Earlier this week, I visited a fourth-grade class at the public school where I live. I try to go every year to different classes, from grade school to high school, to tell students about the universe.
The class had been studying the solar system, in particular the planets and their properties. The teacher gave me carte blanche to do whatever I wanted. I felt that contextualizing planets would be a good idea, telling their story from birth to death, their relation to their parent star, in our case, to the sun.
Given that we humans have been telling stories to children and to each other since the beginning, and that most cultures have some narrative of our origins, there was nothing more natural. Science treads in the same footsteps of our ancestors, answering to our longing to understand where we fit in as we look up to the sky.
"We are stardust," I started, explaining how stars are made of hydrogen, how they burn their entrails to fight the inexorable inward pull of gravity. An "oooh" resounded around the room. About 10 hands, out of 20, went up like rocket ships.
"So everything is stardust then? Even planets? Even Earth?" asked a tall girl. "Yes," I answered. "We all have the same origins that way." "But what about genes? Are they stardust, too?"
That took me by surprise. Did she really know about genes? How awesome was that? "Yes, even genes. After all, genes are just super huge molecules, and any molecule is made of atoms, and atoms come from stars." The teacher sat in the back, smiling, clearly proud of her gang.
I moved on to explain how our sun and the planets were born together, as a giant spinning cloud of hydrogen collapsed. "Anybody know how to make pizza?" I asked. Again, 10 hands went up. A boy said: "Well, we make a big ball of dough and then roll it." "Ok," I said, "but what if you don't roll it? How do you make it flat?" Every hand went up. "You spin it! You spin it!" I smiled, impressed with their enthusiasm and intuition. "Exactly! When you spin a ball, it flattens at the poles and grows at the equator. Most of the stuff goes to the middle, and becomes the sun. The leftover matter bundles up into the different planets."
"But how does the sun shine?" asks a shy boy in front. "It's an explosion," answers another. "You got it," I said. "It's an explosion that has been going on for about 5 billion years!" Eyes widen. "And it's going to go on for about another five billion. A nuclear fusion explosion." I explained what nuclear fusion is — I talked about H-bombs.
"How do you know this?" asked a blond boy in the back. "How do you know all these things are right?" "Amazing question," I said. "In science, we can measure things, verify ideas, contrast our results with other people. Slowly, we get to build theories that explain what we measure and see with our instruments." "But you don't know what made the stars, do you?" the boy insisted. "Well, actually we do, but it starts to get complicated." (I didn't want to go into cosmology, fluctuations in the different types of matter and radiation in the early universe, etc.)
The boy didn't give up. "But if you keep asking and asking, you'd get to what you don't know." "Absolutely!" I said. The boy sighed with relief. Was he feeling threatened? "There is a point where our knowledge stops, and we have to be very careful about how to ask the right questions, questions that science may be able to answer." "Like the Big Bang?" another kid asked, with a big smile. "Yes, like the Big Bang, the event that marks the beginning of the whole universe. We are still trying to figure this one out."
The joy these kids had during that hour was truly contagious. I hardly could speak, so many hands were up most of the time. They would complete each other's sentences, always politely, always thoughtfully, always respectfully. Granted, this may not be a typical public school, given where it is, an affluent town near an Ivy League school. But there was a light in their eyes, the appetite for wonder, the desire to learn, that, I believe, is there in any child, given the opportunity.
I left the classroom energized, inspired, amazed. For one hour, a group of 20 9-year-olds showed me the best in humanity. I'll go back next year, and the year after. Not to teach them — but to let them teach me.
Marcelo Gleiser is a theoretical physicist and cosmologist — and professor of natural philosophy, physics and astronomy at Dartmouth College. He is the co-founder of 13.7, a prolific author of papers and essays, and active promoter of science to the general public. His latest book is The Island of Knowledge: The Limits of Science and the Search for Meaning. You can keep up with Marcelo on Facebook and Twitter: @mgleiser.