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STU Science Team: GravDrives

Discussion in 'General' started by RaptorMonkey, Feb 26, 2017.

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This last post in this thread was made more than 31 days old.
  1. Ronin1973 Master Engineer

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    Yeah, I always found that quirky... considering if you put the plates in the player's inventory and then land the player on the grid, the grid doesn't move. I think trying to solve the bug would be worse than the bug itself. We have a block that generates force outside of Newtonian physics. Applying rules to it might be difficult.

    Since mining no longer generates any stray ore, why not just limit the gravity generator to the player and artificial mass blocks not connected to the grid? Honestly a large stack of components tearing through a spaceship like Alien blood isn't a good thing.
     
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  2. Malware Master Engineer

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    9,600
    I'm always honest.It's quite simply that the grav drive is the topic of this discussion. Some of the aspects you mention (ex. air resistance, asteroid field) I definitely agree with, but not all. Many of those things are deliberate gameplay mechanics choices or simple technological limitations, like the speed limit. Planet sizes are a direct consequence of that speed limit. I'm ok with that. I don't like it, but I accept it. But in my world, two wrongs does not make one right. The grav drive effect is, as demonstrated above, a bug and a destructive one at that. Most (but not all) of the other limitations have a logical explanation and excuse. The grav drive does not.
     
    Last edited: Feb 28, 2017
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  3. gchristopher Apprentice Engineer

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    Yep! That's definitely an internally consistent argument.

    Thanks for listening. I just tried out of the hope that you'd appreciate that sometimes the most fun game mechanics are unintended, emergent properties of a system. (Dwarf Fortress and Skyrim being great examples of games where the most fun game mechanics are both unbalanced/OP and not intentional design decisions by the developers.) If not grav drives specifically, then more compound-block systems like them would be great for the game.
     
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  4. fourthquantum Senior Engineer

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    I've said this before in other threads, one of which was closed because of the heated debate.

    Gravity IS NOT A FORCE, according to the general theory of relativity gravity bends space time and mass moves along it.

    Imagine a ship that has a sail with a fixed electric fan on the deck pointing towards the sail. The ship will move when the fan blows air on the sail because it is moving the medium upon which the sail interacts. You are doing the same with the gravity generator and the artificial mass block. The sail is the artificial mass, the gravity generator is the fan and the bending space time is the air.
     
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  5. halipatsui Senior Engineer

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    F=ma which means a=f/m
    Gravity generator gives same acceleration to any object (1g) which means the energy object receives scales up with its mass. This however does not affect the gravity generator, since you can accelerate brilliards tons of stone with very small energy cost.

    I would like if gravgens used more power if they were accelerating more mass.
     
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  6. bigsteve Trainee Engineer

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    SE uses a physics engine, maybe its physics from an alternate reality.
     
  7. fourthquantum Senior Engineer

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    Or it's a model that takes into account general relativity.
     
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  8. GrindyGears Senior Engineer

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    I personally like what digi's advanced gravity generators mod did, it added an option (that I think should be vanilla as a feature) to have gravity generators apply a counter force relative to how much it was pushing on it, it would make grab drives non functional and would probably help with the bug malware is talking about
     
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  9. halipatsui Senior Engineer

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    Itbwould also add recoil to gravity cannons :woot:
     
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  10. GrindyGears Senior Engineer

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    Unintended side effect, but yes it would.
     
  11. Shatara422 Trainee Engineer

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    Er, no, a fan-sail will not move. At least not the way you think it will.

     
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  12. fourthquantum Senior Engineer

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    The shape of the sail will determine the balance of force, a flat sail will balance perfectly (if you like you could say this is 'flat space') a rounded (curved space from the mass itself) sail will cause movement . it's not a perfect analogy as there would be no 'force' involved to be balanced but it does show that a 'manipulator' (of air in this case) and an interact'or' can be on the same 'thing' and still move. . It IS NOT about balancing newtons laws of motion because there IS NO FORCE involved, it is the bending of space time.
     
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  13. REDSHEILD Junior Engineer

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    888
    Forces due to gravity still follow the conservation and reaction laws. The first reason the grav drive works in game is that the mass block itself has no gravity, thus no method of applying a force to the gravity generator. Now, naturally, any gravity generated by the possible masses of the mass block would be insignificant to the gravity generator's ability to output potentially infinite force. This is the second break of conservation, in that the gravity generator's power usage is constant despite acting on mass, whereas no matter the method of explaining or modeling gravity, in real life there must be an energy input somewhere in order for a gravitational field to do work.

