Could you be more specific? You suggest that there are methods by which dark matter can dispose of kinetic energy, but can you show a method that is purely a gravitational interaction? If dark matter particles ineract with each other non gravitationally then do you agree that the dark matter in the original clusters of bullet cluster collision would have dispersed kinetic energy during the collision and formed a clump at collision point like the hot gas? The colliding hot gas of the colliding clusters interacted and dispersed kinetic energy to form one central clump, while the colliding dark matter haloes did not disperse kinetic energy and "passed straight though" each other. Do you agree that the bullet cluster clearly shows that hot gas has a greater tendancy to clump than dark matter? In that collision the hot gas clumped while the dark matter did not. It could not be clearer. Do you agree that for dark matter to gravitationally collapse it has to interact with itself or normal matter in order to disperse kinetic energy? Do you agree that my demonstration of an object falling through a hole in planet will continue to oscilate forever without friction dispersing kinetic energy as electromagnetic energy? Do you agree that dark matter is generally thought to be non interacting or weakly interacting other than gravitationally? Some additional observations can be made from the comparison of the bullet cluster and the train wreck cluster. They appear to give a conflicting image of the nature of dark matter. In the bullet cluster massive galaxies and stars appear to be relatively unaffected by the collision of two clusters and pass straight through the collision area, as does the dark matter, leaving a region of hot gas and relatively little dark matter where the collision took place. This shows the none interacting nature of dark matter. In the train wreck cluster, the dark matter seems to have remained with the hot gas at the centre of the collision while the massive gaxies have passed through without any dark matter attached to them. This is the opposite of what appears to have happened in the bullet cluster and it is a big puzzle. A closer look at the train wreck image seems to show that some of the dark matter has been dispersed at right angles to the trajectory of the colliding clusters. If dark matter is generated by black holes as I speculated, then one explanation is that black holes in the original clusters that collided to make the train wreck were thrown out sideways by a slingshot effect due to a very close interaction of the black holes during the collision. it is possible that the original clusters had more than one black hole each, in complex orbits around each other that were inherently unstable and easily sent off at tangents during the collision. The dark matter that seems to have been ejected sideways in the train wreck cluster is possibly generated by the slung shot orbiting black holes spiraling outwards at an unusual angle from the collison. The proof would come from locating the black holes in the bullet and train wreck clusters. My bet is that the dark matter stays with the trajectories of the black holes after the collision and that slung shot black holes will be found way off the collision axis of the train wreck clsuter. It should be noted that at this point, no one has offered a viable explanation of why the bullet cluster and train wreck cluster differ so much in their distribution of dark matter after the collsions.