Since its Greek origin, physics has been related to physis, namely, the totality of what is. The realist presupposition that gave birth to physics was the idea that theories provide knowledge about the logos (i.e., order) of reality through the creation of systematic, unified schemes capable to account for the multiplicity immanently found within experience (see for discussion [13, 14]). This was the case for more than two millennia of successful developments from Protagoras and Heraclitus to Plato and Aristotle, and then, up to modern times to Galileo and Newton. But even though modernity — with the creation of classical mechanics — could be regarded as the peak of the Greek theoretical realist program, this period can be also seen as the starting point of the anti-realist re-foundation of science. A process that would culminate in post-modern times, during the 20th century. As Karl Popper would famously describe the situation during the late 1950s:Osiander is the one who wrote the preface to the 1543 Copernicus book, saying that astronomy models can be useful even the underlying motions are not true. He wrote that book's ideas were "not put forward to convince anyone that they are true, but merely to provide a reliable basis for computation." Bellarmino argued that Galileo had not actually proved the motion of the Earth. By 1950, everyone accepted that motion is relative.“Today the view of physical science founded by Osiander, Cardinal Bellarmino, and Bishop Berkeley, has won the battle without another shot being fired. Without any further debate over the philosophical issue, without producing any new argument, the instrumentalist view (as I shall call it) has become an accepted dogma. It may well now be called the ‘official view’ of physical theory since it is accepted by most of our leading theorists of physics (although neither by Einstein nor by Schrödinger). And it has become part of the current teaching of physics.” [43, pp. 99-100]Physical theories would then become to be regarded as an economy of ‘clicks’ in detectors not necessarily linked to the description of reality.
Bohr is the man famous for saying:
There is no quantum world. There is only an abstract quantum physical description. It is wrong to think that the task of physics is to find out how nature is. Physics concerns what we can say about nature.People liked to put words in Bohr's mouth, so he may not have said exactly that.
Apparently the philosophically issues over realism were not settled in 1950, as plenty of physicists and philosophers argue about it today. The word "realism" is a misomer, and the advocates of realism are usually trying to get us to believe in properties that cannot be observed. They are imaginary properties that help make a model work.