In this talk, one of the authors of The Reinvention of Science. Slaying the Dragons of Dogma and Ignorance explores how science has often relied on postulated but unseen entities to explain observations. Historical examples include phlogiston, the luminiferous ether, the homunculus, and crystalline spheres. Some such entities hindered progress, while others were later confirmed. Neptune exemplifies a successful prediction later observed, whereas the hypothetical planet Vulcan was discarded after Einstein’s general relativity explained Mercury’s orbit. Today, cosmology invokes Dark Matter and Dark Energy: will they prove to be “Neptunes” or “Vulcans”?

The second part examines an ongoing paradigm shift concerning the end-Cretaceous mass extinction 66 million years ago. The dominant view attributes dinosaur extinction to a Yucatán asteroid impact, a conclusion widely accepted in science and popular culture. However, research led by Princeton paleontologist Gerta Keller suggests extreme volcanism in India’s Deccan Traps began at least 400,000 years before the impact and had already driven widespread ecological decline. The asteroid certainly impacted, but may have been neither necessary nor sufficient to cause the extinction. Despite this evidence, the impact hypothesis still dominates public understanding, while alternative models incorporating prolonged volcanism continue to develop.