Planets with changing gravity

hunator

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Jul 25, 2014
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yeah... I know that the centre of the galaxy is a black hole... but the sun impiegate 250000000 years to made 1 rotation, so the gravity effects are minimal. also, the Earth has its own gravity, right? so the effects are less than on a space station

It because of distance from center of the galaxy. As you probably know, gravitational force lowers with distance squared (Newton gravitation law Fg=k*m_1 * m_2 /r^2, k-gravitational constant, m_1 m_2 - masses of two object between which force is calculated, r - distance between them). Also be aware that solar system has quite high velocity around center of galaxy, angular velocity might be low, but distance from a center is quite high.
To stick with your example, an orbital station orbiting black hole would have to have high angular velocity to reach stable orbit. But stable orbit also means that gravitational force would be neglected by centrifugal force. As such, person inside space station would be affected only by gravitational force from space station itself. You would need to maintain unstable orbit by thrusters (or other type of engine) in order to have non-zero gravity inside station.
 
Jul 13, 2014
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It because of distance from center of the galaxy. As you probably know, gravitational force lowers with distance squared (Newton gravitation law Fg=k*m_1 * m_2 /r^2, k-gravitational constant, m_1 m_2 - masses of two object between which force is calculated, r - distance between them). Also be aware that solar system has quite high velocity around center of galaxy, angular velocity might be low, but distance from a center is quite high.
To stick with your example, an orbital station orbiting black hole would have to have high angular velocity to reach stable orbit. But stable orbit also means that gravitational force would be neglected by centrifugal force. As such, person inside space station would be affected only by gravitational force from space station itself. You would need to maintain unstable orbit by thrusters (or other type of engine) in order to have non-zero gravity inside station.
I didn't need this explanation about the gravity.
What's the problem about an unstable orbit? If you said the metode to have unstable gravity, you already know it, so it's useful your comment? not a lot. if mic add the black hole dimension without explanate how the station has unstable gravity, you can imaginate ALL you want. So, if you know a metode to do this, what's the problem??? That means only that what I wrote is possible, not?
I'm not english, so I can made some errors. Sorry.
 

hunator

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Jul 25, 2014
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Actually no. What you are proposing is only in case of changing angular velocity in combination with some sort of active force (possibly engine). In current state of technology you would run out fuel very soon. So black hole won't do the trick.
Only way I can think of is artificial gravity. It will be possible to make space station with thrusters that will rotate station. This would generate centrifugal force simulating gravity inside station. By regulating thrusters, you will generate momentum which changes centrifugal force.
Long story short, you can't make situation (rational enough) in which you obtain variable gravity inside of space station other then artificial gravity. That was the whole point.

Don't get me wrong, I'm not trying to be mean in any way (I'm sorry if I was). It is good suggestion, but I think that it should be about "Artificial gravity by thrusters controlled centrifugal force". But I seems to be in frequently asked suggestion, anyway it seem to be right way to do it because thrusters and spinning stations has been added in GC BETA 3.0.0.
P.S. I'm not native speaker my self (I'm Czech).
 
Jul 13, 2014
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Actually no. What you are proposing is only in case of changing angular velocity in combination with some sort of active force (possibly engine). In current state of technology you would run out fuel very soon. So black hole won't do the trick.
Only way I can think of is artificial gravity. It will be possible to make space station with thrusters that will rotate station. This would generate centrifugal force simulating gravity inside station. By regulating thrusters, you will generate momentum which changes centrifugal force.
Long story short, you can't make situation (rational enough) in which you obtain variable gravity inside of space station other then artificial gravity. That was the whole point.

