All right, so I have a game that I already made, the concept is that there are "planets" that do not move and ships that can stand still without being sucked in to the gravity of the planets.

I need some way to explain how those huge planets are standing around the way they are and how the players are able to stay away from the planets.

  • The planets are not necessarily spinning around a star, they could be spinning around any celestial body you want or not spinning around anything at all.

  • I'm not looking for hard science, I'm looking for plausible ways to explain this.

  • The planets are spinning around themselves but not each other.

  • To be even more clear, this does NOT have to be a naturally occurring phenomena. It can be a man made system.

Reference gif: https://media.giphy.com/media/l0Iy1ObhDXY9FW3bG/giphy.gif

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    $\begingroup$ Why do the planets have to be stationary because of their arrangement in a solar system? Couldn't they simply appear stationary for the purposes of the game because they're moving very slowly compared to the ships? Or to put it another way, at first glance it doesn't look like a game where I as the player would demand that the planets be arranged realistically as long as the gameplay was fun - is there something I'm missing that makes that more important? $\endgroup$ – Ben S. Apr 24 '17 at 21:19
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    $\begingroup$ I agree with Ben. The best answer is "because it's fun." If you start worrying about science, you also start worrying about how your planets are easily 20,000 times too close together for "realism." You also probably have to explain why you have a spaceship the size of Mars! Science is pesky! $\endgroup$ – Cort Ammon - Reinstate Monica Apr 24 '17 at 21:30
  • $\begingroup$ Well, like I said, I wanted a plausible explanation for it. Why not explain it if I can? I plan on making more games in this universe, so it's not a one time thing to throw away. Also, I don't really understand what's the case with the downvotes, no explanation given by anyone, not really helpful. I can explain the ship sizes with "they just seem big for gameplay purposes but they're actually really small". The planets looking so close to each other and not being pulled together is a thing I'd have to explain. $\endgroup$ – John Hamilton Apr 25 '17 at 2:56
  • $\begingroup$ Downvotes aplenty, but there's still no explanation. There's also a close flag... I really don't understand what's wrong with the question I'm asking... $\endgroup$ – John Hamilton Apr 25 '17 at 5:48
  • $\begingroup$ We have a fair number of questions on WorldBuilding in the form "Can you please show me how to use the laws of physics to break this law of physics." I think it makes people touchy regarding any physics question which tries to ask something like that. Trying to effectively refute gravity would qualify. Myself, I can't think of any way within the science-based tag to pull this off short of just turning off gravity completely, but I'm curious to see if someone more creative than I can make it happen! $\endgroup$ – Cort Ammon - Reinstate Monica Apr 26 '17 at 18:57

A billion years ago, an advanced race of long-vanished aliens created a spacial dampening field in this star cluster. Whether it was a weapon of mass distruction, an industrial accident, or an intentional act of mega-engineering is unknown but hotly debated.

In any case, the effect is that all objects are locked into position, and experience drag against the damper. Orbital motion is exactly cancelled, and ad-hoc thrust will have normal reaction but the object will experience drag in proportion to the square of the velocity.

This means that the entire star cluster has “ocean mechanics” rather than orbital mechanics. It even means that you can row a spacecraft.

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    $\begingroup$ Oooh, I like this, the plasma weapons that are fired can effectively be torpedoes that do get affected by gravity of the planets, or they could go just above the "surface" of the "ocean" these precursors made. Nice, I'll pick this in a few days if I don't see anything better :) $\endgroup$ – John Hamilton Apr 27 '17 at 5:42

Welcome to Bizarro Physics Department! Kindly step this way we may have an answer for your interesting problem. Firstly, throw away all notions of conventional and rational physics. It's time to turn the dial up to "bizarre"!

Assume the planets all stationary relative to each other because spacetime and gravitation operates differently. Instead being associated specifically and exclusively with mass gravitation is a property of spacetime itself. The general gradient of gravitation across spacetime is flat. This means gravitation is effectively zero everywhere. Except there are exceptions to this rule and exceptions aplenty.

There will be numerous spikes of gravitational potential at points in the fabric of spacetime. Please note these spikes are stationary relative to each other. At the locations of these spikes of gravitational potential this is where planets will form and they will remain relatively stationary to each other.

