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by Jerry Oltion

How Science Works


In this column we've studied how quite a few interesting things work. We've investigated kites, blood tests, space drives, supernovae, orbital mechanics, vaccines, batteries, flying cars, analemmas, printing presses, and plenty more. We've approached them all scientifically, because this is after all a science column, but we haven't yet discussed the underlying principle behind them all. We haven't examined how science itself works.

What makes some activities science and others not? This is a good time to look into the subject. As I write this, America has just elected a president who has vowed to put science back into policy making after four years of ignorance.* You'll be reading this about the time his science-backed initiatives begin to be implemented. You'll be hearing plenty of griping from people whose lives and livelihoods are affected by those initiatives, and plenty of arguments that the science is flawed. Very few of those arguments will be put forth by scientists, however, because scientists know how science works. To refute a scientific argument you need a better scientific argument, not just a different opinion.


The Scientific Method


So how does science work? You've probably heard about the Scientific Method. That's a way of examining a phenomenon and learning about it. I've seen it stated many ways, but the common elements are:

1. Make an observation.
2. Gather information about the phenomenon you're observing.
3. Form a hypothesis (a guess as to what might be going on) and make predictions based on that hypothesis.
4. Test the hypothesis and its predictions in an experiment.
5. Analyze the results of the experiment and draw conclusions. If necessary, modify the hypothesis and run more experiments. Repeat until the hypothesis and the experimental results agree.

There's a lot more to it than that, of course, but that's the basic structure of scientific inquiry. It's a method for learning what's really going on, as opposed to simply what you think might be going on, or what you hope is going on. The goal is to understand the universe rather than dictate to the universe.


Hypothesis vs. Theory


One of the basic rules for the hypothesis is that it must be both testable and falsifiable. That means your experiment should be able to prove the hypothesis right—or wrong if it really is wrong. That means if you observe that baking soda fizzes when vinegar is poured on it, you don't hypothesize that little invisible men are sneaking in from an alternate dimension with little invisible fire extinguishers to fool you into thinking a chemical reaction is taking place. That hypothesis would be difficult if not impossible to test, since you have no control over the purported invisible interdimensional hoaxters. Worse: it's impossible to falsify, since you could always claim that the invisible entities were simply evading detection. It would be more productive to hypothesize that a genuine chemical reaction was taking place, and study that.

Once the hypothesis has passed a few tests and looks relatively robust, it leads to the development of a Theory. The two terms are often used interchangeably, but a hypothesis is more of an educated guess that needs to be tested, while a theory is a more refined explanation of what's going on, and attempts to explain why. It should ideally lead to predictions of other phenomena that can be tested further, which leads to modification of the theory until it becomes widely accepted.


Laws of Nature


When a theory becomes well enough established, it can gain the status of a natural law. For instance we talk about the law of gravity, the laws of motion, or of conservation of matter or energy. What are these laws? Certainly not sets of rules that the universe must follow because we say so. They're sets of rules that we've figured out the universe follows because it more or less has to. Apples fall off trees not because anybody compels them to; they fall because that's how objects behave in the presence of a gravitational field. We've never observed otherwise without applying a force stronger than gravity to counter it, and we've come up with a theory that predicts how gravity behaves with nearly complete accuracy. Hence we call gravitation a "law" and proceed as if it's solved.

But is it? Of course not. New data could come in at any time to force us to rethink gravitation. In fact, people studying the motion of galaxies have come up with a theory called MOND, for MOdified Newtonian Dynamics. Galaxies don't rotate the way Newton's laws of motion say they should, so some scientists theorize that gravity doesn't behave the same way on large scales as it does on small scales. The problem is, they don't have a good mechanism to explain it. They have proposed some experiments that could prove or disprove it, which is a step in the right direction, but so far all the observations we've taken have eliminated rather than proven various aspects of MOND. So at this point it's just a hypothesis that's waiting for a good test to come along that will either confirm or completely deny it.


The Uncertainty Principle


It's important to recognize that nothing in science is known for sure. Scientists learn how things work and make hypotheses and theories and laws to describe them, but they're always open to new interpretations that fit the data better. Newton's laws of motion are spot-on at the velocities we see in everyday life, but when you get up near the speed of light, things get kind of strange. Einstein's theory of relativity built upon Newton's laws and explained how they needed to be modified under certain conditions. Einstein didn't disprove Newton; he expanded Newton's laws and explained how they behaved in extreme situations. Furthermore, Einstein's theory has held up to every experimental test we've thrown at it. By right, we should be calling general relativity a law rather than a theory, but scientists are slow to commit, as they should be. Give it another century or so and we might be calling them "Einstein's laws."

"Theory" is impressive enough. In order to reach that status, the hypothesis behind it has to have survived many tests. Other scientists have to be able to replicate those tests, ideally using different methods to zero in on the same conclusions. The best test of a theory is when a skeptic tries to disprove it and winds up confirming it instead. When all that has happened, and nearly everyone who knows anything about the field in question admits that the hypothesis fits the data and makes testable predictions, it becomes a theory.