Don't get me wrong, I'm not trying to be mean in any way (I'm sorry if I was). It is good suggestion, but I think that it should be about "Artificial gravity by thrusters controlled centrifugal force". But I seems to be in frequently asked suggestion, anyway it seem to be right way to do it because thrusters and spinning stations has been added in GC BETA 3.0.0.
P.S. I'm not native speaker my self (I'm Czech).
run out of fuel. ok. but... I think you know the einstein's formule(energy=matter x lightvelocity at the second power) and... if mic add a machine that create energy using this formule? he's already added the teletrasport, so that means that some machine from science fiction are permitted,not? And what I have just suggested is a machine from science fiction (inter alia, this is possible). so, we've just resolved the problem about the fuel.
 

hunator

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Jul 25, 2014
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I've just lost reply that I already wrote so I'll be brief (sorry about that :D ).
It is possible, inefficient but possible (variable and unstable orbit needed).
This formula is not related in this problem. It is special case of dynamic energy originally for energy of light as particle stream. Einstein made mistake by thinking about light as particle only, there is particle/wave duality. It is not about converting mass to energy.

To finish our conversation, I agree with this (It probably doesn't do any good but anyway :) ):
1) Gravity should be changed.
2) It should be variable/controllable in artificial environments (space stations, maybe even bases with artificial gravity plates - sci-fi)
3) Maybe, just maybe some space time continuum abnormalities that will result in highly localized changes in gravity field. Pulling to some place, inversed gravity etc. as generated very rarely in world (asteroid field), as mobs or as weapon effect. - hell of sci-fi

Anyway, once again you have good idea, but cases in which it can happen showed some flaw. Lets finish talk about physics, <joke>before they will come up with another words than #nerds :) </joke>.
 
Jul 13, 2014
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I've just lost reply that I already wrote so I'll be brief (sorry about that :D ).
It is possible, inefficient but possible (variable and unstable orbit needed).
This formula is not related in this problem. It is special case of dynamic energy originally for energy of light as particle stream. Einstein made mistake by thinking about light as particle only, there is particle/wave duality. It is not about converting mass to energy.

To finish our conversation, I agree with this (It probably doesn't do any good but anyway :) ):
1) Gravity should be changed.
2) It should be variable/controllable in artificial environments (space stations, maybe even bases with artificial gravity plates - sci-fi)
3) Maybe, just maybe some space time continuum abnormalities that will result in highly localized changes in gravity field. Pulling to some place, inversed gravity etc. as generated very rarely in world (asteroid field), as mobs or as weapon effect. - hell of sci-fi

Anyway, once again you have good idea, but cases in which it can happen showed some flaw. Lets finish talk about physics, <joke>before they will come up with another words than #nerds :) </joke>.
I cannot comment your 3rd and 4th lines.
Anyway, I have another idea, without unstable orbit (maybe doesn't work, but I try):
In the galacticraft map you see the sun in the centre of the orbit, but we know that it isn't, so, if the station has an orbit really really really alongated and the black hole is not in the centre, but sideway, you have acceleration(when the station is going near the hole) and deceleration( when the station is going far from the hole) the acceleration is the same than a falling elevator(so there is less gravity) and the deceleration is like an elevator that goes up, so the gravity is more(and slowly became less)! you don't need energy because lots of celestial bodyes has an orbit around black holes, and they use million of years to fall in, not?(mmmh... maybe I inverted the word less and more... but i'm not sure) say me if also you think that this function.
I totally agree for what you say in point 1-2-3.
a personal idea: I like to be named "nerd" (where I live a nerd is a person that know lots of things) and surely the word "nerd" can't offend me, because often say it people that don't know what i'm saying.
it's nice talk with you:):)
 

Buzzrocket

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Jul 8, 2014
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I cannot comment your 3rd and 4th lines.
Anyway, I have another idea, without unstable orbit (maybe doesn't work, but I try):
In the galacticraft map you see the sun in the centre of the orbit, but we know that it isn't, so, if the station has an orbit really really really alongated and the black hole is not in the centre, but sideway, you have acceleration(when the station is going near the hole) and deceleration( when the station is going far from the hole) the acceleration is the same than a falling elevator(so there is less gravity) and the deceleration is like an elevator that goes up, so the gravity is more(and slowly became less)! you don't need energy because lots of celestial bodyes has an orbit around black holes, and they use million of years to fall in, not?(mmmh... maybe I inverted the word less and more... but i'm not sure) say me if also you think that this function.
I totally agree for what you say in point 1-2-3.
a personal idea: I like to be named "nerd" (where I live a nerd is a person that know lots of things) and surely the word "nerd" can't offend me, because often say it people that don't know what i'm saying.
it's nice talk with you:):)

