by Jay Johansen | Oct 29, 2022
I saw a video on YouTube recently, Could we ACTUALLY grow potatoes on Mars?, that brought to mind the question, Is this science? Or more generally, What is science?
The video discusses the question of whether it would be possible to grow (Earth) plants on Mars. It's a very interesting video, worth watching. The narrator discusses the composition of the soil, the lesser sunlight received on Mars, as well as lower gravity and other factors that you might not consider at first.
It's the sort of discussion that many people would call "scientific". I think this is a good example to discuss this question, because it is pretty non-controversial and doesn't stir up emotions and quick reactions.
Let's start by asking, What is science? Historically, the answer is, A process for gaining knowledge by experimentation and observation, or the knowledge gained by this process. That is, the key to science is "experiments".
This is unlike other fields of study.
Suppose you said that you don't believe the Theory of Gravity. We could test it by performing experiments. We could hold a rock at arm's length and let it go. If it falls to the ground, that would be confirmation of the theory of gravity. If it floats in midair, that would prove the theory wrong. Or perhaps your objection is more detailed. You don't doubt that rocks fall when you drop them, but you doubt that they fall at the speed predicted by the theory. In that case we could carefully measure the speed at which the rocks fall. We could, at least in principle, travel to other planets and drop rockes there and measure how fast they fall.
Now consider mathematics. For example, Euclid's Theorem 1 is that it is possible, using only compass and straight-edge, to construct an equilateral triangle on a straight line. That is, to take a line and draw two other lines of exactly the same length to form a triangle. Suppose that you question this. How could you prove Euclid right or wrong? We could not prove this by experiment. Suppse you try Euclid's method, and then you measure the length of the lines with some very precise measuring instrument, and you find they aren't QUITE the same length. A mathematician would reply that you must have been a little sloppy in constructing the lines, that if you had followed Euclid's method EXACTLY correctly the lines must be exactly the same length. The only way to rebut Euclid would be, not to perform an experiment, but to show a flaw in his logic. You would have to go through his steps one by one and show that somewhere along the line he had a logic error.
Or consider history. Suppose you doubt that Julius Caesar really led an army that conquered Gaul. How could we prove this true or false? Again, there is no experiment we could do to study it scientifically. We cannot reproduce the war in Gaul in a laboratory. Even if we somehow recreated the war, that would just prove that it is possible, not that it actually happened that way 2000 years ago. The only way to study the question is to study historical documents.
Note from my examples that "not science" does not mean "false". It certainly does not mean "nonsense". Some questions cannot be studied scientifically by their very nature. They are just not "scientific questions". Some questions can in principle be studied scientifically, but we do not presently have the ability or the resources to perform the experiment. Like my suggestion of travelling to another planet to test the theory of gravity. I am reminded of a book I once read about "near death experiences". What do people really experience when they become clinically dead and are then revived? In principle we could study this question scientifically by killing a large number of people and then attempting to revive them. In practice, there might be some ethical objections to such an experiment.
This difference is what leads to the power of science. Science has an ability to resolve questions and move on that no other field of study does. Sure, we can study historical documents and say, "The consensus is that Caesar really did conquer Gaul." But someone could always reply, "Maybe all the surviving documents are biased. Maybe the Romans made up this story about conquering Gaul to boost their national prestige or to frighten their enemies. Maybe their were other ancient history books that said that Rome did not conquer Gaul but the Romans managed to have them all destroyed." Etc. After all, there are some historical questions that are debated to this day because ancient books give conflicting accounts, or because modern historians consider them implausible, etc. It's very hard to conclusively prove something about the past.
But with science, we perform the experiment and the issue is settled. The experiment confirmed the theory or it refuted it. Question settled, and we can move on. Okay, in real life it's not quite that cut and dried. Sometimes experiments appear to confirm a theory, but subsequent experiments show that the theory was only true under certain conditions, or that it was close enough to appear deceptively accurate but not quite, or that the experimenters simply misinterpreted the results. Just for example, Newton's Laws of Motion were tested over and over again over the course of hundreds of years and appeared to be confirmed. Then Einstein came along and showed that Newton was a very close approximation for speeds much less than the speed of light, but became dramatically wrong as you approached light speed. But that said, still, students of politics today still debate the same issues that Plato and the ancient Greeks debated. Philosophers still debate the same questions that Aritstotle and Socrates debated. Etc. But scientists no longer debate whether the world is flat or round or whether things are made of atoms. Those questions are settled and we can move on.
So now let's get back to the question of whether it is possible to grow Earth plants on Mars. The scientific way to study this question would be to go to Mars, plant some Earth plants, and see if they grow. The problem, of course, is that such an experiment would cost billions of dollars and we just don't presently have the resources to do it.
In the mean time, it is certainly fair to speculate about whether it is possible. It is fair to look at what we know about how plants grow and what they need, and to compare this to what we know about conditions on Mars. Such an analysis could be very technical and rigorous. This might lead some to call it "scientific". But it isn't, really. It's deduction and speculation, not science. The conclusions might be completely true, but they wouldn't be science.
So as I said, I found the video interesting and informative. But without being able to perform the experiment, the video makers could not prove anything in a scientific sense. They listed all the known requirements for plants to grow and discussed how these related to the Martian environment. But a scientifically-minded person would ask, How do you know that you have considered ALL relevant factors? Maybe there's something plants need that you don't know about, or don't fully understand. The only way to truly say would be to perform the experiment.
© 2022 by Jay Johansen
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