Researchers Solve Mystery of the Galaxy With No Dark Matter (phys.org) 102
An anonymous reader quotes a report from Phys.Org: A group of researchers from the Instituto de Astrofisica de Canarias (IAC) has clarified a 2018 mystery in the field of extragalactic astrophysics: The supposed existence of a galaxy without dark matter. Galaxies with no dark matter are impossible to understand in the framework of the current theory of galaxy formation, because the role of dark matter is fundamental in causing the collapse of the gas to form stars. In 2018, a study published in Nature announced the discovery of a galaxy that apparently lacked dark matter. Now, according to an article published in the Monthly Notices of the Royal Astronomical Society (MNRAS) a group of researchers at the Instituto de Astrofisica de Canarias (IAC) has solved this mystery via a very complete set of observations of KKS2000]04 (NGC1052-DF2).
The researchers, perplexed because all the parameters that depended on the distance of the galaxy were anomalous, revised the available distance indicators. Using five independent methods to estimate the distance of the object, they found that all of them coincided in one conclusion: The galaxy is much nearer than the value presented in the previous research. The original article published in Nature stated that the galaxy is at a distance of some 64 million light years from the Earth. However, this new research has revealed that the real distance is much less, around 42 million light years. Thanks to these new results, the parameters of the galaxy inferred from its distance have become "normal," and fit the observed trends traced by galaxies with similar characteristics.
The researchers, perplexed because all the parameters that depended on the distance of the galaxy were anomalous, revised the available distance indicators. Using five independent methods to estimate the distance of the object, they found that all of them coincided in one conclusion: The galaxy is much nearer than the value presented in the previous research. The original article published in Nature stated that the galaxy is at a distance of some 64 million light years from the Earth. However, this new research has revealed that the real distance is much less, around 42 million light years. Thanks to these new results, the parameters of the galaxy inferred from its distance have become "normal," and fit the observed trends traced by galaxies with similar characteristics.
Re: redhsift? (Score:1)
Remember when we all said this theory sounds like bullshit and measurements or coefficients being wrong seems more likely ?
I do.
Warning: (Score:5, Funny)
Galaxies in mirror telescopes may be closer than they appear.
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No, the user suffers from "Trump Trolling Syndrome," when someone realizes how annoyed everyone else is when people bring Trump into any non-politics discussion, so they mention Trump as often as possible for the lulz.
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Disappointing error (Score:3, Insightful)
They have identified a 34.3% error in distance measurements. Once corrected, this explains the "singularity" of this galaxy, or more correctly, returns to the unexplained situation that requires some kind of dark matter to explain its behavior.
While we all understand that science builds on replication and validation of previous experiments and measurements, finding such huge errors makes me quite sad. How confident are other measurements in Astronomy? Can we trust them? After these issues, when presenting other results, people will tend to think that conclusions may probably be wrong but arise from a 30% error in some measurement.
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We might as well not bother anymore. Let's all go back to living in caves.
Re:Disappointing error (Score:5, Informative)
So yeah, one should expect a few weird measurements now and then, if there are not outliers someone is either REALLY good at building their instruments/models or is filtering.
Re:Disappointing error (Score:5, Informative)
A worry would be if people took the original measurements at face value and didn't replicate the measurement. What we have here is an example of science doing exactly what it's supposed to: people check the measurements, find errors, and fix them. That's sort of the whole point
So, to answer your question: no one "trusts" measurements. Everyone looks for hints that something can be improved, and goes out and improves them where possible. Usually the new numbers aren't quite so different from the old ones, so you don't read about them in the popular press. Pick up the arxiv or a a journal, and read some of those articles: a huge fraction of them are people doing exactly what science is supposed to do: making new and better measurements, or figuring out how existing measurements can be better interpreted in light of new ones.
