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Astrophysicists Puzzle over Webb’s New Universe

quantamagazine.org

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Re: Astrophysicists Puzzle over Webb’s New Universe

#111

Post by [deleted] »

idiotsecant wrote: post #53
phyzix5761 wrote: post #8

> Faced with observations of early black holes and galaxies that weren’t expected to exist, scientists have come up with a wealth of new theories to explain them. Now they just need to figure out which ones are true. This subtitle really bothers me. Science isn't about finding out what is true. Science is about finding out what is false and building models to explain the rest. We can never confidently say we know som…

Oh God do we really have to have the pedantic 5 page navel gazing thread about the philosophy of science that ultimately accomplishes nothing other than slightly increasing the entropy of the universe

[deleted]

Re: Astrophysicists Puzzle over Webb’s New Universe

#113

Post by stouset »

hparadiz wrote: post #94

Little red dots are my favorite new concept in astrophysics. This idea that there could be so much matter orbiting a black hole that the matter reaches sun levels of pressure which in turn starts steller fission without there being an star. Mind-blowing

Yep, it’s a super cool concept. A black hole of a given size has a finite amount of matter that it can ingest over a period of time. Trying to stuff more matter into it causes an outward pressure from essentially the friction of the swirling mass of material falling in. This radiation pressure could in theory be great enough to start fusion as would happen in a stellar core.

Also fun is that this puts a limit on the largest possible black hole we should ever see in the universe. If you assume a black hole formed a moment after matter condensed and then ingested the maximum possible from then until now, you get an upper bound for the largest possible black hole according to our current understanding of the universe. This limit is somewhere around 36 billion solar masses.

Re: Astrophysicists Puzzle over Webb’s New Universe

#114

Post by technotony »

stouset wrote: post #113
hparadiz wrote: post #94

Little red dots are my favorite new concept in astrophysics. This idea that there could be so much matter orbiting a black hole that the matter reaches sun levels of pressure which in turn starts steller fission without there being an star. Mind-blowing

Yep, it’s a super cool concept. A black hole of a given size has a finite amount of matter that it can ingest over a period of time. Trying to stuff more matter into it causes an outward pressure from essentially the friction of the swirling mass of material falling in. This radiation pressure could in theory be great enough to start fusion as would happen in a stellar core. Also fun is that this puts a limit on the…

Couldn't those large black holes merge though to get bigger ones?

Re: Astrophysicists Puzzle over Webb’s New Universe

#115

Post by wwind123 »

somenameforme wrote: post #96
Tazerenix wrote: post #34

Earlier quoted context omitted.

The evidence for the big bang is generally not that if you look far enough back in a telescope, the universe looks younger, which is somewhat the layperson's confusion. Evidence for the big bang is about measuring redshift of galaxies throughout universal history, homgeneity and thermal equilibrium of the universe and CMBR, which could only be explained by it all having been in a compressed location where it could re…

I think you're leaving out a major issue there. Homogeneity was not in favor of the big bang. It's actually a major problem - the horizon problem. [1] Parts of the universe (think opposite sides) are not causally connected. Even traveling at the speed of light, there would not be enough time for a particle in one side to reach the other since the birth of the universe. Yet the temperature within these regions is homo…

I kind of understand your frustration about the ad-hoc nature of the Inflation theory. When I was younger I believed the truth must be simple and beautiful - if a theory is complex and ugly then it's not the real truth. But as I get older, now I think the universe is what it is. Things may or may not have a simple or elegant explanation. Theories exist to explain things and make predictions. As long they serve both purposes well, then they are the working theories.

Re: Astrophysicists Puzzle over Webb’s New Universe

#116

Post by rolph »

stouset wrote: post #113
hparadiz wrote: post #94

Little red dots are my favorite new concept in astrophysics. This idea that there could be so much matter orbiting a black hole that the matter reaches sun levels of pressure which in turn starts steller fission without there being an star. Mind-blowing

Yep, it’s a super cool concept. A black hole of a given size has a finite amount of matter that it can ingest over a period of time. Trying to stuff more matter into it causes an outward pressure from essentially the friction of the swirling mass of material falling in. This radiation pressure could in theory be great enough to start fusion as would happen in a stellar core. Also fun is that this puts a limit on the…

a tokomok involving a scale appropriate blackhole is a super cool concept that just came to mind

Re: Astrophysicists Puzzle over Webb’s New Universe

#117

Post by HenryBemis »

This comment will not contribute anything, and/but it is a thought that I had a few days ago, and I cannot 'shake' it. We keep 'discovering', recognising, mapping, etc. And I feel that every 'breakthrough' is "one step closer" (let's say 100 steps total), on a journey that is a thousand miles long. So, for the past 4000 years (or whichever century we can call the 'birth of astronomy'), we have accumulated 'this much' knowledge, and still we know a speck of sand in a vast desert, and perhaps now we have accelerated the rate of knowledge gathering, but still we are SO FAR.. ufff..

Re: Astrophysicists Puzzle over Webb’s New Universe

#118

Post by mejari »

theodorejb wrote: post #39

Instead of questioning whether the Big Bang assumption is true, astrophysicists prefer to perform endless "gymnastics" to try to make the mounting contrary data fit their theory about how the universe began.

The big bang isn't a theory about how the universe began, so I think you have a fundamental misunderstanding of these topics.

Re: Astrophysicists Puzzle over Webb’s New Universe

#119

Post by rhesa »

6thbit wrote: post #15

That’s a beautiful article showcasing our predicament in having access to more information about the universe. Now i have to be the one to ask the dumb defensive question: what makes us so certain that we can trust what we see on James Webb? Can we definitely discard a measurement problem?

Have a look at David Kipping's video on Cool Worlds: https://www.youtube.com/watch?v=QCKrUZeiTJo . It goes into a bit of detail on compensating for systemic issues in JWST.
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