So when people dismiss global warming because it's "just a theory," they're showing a basic ignorance of scientific terminology as well as ignorance of the science of global warming. Gravity is "just a theory," too, but nobody (well, nobody worth taking seriously) worries about falling off the Earth.




Despite the above, skepticism is a good and necessary part of doing science. It's easy to fall in love with a pet theory (so named because the believers have bypassed the hypothesis and testing stage) and lose one's scientific objectivity. When that happens, people will sometimes throw out good data that doesn't fit the theory because they're convinced there's something wrong with the data rather than the theory. That's where skeptics play an important role.

In 1989, when two scientists announced that they had achieved nuclear fusion—a process that in theory requires extremely high temperature and pressure—in a beaker at room temperature, other scientists were quite skeptical. The two scientists involved, Stanley Pons and Martin Fleischmann, did what scientists should do: They described their experimental apparatus and their hypothesis (that palladium electrodes held hydrogen atoms close enough together to undergo fusion) well enough for others to replicate the experiment. The skeptics did just that, and they were unable to achieve the excess heat and neutron emission that fusion would have generated. Cold fusion was eventually proven false by the sheer preponderance of evidence to the contrary.

It's important to note that not just skeptics contributed the data that ultimately falsified cold fusion. Scientists who hoped and believed that it might be true also ran experiments and failed to demonstrate fusion, and as scientists should, they reported their negative results as well.

That's how scientific skepticism works. But the popular notion of skepticism has been distorted into an ugly demonstration of ignorance. There's a difference between skepticism and denial. We can be as skeptical as we want of a scientific theory, and we should be skeptical of the ones that aren't based on rock-solid evidence, but if we deny a theory we had better have enough evidence to refute it scientifically.

Wishing something weren't so doesn't make it go away, and when the data become overwhelmingly weighted toward a particular conclusion, there's little refuting it. That's why Al Gore called his book and movie on global warming An Inconvenient Truth. Whether you like it or not, global warming is real, and we know it's real because the science was done right and the evidence is overwhelming.


Belief vs. Reality


Public opinion polls would have us believe that the popularity of an idea somehow makes it true. But science isn't a popularity contest; it's an expertise contest. So when you read that 97% of scientists believe that global warming is both real and human caused, that's actually kind of irrelevant. Sheer popularity of a theory, even among scientists, doesn't necessarily prove that what they believe is true. What proves it is the data that those scientists have studied, the predictive models that they've run, the independent confirmation of their conclusions by other scientists using different data and different models, etc. The human-caused global warming theory (and I use the word "theory" in its scientific sense) has met those criteria. It's as close to proven as relativity or gravity or the heliocentric theory of planetary motion.




Does that mean you can't have an opinion? Absolutely not. You're free to believe any damn fool thing you want. For instance, I don't "believe in" dark energy. It doesn't feel right to me. 68% of the universe is supposedly made of some form of energy we can't detect, other than that it seems to be propelling everything away from everything else. I suspect we'll ultimately find out that we've made some fundamental oversight or some error in our math, and there'll turn out to be a mundane explanation after all. But my belief doesn't give me the right to say that dark energy is a myth. It doesn't even give me the right to say that dark energy is the wrong explanation for the accelerating expansion of the universe. Why not? Because I have no evidence to support my belief. All I have is a gut feeling, and gut feelings don't count in science. They can act as motivators, and they're wonderful for that—gut feelings have led to many important scientific discoveries—but a gut feeling isn't in itself scientific. So I can say that I don't think dark energy is right, but in the meantime I have to admit that the evidence is pretty strong that dark energy is real. If I had to bet my life on it, I'd go with dark energy because that's what the science supports.

In the case of climate change, which could affect all life on our planet, what any of us believes is irrelevant. It's what the science shows to be true that matters.


The Scientific SWAGger


When you become familiar with science, you learn to do it on the fly. You can make an observation and develop a hypothesis practically instantaneously, based on a store of previous knowledge. We call that the "Scientific Wild-Ass Guess," or SWAG for short.

Suppose you're out at night and see a string of bright lights moving across the sky, all in a neat row. They're eerily silent and move steadily, without blinking the way airplanes do. Your scientifically trained mind quickly throws out several possibilities: A rip in the fabric of space. An alien invasion. A Russian missile attack. The breakup of the International Space Station à la the movie Gravity. A flock of well-trained birds carrying flashlights. Or perhaps it's SpaceX launching another set of Starlink satellites, sixty at a time.

So you count the dots, and see about sixty of them, give or take. Looks like a Starlink launch. No need for alarm, no need to stock up on toilet paper. You don't know for certain that it's Starlink satellites, but that's by far the most likely explanation, and a little searching on the Interthingy will confirm it. It will also show you thousands of people who are freaking out and thinking the world is coming to an end because they don't know how to make a decent SWAG.

Don't be one of those people. Think scientifically instead, and aspire to see the universe as it actually is.


Jerry Oltion has been a science nut since he was old enough to spell "curious." He has written science fiction almost as long, and has done astronomy somewhat less. He writes a regular column on amateur telescope making for Sky & Telescope magazine, and spends many, many nights a year out under the stars.

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