When the Vikings left the familiar fjords of Norway for icy, uncharted territories, they were at the mercy of weather. They had no magnetic compasses and no way to ward off stretches of heavy clouds or fog that made it difficult to navigate by sun. How the explorers traversed open ocean during these times is a mystery that has long captivated scholars.
Norse sagas refer to a sůlarstein or "sunstone" that had special properties when held to the sky. A Danish archaeologist had theorized that these were crystals that revealed distinct patterns of light in the sky, caused by polarization, which exist even in overcast weather or when the sun dips below the horizon.
And now, a study published in Royal Society Open Science suggests the Vikings had a high chance of reaching a destination like Greenland in cloudy or foggy weather if they used sunstones and checked them at least every three hours. In fact, they had a 92 to 100 percent chance of getting within sight of Greenland.
When polarized light passes through calcite, it splits into two beams. By rotating a sunstone against the sky and noting changes in brightness between these beams, one can find the atmosphereís polarization rings and figure out where the sun is.
Steph Yin, New York Times
Before President Donald Trump seized the reins of the Republican Party, outgoing House Speaker Paul Ryan was the closest thing to a bona fide party leader. He had been the partyís vice presidential nominee in 2012, and his strong backing from most factions within the GOP made him a consensus candidate for the speakership. A strong objection from Ryan during Trumpís campaign, a move to withdraw his endorsement, a true rejoinder to Trumpís authoritarian impulses ó these may have made a difference in stopping Trumpís rise, or at least raised barriers to his success. But Ryan, a lifelong ideologue, was willing to risk the constitutional order for the sake of his agenda. Which is to say, tax cuts.
Announcing his decision not to run again, Ryan told reporters that the speakership "is a job that does not last forever. Ö You realize you hold the office for just a small part of our history. So you better make the most of it. I like to think Iíve done my part, my little part in history, to set us on a better course."
It will be up to historians to decide whether Paul Ryan played such a "little part" in Donald Trumpís rise and whether, together, they set the country on a "better course." Thereís no reason to think that verdict will be kind.
Jamelle Bouie, chief political correspondent for Slate
April 20 has become known as a day to celebrate the pleasures of marijuana consumption with parties that traditionally begin at 4:20 p.m. But a study in JAMA Internal Medicine has found that the high spirits may have a price: a significant increase in fatal car wrecks after the "4/20" party ends.
Researchers used 25 years of data on car crashes in the United States in which at least one person died. They compared the number of fatal accidents between 4:20 p.m. and midnight on April 20 each year with accidents during the same hours one week before and one week after that date.
Before 4:20 p.m. there was no difference between the number of fatalities on April 20 and the number on the nearby dates. But from 4:20 p.m. to midnight, there was a 12 percent increased risk of a fatal car crash on April 20 compared with the control dates. The increased risk was particularly large in drivers 20 and younger.
"These crashes really donít have to happen," said the senior author, Dr. Donald A. Redelmeier, a professor of medicine at the University of Toronto. "In the Netherlands, theyíve had legalized marijuana for years, but they have many more interventions ó speed cameras, radar, sobriety checkpoints. The roads in the Netherlands are now much safer than those in the U.S."
Nicholas Bakalar, New York Times
John A. Boehner, the former Republican speaker of the House who once said he was "unalterably opposed" to decriminalizing marijuana laws, has joined a board of directors for a cannabis company with an eye on rolling back federal regulations.
The former Ohio congressman has been appointed to the board of advisers of Acreage Holdings, invoking the need for veterans to access the drug legally to explain his change of heart, Boehner said in a statement a few days ago. The company grows and sells legal weed and operates in 11 states.
Boehnerís acceptance of marijuana tracks with evolving beliefs about the drug and its uses among Americans and even Republican lawmakers, Erik Altieri, executive director for the Washington-based marijuana advocacy group NORML, told the Washington Post.
The move is a stark reversal for the former speaker, who in 2011 wrote a constituent that he was against "legalization of marijuana or any other FDA Schedule I drug," adding that "I remain concerned that legalization will result in increased abuse of all varieties of drugs, including alcohol."
But now, he says, "I have concluded descheduling the drug is needed so that we can do research and allow VA to offer it as a treatment option in the fight against the opioid epidemic that is ravaging our communities."
Spokesman David Schnittger said Boehnerís evolving position has been the result of close study after leaving office.
Current prohibitions have stymied research at Veterans Affairs to evaluate the drugís efficacy in treating post-traumatic stress and physical pain as the result of military service.
Polls show that over 60 percent of Americans favor legalizing marijuana completely, with well over 90 percent in favor of legal medical use.
