ABSTRACT
This chapter demonstrates a similar impasse has again been encountered recently in areas of physics like high-energy physics and cosmology. Carroll is weary of a section of the physics community that deems such theories non-scientific, basing their argument on Popper and falsifiability. Popper is clear about the fact that the demarcation between science and metaphysics that he is seeking is only being done to arrive at a theory of knowledge. Like scientific realism, the constructive empiricism of van Fraasen also accepts a literally account of scientific theories, but only for the observable entities in the theory. Anti-realists refuse to equate the validity of a scientific theory with the existence of the entities it postulates. String theory and, in general, any approach to quantum gravity, can be tested only at energy scales which are so high that they are completely out of the realm of experimental testability.
