Imagine the world waking up one morning to discover that all compasses pointed south instead of north.
It’s not as bizarre as it sounds. Earth’s magnetic field has flipped – though not overnight – many times throughout the planet’s history. Its dipole magnetic field, like that of a bar magnet, remains about the same intensity for thousands to millions of years, but for incompletely known reasons it occasionally weakens and, presumably over a few thousand years, reverses direction.
Now, a new study by a team of scientists from Italy, France, Columbia University and the University of California, Berkeley, demonstrates that the last magnetic reversal 786,000 years ago actually happened very quickly, in less than 100 years – roughly a human lifetime.
A diagram of the movement of the Moon around the Earth (seen here) and a recipe for invisible ink await you in Mary Smith’s Commonplace Book. Help us make Mary’s journal of scientific inquiry more accessible by becoming a digital volunteer at the Smithsonian Transcription Center.
Typically, planets much larger than Earth would be gas giants. That’s what we thought, anyway. But now astronomers have discovered an exoplanet seventeen times heavier than Earth, made up of rock and solids, some 560 light-years away. Not only is the planet exceptionally large for its composition, it’s also surprisingly old. Its parent solar system is 11 billion years old. In order to make the heavier elements needed to create an earthy planet, you require stellar nucleosynthesis—stars merging atomic nuclei into successively heavier elements until they explode, dispersing the mass, which can then form planets. There weren’t a whole lot of heavy elements present in the universe less than three billion years after the Big Bang, but apparently, there was enough to create Kepler-10c. Fascinating.
Think of the implications for life elsewhere in the universe. Although we have yet to confirm its existence, the conditions conducive to it could have appeared much earlier than one would have thought.
Agnodice circa 4th century BCE
Art by Intagliogia (tumblr)
Midwifery is a branch of medicine traditionally reserved for women. As medicine evolved into an academic discipline, female practitioners such as midwives were often pushed out. When Hippocrates (c. 460-370 BCE) founded his school at Cos, he limited female students to an auxiliary program in obstetrics and gynecology. After Hippocrates’s death, the leaders of Athens discovered some female medical practitioners performed abortions and taught contraceptive techniques. In response, the city fathers barred all women from practicing medicine and made working as a female medical practitioner a capital crime. Maternal and perinatal mortality skyrocketed as many Greek women were unwilling to have their baby delivered by a male physician
A young Athenian woman of this period, Agnodice disguised herself as a boy in order to study medicine with Herophilus in Alexandria. After qualifying as a physician, Agnodice was called on to attend a difficult birth. Concerned for her modesty, the mother was unwilling to accept the help of a male physician so Agnodice exposed her body to show she was a biological woman. The mother gratefully accepted Agnodice’s help and as word spread of this rogue female physician, Agnodice’s practice grew.
Jealous that this young physician had become so popular so quickly, Athenian physicians began to accuse Agnodice of seducing her patients. In order to defend herself from these charges, Agnodice publicly revealed her body to show her biological sex. Agnodice was put on trial for violating the law banning female physicians, a crime that carried the death penalty. A mob of female supporters rallied to her defense and Athenian leaders were so moved that they not only spared Agnodice’s life, they changed the law so that female physicians could treat female patients.
Some believe that Agnodice is a mythical figure. There are no known contemporary accounts of Agnodice’s life. She first appears in Gaius Julius Hyginus’s Fabulae, a collection of fables from the first century BCE. Furthermore, the name Agnodice means “chaste before justice” which is in keeping with the ancient Greek practice of naming fictional characters after their virtues. The story of Agnodice’s life may be a parable to understand the need for female physicians such as Aspasia who are known to have practiced medicine around the time Fabulae was composed.
Stephen Hawking is every kind of wonderful in this interview with John Oliver. Pair with Hawking on how the universe works, animated in 120 seconds.
After decades of searching scientists have discovered that a vast reservoir of water, enough to fill the Earth’s oceans three times over, may be trapped hundreds of miles beneath the surface, potentially transforming our understanding of how the planet was formed. Full story here
Photo: Blue Line Pictures/Getty Images
Psychologists and neuroscientists say it is far too soon to declare handwriting a relic of the past. New evidence suggests that the links between handwriting and broader educational development run deep. Children not only learn to read more quickly when they first learn to write by hand, but they also remain better able to generate ideas and retain information. In other words, it’s not just what we write that matters — but how.
“When we write, a unique neural circuit is automatically activated,” said Stanislas Dehaene, a psychologist at the Collège de France in Paris. “There is a core recognition of the gesture in the written word, a sort of recognition by mental simulation in your brain. And it seems that this circuit is contributing in unique ways we didn’t realise,” he continued. “Learning is made easier.”"
An asteroid that exploded last year over Chelyabinsk, Russia, leaving more than 1,000 people injured, collided with another asteroid before hitting Earth, research by scientists shows. Full story
During waking hours, electrical signals travel from dendrites—antenna-like projections at one end of the cell— through the cell body. From the cell body, they then travel the length of the axon, a single long projection at the other end of the cell. This electrical signal stimulates the release of chemicals at the end of the axon, which bind to dendrites on adjacent cells, stimulating these recipient cells to fire electrical signals, and so on. When groups of cells repeatedly fire in this way, the electrical signals increase in intensity. Dr. Bukalo and her team examined electrical signals that traveled in reverse―from the cell’s axon, to the cell body, and out its many dendrites. The reverse firing, depicted in this diagram, happens during sleep and at rest, appearing to reset the cell and priming it to learn new information.
Source: Backwards signals appear to sensitize brain cells, rat study shows, Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD).
Distribution of dark matter in the universe, as simulated with a novel, high-resolution algorithm at the Kavli Institute of Particle Astrophysics & Cosmology (KIPAC) at Stanford University and SLAC National Accelerator Laboratory. (Via Space.com)
Metabolic processes that underpin life on Earth have arisen spontaneously outside of cells. The serendipitous finding that metabolism – the cascade of reactions in all cells that provides them with the raw materials they need to survive – can happen in such simple conditions provides fresh insights into how the first life formed. It also suggests that the complex processes needed for life may have surprisingly humble origins.
"People have said that these pathways look so complex they couldn’t form by environmental chemistry alone," says Markus Ralser at the University of Cambridge who supervised the research.
But his findings suggest that many of these reactions could have occurred spontaneously in Earth’s early oceans, catalysed by metal ions rather than the enzymes that drive them in cells today.
Harvard theoretical physicist Lisa Randall, one of the smartest women in science today and author of Knocking on Heaven’s Door: How Physics and Scientific Thinking Illuminate the Universe and the Modern World, among others, offers this deceptively simple yet brilliant perspective on grasping gravity.
(via It’s Okay To Be Smart)