19 Apr 2024 17:40:09 UTC

Topic 231018

(moderation:

Scientists say they have found evidence of an unknown planet in our solar system. New findings represent the ‘strongest statistical evidence yet’ that Planet 9 exists, researcher says.

https://www.independent.co.uk/space/planet-9-nine-solar-system-b2530985.html

A paper describing the work, ‘Generation of Low-Inclination, Neptune-Crossing TNOs by Planet Nine’

https://arxiv.org/pdf/2404.11594.pdf

George

*Proud member of the Old Farts Association *

Language

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## Yes, they use computation of

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Yes, they use computation of possibilities :

'

... we carry out comprehensive N−body simulations that self-consistently model gravitational perturbations from all giant planets, the Galactic tide, as well as passing stars, stemming from initial conditions that account for the primordial giant planet migration and sun’s early evolution within a star cluster'Seems all encompassing. Anyway this yields

predictions^{*}ie. go and have a look and see if anything is there!'...

herein offer a set of readily-falsifiable predictions, with near-term prospects for resolution'Proper science then. They suggest a measurement of the

orbital distribution of the class of objects considered.Notably the initial timestep was 100 days and an entire simulation time was 4 billion years! If they mentioned where they did the calculations, what hardware was used etc, I can't see that written.

Now if there is a Planet Nine found it will be an amazing thing indeed. For instance it's surface will probably be strewn with all those lost ballpoint pens ... the red ink ones especially.

* That overall methodology of predict-look-see has a long historical pedigree eg. Neptune was discovered (by Johann Gottfried Galle) via looking in the sky where calculations (by Urbain Le Verrier & John Couch Adams independently) said it should be. Post facto it had been seen by several others including Galileo. There's a similar story for Pluto. Gosh all those guys were smart.

Cheers, Mike.

I have made this letter longer than usual because I lack the time to make it shorter ...

... and my other CPU is a Ryzen 5950X :-) Blaise Pascal

## Mike Hewson wrote: Yes, they

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Mike Hewson wrote:Yes, Mike, you are

absolutelycorrect!! I for one couldn't even DREAM of these planets!Proud member of the Old Farts Association## Mike Hewson wrote: Yes, they

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Mike Hewson wrote:Are the "

N−body simulations" they use similar, or even the same, as the MilkyWay Boinc Project is using? I guess I'm wondering if the work being done by MilkyWay is or could be used to find "Planet Nine"?mikey## Short answer : Yes they are

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Short answer: Yes they are similar, but no you can't use their results. Each N-body simulation is different in the number of bodies and the so-called initial conditions plus some other stuff.Long Answer: N-body simulation is a general idea rather than a specific technique. The idea is that the gravitational force law is expressed in terms of two bodies (let's assume they are using Newton's Law of Gravity or some expression derived from that). Now if you only have two bodies in your simulation the mathematics is the simplest, the orbits are all 'conic sections' : circles, ellipses, parabolas, hyperbolas etc, depending on the total energy in the system. Now if you put in even a single extra body (ie. N>2) you can no longer solve the equations in 'closed form', put another way there is no neat mathematical function that describes the situation. But one can solve for the evolution of the system - where are all the bodies and how are they moving - by simulation or mathematical approximation. This is a time step method and each body is assumed to move according to some average influence over a short enough interval. To mitigate the errors of approximation the time steps may vary and the whole situation is subject to checks so that conservation laws (energy, momentum, angular momentum) are upheld. But this explanation is too simple (& dated) to describe what they actually do. There are a lot of references in the paper to earlier studies that have dealt with the methodology. It seems quite a refined, and arcane, field of study so that if Planet Nine is verified as a true finding then the methods are also validated.Cheers, Mike.

I have made this letter longer than usual because I lack the time to make it shorter ...

... and my other CPU is a Ryzen 5950X :-) Blaise Pascal

## Mike Hewson wrote: Short

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Mike Hewson wrote:That helps alot thanks!!

## If there is significant

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If there is significant evidence (or probabilities) for a Planet Nine, scientists should quickly find an appropriate Roman name for it, while there is still plenty of time to think and consider.

## Scrooge McDuck wrote: If

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Scrooge McDuck wrote:I would think there would be alot of support to just bring back Pluto as it was dropped because the then Pluto wasn't a planet after all.

## My vote, not that anyone is

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My vote, not that anyone is counting on me, is for

. ;-)Planet ClaireCheers, Mike.

I have made this letter longer than usual because I lack the time to make it shorter ...

... and my other CPU is a Ryzen 5950X :-) Blaise Pascal

## mikey schrieb: I would think

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mikey wrote:This will lead to an outcry from these people: www.plutoisaplanet.org/