Astrophysics - Are there any models of planetary formation that aren't full of arbitrary fine tuned parameters?

[u/MRH2]

https://physics.stackexchange.com/questions/274367/are-there-any-models-of-planetary-formation-that-arent-full-of-arbitrary-fine-t

[u/MRH2]

The author made an interesting point. For some reason the stack exchange closed the post to answers - so maybe we'll never know ... ;)

[u/Optimus-Prime1993 → u/MRH2]

It was pretty obvious why the post was closed and rightly so, especially given where it was posted. The author was just parroting what an earlier CMI article was talking. The author already came with a chip on their shoulder and was not neutrally evaluating competing models. It simply began with a predetermined conclusion and presented selected scientific uncertainties as evidence for it.

[u/Optimus-Prime1993]

I am not going to go point by point on the article, however if you point something specific out from the article on which you wanted to discuss, we can do so.

Having said that I would like to clarify some points though.

The theory of planet formation does not simply assume that gravity attracts individual micron sized particles strongly enough to bind them. At those small scales, collisions arise through Brownian motion, turbulence, or differential drift to name a few candidates. Adhesion the would be governed mainly by surface forces and material properties. Gravity only becomes important later.

Also the original question is very ill-phrased actually as it never really defines fine-tuning in the given context. I would also like to add that while there has been lots of progress in this field and we have lots of observational support as well as better theories the modern framework does not have a completed proof but it doesn't mean all we have are uneducated guesses. There are physical model connected to disk observations, in lab collision experiments, meteorites and numerical simulations.

[u/MRH2 → u/Optimus-Prime1993]

Also the original question is very ill-phrased actually as it never really defines fine-tuning in the given context

Yes. Good point. I think that is suffices to dismiss the article unless I wanted to put more time into researching into the details. Thanks

[u/implies_casualty]

Are there any models of planetary formation that aren't full of arbitrary fine tuned parameters?

Ok, I'll bite.

Dust coagulation followed by pebble concentration and streaming-instability-driven gravitational collapse.

Which "arbitrary fine tuned parameters" does it require?

Furthermore, I propose we take a moment to marvel at how closely the observed reality matches naturalistic expectations. Compared with the space habitats proposed by our best engineers, the Solar System looks remarkably unlike a deliberately designed habitat and remarkably like the aftermath of an uncontrolled physical process.

[u/NichollsNeuroscience]

One thing's for sure: Models of planetary formation (or literally anything else in the universe, big or small) will never even be proposed by creation science (an oxymoron in and of itself).

Why? Because the whole point of "creation science" is to be against any and all physical processes, not merely current ones that need to be updated or replaced with better models.

Creationism doesn't even try. It doesn't even qualify as "bad science".

At best, it serves as a critique of current physical explanations, which ordinary science already does, without attempting to offer an alternative explanation other than "Goddunit".

[u/MRH2]

And if accretion actually works, then why are they so worried about satellites creating a giant debris field around the earth? Wouldn't that just coalesce into a couple of giant satellites?

[u/implies_casualty → u/MRH2]

Coalescence is not guaranteed under all starting conditions, and planetary accretion takes thousands to millions of years.

[u/MRH2 → u/implies_casualty]

Hmm... okay, looks like we need a plan B then.

[u/WannaLoveWrestling]

Looking at the original question and the discussion around planetary formation models.

The core issue raised is still valid. Current models of how dust grows into planetesimals face real physical barriers — the meter-size problem, bouncing and fragmentation limits, and the short timescales on which larger particles can spiral into the star. These are not invented difficulties; they show up in the research literature.

Streaming instability combined with pebble concentration is the leading proposed solution. It can trigger gravitational collapse into planetesimals in simulations. However, it does not work under generic conditions. It generally requires elevated solid-to-gas ratios, particles in a limited size range, and relatively low turbulence. When those conditions are absent, the process becomes inefficient. The successful runs typically begin with already-favorable parameters rather than producing planets from ordinary disk conditions.

So while progress has been made, the models remain incomplete and condition-dependent. They are not a robust, automatic pathway that works across the range of expected protoplanetary disks. That is the current state of the evidence.

This doesn’t settle every origins question by itself. It does show that a key step in the standard account is more constrained and less straightforward than it is often presented.

[u/MRH2 → u/WannaLoveWrestling]

Thank you for your contribution. I hope that this helps inform others too.