Attention to the Unseen

Paul Sutter writes: Astronomers around the world are in a bit of a tizzy because they can’t seem to agree about how fast the universe is expanding. Ever since our universe emerged from an explosion of a tiny speck of infinite density and gravity, it has been ballooning, and not at a steady rate, either — the expansion of the universe keeps getting faster. But how quickly it’s expanding has been up for a dizzying debate. Measurements of this expansion…

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Anthony Aguirre writes: One afternoon some years ago, I was walking through the snow thinking about other universes. More specifically, I was turning over in my mind the fact that the hospitality provided by our universe depends on many extremely special things. For example, if the electric repulsion between protons in the nuclei of atoms were just a bit stronger, then those atoms, and hence chemistry, and hence life itself, could not apparently exist. And there are many other such…

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Natalie Wolchover writes: In 1981, many of the world’s leading cosmologists gathered at the Pontifical Academy of Sciences, a vestige of the coupled lineages of science and theology located in an elegant villa in the gardens of the Vatican. Stephen Hawking chose the august setting to present what he would later regard as his most important idea: a proposal about how the universe could have arisen from nothing. Before Hawking’s talk, all cosmological origin stories, scientific or theological, had invited…

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MIT Technology Review reports: Back in 1961, the Nobel Prize–winning physicist Eugene Wigner outlined a thought experiment that demonstrated one of the lesser-known paradoxes of quantum mechanics. The experiment shows how the strange nature of the universe allows two observers—say, Wigner and Wigner’s friend—to experience different realities. Since then, physicists have used the “Wigner’s Friend” thought experiment to explore the nature of measurement and to argue over whether objective facts can exist. That’s important because scientists carry out experiments to…

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Marcia Bartusiak writes: Poets often think of time as a river, a free-flowing stream that carries us from the radiant morning of birth to the golden twilight of old age. It is the span that separates the delicate bud of spring from the lush flower of summer. Physicists think of time in somewhat more practical terms. For them, time is a means of measuring change—an endless series of instants that, strung together like beads, turn an uncertain future into the…

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Brian Gallagher writes: In April, in the famous Faraday Theatre at the Royal Institution in London, Carlo Rovelli gave an hour-long lecture on the nature of time. A red thread spanned the stage, a metaphor for the Italian theoretical physicist’s subject. “Time is a long line,” he said. To the left lies the past—the dinosaurs, the big bang—and to the right, the future—the unknown. “We’re sort of here,” he said, hanging a carabiner on it, as a marker for the…

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  Natalie Wolchover writes: In 2014, a graduate student at the University of Waterloo, Canada, named Cohl Furey rented a car and drove six hours south to Pennsylvania State University, eager to talk to a physics professor there named Murat Günaydin. Furey had figured out how to build on a finding of Günaydin’s from 40 years earlier — a largely forgotten result that supported a powerful suspicion about fundamental physics and its relationship to pure math. The suspicion, harbored by…

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