Why Believe Science? Part II

HS #26  2017.9.5

Why Believe Science, Part II

Welcome back. I’ve been waiting all month to continue our discussion of “Why believe science.”

Recall that Francis Bacon ushered in the scientific age by proposing that we come to the natural world with an open mind, form simple coherent hypotheses, and then relentlessly test these hypotheses with experiments – changing our theory accordingly.  

It seems like a reasonable approach. But do you notice what this approach doesn’t accomplish?

Bacon would likely have fully agreed with the 20^th century philosopher Karl Popper who noticed that even the scientific method does not prove anything true. Let me explain.

Suppose I give you a penny and ask you to determine by flipping it whether it is a two-headed penny. If it lands heads each time, you will become increasingly confident that it is two headed. But you will never know for sure - unless you happen to get a tail. Similarly, given a scientific theory, each experiment is designed to prove the theory false. If numerous experiments fail to show that the theory is false, just as with the coin, we become increasingly confident that it may be true. But we never know for sure. In this sense science is open-ended in its search for truth.

Examples of this abound in the history of science. Maybe the most famous concerns gravity. Isaac Newton was the first to realize that the circular motion of planets and the “straight down” motion of a falling apple were both manifestations of the same thing - gravity.  Newton developed the mathematics necessary to understand and predict the behavior of both. He was a genius of the highest order.

But he was wrong. While his equations gave accurate descriptions of just about everything, it faltered just a tiny bit with the orbit of the planet Mercury. Not much, but just enough to leave astronomers wondering.

Three centuries later Albert Einstein solved the problem. His General Theory of Relativity (Essentially: Matter tells space how to curve, and space tells matter how to move) not only explained Mercury’s orbit, Einstein also predicted that light from a distant star should bend a little as it passes the sun. In 1919, prepared in the midst of a world war, the scientific community eagerly awaited the results of measurements taken during a solar eclipse. When his prediction was verified, the name “Albert Einstein” became a household word. Today his theory is used to provide the accuracy needed for the GPS system in your car.

So is Einstein’s theory true?  No scientist would be silly enough to say so. It’s closer to the truth than the previous theories, but no one knows whether it too may be modified as new experiments are done. Indeed, Einstein himself continued working on it his entire life.

While I was at Iowa State University, there was an engineering professor who tested any machine claimed to have perpetual motion. Such a machine would violate the Law of Conservation of Energy, which is probably the most solidly tested claim in all of science. But his point was that science proves nothing true. So he would check (for a fee of $50).

Indeed, we’ll never know whether there even is a final true answer. Consider the numbers, ½, 1/3, ¼, 1/5 . . .  0.  These fractions are all getting closer and closer to 0. So we can think of 0 as the culmination or the Truth towards which the others are converging. However, if 0 weren’t there, then the others would still be getting increasingly close to each other. Similarly it might be that even though each advancing scientific theory gives predictions increasingly close to the previous theory, there may be no fully true answer to be found.

What’s the bottom line?  Here is an important one for me.  Humans are proud and stubborn. That’s true of scientists as much as anyone else. However, there is a sort of self-correcting humility built into the scientific method. The inherent skepticism, the test by experimentation, the required reproducibility by other scientists, the commendation for proving established beliefs wrong, and the inherent inability to consider any answer as final – these taken together can make one confident that the findings of science are (perhaps haltingly) converging to truth about our natural world.

Churchhill famously said, “Democracy is the worst form of government, except for all the others.” Similarly, although it is painstakingly slow and labor intensive, the scientific method has given us a window to discover the truth about the natural world – our home.