NBODYPHSYICS!!!!11!!!

[Arugela]

Have they gone over the idea of nbody physics, but making up for the difference with things like mega eruptions and surface features that actually make them stay in orbit? It could lead to all sorts of fun speculation as to what the planets are made of and how old the system is or various things.

If it's fiction. Use fiction as the solution. But do it in a more realistic way for fun.

If the point of the game is basic orbital mechanics. why not make the planets run off the same logic with the same premiss. Then some of the planets might be moveable. 8d (more than you might think if the balance is delicate enough.)

The kerbils will then make their own demise!!!! (post apocolyptic genre in the making.) with thier level of stupid it only makes sense. 8)

Maybe a mission to keep putting gilly back in place would be fun.

This could be preceded by a mission to super mine a very specific spot(A very dense spot possibly, or the core.) on gilly that just so happens to destabilize it. Then the kerbals, in all their stupidity, have to keep fixing it or make a super engine node to keep it in place until it mines itself out. This then, with enough fast forward, could then result in capturing asteroids with a super collector to refill the planet one day. Or keep refilling it until you get tires and let it drift off. Lots of stupid kerbal things could spring from this.

You could even let the planets intelligently put themselves into the correct orbit as the move away via their actual, "thrusters."

Edited January 18, 2021 by Arugela

[Incarnation of Chaos]

N-body isn't happening in stock

If you want to see it in KSP, go grab yourself a copy of principia and knock yourself out.

[Bej Kerman]

Planets are unimaginably heavy and virtually immoveable. The only purpose Nbody has here is to make the Kerbol system unstable and potentially unuseable. In response to this,

10 hours ago, Arugela said:

Then some of the planets might be moveable. 8d (more than you might think if the balance is delicate enough.)

I say: No, you've got it the wrong way around. Planets are always more difficult to move than you could imagine.

10 hours ago, Arugela said:

Maybe a mission to keep putting gilly back in place would be fun.

It would also take millions of years.

Edited January 18, 2021 by Bej Kerman

[KawaiiLucy]

There is no analytic solution to a problem with more than two bodies, all you can do after 2 is computation which is extremely resource intensive. Furthermore the gravitational force is inversally proportional to the square of the distances, so distant objects pull can be neglected. While yes it would lead into more "realism" it takes away the playability of the game as the stock system would highly likely be unstable. Patched conics are literally 2 body motions btw.

[steuben]

To expand on why it is very unlikely, never is a word used more frequently than wisely, to be added to stock KSP requires the invocation of that dreaded, for some, topic Math!

The first and minor aspect is that a planetary system is one of the classic examples of a chaotic system. Over geologic, and even non-geologic, periods the bodies _will_ wander by a lot. This is why you may have heard of the phrase geologically stable orbit. Or at least something like it. For example the Moon, the Galilean moons, and the planets have geologically stable orbits. But step out side of that the orbits will wander. The  Ancient Greeks called them πλανήτης, not for that reason but it was apt. If you try any simulation of something with n-bodies (excluding n=2) you will rapidly end up with radically diverging progressions even for very slight  changes in initial conditions, and even with the same initial conditions. One of the main definitions of a chaotic system.

The second and major aspect is that the number of calculations goes up with the square of the number of bodies, or near enough that it make no difference. Every body in the simulation interacts with every other body. And digital electronic computers, or their cores, have trouble doing more than one thing at one, though they can fake it really well. Your processing time per cycle will rise _very_ quickly for each additional body added. Start factoring in floating point error and things get very... interesting, very quickly.

Sure you could add in a "calibration period", but the you have to figure out how to deal with "orbital snap"

 

[vv3k70r]

7 minutes ago, steuben said:

The second and major aspect is that the number of calculations goes up with the square of the number of bodies

Almost = n(n-1)

8 minutes ago, steuben said:

Start factoring in floating point error and things get very... interesting, very quickly.

Exactly. I did = I know.

[kspnerd122]

there are several reasons this will never be added. one, KSP's star system is unstable gravitationally, such as the jool system, which destroys itself under Nbody(tested this in Universe Sandbox, with Identical masses) Moons end up colliding and getting ejected, not fun. also, how good is your PC, mine isn't the best right now(I got a better one tho, need to set it up) N body would just make ksp unplayable on anything other than a dedicated gaming PC. and three, it will just make everyone upset(and make the game harder) because now, because jool is so big and so close, it screws up my duna mission and I cannot correct it because I need that fuel to slow down, to orbit, and get home to kerbin.

[jimmymcgoochie]

When you add Principia to stock KSP to get n-body physics, it results in the ejection of Minmus, Bop and possibly Vall from their respective planets’ gravity wells. It’s also a lot harder to know where you’re going if, for example, you’re trying to go from Kerbin to Duna but the gravity of Eve and Jool can knock you off course. Unlike real space agencies, who have supercomputers to crunch the numbers and calculate their trajectories to the nth degree, the average KSP player does not.

Copy your current version of KSP and stick  Principia into it, then just watch the chaos unfold in the tracking station...

[Guest]

On 1/18/2021 at 7:57 AM, Arugela said:

Have they gone over the idea of nbody physics

Yes. It's not happening, but Rask/Rusk will have some kind of bespoke solution that creates some of the challenges associated with it.

On 1/18/2021 at 7:57 AM, Arugela said:

but making up for the difference with things like mega eruptions and surface features that actually make them stay in orbit

/me backs away slowly

Edited January 20, 2021 by Guest

[Arugela]

They could be unrealistic as a joke. That is why I referenced it as fiction. They could make it as unrealistic as the system itself to give the system an explanation. They could even give it infinite fuel to joke the planets are useing cheats. They don't have to calculate it completely. It could be part of the joke.

