As most people do, I suppose, I used to take anything I heard in a science classroom as being the plain, unvarnished truth. But one day in college, sitting in a physics classroom, I changed my mind.
I was taking a physics course as part of my undergraduate degree in chemistry, physics and biology. The instructor had just been talking about centrifugal force -- the force that tends to pull an object outward when it rotates around a center. He had used a small metal ball on the end of a string during his discussion and had spun the ball, likening the string to gravity, which of course holds the Earth in orbit around the sun.
Something popped into my head, a question I had never thought of before. I'll bet you've never thought of it either. I had been listening to people talk about gravity all my life, but it had never occurred to me to wonder exactly what it was. I raised my hand and asked, "What is gravity anyway?"
"Let me show you," the instructor said. He went to the chalkboard and filled it with mathematical equations.
"Thanks," I said when he finished. "I understand that. I see that we can measure the force of gravity, but what exactly is gravity?"
He answered with a frown, pointing toward the chalkboard.
"I just explained that," he said.
"You mean the equations?"
"Yes," he said, rather impatiently.
"But if I ask what light is, or what air is, or what a rock is, I don't get some equations written on the board, I get an answer -- in plain English -- something I can understand. What I'd like to know is, well, what is gravity? What's it composed of?"
He answered with a deeper frown and even greater impatience. "It isn't composed of anything. It's a force."
"But if gravity isn't composed of anything, how does it operate over a distance? Where's the string that holds the earth in orbit? There must be something there. What, exactly, is it?"
Well, I can tell you that I stopped asking questions that day, not because I got answers, but because I wanted to pass the course. I went to the library after class with a lot of questions -- and some strong doubts -- on my mind. It had occurred to me that there were many questions that had been left unanswered in the courses I was taking.
For one thing: What is magnetism? Like gravity, it operates over a distance, but nobody had ever explained how it did it, or had even explained what magnetism actually was.
What I found out in the library was an eye-opener. We don't know what gravity is. We don't know what magnetism is either. Nor do we know what a positive or negative charge is. We don't even know why the mass of a proton is 1,836 times the mass of an electron, even though protons and electrons have equal but opposite charges. We don't know a lot of things. Oh sure, we can measure stuff.
And we can write tons of equations. But we don't know what many things actually are, or how they do what they do.
Despite the fact that the physics instructor I had questioned made it very plain that he thought I was an idiot for daring to ask such questions, I found out that there was another person who once asked the very same questions, someone who was highly concerned about how gravity worked over a distance. In fact, he hesitated to offer his theory of gravitation to the scientific world, without any explanation of how the dumb thing worked.
His name was, of course, Isaac Newton.
When challenged about his newly offered theory of gravity, Newton replied that he had only intended to demonstrate the existence of gravitational attraction and to discover its mathematical laws, not to inquire into what it was.
He didn't know. We still don't know.
The simple truth is that science does not now have, and probably never will have, the answer to many, many questions.