Talk:Nebular hypothesis

Exoplanets
Why is there no mention of exoplanets? Surely the 3,524 exoplanets that have been found have some sort of significance inside of a model which claims to explain their existence? Or is it that the 3,524 exoplanets found defy the nebular hypothesis so there can be no mention of them made here? Elephant in the room Wavyinfinity (talk) 21:39, 10 November 2014 (UTC)


 * Exoplanets are simply not as well studied as our own system. It difficult to know the precise mass and diameter of most of these exo-planets, much less where and how big their various equivalents of the asteroid belt(s) and Kuiper belt(s) are (might be). We simply need to know more. We also need to better understand planetary migration as in the case of the nice model. -- Kheider (talk) 22:10, 10 November 2014 (UTC)


 * The Nice model does not solve the main issues. How did the planets lose their angular momentum? How do 1cm sized particles clump together? How do rocks and minerals form absent the activation energy required for non-spontaneous chemical combination reactions? How do gas giants form from a quickly disappearing disk? It appears to me that the Nice model does not solve anything, but only adds more problems, because now we have to explain how stable orbits become unstable just so they be arranged in the way we see them. Wavyinfinity (talk) 12:57, 11 November 2014 (UTC)


 * I would not worry about it. This nebular hypothesis page is only going to serve as a footnote in history, similar to the flat earth page. Oh and I went ahead and updated that count to make the matter more pressing, I hope you don't mind it bulwarks your point.Trilliant (talk) 13:33, 20 June 2016 (UTC)

-- Kheider (talk) 14:07, 11 November 2014 (UTC)
 * After the planets scatter one another, the planets orbits can become circular by scattering asteroids and comets.
 * The first 1cm sized clumps would have to stick together from low velocity impacts as there were no massive bodies to scatter them into eccentric orbits.
 * We know the Suns birth nebula contained micron-sized diamonds. Partially differentiated nascent planets would contain rocks and minerals.
 * The gas giants formed before the proto-sun matured.


 * These are bad explanations as they completely ignore both chemistry and thermodynamics (see below). Why are chemistry and phase transitions ignored?

Wavyinfinity (talk) 15:20, 11 November 2014 (UTC)


 * Chemistry and hydrated minerals on protoplanets such as 4 Vesta are a major area of planetary study. -- Kheider (talk) 16:10, 11 November 2014 (UTC)


 * So why is chemistry and thermodynamics not mentioned at all on this page, regardless if all the objects in the solar system are comprised of elements and the compounds they form? As well, where in the nebular hypothesis is it mentioned why objects are still hot even 4.5 billion years after they formed and some are not? This article reads like 18th century conjecture and needs to be updated. Wavyinfinity (talk) 20:31, 21 July 2015 (UTC)

how planets form draft--- i want to create a whole article on how planets form, but they won't let me because of this article.Aleks the science lover

Chemistry
Why is there no mention of chemistry? Are not asteroids comprised of rocks/minerals? The gravitational potential energy of a large asteroid does not contain the activation energy to synthesize rocks (non-spontaneous chemical reactions) in outer space. Why is this also completely ignored? Or am I wrong to consider science as a multidisciplinary subject? Wavyinfinity (talk) 12:09, 11 November 2014 (UTC)


 * It literally feels as if this model was invented before chemistry became an actual science. I would suggest placing a tag on this article stating that it is severely out of date and does not reflect modern science. Wavyinfinity (talk) 15:47, 11 November 2014 (UTC)


 * I suggest we keep handwaving and pseudoscience out of Wikipedia. -- Kheider (talk) 16:10, 11 November 2014 (UTC)


 * You haven't answered the question. Why in this entire article the arguably most important physical science ignored?Wavyinfinity (talk) 20:35, 11 November 2014 (UTC)

Thermodynamics
Why is there no mention of thermodynamics? You know, simple phase transitions of matter, plasma (physics) becomes gas, gas becomes solid/liquid matter and vice versa? The writers of this article have completely avoided talk of thermodynamics, regardless if the objects being mentioned are literally made of plasma, gas, liquids and solids. That is like talking of storms but not mentioning rain or winds. Wavyinfinity (talk) 12:17, 11 November 2014 (UTC)

