as the most likely model, but it’s not as well established as, say, germ theory.
I actually had an idea in undergrad (20+ years ago) to probe Hubble Constant variation using quasar reverberation mapping and very-long-baseline-interferometry. Then the professor I was working with pointed out that the baseline I needed was something like 100,000 times earth's orbital diameter.
Back then, one of the sexier ideas was that the universe might have locally different fundamental constants, and that variation could reveal some information about the higher-dimensional "space" that the universe existed inside of. I've been out of that field for a long time though, so I've no idea what the cutting edge is. I just know that the Big Bang theory is still pretty safe.
There are plenty of things wrong in the theory, but none of the evidence suggests that "expansion from a singularity" is wrong, let alone "infinite and eternal" is right.
The Big Bounce[1] hypothesis is a model that "suggests that we could be living at any point in an infinite sequence of universes". So while our current universe may not be infinite there may be some yet undiscovered infinite/eternal natural process that gives rise to universes.
Olber's Paradox[2] and the inability to reconcile it with our current astronomical observations seems to disprove that our current universe is itself infinite.
Strictly speaking, Olber's Paradox is about an infinite, eternal/static, and homogeneous universe with an infinite number of stars; in such a case, the light the dust absorbs would cause the dust itself to start emitting light, which would make it visible [0]. I'm not sure to what extent this paradox applies outside that scenario (e.g., an infinite-but-changing universe)
Why word it like this instead of using 13.5 billion? Is this a common thing to do in astronomy? Or are you trying to make the claim of 13.5 billion years sounds more ridiculous? Genuine question.
This is certainly a troll thread, but have there been ANY experiments in the past few decades that push back against the big bang? Seems like it was hard to accept by many in the beginning but that the evidence is so overwhelming at this point. As someone who isn't a scientist and just listens to a lot of cosmology podcasts, even when they explore crazy theories I haven't heard of anything of an alternate theory in modern cosmology.
I see a few possible takeaways from this. Maybe, these results are weird and might be in error somehow. Maybe, these results are more data that we have big gaps in our understanding of cosmology. Maybe massive headlines should be double checked.
For the laypeople: dark matter is literally defined as "the gap between our existing model and the data we've collected". It is not a model, it is merely an acknowledgment of a lack of one (see: the vagueness of the name "dark matter").
There have been proposed models for why this occurs (WIMPs, etc.) but none have been convincing from a scientific perspective, mainly due to the inherent lack of observations which can justify such models.
It’s careless language which positions scientific theories as normative rather than descriptive. This makes refinement look like failure (“Science told us things that turned out to be wrong!”), when actually refining theories is progress that should be celebrated.
The wording definitely intrigued me, and I understood the implied "given current models". I think sparking curiosity is more important than catering to someone who is not the target audience of a university news article.
Can you suggest an equally terse title that would avoid problems such as "position[ing] scientific theories as normative rather than descriptive" and "mak[ing] refinement look like failure"?
I think you're assigning far too much wrongdoing to this perceived sleight here, I wouldn't even think that saying "our current understanding makes this look impossible" is a way of saying we shouldn't celebrate change and improved understanding, I would instead go the opposite way and think how interesting it is to find things outside our understanding
I'm sympathetic to your point, but this usage of should in a non-normative way is also thoroughly colloquial and understood by pretty much any native english. Maybe there is some slight, subconscious coloration, but I can't think of other things which have had a bigger effect on the public's distrust of science than leaving off "according to our best model" from the end of a sentence.
Without endorsing this particular conjecture, it's encouraging that JWST is generating so much interesting data so soon and leading to lots of theoretical re-evaluation. Astronomy and HEP may seem pretty abstract and pointless to non-nerds, but techniques developed for the collection and analysis of such vast datasets find their way back into more quotidian applications.
You need to bear in mind that some people do not care about knowledge for its own sake, only that which can be instrumentalized. So their response to the discovery of new cosmic facts is not that they're cool but 'what does that have to do with me?' To them, it's just nerds geeking out over stuff for its own sake instead of solving useful problems like ending hunger or making better consumer appliances or the like. You could think of it as a sort of techno-myopia.
