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SXS Collaboration, University of Chicago

Physicists Spot Einstein's Gravitational Waves for the First Time

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SXS Collaboration, University of Chicago

Simulation of two merging black holes in front of the Milky Way. Scientists said the Sept. 14 event was so intense that in the moment before the colliding black holes swallowed each other, they emitted more energy than the rest of the universe combined.

After a decades-long search, physicists have managed to detect ethereal ripples in the very fabric of space, known as gravitational waves—triggered in this case by the death-spiral of a pair of merging black holes—and snared by a sophisticated detector known as LIGO, the Laser Interferometer Gravitational-wave Observatory. The discovery is being described as one of the great physics breakthroughs of the decade, on par with the 2012 discovery of the Higgs boson, and very likely Nobel Prize–worthy.

Lawrence Krauss, a physicist at Arizona State University and author of The Physics of Star Trek, told mental_floss that the discovery “monumental.” The new technology will allow astronomers “to peer into parts of the universe that we’d never could have seen otherwise,” Krauss said. More than that, it will pave the way for a new era in astronomy, one in which gravitational waves will be used to study a wide array of all astrophysical phenomena, many of them never before open to scientific scrutiny. “It’s opened up a whole new window on the universe,” he said—a metaphor that’s been echoed by many of the physicists and astronomers who have been weighing in excitedly on the discovery.

The discovery was unveiled Thursday morning at a packed Washington DC press conference organized by the U.S. National Science Foundation (NSF), which funded the research (with simultaneous presentations by partner institutions in at least four other countries).

The gravitational waves recorded by the LIGO detectors were the result of the violent merger of two black holes, located some 1.3 billion light-years from Earth, explained Gabriela González, a physicist at Louisiana State University and a spokesperson for the LIGO collaboration. One of the black holes was determined to have a mass 29 times that of our Sun, the other was even heavier, with a mass equal to 36 Suns. Although LIGO can only roughly pin down the direction of the signal, González said the black hole pair—now a single black hole, following the cataclysmic merger—is located in the southern sky, roughly in the direction of the Magellanic Clouds, the Milky Way’s small companion galaxies (of course, the black holes are far more distant).

The black hole pair had been locked in mutual orbit for hundreds of millions of years, gradually losing energy through the emission of gravitational waves, and then finally emitting one last “death burst” as the two objects merged into a single entity, González said. “What we saw is from only the last fraction of a second before the merger,” she told mental_floss.

The waves created from that final blast then rippled across the cosmos. After more than a billion years, some of those waves washed silently past Earth on September 14 of last year, where they triggered a tiny “blip” at each of the two identical LIGO detectors (one located in Hanford, Washington, the other in Livingston, Louisiana).

Incredibly, the team of researchers managed to keep the discovery relatively secret for almost six months. When the initial signal was recorded, Caltech physicist Kip Thorne received an e-mail from a colleague. “He said, ‘LIGO may have detected gravitational waves; go and look at this,’” referring Thorne to initial data posted on a private LIGO webpage. “I looked at it, and I said, ‘My god—this may be it!’” Thorne told mental_floss. (Thorne played a key role in the early development of LIGO and is known not only for writing some of the most-read books on gravitational physics, but for his collaboration with Carl Sagan on the book Contact, and with the makers of the smash sci-fi film Interstellar.)

Not everyone was quite so tight-lipped—and in fact rumors had been circulating for weeks leading up to Thursday’s announcement (as mental_floss reported last month). A few people got an early look at the results and couldn’t contain their excitement. McMaster University physicist Clifford Burgess emailed some of the details to colleagues in his department, and the news quickly spilled out via social media. (Burgess described the discovery as “off-the-scale huge.”)

And while there have been a somewhat alarming number of super-hyped physics “discoveries” that failed to pan out in recent years—remember the faster-than-light neutrinos?—the LIGO researchers claim to have ruled out any possible non-gravitational-wave explanation for the signal they recorded. The finding is being published in the peer-reviewed journal Physics Review Letters (the “discovery paper” was released yesterday morning, February 11), along with a series of further papers.

