float gravityMagnitude = G * m_rigidbody.mass * OtherMass.mass / Vector3.SqrMagnitude( OtherMass.transform.position - this.transform.position );
        Vector3 direction = ( OtherMass.transform.position - this.transform.position ).normalized;
        m_rigidbody.AddForce( gravityMagnitude * direction );