> You could think of it as a sort of techno-myopia.
Or, more accurately, you can think about it as a different set of priorities.
For instance, someone might want to spend a ten billion dollars of tax money to survey all the ball pits across the world, and accurately count the number of balls in each at precisely the same moment, just to have that knowledge "for its own sake." Is it myopic not to care about that?
A lot of people meet some of their needs for mysticism and meaning with astronomy, but it's also perfectly valid not to use it that way, and instead see it as blurry pictures of places that aren't even theoretically possible to interact with in any way.
> techniques developed for the collection and analysis of such vast datasets find their way back into more quotidian applications.
Which is different from knowledge "for its own sake." Townies with and without imagination will get behind aspects of the techniques, data, products and byproducts that resonate with them. NASA has plenty of examples.
People who fail to articulate the value of projects like jwst have been neglected by educational institutions and this is but one of the consequences we bear for their failures.
> People who fail to articulate the value of projects like jwst have been neglected by educational institutions and this is but one of the consequences we bear for their failures.
Not necessarily. For one, I'm not talking about being able to articulate some argument for its value, I'm talking about agreeing with that value. To put it bluntly, not sharing that value isn't some kind of personal failure, though a lot of people here seem to mistakenly treat it that way.
There was a time not so long ago that people thought the Sun's heat came from burning a vast amout of coal and did not understand the concept of nuclear energy... today we know better. So by exploring the unknown we may unravel a mystery or discover something that improves the lives of mankind.
> is impossible that the sun should constantly be giving out heat, without either losing heat or being supplied with new fuel. Assuming that the heat of the sun has been kept up by meteoric bodies falling into it…
Neat article, they were asking all the right questions. Calculating how long a coal body could burn, and a mechanism/quantity required to refuel it based on the mass of the solar system
Well, you don't need to persuade me. I love science and hanging out at a science museum or curling up on the couch with some new papers is my idea of a good time. But there are people that just don't get it.
A year or two back I was at a lecture about hummingbirds and the shockingly weird ways they fly and during the Q&A some lady kept asking 'but what's the point of this? Why does it matter?' leaving the lecturer (and everyone else) deeply confused.
I wouldn’t dare make such a claim. I certainly have my doubts about whether to rank those higher than PCR and RNA vaccines, for example. I would guess those having higher “R”, but wouldn’t know how to quantify their “I”.
I need to temper my excitement. What Webb is seeing is some red dots. We didn't expect to see those red dots (not so red, not so big, etc) but they're there.
One interpretation is that these are older (more red shifted), larger (more stars) galaxies. But that's just one explanation. A pretty good one, but still, it could also be something totally mundane and boring. Remember FTL neutrinos?
I'll be ecstatic if the existing model of the universe needs a massive update based on this new data. But it's important to search as hard as we can for answers that aren't the one we really want to see.
It's much more reasonable to think about changing the cosmological or galaxy formational models than it is to consider adding FTL neutrinos. I remember thinking the FTL neutrinos were nonsense as soon as I saw it. You're right that this could be explained differently given time, but it at least seems plausible to me that it could be real.
Low probability, as in 10^-43%: we know pretty much the story that happened after the first 10^-43 seconds [1], and we know the universe became transparent after circa 300,000 years post Big Bang. The oldest known galaxy was GN-z11, ~400 milion years post Big Bang, by JWST the oldest is JADES-GS-z13-0, ~325 million years post Big Bang.
Seems incredible hubris to think we can reverse-calculate to 14 billion years ago with sub-second accuracy when science can't even predict if it'll rain tomorrow.
Seems incredible hubris we can write 4 equations [1] and control some kind of switches at 10^-8 meters to multiply matrices and handle decision-making with sub-second (10^-9) accuracy in the "real world" of objects beyond 10^-3 meters.
Science can predict if it will rain tomorrow: "[a] seven-day forecast can accurately predict the weather about 80 percent of the time and a five-day forecast can accurately predict the weather approximately 90 percent of the time." [2]
Feel free to hubristically read articles such as Cosmic Evolution of Viscous QCD Epoch in Causal Eckart Frame [3] and tell us all where they are wrong. An introductory article into cosmology and inflationary theory [4].
