The More a NASA Scientist Discovers, the More Questions She Uncovers
by Lindy Elkins-Tanton November 3, 2025 (ZocaloPublicSquare.org)
Textbooks are a false front for human knowledge. Science textbooks, at least.
In high school, I eagerly read the biology textbook and the chemistry textbook and the physics textbook. Every question posed had an answer in the back. All the reactions had been tested, all the accelerations calculated. Soon I would be fluent!
In college, classes were harder, and professors began to point out the unanswered questions. The textbook could take us to a certain frontier of the known, but beyond that, no one had figured out the answers. They needed better instrumentation, more years, super-specialized knowledge.
In the 18th century, Joseph Priestley isolated the element oxygen while doing experiments in the house where he worked as a librarian. Now we all learn about oxygen from textbooks. But today, the oxygen isotope 28O still presents a deep mystery: Theory predicts it should be a highly stable atom, but in 2023, scientists finally created it, and it immediately disintegrated. Why? So far, no one knows. The textbooks told a satisfying story about what is known. Explaining what is unknown, of course, is a much harder task.
Textbooks that seemed to know it all sometimes made me feel there wasn’t room for me in science. Everything was named, every process could be calculated, the answers were all there. Nonetheless I started to do scientific research as an undergraduate, under the mentorship of a serious and dedicated geologist. I learned to read peer-reviewed studies and think carefully about how the questions I was asking built upon the work of others.
I began to understand that the knowledge summarized in textbooks was a small compact nugget in the middle of all possible knowledge. It felt like watching the Earth (the sum of all that is known) recede into a speck as I zoomed out into the vast nothingness of space (all that is unknown). What we know is very, very little indeed; almost everything is a question.
There are so many more questions than there are answers, in fact, that we might be tempted to approximate and say we know nothing at all, but that would be a disservice to the years and years of painstaking accumulation of evidence by scientists, and their great leaps to new understanding. DNA! Plate tectonics! In those times of discovery, a new part of our universe came suddenly into focus.
In my research, I was attempting to measure, through experimentation in hot furnaces, the compositions of two minerals when they reached chemical equilibrium. This sounds like a teensy detail and also possibly a snoozefest, but its utility was that knowing these compositions could help geologists determine the temperature and pressure at which a natural rock formed, and therefore the history of the building and erosion of mountains.
Every PhD student knows this experience: I had my very first original research question of my very own, and I guarded it in my hands like a downy chick, breathed on it like an ember. I had broken out of the textbook mindset.
As I worked, I realized that every question was actually a bundle of related questions. What are the compositions of the two co-existing minerals? was bundled with, But what about in the presence of water? At a different pressure? If carbon is added? How long does it take to reach equilibrium in the experiment? In nature? How could you tell if they were not at equilibrium?
Suddenly, instead of one question, I had a dozen—so many that I needed to start giving them away: I needed to build a lab and start mentoring graduate students.
This is a process that many students go through, from being taught that everything is known (the textbook), to finding, with the help of an expert, a question they can work on, and then to thinking of questions on their own. This is the process of becoming a researcher, and a part of the path to becoming an expert.
I have found that the longer I exist as an expert in my own field of science, the less I like to assert a piece of knowledge with great certainty.
Eventually, the researcher learns enough about all the answered and unanswered questions in their area of specialization that they have a mental image of the landscape of knowledge and where its boundaries are—the cliffs after which lie only questions. The landscape of knowledge itself has holes, too, though. There are questions people have skirted around, and they lie like voids in the terrain. Those are the “known unknowns.”
There are also caverns under the terrain, areas of knowledge (or lack of knowledge) that have been covered over with the thin and treacherous boggy soil of “common knowledge.” So many false ideas are taken as true by habit and convention, appearing every day in the news. Sometimes they are propagated by interest groups, but more commonly just by the lazy comfort of common knowledge—no need to question it because no one else will. Everyone knows that the blood in your veins is blue because it has used up its oxygen and is going back for more. (Wrong! Veins appear blue because of how light interacts with skin and blood. Blood oxygenation is only a small part of the answer.)
A dedicated expert (and in fact every person) should constantly ask herself, “How do I know this is true?” The answer can’t be, “I believe it because it feels good.” The dedicated expert discriminates between an assertion, a statement that the speaker wants to be true, and a supported conclusion, a statement with data and reasoning behind it. (A student in my class last year remarked, “I think everything any politician has ever said to me is just an assertion.”)
At this stage of learning and mental sophistication you can enter the expert danger zone. Here, the confidence of knowing one landscape well can bleed into other domains. You see this in some Nobel Prize winners. People begin treating them as experts and oracles of all subjects, and some prize winners seem to come to believe it themselves. They speak with (mistaken) confidence on most any subject.
The truth is that even in our most familiar home landscapes of knowledge, we know very little. Every piece of knowledge I might cite is coated in layers of caveats, and subject to multiple modes of analysis. I might say with confidence that blood in veins appears blue when seen through the skin, but others might say, only for particular skin colors, or ages of people, or angles of wavelengths of light.
I have found that the longer I exist as an expert in my own field of science, the less I like to assert a piece of knowledge with great certainty. What, in the end, shed of all the caveats, do we absolutely know with certainty will be true forever? What is a piece of knowledge that is immutably added to the canon of human thought?
The gravitational constant, which determines the strength of gravity between two objects, might be one. But wait, it’s only true in a classical Newtonian environment, and it isn’t true when velocities are a significant fraction of the speed of light. A piece of knowledge is a delicate thing, to be treated with great caution, hemmed in as it is by the specific circumstances under which it applies.
Developing experts reach a fork in their roads. Some start to think they can answer any question, expound upon any topic. Others come to think they know almost nothing. This is the more humble path, and the better, and possibly the one less traveled. This is the path that leads us more surely toward deep knowledge. Where are you on your path?
Lindy Elkins-Tanton is the lead of the NASA Psyche mission and director of the University of California, Berkeley, Space Sciences Laboratory. She strives to be on the second path.
What does it mean to be an expert? In a new series, Zócalo publishes essays by and about experts—exploring the things they know, the reasons people seek their input, the ways they matter (and don’t), and their shifting place in the world today.
Primary editor: Sarah Rothbard | Secondary editor: Eryn Brown
I’ve greatly appreciated the following aphorism: “The specialist knows more and more about less and less until s/he eventually knows everything about nothing; the specialist knows less and less about more and more until s/he eventually knows nothing about everything.”
To which I add: “In the well-lived life, the goal is to know more and more about more and more, which is a difficult but noble goal.”