Think You Can Leave Relativity to the Astrophysicists? THINK AGAIN
By Shannon Burgert
Jeff Bennett believes that if people understood relativity, they would be more thoughtful in the way they lead their lives. Fortunately, he says, relativity is much easier to understand than most people believe. The trick? It’s very different from the perception that most of us have of space and time.
Bennett, who characterizes himself as a science teacher, also happens to have a Ph.D. in astrophysics. In his recent book What Is Relativity? An Intuitive Introduction to Einstein’s Ideas, and Why They Matter, Bennett uses simple examples and diagrams to explain relativity for the rest of us. “This is so cool, I want everyone else to know about it,” he says, adding that it’s also incredibly important.
“Relativity is in everything we do,” says Bennett. “It explains why the sun shines; it explains why radios work; it’s involved in every electronic in your home. If relativity wasn’t correct, your appliances wouldn’t work.” GPS is one example. Because space and time are influenced by gravity, the clocks orbiting on satellites run differently than clocks do on earth. “If you didn’t take that into account, you wouldn’t get anywhere close to where you want to be,” Bennett says, explaining that time runs slower for things moving fast, and that time also runs slower deeper in a gravitational field. (The book explains why.)
“You can live your life without knowing this stuff, but given that it shapes our whole scientific perception of space, time and gravity, don’t you want to know something about it?” Bennett asks.
Black Holes Don’t Suck
Bennett himself became enthralled by the Apollo space missions as an elementary-school student, and he was among Carl Sagan’s captivated viewers. After a freshman course on relativity, Bennett changed his college major from engineering to physics. His books range from college-level textbooks to five children’s books that are currently orbiting on the International Space Station (check out Story Time From Space on Facebook). Bennett’s Beyond UFOs was required reading for incoming freshmen at Miami University in 2008, Math for Life won a Colorado Book Award, and On Teaching Science is due off the press this summer.
Part of Bennett’s mission is to dispel scientific myths. One, for instance, is that if the sun were to become a black hole (which it won’t), we’d all get sucked in. “Black holes don’t suck,” says Bennett—pun intended. If our sun turned into a black hole (without changing its mass), Earth would continue to orbit as it does now. In fact, Bennett says, because black holes are so small, falling into one by accident is harder than pretty much anything else in the universe. Another misconception: Everything is relative. “Relativity” only applies to one’s motion in time and space compared to that of others.
Our Indelible Mark
Bennett takes many lessons from relativity, and this takes us back to his assertion that people would act more thoughtfully if they understood its implications. Through raw brain power, Bennett says, Einstein demonstrated the potential of our species, not just in our ability to comprehend the cosmos but also in our commitment to humanity. “It’s not an accident that he was also a major humanitarian. Because of what he could do with science, he saw the potential of the human species when we act well.”
Although we only perceive a three-dimensional world in which space and time are separate, relativity illuminates a fourth dimension, one that gives further meaning to Einstein’s theory. The reality, he says, is that space and time are intertwined, and that if we could see all four dimensions at once, there would be no distinction between past and present.
“There is a permanence in everything we do,” Bennett emphasizes. “I call it ‘our indelible mark on the universe.’ If people understood and absorbed that, they’d be more careful about how they live their lives, because they’d want to make a mark on the universe in a way that they’re proud of.”
Shannon Burgert is a teacher and writer.