Then we'd have a different set of observations that conflict. We know the age of the universe from several different directions: the rate at which distant galaxies move, the temperature of the cosmic microwave background, the temperature of white dwarfs, etc.
These agree to within a relatively small range. If the number were substantially different, it would imply that something deeply fundamental (and probably several deeply fundamental things) was wrong.
It's much more likely that our understanding of galaxy formation is wrong. That's much less fundamental, and much harder to observe.
It's just like debugging code. You start with the obvious stuff. It's much more likely that the error is in your program, for example, and not in the compiler. That's not proof, but you'd be foolish to start anywhere else.
Well youngsters, let me tell you. When I was your age gravity was faster. Now I don't mean stuff fell faster. Not a bit. It was just that everybody got on with the business at hand. Something pulled on you and you fell down. None of this shilly-shallying we got nowadays. Back then, a whole solar system would collapse down in a week, 10 days tops. But then all the baryons decided we needed "organization" and "processes". Every few billion years some bright spark would come up with a sure-fire way to "avoid all the chaos". So everybody would spend a million years arguing about what was now the best way to fall down. Meanwhile all the dark matter would mill around in confusion, going to meeting after meeting and not getting anything done, before finally giving up and just stop any interaction. 'Cept for gravity, of course. There's always gravity. It's just slower now.
I often wonder - what if "something" happened 13.8 billion years ago that generated the CMB but it wasn't the beginning of the universe? If we keep detecting galaxies all the way back to that point...
We need a new look at cosmological redshift. It bugs me tremendously because it violates conservation of basically everything (energy, momentum, angular momentum).
I find the entire thing extremely unphysical because of that. Why should just this one thing violate that? Just photons, nothing else? Are gravitational waves also stretched? Why can't we duplicate the effect in a lab?
Funny thing is you can make spectrum shifts with electricity. But since the current cosmological model doesn't allow for much electricity in space (and we should ask why) they can not explain it any other way than it being a Doppler shift.
Physical and Mathematical Consistency of the Janus Cosmological Mode (Jean-Pierre Petit, Gilles D’Agostini, and Nathalie Debergh)
> in 2008 and 2009, Hossenfelder in [17] and [18] builds her own bimetric model involving negative mass, from a Lagrangian derivation where she produces a system of two coupled field equations. [...] Actually, although sharing many similarities, having the same kind of coupled field equations regarding negative mass, a fundamental difference remains between Hossenfelder’s bimetric theory and the Janus Cosmological Model.
> Indeed, Hossenfelder doubts that the second entity can have an important effect on the distribution of standard matter, qualifying the gravitational coupling between the two species as “extremely weak”. This is because “for symmetry reason” she considers that the absolute values of the mass density of the two populations should be of the same order of magnitude. Such hypothesis leads to a global zero field configuration, which does not fit with observations, as she notices. Then, examination of possible fluctuations seems to be her main concern. Not perceiving that a profound dissymmetry is on the contrary the key to the interpretation of many phenomena, including the acceleration of the cosmic expansion, she will not develop her model further during the following decade, focusing instead on other research topics.
> Nonetheless, Hossenfelder points out a “smoking gun signal” that could highlight the existence of invisible negative mass in the universe, through the detection of diffracted light rays caused by diverging lensing, an effect previously predicted in [13]. We indeed showed from 1995 that photons emitted by high redshift galaxies (z > 7) are diffracted by the presence of invisible conglomerates of negative mass on their path. This reduces the apparent magnitude of such galaxies, making them appear as dwarf, which is consistent with observations.
> Another feature of the scenario becomes clear from the pre- viously discussed example of the Schwarzschild metric. If there was a localized source of negative energy, it would act as a gravitational lens - but unlike usual matter this would be a diverging lens since it would repel our (usual) photons. Such a lensing event would typically lower the luminosity of the source, an effect that could potentially add up over distance if the distribution of such sources is substantial. The detection of a diffractive lensing event could serve as a smoking gun signal for the here proposed scenario.
