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Author Topic: Time shift effects ratio of angular speed / gravity of system?  (Read 5452 times)

Sam

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Hi,
raising the time steps in about every scenario I can load or make myself causes orbiting masses to catapult themselves out of a system. better said: apparently the program seems to multiplicate the angular speed of the orbiting masses and the gravity of the central mass, to achieve the variation in time steps towards time shift. this multiplication seems to be a bit rough, causing the ratio to slip, catapulting orbiting masses out of their systems. i suppose the most likely source for such an error would be an overly rough estimation of decimal places in object parameters.
i guess this is a fairly common effect and observation, although i couldn't find any mention of it here. however this could also be due to me being less observant than i should. sorry, if that is true.

i guess my first question is: did i do something wrong?
the second one would be: can this be fixed?

i just found this simulator and pretty much instantly fell in love with it and to be honest, i will most likely donate a few bucks anyway, but if i could use US to simulate extreme time shifts that would be awesome.

also: i am a graphic designer and have way too much time on my hands. if you have some use for someone with that background like me (pro bono, of course), drop me a line and we can talk about it. my specialties are interface design and web design.
« Last Edit: August 23, 2009, 03:52:18 AM by Sam »

witold

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Re: Speed affects angular speed/gravity of system?
« Reply #1 on: August 22, 2009, 01:49:27 PM »
also: i am a graphic designer and have way too much time on my hands. if you have some use for someone with that background (pro bono, of course), drop me a line and we can talk about it. my specialties are interface design and web design.

I think background can,t be change

And problem of too high timestep can,t be fixed

Sam

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Re: Speed affects angular speed/gravity of system?
« Reply #2 on: August 22, 2009, 01:51:20 PM »
by "if you have some use for someone with that background" i meant: "if you have some use for someone like me"

witold

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Re: Speed affects angular speed/gravity of system?
« Reply #3 on: August 22, 2009, 02:33:33 PM »
by "if you have some use for someone with that background" i meant: "if you have some use for someone like me"

aaaaaa I,m sorry for that :D

monmarfori

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Re: Speed affects angular speed/gravity of system?
« Reply #4 on: August 22, 2009, 03:15:11 PM »
The system of some galaxies will repel from its black hole far away. but some few stars may remain orbiting. Otherwise you speed it a more more times. Universe Sandbox will crash.

hbmp88

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Re: Speed affects angular speed/gravity of system?
« Reply #5 on: August 22, 2009, 03:19:36 PM »
So.... you didn't buy it yet?

Sam

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Re: Speed affects angular speed/gravity of system?
« Reply #6 on: August 23, 2009, 01:20:49 AM »
So.... you didn't buy it yet?

not yet. just found US about two hours before my first post. and before i'll purchase it, i voiced my only major concern. i feel that is pretty straightforward.

Dan Dixon

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Re: Time shift effects ratio of angular speed / gravity of system?
« Reply #7 on: August 23, 2009, 06:01:07 AM »
i guess my first question is: did i do something wrong?

I'm of the software design philosophy that the user is (almost) never wrong.

No, you didn't do anything wrong, but you did run the simulation so fast that the accuracy dropped so low that the system threw itself apart.

the second one would be: can this be fixed?

I can fix this by providing better messaging or adjustable limits that let you know when you have exceeded the 'safe' bounds of the simulation speed (the time step).

You can fix this by not running the simulation so fast. :)

Why do systems throw themselves apart when I turn up the time step?

A numerical explanation:
http://universesandbox.com/about/faq.htm

Why don't other space programs do this?

Universe Sandbox is different than most other space simulators. It starts with known positions and velocities of planets and moons. In order to play the simulation and draw the next frame it simulates the effect of gravity over specified time (the time step) for that frame to determine a new position and velocity.

Most other space simulators use complex mathematical formulas and charts that are able to calculate a position and velocity for any date. They are not dynamically calculating the forces of gravity. And they don't let you create massive black holes that destroy the universe.

Let me know if anything's unclear.
« Last Edit: August 23, 2009, 06:07:20 AM by Dan Dixon »

atomic7732

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Re: Time shift effects ratio of angular speed / gravity of system?
« Reply #8 on: August 23, 2009, 10:06:48 AM »
AstroGrav calculates gravity well. I think they go good together. Dan, you should partner with AstroGrav, and make systems that can convert between!

Sam

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Re: Time shift effects ratio of angular speed / gravity of system?
« Reply #9 on: August 23, 2009, 12:33:22 PM »
Let me know if anything's unclear.

Thanks for your reply. :)