How does the former ether theory raise questions about whether scientific theories describe reality?

The former ether theory serves as a central case study in the philosophy of science, challenging the realist assumption that successful scientific theories provide a literally true description of reality.1

The ether was a theoretical substance once believed to be the necessary medium for electromagnetic waves. While the theory—notably the work of Augustin-Jean Fresnel—was spectacularly successful in predicting phenomena like diffraction and interference, the Michelson-Morley experiment and the subsequent development of special relativity led to its abandonment.231

This history creates a dilemma for scientific realism:
* The Challenge: If a theory can be empirically successful while positing entities that do not exist (like the ether), it undermines the argument that success implies truth.1
* The Realist Response: Modern "piecemeal realism" argues that we should not assess theories as wholes. Instead, we can distinguish between the parts of a theory responsible for its predictive success—which are often retained as approximately true—and the auxiliary hypotheses (like the ether) that are discarded.1

Ultimately, the ether theory forces a more nuanced view of how science maps onto reality, suggesting that while theories are powerful instruments, their claims about unobservable entities require careful, case-by-case evaluation.41