It’s a discovery nearly a quarter-century in the making: LIGO was spearheaded by Caltech and MIT in 1992, and now involves nearly 1000 researchers from the UK, Germany, Australia, and beyond. With a total cost of more than $600 million, LIGO is the largest project ever funded by NSF.

Einstein predicted the existence of gravitational waves, based on his newly developed theory of gravity, known as general relativity, in 1915. Gravitational waves are literally ripples in spacetime, created whenever massive objects throw their weight around—for example, when ultra-dense stars, known as neutron stars, collide, or when a star blows up in a supernova. In fact, any time masses accelerate, gravitational waves are produced—even doing dumbbell-lifts at the gym would produce them—but such waves would be infinitesimally weak, and quite impossible to measure. Even the waves from the black hole merger were so faint that they required the massive LIGO detectors to finally pick them up.

“It’s just really, tremendously exciting,” physicist Clifford Will of the University of Florida, one of the world’s leading authorities on general relativity, told mental_floss. “We’ve just finished celebrating the 100th anniversary of GR [general relativity], so this is icing on the cake.”

David Spergel, a physicist at Princeton, tweeted: “Up to now, we have only seen the universe. Now, for the first time, we can hear," adding, "The universe is playing a beautiful tune and LIGO just heard it.”

Gravitational waves alternately stretch and shrink space, by a tiny amount, as they pass by. Inside each of the LIGO detectors, laser beams bounce back and forth between mirrors attached to weights. A passing gravitational wave causes a slight change in the distance the laser beam travels, which leaves a telltale pattern (known as an interference pattern) in the recorded laser light. (Having two detectors located more than 2000 miles apart helps rule out false-alarm signals that might register at only one site.)

“We saw the same waveform—the same signal—in the two detectors,” González told mental_floss. Recording such signals by chance might happen “once in every 200,000 years,” she said.

LIGO went online in 2002, but with only a fraction of its current sensitivity. The detectors were upgraded last fall in an effort known as “Advanced LIGO.” The actual stretching caused by the passing gravitational wave is mind-bogglingly small, causing the detectors to grow or shrink in length by a distance equivalent to just 1/1000th of the width of a proton.

The success of the LIGO detectors is “a wonderful testament to the perseverance and ingenuity of the scientists,” Krauss said. “I never thought I’d see this in my lifetime.”

Astronomers and physicists expect the new technique to reveal the universe in a new light, as the first optical telescopes did when Galileo first used them to study the night sky 400 years ago, and as the first radio telescopes did in the mid-20th century.

Editor's note: This story has been significantly updated to include input from a main LIGO researcher and additional outside experts, as well as with more comprehensive details about the extraordinary find.

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Stones, Bones, and Wrecks
Archaeologists Are Recreating Recipes from 17th-Century Ships
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Arthur Tanner/Getty Images

If ships’ logs and sailors' diaries are to be believed, the gastronomic situation during early voyages across the Atlantic was dire.

“Lady Sea will not tolerate or conserve meat or fish that is not dressed in her salt,” wrote Spanish explorer Eugenio de Salazar in his complaint-filled 1573 letter that’s now dubbed “The Landlubber’s Lament.” He griped that water is rationed “by the ounce, as in a pharmacy,” and he described wooden plates “filled with stringy beef joints, dressed with some partly cooked tendons.” Other food, Salazar said, is so “rotten and stinking” that you’d be better off losing your sense of taste and smell just to get it all down.

Most chefs would be happy to leave this grim slice of food history behind. But a group of archaeologists in Texas has just begun an unusual experiment to faithfully recreate the menu onboard a typical transatlantic sailing ship. By doing so, they hope to learn more about sailor nutrition.