    The third and final problem is that, given that the objects accelerated by the gravity generator are too light to affect it gravitationally, the gravity generator breaks reaction symmetry. Any force, even the "fictitious" forces such as centrifugal force, has a reaction force. In order for the gravity generator to accelerate a one tonne mass block at one gravity, it must exert the resultant force on itself as well. The same asymmetry that makes gravity cannons recoilless in game lets gravity drives work.

    Saying that the gravity generator can just "warp space" and achieve this acceleration without breaking these symmetries is just as ludicrous as saying that you can change the CoM of an object without changing the shape of its gravitational field, thus letting it accelerate itself.
     
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  14. fourthquantum Senior Engineer

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    Can you define what you mean by this? Because, again, gravity is not a force. There is no force DUE to gravity.
     
  15. halipatsui Senior Engineer

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    How exactly can you overcome that with a different sail :eek:
     
  16. fourthquantum Senior Engineer

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    A curved sail
     
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  17. halipatsui Senior Engineer

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    Curwed which way?

    Would appreciate a source for this too
     
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  18. fourthquantum Senior Engineer

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    The video itself 4:50
     
  19. halipatsui Senior Engineer

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    But this is a different situation.
    Here the propeller is pushing the craft because sail is only partially blocking it due to its geometry.
    But it is still not possible to push its own sail to move.
     
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  20. fourthquantum Senior Engineer

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    A mass bends space time (artificial mass block), the gravity generator bends space time as well.

    If the bent space time of the mass exactly matched the bent space time of the gravity generator then there would be no movement. If the bent space time of the mass is different to the bent space time of the gravity generator, then there will be movement.

    You would also need a mass the size of earth to generate 1g that the gravity supposedly generates. This means the gravity generator is bending space time more prominantly than the artificial mass block so it will move no matter what.
     
  21. REDSHEILD Junior Engineer

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    888
    Gravitational (or indeed any) warping of space time exerts forces on affected objects, in proper proportion to their mass. Despite what is taught it schools, acceleration due to gravity is not equal for objects of all masses, it only appears that way because the mass of the Earth is so much larger than any other mass it affects at human scales. If you were to drop a mountain and a person in a vacuum under careful measurement, the mountain would fall faster. Of course, you don't really notice this until you get within about five or so orders of magnitude of the larger mass. If you dropped the moon in free fall it would be more noticeable, the difference between the net acceleration and the acceleration of the object by the Earth following this ratio: a(n)=a1+(a1*(m1/m2)). The moon is about 81 times less massive than the earth, so it accelerates the Earth at 1/81 the rate that the Earth accelerates it.

    This would not occur if there were no imbalance in forces due to imbalance in mass and thus imbalance in field geometry.

    The gravity drive creates a self-perpetuating imbalance of forces that will never reach an equilibrium, and indeed violates both Newtonian motion laws and relativity. Under both classical mechanics and relativity forces are also relative, but the ones exerted by the gravity generator are not; they are absolute and infinite in potential magnitude, only relative in direction. Under interactions between two separate grids this is only noticeable due to the speed indicator, but it becomes truly obvious when you make a gravity generator act on its own grid.

    The forces present in gravitational interactions may be consequential of gravity, but that does not make them any less as forces. Indeed the very nature of gravity necessitates at the very least force-like interactions, due to the fact that reaction forces work to counter it and that acceleration in general is indistinguishable from gravity.
     
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  22. RaptorMonkey Trainee Engineer

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    In other words, the earth cant be moved by its own gravity, another body needs to be there, gravity is the force exerted on one body by another.
     
  23. REDSHEILD Junior Engineer

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    888
    That's a decent approximation, but really the forces are simply results of the geometry of space time affected by mass. Gravity fields don't produce work by themselves, the only allow the existence of a gradient of potential and realized work. Potential being highest when "at the top" of the gravity well, lowest or most "realized" when "at the bottom"

    Anyone saying that its properties as a field make it unbeholden to rules of symmetrical reactions and conservation of momentum should sit down with two magnets, tape the like poles together, and then wonder why the system doesn't move.
     
  24. fourthquantum Senior Engineer

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    Again you are thinking of this in terms of Newtonian physics. a magnet does not manipulate the medium upon which they are placed upon.

    Look at it like this. If I had a big gun, that's pointed towards the ground, attached to a car. This big gun creates a crater in the ground beneath the car and the car is not effected by the explosion, what happens?

    Will it remain stationary or will it go into the crater?

    The gravity generator is the gun creating a distortion of the medium (ground) upon which mass (car) interacts. It doesn't matter what the gravity generator (gun) is attached to.

    The energy expelled by the gun (gravity generator) to create that crater in the ground (space time) will be more than the kinetic energy given to the car (mass) moving within the crater. Energy is conserved.

