Viewing profile — astro123

Measurements of pretty much any time in the universe can test predictions made by models of the early universe. One of the main reasons we think there was inflation is from late ti…

Inflation happened during the first tiniest fractions of a second post big bang. No telescope is going to make direct observations of the inflationary period so I'm not sure what y…

I worked with someone (this is in astronomy) who said that papers in nature were the most likely to be wrong. They are in nature because they have a dramatic (new/unexpected) resul…

Small stars live a very long time. A star of the mass of our sun has a lifespan of ~10 billion years which gets you almost back to the beginning of the universe (~13 billion). This…

That's a weird distinction to try to make. Metal does mean the elements, not the spectral lines. The presence of those elements is usually inferred from the spectral lines, but if …

> It seems significant that the lens galaxy has little dark matter I don't see that in the article? They centered on galaxy clusters which contain huge amounts of dark matter. DM i…

I think it was taken at a particular time. If it were the closest, venus would be closer than the sun. Skimming the paper it looks like it was the positions in Aug 2003

The early universe's expansion was not accelerating, as the early universe was not dominated by dark energy. I don't know off the top of my head exactly when that changed, but z=0.…

There's no strong lensing there. If the background galaxies were lensed enough to have multiple images they would also be incredibly distorted. But that does look like a small grou…

Eek! I guess I'm more OK with this now...

The best suggestion I have is https://astrobites.org/ These are paper summaries, written by people in the field, where you are probably the target audience. I don't read it myself,…

Yup, by fringe I meant "On the edge of what reasonable people are working on". But maybe it's not a great term if people misunderstand.

That's a fair point. I love reading computer hardware rumours, most of which are probably total garbage (and probably obviously so to anyone in the field). And in this case, whethe…

No-one is making an argument by authority. Here is a nice popular article that outlines some of the issues with MOND https://www.forbes.com/sites/startswithabang/2018/03/06/only...…

The astrophysics journal (ApJ) is a really good journal. A majority of good astronomy papers are published in ApJ or in MNRAS. Big things go in Nature/Science + then there are othe…

I only skimmed the paper past the abstract, but for what it is worth. The MOND favouring group is a fringe of the cosmology community. The vast majority feel that there is enough e…

I'm not suggesting that at all! I'm just saying it took 30 odd years to take off/break out of the nuclear physics world. Though rereading my first comment that wasn't entirely clea…

Kringing is the same thing as gaussian process regression, and astronomers use GPs a fair bit. I'm not sure whether they are used more widely. My favourite forgotten/isolated stati…

I didn't know about that, that's really cool! Thanks for letting me know.

I don't think that is right, though I'm not a GW expert so please tell me if I'm wrong. I think they know the difference just by looking at the mass. i.e. we think it is hard to fo…

That's an interesting question. I've never thought about it or seen that taken into account (its not something we fit to when constraining cosmology) I just looked around and LIGO …

I highly recommend these books by Alan Hirshfeld [1][2]. The first is about the discovery of parallax, and the instrument that was used to do this in 1838 was built by Fraunhofer. …

We have! A constraint on dark matter is that it needs to be around at very early times. Before the time of the CMB (400 000 years after the Big Bang). If there wasn't dark matter a…

While yes, better launch capability == cheaper to put telescopes in orbit == good for astronomy, its not that simple. Interferometry is HARD. The Keck telescopes which sit 100m apa…

The argument is actually really really simple. If it started from within the solar system, it would not (barring some three body interaction) have enough energy to escape. But, we …