New class of galaxy has been discovered, made almost entirely of dark matter
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Re: New class of galaxy has been discovered, made almost entirely of dark matter
#2This is significant. Now astronomers can study dark matter with less interference from the regular matter background. So you have a more broad range of objects to study, from galaxies with lots of regular matter, to galaxies with almost none of it.
Hopefully this will accelerate DM research. It will certainly provide lots more data.
Re: New class of galaxy has been discovered, made almost entirely of dark matter
#3This is significant. Now astronomers can study dark matter with less interference from the regular matter background. So you have a more broad range of objects to study, from galaxies with lots of regular matter, to galaxies with almost none of it. Hopefully this will accelerate DM research. It will certainly provide lots more data.
Let's just hope the cables were all connected correctly.
https://en.wikipedia.org/wiki/Faster-than-light_neutrino_ano...
Re: New class of galaxy has been discovered, made almost entirely of dark matter
#4This is significant. Now astronomers can study dark matter with less interference from the regular matter background. So you have a more broad range of objects to study, from galaxies with lots of regular matter, to galaxies with almost none of it. Hopefully this will accelerate DM research. It will certainly provide lots more data.
One thing I don't understand and maybe someone can take the time to explain.
Why does it have to be this "Dark Matter" causing the mass differences we've been seeing? How do we know it isn't undetectable-through-normal-means normal matter, or aliens, or mistakes in our calculations/observations, or anything else?
Since we haven't been able to detect dark matter, it seems from my layman point of view that any of the above "hypotheses" are equally viable.
What am I missing that makes astronomers and physicists so sure that this "dark matter" exists?
Edit: Thanks for all the great responses! I'm not going to respond to each response, but the discussion has been enlightening.
Re: New class of galaxy has been discovered, made almost entirely of dark matter
#5This is significant. Now astronomers can study dark matter with less interference from the regular matter background. So you have a more broad range of objects to study, from galaxies with lots of regular matter, to galaxies with almost none of it. Hopefully this will accelerate DM research. It will certainly provide lots more data.
One thing I don't understand and maybe someone can take the time to explain. Why does it have to be this "Dark Matter" causing the mass differences we've been seeing? How do we know it isn't undetectable-through-normal-means normal matter, or aliens, or mistakes in our calculations/observations, or anything else? Since we haven't been able to detect dark matter, it seems from my layman point of view that any of the a…
I think dark matter is a synonym for "undetectable-through-normal-means matter". It's just a description of something mysterious causing effects that some kind of matter would cause. It could be a mix of different kinds of undetectable matter, or some fundamental flaw in our understanding of matter and gravity, or something else.
The arguments against aliens and mistakes are presumably that the effects appear consistently across the whole visible universe, and through many different measurements.
Re: New class of galaxy has been discovered, made almost entirely of dark matter
#6This is significant. Now astronomers can study dark matter with less interference from the regular matter background. So you have a more broad range of objects to study, from galaxies with lots of regular matter, to galaxies with almost none of it. Hopefully this will accelerate DM research. It will certainly provide lots more data.
One thing I don't understand and maybe someone can take the time to explain. Why does it have to be this "Dark Matter" causing the mass differences we've been seeing? How do we know it isn't undetectable-through-normal-means normal matter, or aliens, or mistakes in our calculations/observations, or anything else? Since we haven't been able to detect dark matter, it seems from my layman point of view that any of the a…
"undetectable-through-normal-means matter" is by definition not normal matter. We do not know what it is, so we have a placeholder name for it: "dark matter", i.e. matter that does not shine in the EM spectrum. We have theories about what it is, but most of the mundane ideas (like cold dust) have been ruled out by observations. Now we are left with all these stranger ideas. "Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth."
Re: New class of galaxy has been discovered, made almost entirely of dark matter
#7This is significant. Now astronomers can study dark matter with less interference from the regular matter background. So you have a more broad range of objects to study, from galaxies with lots of regular matter, to galaxies with almost none of it. Hopefully this will accelerate DM research. It will certainly provide lots more data.
One thing I don't understand and maybe someone can take the time to explain. Why does it have to be this "Dark Matter" causing the mass differences we've been seeing? How do we know it isn't undetectable-through-normal-means normal matter, or aliens, or mistakes in our calculations/observations, or anything else? Since we haven't been able to detect dark matter, it seems from my layman point of view that any of the a…
> undetectable-through-normal-means normal matter
I assume by this you mean dust and planets and such. https://medium.com/starts-with-a-bang/could-dark-matter-just...
That also goes for 'aliens', because presumably, they'd also be made of normal matter, and if they're not, then we're back to some exotic form of matter like dark matter.
As far as being a mistake, it could be possible that we are fundamentally misunderstanding something about how gravity works. That would be as interesting a result as dark matter, to be honest.
Re: New class of galaxy has been discovered, made almost entirely of dark matter
#8This is significant. Now astronomers can study dark matter with less interference from the regular matter background. So you have a more broad range of objects to study, from galaxies with lots of regular matter, to galaxies with almost none of it. Hopefully this will accelerate DM research. It will certainly provide lots more data.
One thing I don't understand and maybe someone can take the time to explain. Why does it have to be this "Dark Matter" causing the mass differences we've been seeing? How do we know it isn't undetectable-through-normal-means normal matter, or aliens, or mistakes in our calculations/observations, or anything else? Since we haven't been able to detect dark matter, it seems from my layman point of view that any of the a…
The only thing we're sure it exists is - there's something out there that acts exactly like normal matter with mass, and it interacts gravitationally with itself and with regular matter, but it doesn't seem to interact in any other way.
That's it. The name "dark matter" is a bit optimistic, because we don't even know if it's anything like "matter".
It's not a fluke in the equations, it's not a fifth fundamental force. All these alternatives have been shown to be very unlikely.
It's not "normal" matter because that one would interact in ways other than gravity, too, and it would tend to make "clumps" (stars, planets). This one doesn't make clumps.
So, yes, it's pretty certain that it exists, but nobody knows what it is. Its only attribute observed so far is its mass. Maybe we should call it "dark mass" instead.
Re: New class of galaxy has been discovered, made almost entirely of dark matter
#9Archive.is linkage for those who can't get past the paywall:
Re: New class of galaxy has been discovered, made almost entirely of dark matter
#10This is significant. Now astronomers can study dark matter with less interference from the regular matter background. So you have a more broad range of objects to study, from galaxies with lots of regular matter, to galaxies with almost none of it. Hopefully this will accelerate DM research. It will certainly provide lots more data.
One thing I don't understand and maybe someone can take the time to explain. Why does it have to be this "Dark Matter" causing the mass differences we've been seeing? How do we know it isn't undetectable-through-normal-means normal matter, or aliens, or mistakes in our calculations/observations, or anything else? Since we haven't been able to detect dark matter, it seems from my layman point of view that any of the a…
Basically, dark matter is something that has gravitational pull, but shows no other evidence of its existence. We have seen evidence for dark matter in galaxy rotation curves, galaxy cluster interactions, and the cosmic microwave background fluctuations, so we know it's not a mistake (each of these measurements are independent and do not share common systematic errors). We know it's not normal matter (e.g. black holes), because we at least somewhat understand the physics of how normal matter works, and we would expect to see something observationally if it is just normal matter. Since it is not normal matter, using Occam's razor, we can only postulate it is something that has gravitational pull but doesn't interact otherwise. Perhaps once we figure out how to study dark matter, we can tease out some of its properties and it won't just be all lumped together as "dark matter".