A Bi-Metric Theory with Exchange Symmetry (Sabine Hossenfelder)
> Another feature of the scenario becomes clear from the previously discussed example of the Schwarzschild metric. If there was a localized source of negative energy, it would act as a gravitational lens - but unlike usual matter this would be a diverging lens since it would repel our (usual) photons. Such a lensing event would typically lower the luminosity of the source, an effect that could potentially add up over distance if the distribution of such sources is substantial. The detection of a diffractive lensing event could serve as a smoking gun signal for the here proposed scenario.
I admit that I was damned surprised that the JWT launched and deployed correctly, but I am glad it did. It's helping usher in a new wave of data, and helping to remind people that science is as much finding out how you're wrong as it is finding out if you're right. Once LISA comes on board, we'll have nice new toys to explore the past with.
> that shouldn’t exist
Articles should be more careful. It isn't that much longer to say "that aren't predicted by current models".
Not at all. Astrophysics is one of those dogma heavy fields. We have such a limited set of observations on what is such a large space. Every data point we collect will be from within the solar system. Given this, the mainstream astrophysicists should be humble and open to better models. They are not.
I always find it perplexing how shocked they claim to be when they find something that may indicate they were wrong, is this some kind of insane ego driven lack of self awareness? Of course we’re going to be more wrong than right about freakin space.
They all know this is how science works. It's nonetheless surprising. They're not shocked that they're wrong, they're shocked about what this could imply about the universe.
101 comments
[ 2.8 ms ] story [ 184 ms ] threadIf you're going to quote, I would suggest to do it fully.
I took away the premise just fine without getting hung up on elementary grammar.
Although in this case it looks like the automated modding of the title.
A singularity means that all timelines goes through it, but it is impossible to make continues extension of the timelines past the singularity in the current physical models. That literally means that anything is possible with the timeline prior that. The timeline can jump, be replaced by a set of random points, became a multidimensional surface, go back etc. It may even indeed disappear, but we do not know.
The timeline is certainly up for grabs, there are uncertainties in the various ways we measure or infer distances and the age of objects, but so far nothing that invalidates the overall scheme. Roger Penrose's idea of conformal cyclic cosmology is a plausible alternative, but even that still has an event in our past that looks an awful lot like a big bang. There are just too many observations any alternative theory needs to explain, like galactic red shift and the cosmic background radiation. If stars are infinitely old, how come they still have any hydrogen left?
It's always a good idea to keep an open mind though. What are the alternatives you think have legs?
But as a non-physicist I recognize that my "theories" are just for funsies and have less value than bellybutton lint.
> Twenty-thousand years in the future, Cass, a humanoid physicist from Earth, travels to an orbital station in the vicinity of the star Mimosa, and begins a series of experiments to test the extremities of the fictitious Sarumpaet rules – a set of fundamental equations in "Quantum Graph Theory", which holds that physical existence is a manifestation of complex constructions of mathematical graphs. However, the experiments unexpectedly create a bubble of something more stable than ordinary vacuum, dubbed "novo-vacuum", that expands outward at half the speed of light as ordinary vacuum collapses to this new state at the border, hinting at more general laws beyond the Sarumpaet rules. The local population is forced to flee to ever more distant star systems to escape the steadily approaching border, but since the expansion never slows, it is just a matter of time before the novo-vacuum encompasses any given region within the Local Group.
https://en.m.wikipedia.org/wiki/Schild's_Ladder
Also, the Big Bang "theory" is a theory in the technical sense, in that the overwhelming majority of evidence ever collected is at least neutral towards the Big Bang, to say nothing of the virtually incontrovertible evidence in support (esp. the cosmic microwave background radiation, redshift correlated with distance to virtually all extra-galactic objects, low metalicity in ultra-distant (read early) objects, etc etc etc). It could still be wrong, but we'd need some other theory that adequately explains all the available evidence, and makes several new, testable predictions that are also observed to be correct. The term "theory" is not used colloquially here as a fancy way to say "guess" or "idea" (those are, in the same technical sense, best called "conjectures" or (generously) "hypotheses"). It has a very narrow meaning here, and dismissing the Big Bang theory as "just" a theory really reveals your ignorance on the subject here.