Accretion disks claimed to be very hot
The text says: "Initially very hot, the disk later cools in what is known as the..." The temperature in accretion disks in all phases of their evolution has complex spatial gradients. They are hot (up to 2500 K) near the star and warmer (few 100 K) on their surface and the outer accretion shock, but there are large regions even in young accretion disks with temperatures of a few 10 K only. Hence the current sentence is wrong, and I would remove it. — Preceding unsigned comment added by 90.18.196.171 (talk) 09:22, 26 August 2023 (UTC)

Plasma
The forth state of matter is not mentioned in this entire article, even though all hot stars are comprised of it. You do not have to believe me, read the entire article! The words plasma or ionization or recombination are not mentioned anywhere. The most abundant observed state of matter in the entire universe is ignored. Why?Wavyinfinity (talk) 21:27, 11 November 2014 (UTC)

Three Theories of Planet Formation Busted
http://news.nationalgeographic.com/news/2011/02/110222-planets-formation-theory-busted-earth-science-space/

This is in response to the statement, "(explanation) including the nearly circular and coplanar orbits of the planets." Yet the article via National Geographic clearly points to, "newly discovered star systems defy existing models of how planets form", and "theory has struck out", and "theory has implications not born out in reality."

The nebular hypothesis is falsified theory because it does not represent reality. I cannot see that being any clearer. Why is it not mentioned that exoplanets falsify this theory (hypothesis)? This has been known for over 4 years now, as the article was written Feb. 20, 2011. Wavyinfinity (talk) 12:42, 7 June 2015 (UTC)
 * Any more sources beyond that? Because while I agree it should be said in the article if confirmed, the article you gave makes pretty clear the theory is falsified according to one specific expert, and that other experts aren't nearly so sure the theory itself is wrong, rather than the models. ("Still, some experts aren't quite ready to give up on current theories,"; "To run enough simulations to get a meaningful distribution of possible results, he said, it's necessary to use stripped-down versions of these models. But the "quicker" models come at a price, and their failure to match exoplanet reality doesn't necessarily mean theory is wrong.").


 * So, can we say on basis of this single article that the theory is busted? Not really. We can probably safely say that the models in use do not work&mdash;both of the experts they cited certainly agree on that much, as would anyone who compares said models with the data we currently have&mdash;but to proclaim in Wikipedia's voice that it "is a falsified theory" rather than that "According to Geoffrey Marcy, the theory is falsified" goes a bit far when based on just this one article&mdash;an article that gives another explanation, also cited to an expert, for the differences between the models and the actual data to boot. AddWittyNameHere (talk) 14:55, 7 June 2015 (UTC)


 * Here is another article stating quite clearly that, "extra-solar giant planets has however revealed an unexpected large diversity among these systems which cannot be explained within the framework of this working paradigm."http://adsabs.harvard.edu/abs/2001AGM....18S0407B This is obviously in reference to Hot Jupiters. As well, when one digs deeper it has become clear that even more objects which outright falsify the nebular hypothesis have been found, "astronomers were surprised to find that six out of a larger sample of 27 were found to be orbiting in the opposite direction to the rotation of their host star the exact reverse of what is seen in our own Solar System. The new discoveries provide an unexpected and serious challenge to current theories of planet formation." http://www.astro.gla.ac.uk/nam2010/pr10.php Should we assume that "serious challenge to current theories" as something that will go away? Or does it mean that the current theories are false? As well, no mention is made of these retrograde objects in the nebular hypothesis page. Again, these realizations happened four years ago, yet not a peep on this page about the controversy? Why? It is becoming obvious this page is outdated and should probably not be trusted as a credible source for accurate, up to date information.Wavyinfinity (talk) 19:19, 21 July 2015 (UTC)
 * What you cite are not scientific publications. At best it is just one abstract from an obscure conference. You have failed to cite a single publication from any peer review journal. Ruslik_ Zero 10:47, 22 July 2015 (UTC)


 * I wouldn't say they are busted, the simple versions don't include possible instabilities which can result in encounters between planets. In the Nice model the planetesimals damp the inclinations of the planets but this may not have been sufficient if Jupiter encountered Saturn, if more than one Jupiter-massed planet formed, or if their migration continued without a 'Grand Tack' leaving massive planets in close proximity. Encounters can leave planets with large eccentricities and inclinations which will remain if the planet is much more massive than the planetesimal disc that remains after they've formed. Agmartin (talk) 19:37, 7 March 2016 (UTC)

Recent Research
A couple of papers describing new models for the formation of planetesimals. New Paradigms For Asteroid Formation, The multifaceted planetesimal formation process.