“We use modern standards to extrapolate health from the past,” project leader Grace Tsai, a doctoral student in Texas A&M University’s nautical archaeology program, tells Mental Floss. “But you won’t know [the food’s] nutritional value until you actually make it with a historical recipe and get that tested in a lab.”

Over the last few months, Tsai and her colleagues have been perfecting 17th-century recipes for provisions like ship’s biscuit (a long-lasting dry cracker) and salted meat. On August 19, they loaded their canvas sacks and heavy barrels into the hold of a 19th-century tall ship named Elissa that’s moored in Galveston. They’ll perform nutritional and microbial analysis on the food every 10 days over the next three months.

A barrel used to store the research team's salted beef
Erika Davila

Without canning or refrigeration, salting was indeed the most popular way to preserve food for long journeys. And when sailors would reach new lands, they preserved whatever animals they could hunt. Richard Wilk, an anthropologist at Indiana University who is not affiliated with the project, said there are some accounts of hungry sailors in the Southern Hemisphere stuffing casks with salted penguins. “Basically, if it was meat and they could salt it and dry it, then they could carry it around with them,” Wilk tells Mental Floss.

Nearly every account from European vessels between the 16th and 18th centuries lists salted beef, which is similar to corned beef, among the provisions, Tsai said. So her team butchered a steer and a hog to make salted beef and salted pork. They based their cuts of meat on the bones that were found at the shipwreck of the Warwick, an English galleon carrying supplies to Jamestown, Virginia, that sank in 1619 off the coast of Bermuda during a hurricane. They followed a recipe from a 1682 English text on salting food, ordered salt from France, and consulted local environmental officials in Texas to find the purest river water to make their brine.

Though it was probably warm and flat, beer could make or break a voyage, too. Useful as a social lubricant, beer was also often cleaner than drinking water, and it provided some calories, nutrients, and probiotics, Tsai noted. One bit of American lore that suds enthusiasts love to cite is that beer might have played a role in the lost Mayflower pilgrims’ decision to settle down at Plymouth, Massachusetts. “We could not now take time for further search or consideration, our victuals being much spent, especially our Beere,” Governor William Bradford explained in his diary.

Tsai plans to add casks of 17th-century-style English beer to the Elissa in November. To make their own brew even closer to the original, the Texas team is trying to secure a yeast culture from 220-year-old bottles of beer found at a British shipwreck in Australia. (Tsai said a sponsor of the project, Texas's Karbach Brewing Company, will eventually make a commercial version of their historical beer.)

Changes in temperature and humidity, and the rocking of the waves, could have affected the food on early transatlantic voyages, too. That’s why the researchers are storing their supplies in the Elissa instead of a lab. They expect to find not just colonies of microbes, but insects, too. “The ship’s biscuit would almost always grow weevils,” Tsai said. And English sailors, sticklers for tradition, didn’t use an airtight container for the crackers, but a canvas bag. Exposed to sea air and humidity, the biscuits often became moldy and mushy over time.

Salted beef made with an 18th-century recipe
The team made this salted beef using a 17th-century recipe.
Grace Tsai

In some ways, the project in Texas isn’t a totally new idea. In recent years, brewers have attempted to resurrect Egyptian ales and Iron Age meads. Experimental archaeologists have tried to recreate Stone Age barbecues and butchering techniques. Food historian Ken Albala of the University of the Pacific pointed out that sites like Hampton Court Palace in London, Colonial Williamsburg, and Plimoth Plantation serve historical meals regularly, though those institutions tend to be less adventurous about preserving and curing. “Modern people are indeed very frightened about food poisoning, so things like this that can go wrong are usually beyond their comfort zone,” Albala, who is not involved in the Texas project, tells Mental Floss.