Effectively gravitation will be a localized phenomena. If we assume the gravitation emerging in spikes from spacetime will only attract the mass constituting the mass incorporated in planets. While the gravitational mass of the planetary matter does not attract the gravitational mass of planets. Effectively the planets do not gravitational attract each other, the gravitational mass in any planet is attracted to the gravitation in the sharp gravitational gradients of the spacetime spikes. The planets won't attract each other, so the system won't collapse together. This universe will resemble an assemblage of stationary planets.

Any mass at a distance from the spacetime spikes won't be attracted. This means other planets won't be pulled together. Nor spaceships be attracted. This means if a spacecraft is at relative rest with respect to the system of planets it won't be moving and it won't fall, move or be attracted to any of the planets.

The bizarro cosmology outlined in this answer may satisfy all the criteria sought by the OP or something may have been left that renders this conceptual contrivance nonsense. If so, this can be done in the comments.

A side-note: there is nothing to prevent planets rotating on their axes.

  • $\begingroup$ I've been thinking on your answer for a day or so and I think I finally understand what you mean. One questions though: would this make it possible for the ship weapons that are fired to be affected by the planets' gravity? $\endgroup$ – John Hamilton Apr 27 '17 at 5:46
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    $\begingroup$ @JohnHamilton If by ship's weapons you mean they have mass, then yes. Basically assume what I'm calling a spike occupies a volume around any massive object like a planet, effectively its gravity will act on missiles in the same a normal planet of the same mass would. The spikes are the equivalent of Higgs fields for gravitational mass. Planets would have something resembles a normal gravity field to a certain distance, say, 500,000 km for an Earth-mass planet. It can have moons, satellites, spaceships & space-stations orbiting it. Beyond the field limit [continues] $\endgroup$ – a4android Apr 27 '17 at 10:23
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    $\begingroup$ gravity falls to the near-zero value for spacetime generally. The positionings of the gravity spikes can be something a crystal lattice with regular spacings between them. Planets would form where the gravity spikes are. There could be an extremely gravity field centred around the spikes. This will help matter to tend towards the spikes and form planets there. Mass only gains gravitational mass when in the influence of spikes and this spacetime generally. This weird cosmology works by redefining gravitational mass and the way spacetime works gravitationally. The rest of physics is the same. $\endgroup$ – a4android Apr 27 '17 at 10:29

First off, I agree wholeheartedly that "because it's fun" is a perfectly good answer, and that not every game in space needs realistic space-physics to explain the setting of the game. Most "orbit" type games (where you're trying to shoot a small projectile through gravitational fields) don't have any explanation as to how these masses exist or why they don't move.

One plausible explanation, though, is that you've simply constructed a reference frame that makes the planets seem stationary. If all of your planets and your spacecraft are orbiting some much larger, distant object at the same speed, your frame of reference would see those planets as stationary relative to your craft. Assuming they're much closer than the orbited object and considerably more massive than your projectile, their local gravities could be all that you reasonably concern yourself with.

  • $\begingroup$ Yeah, the projectile is assumed to be small but represented bigger than it's actual size. Ships look bigger than they actually are as well. This is a nice, clean explanation, but I'm not sure the players will get it. JDlugosz's answer seems like the best one to use for the game, although I'd use yours if I were writing a book :D $\endgroup$ – John Hamilton Apr 27 '17 at 5:52

You need to take advantage of Lagrangian Points.

Whenever one massive body orbits another, there are five points surrounding them where other massive bodies will be in equilibrium, in terms of gravity, with the first two bodies and with each other.

Several of Jupiter's moons orbit at each other's L4 and L5 points, including the trio of Calysto, Telesto, and Tethys. These three objects could be said to be, loosely speaking, at rest with respect to each other. If in addition, all three were tidally locked to Jupiter, meaning they always show the same face to Jupiter, then they would also always show the same face to each other.

If three moons can do it around a planet, it isn't hard to image that somewhere there are three planets doing it around a star. Further, clusters of ships should be able to park around the L1, L2, and L3 points without getting "sucked in."

  • $\begingroup$ This is a good hard-science answer, but unfortunately, the planets are randomly generated and don't really have any logic to them, that's why I'm looking for a science-based answer that has some fiction to it. Still, the answer has my upvote at the very least :D $\endgroup$ – John Hamilton Apr 27 '17 at 5:40
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    $\begingroup$ @JohnHamilton - I didn't realize your game had a preliminary set up and claim territory round (similar to Risk or Settlers of Cataan, I guess?) So, yeah, this would not work for you. Thank for voting anyway. $\endgroup$ – cobaltduck Apr 28 '17 at 12:19

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