Unchanging observer drives the evolutionSa-akSi means 'that eye'. It is the 'witnessing' eye, the eye of 'third party' that is witnessing, but not interacting with what's happening or not changing due to the interaction. It is the 'unchanging observer'.
This un-changing observer is there in everything. In every piece of Universal evolution, there is a third party observer, who does not interact. This third party observer, though not-interacting, propels the evolution. Without this observer, evolution will not happen.
Observation of the 'self' propels evolution (1).That is the unchanging observer that propels the evolution is not outside but inside and is a part of the 'self'.
cakSusa satyata and sAkshiWhen something external is observed, it brings up the relative 'reality' or 'existence'. (cakSusa satyata). The observation of something external leads to interactions between observer and observed. The 'aprati-grahah' nature (unseizable nature) becomes 'prati-grahah' (seizable nature) causing interactions between them (2).
In this case the observer and observed changes their characteristics. Depending on the micro-macro nature of both a newer reality or existence dawns on one or both (2)
But when one of the observer or observed is of unchanging nature not influenced by interactions, then it becomes the 'observer' and drives the evolution. This unchanging observer is the 'witness' or the 'sa-akSi' or sAksi.
Dark Matter as unchanging observerAt the start of the Universe, dark matter is the 'observer' of matter. It is the 'bed' on which the 'interacting matter' evolves. Interacting matter (or simply matter) interacts with electromagnetic, strong and weak fields and evolves into more complex forms of matter. This is the 'sacrifice' or 'Yajna'. The dark matter that does not interact remains the witness or observer of this evolution, as it does not interact with matter in anyway.
Though dark matter is only an observer/witness/sAkshi, it bends the spacetime more than what matter could have done. This results in bringing matter together and making matter interact more. It builds gravitational pressures that heats up the molecular clouds to kick-start nuclear fusion, thus bringing the next stage of evolution.
Dark matter and matter are part of the same thing. Hence this 'observation' is observing the 'self'. Thus mere observers or witnesses that do not interact, just remain the third eye witness drive the evolution.
Neutron as unchanging observerDuring nucleo-synthesis, neutron is the 'observer' of atomic nucleus. Atomic nucleus has neutrons and protons. Protons interact with electrons and build up larger elements, compounds, long polymer chains and the biological life even. But neutrons remain just observers or witness in the nucleus. It does not interact with electrons or protons.
Though neutron is only an observer/witness/sAkshi, it facilitates the binding of positive charged protons into each other. Without the neutron, the protons would repel away each other. But neutrons reduce the electromagnetic repulsion, bind the protons and make it into an atomic nucleus, thus bringing the next stage of evolution.
Neutron and Proton are part of the same atomic nucleus. Hence this observation is observation of the 'self'.
Catalysts as unchanging observersIn Chemical or biological processes, be it synthesis of proteins or DNA replication, catalysts are involved. Catalysts are those that do not undergo any change, just remain a witness/observer, but drive the evolution of biological processes
Catalysts are part of the same system whose evolution they drive or propel.
So witnessing/observing the 'self' is a key principle in the Universal evolution. This applies to human beings also.
Being an unchanging observer drives our evolutionWhen human beings observe the 'self', become an observer/witness for themselves, their bonding become easy, balanced and happy. They become catalysts for driving their own evolution into next stage of evolution.
One can truly be the witness or 'unchanging observer' of one's own, but not others. So one has to develop being a total independent observer of oneself.
This is what ashtavakra gita also says. Be an observer of yourself. The detached, un-changing, thought that becomes of the 'observer' drives our evolution into future stages. Hence it is the 'Atman' or 'I' or 'self'.