Decades after its launch, the Voyager spacecraft has yet to find signs of intelligent life beyond Earth. (ASSOCIATED PRESS)

Are we nearing the end of science? That is, are we running out of answerable questions, leaving us with only some mop-up duty, working around the edges of the great scientific achievements of Darwin, Einstein, Copernicus, et al.?

This was the provocative thesis nearly two decades ago of John Horgan, the Scientific American writer who had spent years interviewing luminaries in a variety of fields and had come away with a decidedly jaundiced view. His book “The End of Science” introduced the reader to superstars and geniuses, most of whom seemed slightly smaller in stature by the time Horgan left the room.

Naturally the professionals in the world of science were aghast. Horgan all but said they were wasting their time on marginalia. A delightful romp of a book, it nonetheless suffered from the declarative nature of the title, which had the loud ping of overstatement. There is the provocative and then there is the insupportable.

There’s a somewhat related line of argument that has been advanced by professor of medicine John Ioannidis, who says most scientific studies are wrong, their results not reproducible and likely fatally skewed by the unconscious desires of the researcher for a certain result.

And he may be onto something. Last month, Francis Collins, head of the National Institutes of Health, and Lawrence Tabak, NIH’s principal deputy director, published a column in the journal Nature stating that the scientific community needs to take steps to address “a troubling frequency of published reports that claim a significant result, but fail to be reproducible.”

They list a variety of factors that lead to the lack of reproducibility, including the way some scientists use a “secret sauce” to make their experiments work and the way they withhold crucial details from publication.

But it’s unlikely that science, as a whole, is going to run out of legitimate discoveries, and certainly there are questions to keep everyone in business into the distant future.

Nearly 20 years ago I typed up a list of “five simple questions that many scientists might accept as a core curriculum of the unknown” (The Washington Post, Aug. 11, 1996):

1. Why does the universe exist?

2. What is matter made of?

3. How did life originate?

4. How does consciousness emerge from the brain?

5. Is there intelligent life on other worlds?

The simplest questions are the hardest. For example, the origin of the universe isn’t something you can reproduce experimentally, to test the “why” of it — and so even if you could detect the first sparks of the big bang you would know merely what happened and not necessarily why it happened. You would have correlation/
causation issues.

The Large Hadron Collider, near Geneva, has been smashing particles in an effort to discern what the universe is made of, but the physicists are nowhere close to nailing that down. In fact, just the other day they announced, in effect, “We’re gonna need a bigger collider.”

The origin of life is tricky because by the time you get anything big enough and robust enough and complex enough to form a fossil, you’re already way, way past the point of origin. How do you get the first cell? How do you get rolling with this life business?

Consciousness may be an innately murky enterprise, and the issue of intelligent aliens remains completely speculative. Our big radio telescopes have heard not a peep so far. Maybe the Voyager spacecraft will bump into something out there in interstellar space (but don’t count on it).

And there are so many smaller questions, too, for scientists to work on: What exactly caused the Permian mass extinction some 250 million years ago (Siberian vulcanism?) and why did some species survive that while so many died out? Moving to more recent times: How and when did humans migrate around the world? Did they populate the Americas in a single migration or in multiple waves by land and boat?

Talk about unknowns: Most of human existence was, and is, prehistoric — lost in the fog, like my senior year in high school.

This is an abridged version of an article that appeared on Achenblog.