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How would we ever know? Not all claims of knowledge, fact are tested, replicated. How much of what we think we know about anything is utter bullshit? Until the assumptions made in this story were more thoroughly investigated they were âfactsâ(TM). Had no one bothered to investigate further theyâ(TM)d still be accepted as fact.
The more important and/or weirder the measurement, the more likely it is that someone will go and follow up. The only galaxy we've seen that didn't seem to have dark matter in it? I'm sure that everyone doing galactic dynamics was probably thinking about how to cross check that one.
Something that many people seem not to realize: scientists really enjoy proving people wrong. The more important the point, or the larger the correction that needs to be made, the more people want to check it.
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I start a stats lecture with a big black Jobs-like slide with the worlds "all measurements are wrong."
All data contains noise and bias. You can deal with noise by collecting more data. Dealing with bias, like in this situation, usually involves figuring out where it's coming from and fixing the problem.
But all data is wrong, no matter how good it is, so you can never trust it beyond the confidence interval*.
* and all confidence intervals have a little asterisk with a footnote, e.g. "19 times out of 20, prov
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A worry would be if people took the original measurements at face value and didn't replicate the measurement. What we have here is an example of science doing exactly what it's supposed to: people check the measurements, find errors, and fix them. That's sort of the whole point
So, to answer your question: no one "trusts" measurements. Everyone looks for hints that something can be improved, and goes out and improves them where possible. Usually the new numbers aren't quite so different from the old ones, so you don't read about them in the popular press. Pick up the arxiv or a a journal, and read some of those articles: a huge fraction of them are people doing exactly what science is supposed to do: making new and better measurements, or figuring out how existing measurements can be better interpreted in light of new ones.
I think the question the GP was pointing toward, is this a human calculation error that resulted in the closer measurement or an error with the formula used to measure the distance. If the error is human, oops... if the error is with the formula, have all previous galaxies been adjusted for the correction to the formula? If so does this impact other theories, or is it simply a corner case with no impact to the rest of astronomy?
Re:Disappointing error (Score:4, Informative)
(Same goes for carrying units. A number by itself is meaningless. The units must be specified, and should never be assumed. If you don't include units, you end up with what happened to Mars Climate Orbiter [wikipedia.org]. It's frequently characterized as a metric/Imperial units snafu, but it was really a failure to write down units and assuming what the units were. The orbiter could've been lost the same even if everything were done in metric. e.g. The numbers were given in kilonewtons and the people reading them assumed they were newtons.)
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Same goes for carrying units. A number by itself is meaningless. The units must be specified, and should never be assumed.
This is my constant pet peeve in the operations side of software development. It's rare to find a dashboard where the axes are even labelled, let alone labelled with units! Label your damn axes, people! [axeandanswered.com]
It's exasperating to be looking for which service is misbehaving, and it's unclear whether the response time displayed in the dashboard is in milliseconds or seconds.
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I can't believe it's that prevalent among "smart people". I got a fucking business degree, which is derided nonstop on this site, and I had it drilled into me very early that you label that shit or your a fucking piece of shit moron who should be buried up to his head and stoned.
That's a good point, and highlights the fact that there's not really any formal education around ops yet. Even though it has become the norm in the industry, and could seriously benefit from academic insight and training, CS programs are currently turning up their nose at this reality.
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That's a good point, and highlights the fact that there's not really any formal education around ops yet. Even though it has become the norm in the industry, and could seriously benefit from academic insight and training, CS programs are currently turning up their nose at this reality.
I got a lot of this stuff pounded into my head in my CS/CE days at university. It was certainly formalized then. But the ops/sysadmin/programmer world is also full of folks with the "you don't need a formal education / self-taught is the best / why waste all that money on education / college is for suckers" attitude.
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I got a lot of this stuff pounded into my head in my CS/CE days at university. It was certainly formalized then. But the ops/sysadmin/programmer world is also full of folks with the "you don't need a formal education / self-taught is the best / why waste all that money on education / college is for suckers" attitude.
