# Gravity Field Simulation

## Main Question or Discussion Point

Looking for feedback on a simulation I created to show how using a displacement field can be used for simulating gravity on a large and small scale.

Click multiple times to create points of mass. Each point you add "pinches" the field. There are no point-point relationships here. The points are influenced by the field using a pressure vector derived from the field.

Click and drag to create points with initial velocity.

Try leaving the settings as is for a bit. Some interesting formations appear.

Let me know what you think.

(I originally posted this in the GR forum because of the displacement bit. Another member recommended I post it here.)

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fantastic

Nabeshin
This is wonderful! I'm very jealous of your ability to create something like this.

Hao
This is very impressive!

If you initialized your gravitational potential as an array of (x,y) points, what spatial resolution did you choose?

It would be interesting to implement an energy and total linear momentum function which calculates the total energy of the system to see how it deviates from the expected value (conservation of energy).

The scaling of the programs seems to be N. Is this due to the fact that you only evaluate gravitational potential from each particle at the every point on the x-y array?

Is the large default size of the particles there to compensate for the discreteness of the x-y array?

How did you account for singularities if a particle happens to be very very close to a gravitational potential node?

Did you model particles as point masses or mass densities for purposes for calculating gravitational potential?

When two hard spheres collide, they should recoil completely (elastic collision). This doesn't seem to happen.

i really like how it simulates revolving bodies. Kudos for that :)
edit: when i choose radius 0 the object is still there even thought i cannot see it. I would like to be able to create field without masses, just to experiment with the attraction

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Hao, thanks for the feedback!

"If you initialized your gravitational potential as an array of (x,y) points, what spatial resolution did you choose?"

The current resolution is the same as the native screen resolution of the active area. This can be scaled up or down independent of the screen res.

"It would be interesting to implement an energy and total linear momentum function which calculates the total energy of the system to see how it deviates from the expected value (conservation of energy)."

Interesting to hear that suggestion. One reason for building the simulation was to eventually simulate an energy field from which points of mass "condense", therefore reducing then total energy of the field.

"The scaling of the programs seems to be N. Is this due to the fact that you only evaluate gravitational potential from each particle at the every point on the x-y array?"

That is correct.

"Is the large default size of the particles there to compensate for the discreteness of the x-y array?"

No, it is arbitrary and there to represent how a stable mass might react in a field.

"How did you account for singularities if a particle happens to be very very close to a gravitational potential node?"

The potential is always calculated by the delta of adjacent nodes. If the delta was 0, the previous vector of the point would not change.

"Did you model particles as point masses or mass densities for purposes for calculating gravitational potential?"

Mass/energy densities. The intent is to show all interation as a result of varying densities of the energy field.

"When two hard spheres collide, they should recoil completely (elastic collision). This doesn't seem to happen."

An elasticity parameter can be added for that. A question though, if they were the smallest points of mass would elasticity apply?