Alex Horton and Christopher Ingraham, Washington Post
In an effort to protect students in the event of a mass shooter, a school district in Pennsylvania has "symbolically" armed its teachers ó with miniature baseball bats. The Millcreek Township School District in Erie County, Pa., recently distributed 16-inch wooden sluggers to each of its 500 or so teachers as a way to emphasize fighting back as a possible response to an active shooter, according to superintendent William Hall.
"Theyíre the little souvenir bats that you buy in baseball parks," Hall said. "They could be used as a weapon, but so could a number of things in a classroom." Millcreek officials have periodically discussed how to respond to school shootings for about five years but always with a focus on hiding from an attacker.
"Obviously, after Parkland, we went back and looked at our active shooter and hard lockdown response and realized that it had to change," Hall said. "We had basically adopted the Ďjust lock the doors and turn the lights out and hideí approach in terms of the response. Ö (The modified plan) includes not just hiding but also running and, as a last resort, having to fight as necessary."
Shortly after the Parkland shooting, the district sent out a survey asking how parents would feel about arming people at its schools who were not police officers. "We were wanting to gauge how our community felt about having a non-SRO gun presence," Hall said. "Thereís an expense involved in that, laws and training and liability ó itís problematic, obviously."
The survey also included a space people could write in suggestions for other ways to protect students. People suggested arming teachers with rat poison, Mace and, yes, baseball bats. The district decided it would move forward with nearly a dozen safety improvements, including building a concrete wall and an open walkway linking two of its campuses, installing security film on its windows and constructing "secured entrances" at five of its schools over the summer.
"We want to change the culture in our district to incorporate best practices," Hall said. "The little miniature bat was more of a symbolic gesture. Ö Unfortunately, it might come down to a situation where itís one on one. Itís about educating people that you may need to find something in that immediate environment to protect yourself."
Amy B Wang, Washington Post
In many Asian cultures, people rarely, if ever, utter the words "I love you." But in America "I love you" can be used as an endearing greeting from lovers, as a supportive term from parents to their children and even as a casual goodbye to friends: "That was an amazing brunch, letís do it again soon. I love you, bye!"
American culture is just much more intimate than what I was used to growing up. If I said "I love you" to my parents, they would probably think Iím crazy or that I have terminal cancer. I have said it to my friends sometimes, in a drunk-guy-at-the-bar way. "Hey, I love you, bro, youíre awesome, man." And I have said it to one girl, but to be honest Iím not sure I meant it ó it just seemed like the right answer at the moment.
She was wonderful, and two months into our relationship she told me, "I really like you." I said, "I really like you too." Then she said, "I really, really like you," and looked into my cornea. And I said, "Yes, I really, really like you too!" Frustration came over her and she pushed on: "No! I mean, like, I really, really, really like you!" Aha ó I finally realized what she meant, so I gave her the answer she was looking for: "Oh yeah, I love you."
That was a regrettable mistake from this naÔve people pleaser. We eventually broke up because we both realized I didnít mean that.
So what does it really mean to say "I love you?" Does it mean nothing more than "Youíre cool"? Or is it actually a magical phrase?
I asked my 70-year-old Chinese father, "Dad, why donít we ever say ĎI love youí?" And he said, "We donít have to always say I love you, itís understood." Maybe heís right.
Jimmy O. Yang, an actor, comedian and the author of "How to American," wrote this for the New York Times
Why do cracking knuckles make that sound? Crack them, and get out the calculator
nyt had mri of cracking knuckles
You might be surprised to learn that where exactly the sound of cracking knuckles is coming from ó what precisely in the knuckle produces it ó is still a subject of scientific research.
For more than 50 years people have been publishing scholarly papers about what is going on in your finger as you pull it. Lately an older theory, that the sound arises from the popping of a bubble in the joint, has been challenged by one that holds that the formation of the bubble itself is responsible. Two researchers in France reveal a mathematical model of a cracking knuckle and suggest that the old theory could explain the sound.
Where the two bones of the finger meet, a little lake of synovial fluid keeps them from grinding on each other. There is gas dissolved in the synovial fluid, mostly carbon dioxide, and it usually stays there. However, when the bones are pulled away from each other, thereís a sudden drop in pressure in the middle of the joint. Lower pressure allows the gases to come together, forming bubbles. Earlier work had suggested the collapse of such structures was behind the noise.
The French researchers created a mathematical model of a joint with a bubble in it and ran simulations, comparing the theoretical sounds of the bubble collapsing in the model with recordings of cracking knuckles. They found that the sounds predicted by the model would have the volume and frequency to match the recordings fairly well.
Veronique Greenwood, New York Times