Tsai saw those limitations firsthand while doing research at Colonial Williamsburg. Dressed like a colonial boy (the adult clothes were too big for her), she went behind the scenes at the living history museum for two weeks to learn more about handling the watertight oak barrels she’ll be using for the project. She noticed that the cooks at Colonial Williamsburg were using a brine recipe for salted beef that called for 35 pounds of salt to 8 gallons of water, but her 17th-century recipes say the brine is ready when it floats an egg. “That’s actually a lot less salt,” Tsai said. While historical reenactors may alter recipes for public safety reasons, the Texas team is aiming for authenticity.

When the team opens the barrels, they’ll look for caloric content, water content, sodium, vitamins, and minerals. Tsai is particularly interested in what kinds of bacteria she’ll find growing on the food—not just the disease-causing bugs, but probiotics, too.

“We barely ever eat anything that has probiotics anymore, and even when we do it’s a strict genre,” Tsai said. She suspects that sailors ingested a more diverse group of microbes than we do today, and investigating these organisms could shed light on changes in the human gut microbiome as modern diets have become bound to better hygiene standards.

A barrel full of salted beef is loaded into a tall ship
A barrel of salted beef is hoisted into the Elissa.
Grace Tsai

“If they do it correctly, the food should still be palatable, but whether it’s going to stand up to modern scientific standards of 'ok to eat,' I can’t really guess,” Albala said. “Of course, on many ships in the past, the food did indeed go bad. Sometimes they ate it anyway because they had no choice. It would have been a luxury to toss it.”

Because of safety concerns (and institutional review board restrictions), Tsai and her colleagues won’t get to eat the meat they’re storing on board the Elissa. But she has an idea of how the salted beef might taste after preparing some she got from Colonial Williamsburg. “You know that metallic taste you get when you have a bloody nose? It tasted like that.”

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17 Little-Known Facts About Max Planck
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Hulton Archive/Getty Images

These days, Max Planck’s name comes up most by way of the prestigious scientific institutes named after him. (The Max Planck Society runs 83 throughout Germany and the world.) But who was the real Max Planck, and why would there be so many research centers in his name? Here are 17 facts about the theoretical physicist.

1. HE CREATED ONE OF THE PILLARS OF MODERN PHYSICS.

There are two theories that modern physics uses to explain the universe. There is relativity—Einstein’s work—and there is quantum theory, invented by Planck. In the late 1890s, he began his work studying thermal radiation and found a formula for black-body radiation, one that eventually became Planck’s Law. To explain why his formula worked, he introduced the idea of packets of energy he called “quanta,” giving rise to the branch of quantum physics.

He himself was surprised at the radical nature of his own discoveries, writing, “My futile attempts to put the elementary quantum of action into the classical theory continued for a number of years and they cost me a great deal of effort.”

By the time he died, though, Planck was a legend in the scientific world. “Max Planck was one of the intellectual giants of the 20th century and one of the outstanding intellects of all time,” The New York Times wrote upon his death in October 1947, ranking “with the immortals of science, such as Archimedes, Galileo, Newton, and Einstein.”

2. AND HE HELPED NAME THE OTHER ONE.

Planck helped popularize the term “theory” to describe Einstein’s relativity work. In a 1906 talk, he referred to the model of physics put forth by Einstein as “Relativtheorie,” which became “Relativitätstheorie,” or “relativity theory.” Einstein himself referred to it as the “relativity principle,” but Planck’s terminology caught on.

3. HE WON A NOBEL.

Planck was a highly respected academic in his lifetime. As science writer Barbara Lovett Cline explains, “In Germany at this time only princes and barons were accorded more respect than professors,” and Planck was no exception. He racked up a multitude of awards in his academic career before finally winning the Nobel Prize in Physics at the age of 60. He received more nominations for the Nobel from a wider range of physicists than any other candidate at the time. He finally received the prize for 1918 “in recognition of [his] epoch-making investigations into the quantum theory,” as the president of the Royal Swedish Academy of Sciences said upon presenting the award.

