astroH

7 ms·

1.
by astroH 1y ago
a lot better...we can excite these atoms in a lab and simply measure what comes out. often times don't even need a model because spectroscopy can be fully empirical for many transitions
2.
by astroH 2y ago
And so you have proved my point. The observations presented in this article can be made consistent with both...as such one should think about stronger tests of both LCDM and MOND.
3.
by astroH 2y ago
Again, LCDM and galaxy formation are two different things. "...and we didn't see what we were expecting at all..." It depends on who you ask. There were many pre-JWST models that did well in this regard. A particularly intere
4.
by astroH 2y ago
This is a misrepresentation of what I am saying. By no means am I casting an aspersion on JWST. I am casting an aspersion on this particular observation as a test of MOND and LCDM. Also I highly disagree about your comments on my line of re
5.
by astroH 2y ago
In my opinion, this article is misleading at best. "...scans of ancient galaxies gathered by the JWST seem to contradict the commonly accepted predictions of the most widely accepted Cold Dark Matter theory, Lambda-CDM." --> LC
6.
by astroH 2y ago
So I think it is fair to say they did exist. If we believe in Big Bang Nucleosynthesis then heavy elements had to come from somewhere making the first generation of stars (whatever their properties may be) be Population III. I agree that wi
7.
by astroH 2y ago
Multiple generations is perhaps an overstatement. The first oxygen in the Universe came from what we call Population III stars which is the first generation of stars to form after the Big Bang and what separates these from other stellar pop
8.
by astroH 2y ago
I wouldn't say it's too damaging yet. There is a general trend where these early galaxies are brighter than we had thought by simply extrapolating models that were built prior to JWST, but these make numerous assumptions on how ef
9.
by astroH 2y ago
It's a lot less sophisticated than that. They take images in multiple filters. In the context of JWST of order 10 filters (sometimes more sometimes less). Source extraction is then performed on the images by essentially identifying bri
10.
by astroH 3y ago
While in general, 'metal' means all elements except for hydrogen and helium, in this specific case, 'metal' really means oxygen. They are using the measurement of the [O III] 4363 line to estimate a gas temperature which
11.
by astroH 4y ago
Indeed, but we define their "metallicity" (mass fraction of elements heaver than helium) typically by the gas that they formed from. And the key point is that since they form from metal-free gas, you don't expect to see emiss
12.
by astroH 4y ago
These systems are very far away because you are looking more than 13 billion years back in time. The argument is JWST has a small field of view and these Pop III stars are like flashes in comparison to the age of the galaxy. So the probabil
13.
by astroH 4y ago
I think this is perfect! If only we can convince the author of the article...
14.
by astroH 4y ago
Unfortunately not. These stars have no elements heavier than hydrogen and helium so you wouldn't be able to create a rocky planet that's habitable. Furthermore their lifetimes are only 3 Myr which is much to short to form a rocky
15.
by astroH 4y ago
As an expert in this space, I can confidently tell you that nothing about this observation is conclusive about the presence of the "First Stars" or what we call "Pop. III" Stars. By definition, the first stars are nearly
16.
by astroH 4y ago
So MOND does predict more galaxies at high redshift however it also predicts earlier reionization than LCDM which it turns out not to be true and the mass function of clusters is not what we see purely based on X-ray temperatures. So gettin
17.
by astroH 4y ago
I have to say, this article is exceptionally disappointing. As someone who works in this space, there are numerous misleading depictions about the state of the field. Almost any respectable simulation shows that disk galaxies are widely pre
18.
by astroH 4y ago
I think this is perhaps the wrong way to think about it. 50 million years represents ~14% of the age of the Universe (at 350 Myr) so it's really quite a big jump. Considering stars aren't thought to form until 200-250 Myr after th
19.
by astroH 4y ago
A lot of the work on distant galaxies is not being done with gravitational lensing. The idea is that you use massive objects in the foreground, like galaxy clusters, to focus light from the background. Depending on orientation, we can get m
20.
by astroH 5y ago
Echoing previous responses, it depends on what you want to learn. Gravity on large scales is fairly well understood (or at least many astrophysicists believe this to be the case). If there are large scale structure observables that are only
21.
by astroH 6y ago
Couldn't agree more. Moreover, given that a huge part of the value of the degree is related to the prestige of the University, bad-mouthing your own institution only serves to reduce the value of your own degree. Who cares if I write
22.
by astroH 6y ago
Could you elaborate a bit more on this? I have thought about employing NNs in this way for quite a while but the thing I never wrapped my head around was ensuring how it generalizes to different problems.
23.
by astroH 6y ago
Modified gravity is still being actively explored and I would argue taken very seriously but not in the context of dark matter, rather in the context of dark energy. So in a sense, yes, modified and dark matter combined are both possible i
24.
by astroH 6y ago
The best evidence for dark matter is arguably the CMB. The strengths of the individual peaks are highly suggestive of dark matter, in particular the third peak. Furthermore, most MOND simulations on cosmological scales still require dark
25.
by astroH 7y ago
Nebula isn't a physician-ordered test, nor does it come with the bioinformatics pipeline needed for rare conditions or genetic counseling. It's quite simply a different product for a different purpose.
26.
by astroH 7y ago
Yes, we could test two potential parents to see if they are carriers. Depending on what you're looking for though, if it's a specific mutation, there might be a slightly cheaper option on the market as our test is very broad spec
27.
by astroH 7y ago
Very much appreciate the comment. The sequencing is done at a lab in Maryland.
28.
by astroH 7y ago
Our test won't detect Huntington's unfortunately.
29.
by astroH 7y ago
Both good suggestions. The hard-drive idea is totally doable and something we have considered. In terms of the analysis, it's not quite a program that you can run on your own computer. You can rank variants this way but you need a t
30.
by astroH 7y ago
Thanks for the comment and we totally agree. The only way to prove we care about privacy is to live it and be as transparent as possible.

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