When two high energy nuclei collide with each other, the hard and soft gluons "hidden" in their wavefunctions are freed. Then the produced system of the hard gluons begins to interact with the system of the soft gluons. Sometimes the system of the soft gluons is called the low energy source which feeds in energy to the system of energetic hards gluons. In this case, the soft gluons from the low energy source comes into the system of hard gluons spherically and symmetrically in the phase space. As I know this radiation of the soft gluons is generally considered constant in time. I need to know why ? And I wish to know why the system of the hard gluons should be inside the system of the soft gluons (since the soft gluons are incoming from all directions)? Does anybody know the answers to these questions ?