"Now since the consequences of Quantum Mechanics makes us see that there is an observer only" - comment posted on a group I am in.
I don't share this view of Quantum Electro-Dynamics. What QED, and entanglement in particular make clear, is that the world, and creation, and human reality, are all connected. The difference is crucial to the boundary of our mind-sets between a human-centric and a cosmic-centred frame for existence.
Granted, we have passed beyond the notion of objective truth, but even Godel's theorem told us that there was no such thing through mathematical logic; quantum perspectives were not required.
We are obliged to accept that the world is filled with paradox. But this is also the joy, that Newton's billiard ball model with its "if we understood all the rules everything would be predictable", is dead - as dead as the world it would create.
Reality is neither individually subjective nor externally objective. It is a co-creative and emergent unfolding as the realm of consciousness shapes the behaviour of matter. So the post-truth world does not say that there is no truth. It says that truth is what it is created to be, including human truth, and that is very much SD, and very contingent.
In effect truth is a continuum. We do know a lot of the rules of the material world - how physics and chemistry work, and a good amount of biology and genetics. At the same time there is much that we do not know, because our understanding, for instance, of how our consciousness shapes our body and its health, is fragmentary. We know that mind-body medicine, placebos and energy healing can work but our knowledge of how and why are very limited.
And at the creative farther edge of that continuum is a truth which is beyond subjective observation; rather it is subjective creation and co-creation. Our consciousness individually and collectively shape the unfolding of reality. "The Secret" and "Law of Attraction" as well as the concept of prayer may be simplistic but they are not entirely wrong.
Whether or not you accept that last paragraph as a valid description of human reality, this much is certain. Life is an unfolding co-creative process involving interactions between inconceivably large numbers of elements, from the smallest quanta to the cosmic and galactic. Whether you choose to observe or participate, life depends on the fundamental chaos and the unfolding of that continuum of truth, because without the freedom of chaos there is no creation. And you have choice, whether at the level of action or of consciousness? What will you choose today?