I know, reality sucks. But why do people hate reality sooo much that they deny it?
The problem is that stating "the universe is real" doesn't say much. In particular, with respect to biocentrism or other (sometimes even mainstream) views like that espoused by Lanza and Berman, one can say that there is an external reality independent of us while also claiming that what we perceive depends upon both our own perceptual and cognitive faculties as well as an intersubjective participatory "creative" component.
In short, that one can assert (and many have) that "the universe is real" and also that "our reality is inherently subjective".
In my personal experience, those that tend towards antirealist views are all physicists (not because such views are mainstream here as opposed to elsewhere, but a selection bias resulting from the fact that I don't interact often with e.g., geologists or paleoclimatologists). Most of the time, the antirealism here is due to an adherence of the so-called orthodox interpretation of QM, with the antirealist-type baggage of the Copenhagen interpretation(s). In other words, it's because the most used textbooks and courses still teach a simplified version of QM with a built-in, implicit interpretation that is taught as if it were known. Most of those with this view do not, I think, actually believe that "there is no quantum world" despite having heard this quoate (which Bohr is supposed to have said).
More serious are those in quantum foundations, where we find two camps taking explicit, deliberate stances on this matter. One the one hand, there are those whose acceptance of the many-worlds interpretation, Bohmian mechanics, and similar realist, ontological interpretations of quantum systems is due to a desire to explicitly reject the received antirealist tradition in QM and to eschew any adherence even to the formulation of QM (or at least its nomenclature and structure) that smacks of antirealist perspectives.
On the other hand, there are those whose view ranges all over the place yet has in common that quantum theory tells us clearly the world we experience cannot be made up of systems that are independent of observers. As Mermin put it (in)famously, "
We now know that the moon is demonstrably not there when nobody looks" (he repeated this sentiment in another popular science article shortly after:
Is the moon there when nobody looks?)
I've been meaning to write a post on this sort of idea, because most of the popular versions of how QM suggests that reality is determined by the observer are overly sensational and fail to adequately explain what kind of empirical and theoretical evidence could possibly support this sort of view.
So we have, for example, the Veiled Realilty of d'Espagnat, the agent-centric informational probability interpretation of the QBists, the more general information-theoretic interpretations, the pragmatists view, the modal view, the somewhat more traditional updated orthodox/Copenhagen view, the operationalist approach, the various relativists (including but not limited to Rovelli's Relational Quantum Mechanics), etc.
All these views involve accepting the idea that our most fundamental physical theories tell us that physical reality is in some sense observer dependent in a manner is more radical than the Kantian-type (in which we experience an observer-dependent reality of an external reality that is not shaped by our observations and experiences). Wheeler's participatory universe is not so much radical in and of itself as it is radical in both the name and the central thought experiments he used to elucidate this take (so to with his famous "it from bit"). Wheeler devised a now famous version of the two-slit experiment that involved light from distant galaxies, a quasar, and gravitational lensing. That's the basis for Delayed-choice experiments, in which it is supposedly shown that our decisions on what we decide to observe determine the nature of the phenomena and properties of systems (the simplistic way of stating this is something like "if we take the double slit experiment, and change the design, instead of just finding that we can either choose to learn which path an electron or photon or whatever takes OR choose to observe the interference pattern, we can choose to reveal EITHER characteristic of such systems AFTER it is supposed to have or have not traversed a particular path").
At the heart of the matter is the fact that QM was developed out of and based upon the phase space of classical mechanics. It is much more elegant and convenient when, in dealing with larger systems of any appreciable degree, to encode the information about the system not in terms of the actual position and momentum of the individual classical particles making it up, but a generalized coordinate system in which we care only about the degrees of freedom of the system.
The problem stems from the fact that, in the case of classical phase space, there is at least in principle a way to go back and forth between the phase space description and the classical Newtonian description, i.e., the abstract description and the one with a 1-1 correspondence between the "bodies" that make up the system (each with a definite position and momentum in "real" 3D space).
This isn't the case for QM. For both experimentalists and theorists, most of the work in QM concerns finding the right Hamiltonian for a given system. This means determining what the degrees of freedom of the system consist of and how best to encode them in the formalism.
That's not a classical question. It's not a classical question because in classical physics we start with the knowledge/assumption that the parts of the system we are interested have definite values at all time and we don't need to keep track of how we "prepare" the system to specify its state. In QM, all we have access to is a preparation procedure that we then end up calling the "state" of the system. So the question becomes how are we supposed to understand a particular encoding of degrees of freedom in terms of physical reality?
