Galactic blackholes (or blackhole like entities) could serve as a test for the proposal. Galactic blackholes are supermassive having masses measured in billions of solar masses. These blackhole like entities is thought to grow rapidly as matter falls into them. In this process light is emitted and makes the blackhole a quasar (see this), one of the most luminous objects in the Universe.
TGD based model predicts that the seed of galaxy would be formed in the reconnection of cosmic strings and consist of dark matter. If galaxies are formed in this manner, the blackhole like entity formed in the reconnection point would get its mass from cosmic strings as dark mass and visible galactic mass would result from dark matter "boiling" to ordinary particles (as in the decay of inflaton field to particles). Matter from cosmic strings could flow to the reconnection point and a fraction of antimatter would remain inside cosmic string as dark matter.
During the "boiling" period intense radiation is generated, which leads to ask whether an interpretation as a formation of a quasar makes sense. The flow of matter would be from the blackhole like object rather than into it as in the ordinary model of quasar. Quasar like objects could of course be created also by the standard mechanism as ordinary matter starts to fall into the galactic dark blackhole and transforms to dark matter. This would occur much later than the formation of galactic blackhole like objects and galaxies around them.
Now three odd-ball quasars have been discovered in the early universe (13 billion years in past, less than billion years after Big Bang) by Eilers et al (see this). The authors conclude that the most compelling scenario is that these quasars have been shining only about 105 years. This time is not enough to build the mass that they have. This challenges the standard mechanism for the formation of galactic blackholes. What about the situation in TGD Universe? Could the odd-balls quasars be quasars in the usual sense of the word being created as ordinary matter starts to fall to the galactic dark matter blackhole and transforms to dark matter? Quantum phase transition would be involved.
See the the chapter Breaking of CP, P, and T in cosmological scales in TGD Universe or the article with the same title.