Stars may form 10 times faster than thought
science.org
science.org
I'm sure this has been taken into account already (by actual scientists much smarter than me) but, how do we know it isn't dark matter causing the collapse to happen faster than thought? Seems like a reasonable question to me. Lack of gravitational lensing?
(edit:) Also
>thanks to weak magnetic fields ... Zeeman effect etc
This is a bit questionable to me. I understand the Zeeman effect, or thought I did, but I don't understand how it can be thanks to a "weak" magnetic field.
The average density of dark matter is way too small. It's significant on the scale of a galaxy because it doesn't clump, so its density is basically the average density everywhere (denser towards the center and less dense further out, but still of the same rough order of magnitude), instead of being isolated clumps surrounded by huge expanses of empty space, as with ordinary matter. But on the scale of a single stellar system the density of dark matter is so small that its effect on the dynamics is negligible.
Good explanation of low density of dark matter as measured by squirrels.
>Magnetic fields tend to slow the gas collapsing, so finding that the fields were lower than expected decreases the expected time of collapse.
I think this part might be backwards, wouldn't it increase the expected time of collapse, which is to say stars may form faster than thought?
(edit: no, I'm just tired and wrong, yet again...)
>We look at the age of the whole solar system, because it all came together around the same time.
>To get this number, we look for the oldest things we can find. Moon rocks work well for this. When astronauts brought them back for scientists to study them, they were able to find out how old they are.
Core of Theia sunk into Earth and there is some recent imaging showing what may be the second core.
https://www.iflscience.com/environment/fragments-of-the-plan...
Hmm, sounds dubious, but I will read on. A short while later it leads me to the paper[0] and I spend a few more minutes on that, finding myself asking: how do we know the zircon fragments aren't from a meteor that is much older? Surely all the fragments came from approximately the same area, yes? Or maybe not?
But nah, these knowledgeable astronomers must have already thought of all this stuff.
Astronomy is just filled with rabbit holes I guess.
Radiometric dating tells you when the sample you are dating last solidified. Of course the atoms in the sample themselves existed before that, but that doesn't matter for radiometric dating since what is being measured is not the age of the atoms but the time the sample, the piece of rock you're analyzing, last solidified.
> Surely all the fragments came from approximately the same area, yes?
Um, yes, since the Apollo 14 astronauts only collected samples from a very small area.
> nah, these knowledgeable astronomers must have already thought of all this stuff.
Yes, in fact, they have, plus a lot more things that haven't even occurred to you.
Exactly. Like that comment about the JWST last week that was wondering why they didn't bring down the number of single-points-of-failure. Backseat driving at its best.
No, I am not the smartest person here. I understand that. A few days ago I asked a question and people told me to get more involved in HN with commenting and posting and such. People also warned about gatekeeping. I had seen it talked about with regards to HN before, but never really noticed it. So then I try to get more involved and now I understand.
I am not trying to be an "armchair contrarian" or "backseat driver" or anything of the sort. I am just wondering out loud on the internet. And I don't think I was JAQing off either.
(and btw jason, I'm not a tech industry clown, I'm just a nobody clown.)
Statements like these...
> Hmm, sounds dubious, but I will read on.
> But nah, these knowledgeable astronomers must have already thought of all this stuff.
...do not lend support to your claim here.
Not knowing much about an area of science on which many people have spent a lot of time and effort is fine. Being dismissive about it without knowing much about it is not.
For the record, the 'sounds dubious' comment was directed at the claim that we know the "exact" age of the moon. It is more a criticism of shoddy journalism than a statement of my knowledge of the subject. I know enough to know that we cannot pinpoint the "exact" age of the moon.
And the 'knowledgeable astronomers' claim was almost more of a meek confession that idk wtf I am talking about. It was not meant sarcastically at all. I know a little, but not as much as people who went to school and do this stuff professionally.
Everyone, please note: I'm not trying to back-peddle or make excuses or anything like that here, just explaining my reasoning.
(Edit: but thanks for the criticism, it really does help to see your point of view on these things. This is a discussion board after all.)
Yes, I agree shoddy journalism is a pain. I never even read the articles, I just look for a link to the actual paper (btw, thank you for providing it).
My charitable reading of the parent post is that asking these obvious questions first, then hunting down the answer is an incredible way to learn how "we" know things.
I think it's a perfectly fair way to note that the poster doesn't have the complete story yet.
No wonder some cultures think Rabbits live on the moon.
That would be a rounding error on a reasonably precise and accurate estimate of the age of the universe (which I don't think we have yet.)
As for cosmological/other physical implications, it's a "well, now we know more" result.
1. https://astronomy.stackexchange.com/questions/156/how-long-d...
Not really. Don't we estimate the age of the universe by estimating how redshifted the CMB is compared to what we would expect given initial conditions?