public Vector3 applyForces(ref Vector3 shipPos, float shipMass, float timestep)
    {
        Vector3 r = shipPos - transform.position;

        Vector3 pushVelocity = new Vector3(0.0f, 0.0f, 0.0f);
        Vector3 pushForce    = new Vector3(0.0f, 0.0f, 0.0f);

        if (r.magnitude < innerRadius)
        {
            //destroy ship via explosion
            ObjectGeneratorScript obs        = GameObject.Find("ObjectGenerator").GetComponent <ObjectGeneratorScript>();
            GamePlayManagerScript gms        = GameObject.Find("GamePlayManager").GetComponent <GamePlayManagerScript>();
            ShipScript            shipscript = obs.playerShip.GetComponent <ShipScript>();

            shipscript.DieWithExplosion();
            gms.StartCoroutine("GameOverandReset");
        }
        else
        {
            pushVelocity.x = (outerRadius / r.x) * strength;
            pushVelocity.y = (outerRadius / r.y) * strength;
            pushVelocity.z = (outerRadius / r.z) * strength;
            pushForce      = pushVelocity * (shipMass / timestep);
        }

        return(pushForce);
    }