    In terms of physics, what can't be explained is the existence of the gravity generator and the artificial mass block. The amount of energy required for these to work, using current physics, is phenomenal. But IF they exist then a gravity drive is possible.
     
    Last edited: Mar 3, 2017
  25. Malware Master Engineer

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    9,600
    This whole discussion is moot anyway.

    1. The issue is that the effect enabling the gravity drive is a bug, and even completely ignoring the existence of the gravity drive, it's a disruptive one at that. This has nothing to do with physics what so ever.

    2. The gravity drive won't be patched out now, unless there's a clear majority to do so - and I don't expect that to happen.
     
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  26. REDSHEILD Junior Engineer

    Messages:
    888
    Here's the problem with that: your car will eventually (ignoring geology) hit the bottom of the potential gradient it is on, i.e. the bottom of the Earth's gravity well. The gravity drive creates an infinite gradient which exists in one direction and has no bottom yet has a constant slope, and it does this to produce actual motion. The closest theoretical propulsion is the Alcuberrie drive, but that does not actually create motion in the object because it warps space symmetrically around it. As far as we know, there is no way to create a true asymmetrical gravitational field, by which I mean one where it is able to warp some space without warping the rest of it around the event.

    This would be like creating a section of a gravitational wave without the rest of it.

    All motion due to gravity in either Newtonian mechanics or relativity is the result of energy potentials relative to the gravity field. A gravity field cannot create work, it can only extract it. The gravity drive not only creates work, it does so in excess of its energy input.

    As far as the game goes, I would be "happy" if they decided to ensure that the gravity generator's energy consumption varied in proportion to the work it is producing. You could keep your glorified dean drive but you'd have to pay for it at least.

    They don't exist. So stop pretending you can abuse relativity to act like they can.
     
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  27. fourthquantum Senior Engineer

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    1,286
    In your analogy satellites orbiting the earth would just 'stay' and not move with the earth in it's orbit around the sun.

    I'm not abusing general relativity at all. I have not said an artificial mass block or gravity generator exist, in fact, I said they probably can't exist with the current laws of physics we have. But if they do exist then a combination of those 'things' could potentially give you a gravity drive. Removing a gravity drive from the game would make it less realistic.
     
  28. halipatsui Senior Engineer

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    Mmm. I dont think so.
     
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  29. REDSHEILD Junior Engineer

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    888
    Please explain how you got that from what I said. In no way is my presentation of gravity inconsistent with orbital mechanics. Gravity fields are perfectly capable of doing work, they simply cannot create work, as unlike reaction thrusters which convert chemical energy potentials into kinetic energy, i.e. create work, the gravity field can only do work via existing kinetic energy and can only modify the vector of that energy or bring it to a rest state relative to the field's coupled mass. Gravity cannot do work on its own mass other than bringing it further towards a state of rest, which is the problem of the gravity drive, which does work on a coupled mass in a way that doesn't bring that mass to rest. The gravity drive is as ludicrous as saying you can move the center of mass of an object without changing the shape of its gravity field with it. It's akin to saying that you can move a planet's CoM 1 diameter away and make the planet pull itself along. You can't do that.

    This is the same as saying "and then a miracle occurs..." in the middle of a proof. Gravity generators in the game have been a concession from their very beginning, they do not work under relativity, and their effects are absolutely impossible under the Newtonian physics of the game itself. The game is built to Newtonian physics, and under Newtonian physics an object cannot push itself without undergoing some form of reaction and momentum transfer. This is also true of relativity, but you keep ignoring it there in favor of "bu-but gravity is a field not a force" without addressing the fact that under the gravity drive, momentum is not conserved and symmetry is broken. Even under the assumption that geometric spacetime gravity fields do not exert forces (they do), there is still this issue of momentum. Gravity can manipulate momentum, and it can transfer it, thus if there is a change in momentum between a mass block and a gravity generator, there must be a symmetrical exchange of momentum to account for this. Given that they are part of the same grid and do not move relative to each other, there is clearly no change in their relative momentum, thus the system should not move despite any influence by the gravity generator, and if it does move due to the gravity generator, momentum has not been conserved.
     
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  30. fourthquantum Senior Engineer

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    1,286
    Again you are making the assumption (with your change of momentum analogy) that there is a force on the gravity drive and a force on the mass.

    How do you explain the a pendulum at the top of its swing where it no longer has kinetic energy but potential energy? What you are describing is a stability point but what is making the system stable? In general relativity we use something called the metric tensor, which describes how gravity gives things 'potential energy'. IF the gravity generator works it will also have a metric tensor that describes how it forms the space around it (to give it gravity). It will have a mass potential energy that could be kinetic if there is no stability point preventing mass from moving.
     
    Last edited: Mar 3, 2017
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