Science writer John Horgan at Scientific American explores the topic of whether scientific discovery has finally "hit a wall". Horgan wrote a book on this question several years ago titled The End of Science, and he observes that important discoveries are diminishing even as research efforts are multiplying.
It's as if science is approaching an asymptote.
Perhaps mankind has indeed come to the end of what can be learned, but historically the belief that something couldn't be known was often overturned in surprising was soon thereafter. In the 19th century French philosopher August Comte wrote that the chemical composition of the sun would be forever unknowable to us.
A few years later the development of spectroscopic analysis enabled researchers to discover that the sun was mostly hydrogen. This was followed by the discovery of a completely new element on the sun, helium, which led to the realization that the process of nuclear fusion was the source of the enormous energy the sun was producing.
Examples like this and others should make us cautious about predicting the end of discovery.
Perhaps a better way to think of the diminution of scientific progress is not in terms of hitting a wall but in terms of having taken the wrong exit off the interstate and winding up in a cul-de-sac.
Think of the interstate as the metaphysical highway which facilitated so much of the progress of the last five hundred years. Science prospered for centuries because it was nourished by the assumptions of a theistic worldview – that the universe was intelligible because it was created by an intelligent Being and therefore might yield its secrets to reason, that it was not itself sacred and was therefore a fit object of study, and that being a gift of God it was worth studying.
Rodney Stark has written that of the fifty two most productive scientists at the start of the scientific revolution fifty of them were Christians and the majority of these were devout. I doubt that the same could be said today and perhaps the difference in worldview makes a significant difference in one's approach to science.
These theistic assumptions and others were the metaphysical drivers of the work of those who sought to “think God’s thoughts after Him”, and even after Christianity fell into disfavor in the West in the 19th and 20th century the intellectual momentum it had created carried scientific discovery well into the present era.
But as people like Horgan tell us, that momentum seems to be dissipating, and it could well be because naturalism lacks the metaphysical resources to sustain the scientific enterprise, largely because it rules out apriori the possibility that the world is intelligently, intentionally designed. It rules out the possibility that mind, not matter, is the fundamental reality.
Sometimes in science a shift in the way one looks at problems or looks at the evidence can be exceedingly fruitful. Perhaps a shift in our assumption that materialism is the correct metaphysical foundation for science would be like backing out of the cul-de-sac and getting back out on the highway of scientific progress.