private Vector3D getAcceleration(Body body1, Vector3D position){
		Vector3D aTotal = new Vector3D();
		for (int i=0; i < bodies.size(); i++) {
			Body body2 = bodies.get(i);
			if (body1 == body2) {
				break;
			}
			double rSquared = position.clone().distSquared(body2.position);
			if (rSquared == 0 || body1.mass == 0) {
				break;
			}
			Vector3D a = Vector3D.normalize(
					position.clone().subtract(body2.position)).multiply(
					6.67384E-11 * body2.mass / -rSquared);
			aTotal.add(a);
		}
		return aTotal;
	}