I still lean towards the Big Bang as the most likely model, but it’s not as well established as, say, germ theory.
I actually had an idea in undergrad (20+ years ago) to probe Hubble Constant variation using quasar reverberation mapping and very-long-baseline-interferometry. Then the professor I was working with pointed out that the baseline I needed was something like 100,000 times earth's orbital diameter.
Back then, one of the sexier ideas was that the universe might have locally different fundamental constants, and that variation could reveal some information about the higher-dimensional "space" that the universe existed inside of. I've been out of that field for a long time though, so I've no idea what the cutting edge is. I just know that the Big Bang theory is still pretty safe.
There are plenty of things wrong in the theory, but none of the evidence suggests that "expansion from a singularity" is wrong, let alone "infinite and eternal" is right.
Olber's Paradox[2] and the inability to reconcile it with our current astronomical observations seems to disprove that our current universe is itself infinite.
[1] https://en.wikipedia.org/wiki/Big_Bounce
[2] https://en.wikipedia.org/wiki/Olbers%27_paradox
[0]: https://www.scientificamerican.com/article/why-is-the-night-...
Why word it like this instead of using 13.5 billion? Is this a common thing to do in astronomy? Or are you trying to make the claim of 13.5 billion years sounds more ridiculous? Genuine question.
There have been proposed models for why this occurs (WIMPs, etc.) but none have been convincing from a scientific perspective, mainly due to the inherent lack of observations which can justify such models.
Can you suggest an equally terse title that would avoid problems such as "position[ing] scientific theories as normative rather than descriptive" and "mak[ing] refinement look like failure"?
I think you're assigning far too much wrongdoing to this perceived sleight here, I wouldn't even think that saying "our current understanding makes this look impossible" is a way of saying we shouldn't celebrate change and improved understanding, I would instead go the opposite way and think how interesting it is to find things outside our understanding
"Shouldn't exist" is cargo cult psuedoscience terminology.
To me it implies that the model has more weight than the universe.
I think it demonstrates a sloppy framing of the topic.
We don’t know.
That’s point of building it!
Or, more accurately, you can think about it as a different set of priorities.
For instance, someone might want to spend a ten billion dollars of tax money to survey all the ball pits across the world, and accurately count the number of balls in each at precisely the same moment, just to have that knowledge "for its own sake." Is it myopic not to care about that?
A lot of people meet some of their needs for mysticism and meaning with astronomy, but it's also perfectly valid not to use it that way, and instead see it as blurry pictures of places that aren't even theoretically possible to interact with in any way.
> techniques developed for the collection and analysis of such vast datasets find their way back into more quotidian applications.
Which is different from knowledge "for its own sake." Townies with and without imagination will get behind aspects of the techniques, data, products and byproducts that resonate with them. NASA has plenty of examples.
Not necessarily. For one, I'm not talking about being able to articulate some argument for its value, I'm talking about agreeing with that value. To put it bluntly, not sharing that value isn't some kind of personal failure, though a lot of people here seem to mistakenly treat it that way.
https://www.scientificamerican.com/article/experts-doubt-the...
Neat article, they were asking all the right questions. Calculating how long a coal body could burn, and a mechanism/quantity required to refuel it based on the mass of the solar system
A year or two back I was at a lecture about hummingbirds and the shockingly weird ways they fly and during the Q&A some lady kept asking 'but what's the point of this? Why does it matter?' leaving the lecturer (and everyone else) deeply confused.
One interpretation is that these are older (more red shifted), larger (more stars) galaxies. But that's just one explanation. A pretty good one, but still, it could also be something totally mundane and boring. Remember FTL neutrinos?
I'll be ecstatic if the existing model of the universe needs a massive update based on this new data. But it's important to search as hard as we can for answers that aren't the one we really want to see.
[1] https://en.wikipedia.org/wiki/Timeline_of_the_early_universe...
Science can predict if it will rain tomorrow: "[a] seven-day forecast can accurately predict the weather about 80 percent of the time and a five-day forecast can accurately predict the weather approximately 90 percent of the time." [2]
Feel free to hubristically read articles such as Cosmic Evolution of Viscous QCD Epoch in Causal Eckart Frame [3] and tell us all where they are wrong. An introductory article into cosmology and inflationary theory [4].
