stt.setSpeedOfLight(3);
stt.setSimulationWidth(100);
stt.setSimulationHeight(100);
stt.addForce(new ConstantForce());
stt.addForce(new SpringForce());
stt.setParticleList(new ArrayList<Particle>());
stt.setBoundary(GeneralBoundaryType.Periodic);
stt.setParticleSolver(new EulerRichardson());