It's just on rails with nbody instead of pure on rails. The idea is more internal consistency than is is pure nbody.

Edited January 20, 2021 by Arugela

[Guest]

3 hours ago, Arugela said:

It's just on rails with nbody instead of pure on rails.

You can't have n-body on rails, any more than you can have corners in a circle.

[Arugela]

I meant effectively on rails. By having unrealistic large burns.

[James M]

On 1/18/2021 at 11:55 AM, Bej Kerman said:

Planets are unimaginably heavy and virtually immoveable. The only purpose Nbody has here is to make the Kerbol system unstable and potentially unuseable. In response to this,

I say: No, you've got it the wrong way around. Planets are always more difficult to move than you could imagine.

It would also take millions of years.

"With a large enough lever, man could move the world"

I pictured a huge stick structure going for miles off Gilly's surface and then a huge amount of engines at the end spinning it faster xD 

[vv3k70r]

On 1/20/2021 at 1:15 PM, Arugela said:

I meant effectively on rails. By having unrealistic large burns.

So on rails or on body physics?

What to refer when planing manouver?

 

[Meecrob]

On 1/20/2021 at 4:03 AM, Arugela said:

They could be unrealistic as a joke.

You might be missing the point of why most people play KSP.

[Bej Kerman]

On 1/20/2021 at 9:03 AM, Arugela said:

They could be unrealistic as a joke. That is why I referenced it as fiction. They could make it as unrealistic as the system itself to give the system an explanation. They could even give it infinite fuel to joke the planets are useing cheats. They don't have to calculate it completely. It could be part of the joke.

It's just on rails with nbody instead of pure on rails. The idea is more internal consistency than is is pure nbody.

Yes, why not enable everything in the cheat menu by default as a 'joke'? "Make it unrealistic" won't make your ideas any less bad as the entire point of KSP is that even the most unrealistic parts of the game are semi-realistic. IRL you won't find 600km dwarf planets with a thick atmosphere and 1g of gravity, but the way the laws of physics are set up in KSP allows most physics to mirror the real world decently. But, in either universe, moving planets is an absurd and silly idea. Claiming it's a joke doesn't make it any less absurd or any more logical.

[Incarnation of Chaos]

11 hours ago, Bej Kerman said:

Yes, why not enable everything in the cheat menu by default as a 'joke'? "Make it unrealistic" won't make your ideas any less bad as the entire point of KSP is that even the most unrealistic parts of the game are semi-realistic. IRL you won't find 600km dwarf planets with a thick atmosphere and 1g of gravity, but the way the laws of physics are set up in KSP allows most physics to mirror the real world decently. But, in either universe, moving planets is an absurd and silly idea. Claiming it's a joke doesn't make it any less absurd or any more logical.

Nor save you from the performance implications

Firing a thruster to keep this planet on it's wanted path, on top of the calculations for how that affects the rest of the bodies? Well you'd end up needing more thrusters on more planets, and i could see race conditions developing quite easily leading to all the issues of N-body with none of the advantages of it when realistically implemented.

But you probably would see several planets exceed the speed of light as they rode the imaginary thruster kraken out of the Kerbol system, so at the least it would be a hell of a show while unraveling.

[RealKerbal3x]

@Arugela This is a good video on why moving even the tiniest moon is really hard:

 

[Arugela]

I know it's hard. I was going for parody using volcanoes or similar to explain the already existing unrealism. It's following internal logic.

[Bej Kerman]

1 hour ago, Arugela said:

I know it's hard. I was going for parody using volcanoes or similar to explain the already existing unrealism. It's following internal logic.

And that's why no-one finds the idea appealing.

[SpaceFace545]

On 1/18/2021 at 11:55 AM, Bej Kerman said:

I say: No, you've got it the wrong way around. Planets are always more difficult to move than you could imagine.

Unless you do it Wandering Earth style.

eg: hundreds of thousands of massive fusion engines that somehow run off of rocks.

[Bej Kerman]

1 minute ago, SpaceFace545 said:

On 1/18/2021 at 4:55 PM, Bej Kerman said:

I say: No, you've got it the wrong way around. Planets are always more difficult to move than you could imagine.

Unless you do it Wandering Earth style.

eg: hundreds of thousands of massive fusion engines that somehow run off of rocks.

 

Fortunately, nothing we've observed has that many colossal volcanoes erupting 24/7.

[Incarnation of Chaos]

5 hours ago, SpaceFace545 said:

Unless you do it Wandering Earth style.

eg: hundreds of thousands of massive fusion engines that somehow run off of rocks.

....While I'd have no idea how you'd achieve it terrestrially, the primary component of rocks is Silicon.

Spoiler

https://en.wikipedia.org/wiki/Silicon-burning_process

I can't think of a single material that would be able to contain the resulting temps and radiation, and by the time you consumed enough rocks to move the planet you might have very well consumed a decent portion of it's entire mass. But from a pure "Is it physically not impossible" standpoint, you might be able to run Fusion Reactors off "Rocks" by doing something similar.

 

[Bej Kerman]

https://youtu.be/Dgu1syQP124

TL;DW: Trying to use any planet as a rocket would destroy it.

[Incarnation of Chaos]

14 hours ago, Bej Kerman said:

https://youtu.be/Dgu1syQP124

TL;DW: Trying to use any planet as a rocket would destroy it.

Don't remember what he said exactly, but wasn't it essentially that the force from acceleration would overcome the gravitational force keeping the planet bound?