If the degree doesn't actually teach the critical stuff for doing the job, they are manifestly correct! For many skills needed for a developer, a CS degree in fact helps a lot, which is why the lack on the ops side is so noticeable.
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If the degree doesn't actually teach the critical stuff for doing the job, they are manifestly correct!
Sure. I mean, I can't discount that there are bad degrees out there, or at least ones that don't teach you things you need to know.
But maybe my most positive last experiences at college were like that, forcing me into these topics where it might not have occurred to me to seek them out on my own. The problem with the "scratch the itch" free software world is sometimes there are courses that teach you very valuable skills that you might have discounted before. Or they weren't intellectually stimulating or in
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Not finding galaxies without dark matter (or dark matter without galaxies) makes me think that the MONAD/TeVeS or another alternative could be possibly correct, versus the current hypothesis of mostly non-baryonic dark matter.
Now there's some problems with alternat
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They have identified a 34.3% error in distance measurements. Once corrected, this explains the "singularity" of this galaxy, or more correctly, returns to the unexplained situation that requires some kind of dark matter to explain its behavior.
While we all understand that science builds on replication and validation of previous experiments and measurements, finding such huge errors makes me quite sad. How confident are other measurements in Astronomy? Can we trust them? After these issues, when presenting other results, people will tend to think that conclusions may probably be wrong but arise from a 30% error in some measurement.
We live on a rock, and we try to make sense of the electromagnetic radiation that just happens to fall on us.
That should be, but won't be, sobering. You'll be told that we actually have a great handle on all of this.
That's funny (Score:2)
I didn't catch that when I read the summary.
Let's Get Some Reproducible Verification (Score:1)
I really hate the dark matter theory. In my mind, if you're relying on dark matter, you may as well ascribe it to God.
This explanation feels far more comfortable, but lets get some better verification before we accept yet another sketchy theory as rote.
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I really hate the dark matter theory. In my mind, if you're relying on dark matter, you may as well ascribe it to God.
It is nowhere near that bad. "Dark matter" is some effect we haven't figured out yet, but we may very well find out in the future. Could be as the name implies, some kind of matter that doesn't shine light at us. Maybe better future instruments will be able to see it, then. Could be a different theory for long-range gravitation, which we may be able to measure someday.
We'll see. Once, they thought it impossible to figure out the chemical composition of a star too.It was impossible, for people who relied o
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I presume his gripe is that, at least in popular media, 'dark matter' is not some placeholder theory, it is a very confident statement that there is matter present that we cannot observe for reasons unknown, and that's why our observations don't jive with current theory.
In reality, it's a placeholder guess to fill the gaps for everywhere our theory based math does not currently work out.
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It's not that the theory is a bad one, it's the fact that it is treated as established fact rather than an unproven theory. Also insofar as theories goes, it's much closer to a hypothesis, as the very concept is flexible enough to be very hard to disprove. It can't be used to make specific predictions. If you see a stronger effect than usual, it simply means there's more of it. If it's a weaker effect than usual, it simply means there must be less of it. Dark matter is in theory falsifiable, but in prac
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Don't worry, The Laws of Physics and universals Constants just "happened" from nothing! /s
DOH. I mean they have always existed.
Double DOH!
ARGH. /s
The point is, EVERYONE has faith. If you didn't have faith then why do you have your beliefs???
At some point you have to stand on SOME foundation because otherwise the alternative is the irrational / illogical belief that something can come from nothing. This isn't true regardless of how many stupid Cosmologists and Mathematicians try to show something came from
Speed of light (Score:3)
Imagine two objects traveling in the opposite direction each just over half the speed of light. You are on one of them, will you ever be able to see the other?
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Yes. Because Relativity.
Actually, even without Relativity, you'd be able to see the one from the other. Because light (moving at c) left the one headed for the other (moving at c), so the light would eventually catch up...
