One of my greatest fears growing up (OK, I was a weird kid) was that I was getting opposing sides of a story without knowing it. I read a lot of different kinds of science books. I read books about evolution, I read books about astronomy, I read books about physics, chemistry, dinosaurs, nuclear power, all sorts of animals and ecosystems, ancient humans, and on and on. The books I was most attracted to were the ones in which I felt the author was talking right to me, as if we were in the same room and this was a private lesson meant just for me.

I always worried, though. What if this author’s voice and that author’s voice weren’t really the same voice at all? What if author A started with one set of assumptions (the Earth is 4.6 billion years old, for instance), but author B started with a completely different set (no, the Earth’s only 6 thousand years old, silly. Everyone knows that). Which voice of authority should I believe? Could it be that biologists had this beautiful story all laid out, but behind the scenes physicists were all shaking their heads and wondering how anyone could believe such baloney?

Fortunately, Isaac Asimov, Carl Sagan, and others showed me that modern science really is one story. There might be disagreements within fields, but everyone agrees on the basic framework. It wasn’t always so.

I wonder how I would have reacted to the disagreement between physics (led by William Thomson) and biology (led by Darwin) had I been reading around 1900. Darwin said the Earth had to be hundreds of millions, maybe even billions, of years old to give evolution time to work. Thomson said the Earth could be no more than a few million years old, due to its internal temperature. Probably I’d have sided with the physicists. They had the numbers, after all.

But the physicists were wrong. What Thomson didn’t know – couldn’t have known – was that there was a hidden heat source in the Earth, radioactive decay. I’ve always thought it was beautiful that not only did radioactive decay give Darwin the billions of years his theory needed, it also gave a yardstick for measuring those billions of years.

Of all the beautiful things about modern science, I think the most beautiful must be the way it all hangs together so elegantly. In another hundred years, will science still work this way? Or will our ideas seem as quaint and out of place as the disagreement between Darwin and Thomson?

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