It's Just a Theory...

8/12/07 – 8/18/07
by C. Zaitz

If science is based on “theories,” how do we know they are true? After all, a theory isn’t necessarily truth or law, is it?

All scientific theories begin as a hypothesis, or a possible answer to a question we ask. For the question, “Why don’t we fall off the earth if it’s round?” we could invent some pretty cool explanations. For example, we have seen how magnets on earth attract each other, and we know that iron can be magnetic. If earth is a big magnet, maybe it pulls the iron in our blood toward it. But then we remember that feathers and leaves also fall to earth and they have no iron in them. Oops, back to the drawing board with our hypothesis.

We will have to gather observations and do experiments to come up with another hypothesis. We have to design experiments that will test exactly what we want to test without introducing too much error. And we have to accept the answers we get, even if they don’t agree with our hypothesis. The key to scientific theories is that they need to be falsifiable. That means that we must be able to test to see if a hypothesis fails. If it does, we have to refine it or chuck it completely. If we make all reasonable tests and it holds up, it may become a theory.

In the late 17th century when Sir Isaac Newton began to think about what made apples fall and held the moon in orbit, he didn’t have a word for the force he was trying to describe. He wasn’t trying to prove a theory; he was trying to find a reasonable hypothesis to explain his observations. He needed a mathematical way to describe how objects move, so he developed calculus. With that tool, he was able to find an equation that worked in every case he tried. Finally he came up with a name for what he was describing, from the Latin, “gravitas,” meaning weight or heaviness. Today we call them the Laws of Gravitation, but they are really theories that have held up over time and trials. But new technology brings new tests.

By the beginning of the 20th century, Albert Einstein was able to test the laws of gravity around a massive object, the Sun, and found that the “laws” needed to be modified. By the time he was done, he had changed the way we think about gravity. No longer do we imagine it as an invisible magnet, but more like a fabric in which we are all embedded. Our movements are shaped by this fabric, which itself is shaped by mass. We follow its curves like golf balls on a putt putt course. Einstein called it spacetime, and scientists are still unraveling the implications today.

The word theory deserves more “gravity” than it is usually given. In order for a hypothesis to be scientific and to become a theory, it has to be tested. That’s why religious or “new age” ideas are often not considered to be in the realm of science. I believe it’s important for us to understand how science works. Otherwise we might never have known how gravity works, and therefore never be able to fly a rocket to the moon. Scientific theories are the only things that let us do that.

Until next week, my friends, enjoy the view.