[1] https://en.wikipedia.org/wiki/Maxwell%27s_equations#Macrosco...
[2] https://scijinks.gov/forecast-reliability
[3] https://inspirehep.net/files/b54851f57716f3e8fb650bc1c057ba1...
[4] https://cds.cern.ch/record/1059055/files/p197.pdf
These agree to within a relatively small range. If the number were substantially different, it would imply that something deeply fundamental (and probably several deeply fundamental things) was wrong.
It's much more likely that our understanding of galaxy formation is wrong. That's much less fundamental, and much harder to observe.
It's just like debugging code. You start with the obvious stuff. It's much more likely that the error is in your program, for example, and not in the compiler. That's not proof, but you'd be foolish to start anywhere else.
I find the entire thing extremely unphysical because of that. Why should just this one thing violate that? Just photons, nothing else? Are gravitational waves also stretched? Why can't we duplicate the effect in a lab?
> in 2008 and 2009, Hossenfelder in [17] and [18] builds her own bimetric model involving negative mass, from a Lagrangian derivation where she produces a system of two coupled field equations. [...] Actually, although sharing many similarities, having the same kind of coupled field equations regarding negative mass, a fundamental difference remains between Hossenfelder’s bimetric theory and the Janus Cosmological Model.
> Indeed, Hossenfelder doubts that the second entity can have an important effect on the distribution of standard matter, qualifying the gravitational coupling between the two species as “extremely weak”. This is because “for symmetry reason” she considers that the absolute values of the mass density of the two populations should be of the same order of magnitude. Such hypothesis leads to a global zero field configuration, which does not fit with observations, as she notices. Then, examination of possible fluctuations seems to be her main concern. Not perceiving that a profound dissymmetry is on the contrary the key to the interpretation of many phenomena, including the acceleration of the cosmic expansion, she will not develop her model further during the following decade, focusing instead on other research topics.
> Nonetheless, Hossenfelder points out a “smoking gun signal” that could highlight the existence of invisible negative mass in the universe, through the detection of diffracted light rays caused by diverging lensing, an effect previously predicted in [13]. We indeed showed from 1995 that photons emitted by high redshift galaxies (z > 7) are diffracted by the presence of invisible conglomerates of negative mass on their path. This reduces the apparent magnitude of such galaxies, making them appear as dwarf, which is consistent with observations.
> Another feature of the scenario becomes clear from the pre- viously discussed example of the Schwarzschild metric. If there was a localized source of negative energy, it would act as a gravitational lens - but unlike usual matter this would be a diverging lens since it would repel our (usual) photons. Such a lensing event would typically lower the luminosity of the source, an effect that could potentially add up over distance if the distribution of such sources is substantial. The detection of a diffractive lensing event could serve as a smoking gun signal for the here proposed scenario.
Source: http://www.ptep-online.com/2019/PP-56-09.PDF
--
A Bi-Metric Theory with Exchange Symmetry (Sabine Hossenfelder)
> Another feature of the scenario becomes clear from the previously discussed example of the Schwarzschild metric. If there was a localized source of negative energy, it would act as a gravitational lens - but unlike usual matter this would be a diverging lens since it would repel our (usual) photons. Such a lensing event would typically lower the luminosity of the source, an effect that could potentially add up over distance if the distribution of such sources is substantial. The detection of a diffractive lensing event could serve as a smoking gun signal for the here proposed scenario.
Source: https://arxiv.org/pdf/0807.2838.pdf
--
On the concept of apparent mass in two-sided/bi-metric universes:
https://januscosmologicalmodel.com/negativemass#conjugatecur...
--
From last week's thread about black holes without a singularity:
https://news.ycombinator.com/item?id=34817326
> that shouldn’t exist
Articles should be more careful. It isn't that much longer to say "that aren't predicted by current models".
https://youtu.be/Fqfap3v0xxw
For those like me who don't know what LISA is: https://en.wikipedia.org/wiki/Laser_Interferometer_Space_Ant...
Seems like an amazing project