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adding a second observer traveling along the same path at a different speed would give photons two different velocities at the same time
That's where you are going wrong. Time and space are relative to each observer, depending on their speed. Light is always traveling at c relative to each observer. But velocity is dx/dt, where neither x or t are the same for each observer.
Re:Speed of light (Score:5, Informative)
Your question pre-supposes that your location as an observer of these two galaxies is special. That you observe one galaxy moving in one direction at 0.5c, and the other moving in the opposite direction at 0.5c, may be correct in your frame of reference, but that hardly makes it the One True Reference.
In the frame of reference of me (living in one galaxy), what do I observe of the other galaxy. It is, unfortunately, a bit early for me to sort out (plus, I have a day job). But the result will come from applying Special Relativity, in which speeds never add in the "intuitive" way of our everyday experience. After going through the math, I expect you'll find that, in my frame of reference, the speed of the other galaxy is a large fraction of c, but not c itself. At a guess, I'd say it's probably sqrt(1 - 0.5^2 / c^2) = 0.866c, if only because that Lorenz transformation shows up all the time.
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But the result will come from applying Special Relativity, in which speeds never add in the "intuitive" way of our everyday experience. After going through the math, I expect you'll find that, in my frame of reference, the speed of the other galaxy is a large fraction of c, but not c itself.
For anyone who's interested: if two galaxies, in some reference frame, are each moving away from each other at 0.5*c; then, in the reference frame of one of the galaxies, the other galaxy will be moving away at 0.8*c. You can get this by substituting v=u'=0.5*c into the first velocity-addition formula here [wikipedia.org].
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Imagine two objects traveling in the opposite direction each just over half the speed of sound. You are on one of them, will you ever be able to hear the other?
Yes. Sound still travels at the same speed: 343 m/s. If, for instance, you're standing still, and something is moving away from you at 300 m/s, and at point X it makes a sound... it's not like sound is moving from point X to you at 43 m/s. The sound is traveling at 343 m/s. But the frequency of the sound will be modified by the Doppler Effect. If the sound coming from the second is already low frequency, the shift may be enough that the sound that reaches the first object is too low-frequency to be audible
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Imagine two objects traveling in the opposite direction each just over half the speed of light. You are on one of them, will you ever be able to see the other?
You did not specify the direction. If they are on a collision course, you are going to see the other one very well soon enough ;)
Now if they are moving away from each other, more properly formulated, the question would be: an observer sees two object moving away him at a bit more than half the speed of light, in opposite directions. You are on one of them, is the other moving away from you faster than the speed of light. And the answer is no, it is moving away at something like 0.8c, so you will eventually
Finally! (Score:2)
If they were deeply offensive, they didn't have anything whatsoever to do with the article. Yay for getting them out of the way so we can have a conversation.
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If they were deeply offensive,
Well, the Quran says nothing about dark matter or special relativity. So this entire subject needs to be deleted. On the basis of its being offensive.
Of course, being offensive is a matter of your frame of reference. So I guess it can stay.
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One should document this then.
I worry sites are obeying censorshio laws from dictatorships or places without a first amendment. On the high seas, freedom should prevail, not pirates.
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Now we need these guys to move on to Cold Fusion and we are all set.
People did. In droves. And found no cold fusion.
I was in grad school at the time. That was a great example of something both so big and so weird that everyone and their dog (even people not normally in that field) went off and investigated. Even theorists were busting out old lab equipment to see what they could find.
you mean this one? (Score:2)
Wake us up when they find some. As far as we know so far, there might not be any.
Re: Researchers Solve Mystery of the Galaxy (Score:1)
Aether (Score:1)
Watching all those "scientist" clowns trying to understand universe based on premise of "vacuum" reminds me of people trying to understand how is it possible to arrive at the same spot if you go east or west when the Earth is - in their understanding - flat.
Objects in telescope's mirror (Score:2)
are closer than they appear
#JurassicGalaxy