And another which integrates accretion, migration and recent models of protoplanetary discs. The growth of planets by pebble accretion in evolving protoplanetary discs

I've written articles for streaming instability and pebble accretion and am now looking at how and where to integrate parts of these topics into articles like this one. Suggestions welcome. Agmartin (talk) 19:19, 7 March 2016 (UTC)

Subsection "Problems and criticism" needs work
Subsection 2.2 Problems and criticism looks like it needs work. The tone, whether intentional or not, smacks of Intelligent design (a form of creationism). For example: "The formation of planetesimals is the biggest unsolved problem in the nebular disk model. How 1 cm sized particles coalesce into 1 km planetesimals is a mystery." Our own article Planetesimal does a pretty good job of summarizing what scientists have come up with. Of course there are kinks to be worked out, but it is not "a mystery."

Next: "The formation of giant planets is another unsolved problem. Current theories are unable to explain how their cores can form fast enough to accumulate significant amounts of gas from the quickly disappearing protoplanetary disk." Over the last few weeks, I've read a bunch of research papers on this. There are apparently quite a few mechanisms by which this could have occurred. It's just a matter of reaching a consensus on which one is the most likely, or if it was a combination of mechanisms.

The last paragraph in this subsection, which quotes Newton as saying "the growth of new systems out of old ones, without the mediation of a Divine power...is absurd" should be moved to the history section.

Finally, the title of this subsection should be changed to something like "Current issues." The phrases "unsolved problem" and "unsolved mystery" stand out like sore thumbs. Zyxwv99 (talk) 22:51, 25 March 2016 (UTC)
 * The formation of planetesimals is discussed in the 'Protoplanetary disks' section with a couple of proposed solutions mentioned. Perhaps a few brief sentences should be added mentioning these in the 'current issues' subsection as has been done with angular momentum. The migration of the planets is also an evolving field. In addition to the Grand Tack, I have seen planet traps, where the structure of disk causes migration to halt; and things like co-rotational torques, heating torques discussed recently. Agmartin (talk) 21:10, 26 March 2016 (UTC)

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Hierarchical collapse
The NGC 2174 or Monkey Head Nebula article states 'The nebula may have formed through hierarchical collapse.' Should 'hierarchical collapse' link to 'Nebular hypothesis' please, or is there a better target? John a s (talk) 15:33, 17 April 2019 (UTC)
 * This is a possible alternative https://en.wikipedia.org/wiki/Star_formation#Cloud_collapse Agmartin (talk) 16:41, 17 April 2019 (UTC)
 * Thanks! 19:00, 17 April 2019 (UTC)

General Editing Note
I'm a new editor and don't know a lot about this topic, but wanted to point out that the introduction is not pleasant to read- I think it could be condensed a little bit and some parts reworded. E.g. I was especially thrown off by the sentence "They considered that sun was surrounded by a solar nebula containing mostly the hydrogen and helium along with what may be termed as dust" ; I had to go back and re-read to figure out the antecedent of "they" and "that sun" was confusing. Maybe switch to "They considered that the early sun was surrounded.." or "Scientists considered that the early sun was surrounded.."? Fluffystat (talk) 22:47, 25 June 2020 (UTC)

Introduction
Why this insertion in the introduction? https://en.wikipedia.org/w/index.php?title=Nebular_hypothesis&type=revision&diff=921654431&oldid=921653936

It is not an article on Chamberlin theory, moreover the next sentence after this theory is "It is the most widely accepted model" which is ambigious. 2A01:E0A:589:4E20:2927:EA5F:D928:3D3 (talk) 17:31, 2 July 2020 (UTC)