We sometimes hear people speaking about “gaps” in our scientific knowledge. People often speak as if there were merely a few cracks or gaps in our scientific knowledge, and that in the not-too-distant future those gaps will be filled in (perhaps rather like some construction worker filling in a few cracks in a wall).
Is it correct to speak in such a way? No, it isn't. But the reason is not that our scientific knowledge is perfect. The reason is that our scientific knowledge is so fragmentary and so tiny that it is misleading to use the term gaps or cracks to refer to what we don't know. What we should be saying is that what we do know is tiny, and what we do not know is vast.
Consider the current state of our knowledge. We know about the surface of our planet and a few other planets. But we live in a vast universe of billions of galaxies, many of which have billions of stars. So we know nothing about 99.999999999999% of the planets of the universe.
We also know basically nothing about most of the matter and energy in the universe. Scientists say that 96% of the matter and energy is dark matter and dark energy, which we know basically nothing about. We also have no idea what caused the origin of the universe billions of years ago. There are many mysteries regarding how we got from the supposedly infinite density of the Big Bang to the orderly state the universe is in now.
Considering only our ourselves and our planet, we know almost nothing about mysteries such as the origin of life and how our brains work. There is much evidence of some great psychic reality that we are almost completely ignorant about. Unraveling how the brain works seems a thousand year project that we have barely started.
Given such realities, is it accurate to say that there are “gaps” or “cracks” in our knowledge? No, because such a term implies that we have learned a good fraction of what there is to know. If someone asked you how much you know about quantum chromodynamics, it would be most misleading for you to say that there are gaps in your knowledge of quantum chromodynamics (as that would imply you know a large fraction of that topic). You should instead say that you know nothing or virtually nothing about such a topic.
Rather than speaking of gaps in our scientific knowledge, it is more truthful to say that our knowledge of nature is fragmentary, and that we have acquired only a few pieces in the vast jigsaw puzzle of nature. In the great million-year project of unlocking the universe's secrets, we are merely fledglings and newbies.
Those who sell a story of scientific triumphalism often speak as if scientists are like college juniors or seniors with not terribly much left to master in the curriculum. But instead they (and the rest of us) are all like kids who have merely finished the first few weeks of kindergarten.
Imagine a little child who makes a trip to the seashore. After he observes a few seagulls and fills up a bucket with shells, pebbles, and starfish, he may congratulate himself on his splendid progress in understanding nature. But ahead of him lies the vast and mysterious ocean, the mysteries of which he has barely begun to unravel. That little child is like humanity, which has so far accumulated only a few scattered fragments of nature's deep and mysterious truths, too vast in number to be enumerated.
Schematic diagram of human knowledge