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,
Physics
June 7, 2019
Physicists debate Stephen Hawking’s idea that the universe had no beginning
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
May 13, 2019
A bizarre form of water may exist all over the universe
Joshua Sokol writes: Recently at the Laboratory for Laser Energetics in Brighton, New York, one of the world’s most powerful lasers blasted a droplet of water, creating a shock wave that raised the water’s pressure to millions of atmospheres and its temperature to thousands of degrees. X-rays that beamed through the droplet in the same fraction of a second offered humanity’s first glimpse of water under those extreme conditions. The
April 27, 2019
Mystery of the universe’s expansion rate widens with new Hubble data
NASA reports: Astronomers using NASA’s Hubble Space Telescope say they have crossed an important threshold in revealing a discrepancy between the two key techniques for measuring the universe’s expansion rate. The recent study strengthens the case that new theories may be needed to explain the forces that have shaped the cosmos. A brief recap: The universe is getting bigger every second. The space between galaxies is stretching, like dough rising
April 24, 2019
Experiments that make quantum mechanics directly visible to the human eye
Rebecca Holmes writes: I spent a lot of time in the dark in graduate school. Not just because I was learning the field of quantum optics – where we usually deal with one particle of light or photon at a time – but because my research used my own eyes as a measurement tool. I was studying how humans perceive the smallest amounts of light, and I was the first
April 15, 2019
The interplay that brings together order and disorder
Alan Lightman writes: Planets, stars, life, even the direction of time all depend on disorder. And we human beings as well. Especially if, along with disorder, we group together such concepts as randomness, novelty, spontaneity, free will and unpredictability. We might put all of these ideas in the same psychic basket. Within the oppositional category of order, we can gather together notions such as systems, law, reason, rationality, pattern, predictability.
March 22, 2019
A quantum experiment suggests there’s no such thing as objective reality
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
January 27, 2019
Inside the struggle to define life
Ian Sample writes: All the brain cells of life on Earth still cannot explain life on Earth. Its most intelligent species has uncovered the building blocks of matter, read countless genomes and watched spacetime quiver as black holes collide. It understands much of how living creatures work, but not how they came to be. There is no agreement, even, on what life is. The conundrum of life is so fundamental
January 12, 2019
Emergence: How complex wholes arise from simple parts
John Rennie writes: You could spend a lifetime studying an individual water molecule and never deduce the precise hardness or slipperiness of ice. Watch a lone ant under a microscope for as long as you like, and you still couldn’t predict that thousands of them might collaboratively build bridges with their bodies to span gaps. Scrutinize the birds in a flock or the fish in a school and you wouldn’t
September 22, 2018
The crisis inside the physics of time
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,
September 3, 2018
Studying time is like holding a snowflake
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,
July 22, 2018
The peculiar numbers that could underlie the laws of nature
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
May 30, 2018
The Standard Model of particle physics: The absolutely amazing theory of almost everything
How does our world work on a subatomic level? Varsha Y S, CC BY-SA By Glenn Starkman, Case Western Reserve University The Standard Model. What dull name for the most accurate scientific theory known to human beings. More than a quarter of the Nobel Prizes in physics of the last century are direct inputs to or direct results of the Standard Model. Yet its name suggests that if you can
May 28, 2018
What are the limits of manipulating nature?
In Scientific American, Neil Savage writes: Matt Trusheim flips a switch in the darkened laboratory, and an intense green laser illuminates a tiny diamond locked in place beneath a microscope objective. On a computer screen an image appears, a fuzzy green cloud studded with brighter green dots. The glowing dots are color centers in the diamond—tiny defects where two carbon atoms have been replaced by a single atom of tin,
May 9, 2018
Free will, video games, and the most profound quantum mystery
David Kaiser writes: The word “predictable” first entered the English language two centuries ago. Its début came in neither a farmer’s almanac nor a cardsharp’s manual but in The Monthly Repository of Theology and General Literature, a Unitarian periodical. In 1820, one Stephen Freeman wrote a dense treatise in which he criticized the notion that human behavior—seemingly manifest “amidst the conflicting, boisterous, unreasonable wills of men, all acting, as they