The reason I said nerd was because I did not understand even 10% of what you guys were talking about lol.
 

hunator

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Jul 25, 2014
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In this case player won't be able to feel this force. You know the gravity works somehow different than mechanical force. Gravity has got effect on every element of the mass rather than mechanical force which has effect on point of contact. As such every point in player's body and station construction would have same acceleration. For example you would be in centre of sphere on such orbit you will remain in center of this sphere no matter if you are accelerating or decelerating, you wouldn't notice because sphere would accelerate as well.
This could be proofed by this:
Fg=k*m_1*m_2/r^2 (m_2 is orbiting m_1)
F=m_2*a (a is acceleration)
->a=k*m_1/r^2 (a doesn't depend on mass, so gravity effect every mass inside of object if it is small enough - dr/dV_2->0)
I know it is not easy to imagine, I've spend about 30min to explain it to my father (he has got master degree in eng. so he should know it already) without success :) .
It is crucial to choose proper system in which you make calculation in this case system is station to player so difference of "a" from system sun-station is 0 so no gravity from sun has effect on gravity noticeable by player inside station (like free fall).
I'm also not offended by the word nerd, after 4 semesters of physics and 5 semester of math I'm used to it :D .
 
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Jul 13, 2014
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In this case player won't be able to feel this force. You know the gravity works somehow different than mechanical force. Gravity has got effect on every element of the mass rather than mechanical force which has effect on point of contact. As such every point in player's body and station construction would have same acceleration. For example you would be in centre of sphere on such orbit you will remain in center of this sphere no matter if you are accelerating or decelerating, you wouldn't notice because sphere would accelerate as well.
This could be proofed by this:
Fg=k*m_1*m_2/r^2 (m_2 is orbiting m_1)
F=m_2*a (a is acceleration)
->a=k*m_1/r^2 (a doesn't depend on mass, so gravity effect every mass inside of object if it is small enough - dr/dV_2->0)
I know it is not easy to imagine, I've spend about 30min to explain it to my father (he has got master degree in eng. so he should know it already) without success :) .
It is crucial to choose proper system in which you make calculation in this case system is station to player so difference of "a" from system sun-station is 0 so no gravity from sun has effect on gravity noticeable by player inside station (like free fall).
I'm also not offended by the word nerd, after 4 semesters of physics and 5 semester of math I'm used to it :D .
right. the unstable orbit won.
When I will have better ideas i will talk you, so we can have other interesting discussion!:)
you're totally right, because I explanate my idea terribly and I said a thing completely different from what I intend... i'm the worst english of ever!:D
ps: don't kill me for my HUGE mistake...
 
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Buzzrocket

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Jul 8, 2014
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right. the unstable orbit won.
When I will have better ideas i will talk you, so we can have other interesting discussion!:)
you're totally right, because I explanate my idea terribly and I said a thing completely different from what I intend... i'm the worst english of ever!:D
ps: don't kill me for my HUGE mistake...

It should be "I'm the worst at English". :D All hail the Grammar Nazis
 

hunator

Member
Jul 25, 2014
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right. the unstable orbit won.
When I will have better ideas i will talk you, so we can have other interesting discussion!:)
you're totally right, because I explanate my idea terribly and I said a thing completely different from what I intend... i'm the worst english of ever!:D
ps: don't kill me for my HUGE mistake...
You can rest now, I'm not going after you :D Maybe I'm getting weaker or lazier, but I'm not hunting down people anymore. :D

Seriously, no harm done and I'm also looking forward to our discussions in the future.
 

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