4. HE WAS ONE OF EINSTEIN’S EARLIEST SUPPORTERS.

Planck recognized the importance of Einstein’s work on relativity early, and was one of the first important boosters of his theories. “Einstein may be considered Planck’s second great discovery in physics,” J.L. Heilbron writes in his book The Dilemmas of an Upright Man: Max Planck as a Spokesman for German Science, “and his support, in Einstein’s judgment, was instrumental in securing the swift acceptance of new ideas among physicists.” At the time, Einstein didn’t have a Ph.D. or work at a university, and the support of an established, famous scientist like Planck helped usher him into the mainstream. Though he would remain skeptical of aspects of the younger scientist’s work—like his 1915 research on “light quanta,” or photons—the two remained friends and close colleagues for much of their lives. According to Planck’s obituary in The New York Times, “When the Physical Society of Berlin conferred on him a special medal, he handed a duplicate of it to his friend, Einstein.”

5. HE WAS A GREAT MUSICIAN.

Planck was a gifted pianist and almost dedicated his career to music instead of physics. He hosted musical salons at his home, inviting other physicists and academics as well as professional musicians. Albert Einstein attended [PDF], sometimes picking up the violin to play in quartets or trios with Planck. According to Heilbron, “Planck’s sense of pitch was so perfect that he could scarcely enjoy a concert,” lest it be ruined by an off-key note.

6. A PROFESSOR WARNED HIM NOT TO GO INTO PHYSICS.

Not long after the 16-year-old Planck got to the University of Munich in 1874, physics professor Philipp von Jolly tried to dissuade the young student from going into theoretical physics. Jolly argued that other scientists had basically figured out all there was to know. “In this field, almost everything is already discovered, and all that remains is to fill a few holes,” he told Planck. Luckily, the budding scientist ignored his advice.

7. HIS LECTURES WERE STANDING-ROOM-ONLY.

Though he was described as a bit dry in front of a classroom, Planck’s students loved him. English chemist James Partington said he was “the best lecturer [he] ever heard,” describing Planck’s lectures as crowded, popular affairs. “There were always many standing around the room,” according to Partington. “As the lecture-room was well heated and rather close, some of the listeners would from time to time drop to the floor, but this did not disturb the lecture.”

8. HE KEPT A STRICT SCHEDULE.

In The Dilemmas of an Upright Man, Heilbron describes Planck as an “exact economist with his time.” He ate breakfast precisely at 8 a.m then worked in a flurry until noon every day. In the evenings and during university breaks, though, he relaxed and entertained friends. His routine involved “a rigid schedule during term—writing and lecturing in the morning, lunch, rest, piano, walk, correspondence—and equally unrelenting recreation—mountain climbing without stopping or talking and Alpine accommodation without comfort or privacy,” according to Heilbron.

9. HE WAS A LIFELONG MOUNTAIN CLIMBER.

Planck stayed active throughout his life, hiking and mountain climbing well into old age. In his 80s, he still regularly climbed Alpine peaks reaching more than 9800 feet in height.

10. HE WAS PRETTY GOOD AT TAG.

“Planck loved merry, relaxed company and his home was the center of such conviviality,” famed nuclear physicist Lise Meitner described in 1958 (as quoted by the Max Planck Society). “When the invitations happened to be during the summer term, there would be energetic games in the garden afterwards in which Planck participated with downright childish glee and great adeptness. It was almost impossible not to be tagged by him. And how visibly pleased he was when he had caught someone!"

11. THE GESTAPO INVESTIGATED HIM DURING WORLD WAR II.

Due to his outspoken support of Jewish physicists like Einstein, Planck was labeled by the nationalist Aryan Physics faction of academics as being part of a grand Jewish conspiracy to keep German scientists from appointments in university physics departments Along with other physicists in Einstein’s circle, he was called a “bacteria carrier” and a “white Jew” in the official SS newspaper, Das Schwarze Korps, and his ancestry was investigated by the Gestapo.

12. HE PERSONALLY ASKED HITLER TO LET JEWISH SCIENTISTS KEEP THEIR JOBS.

Though Planck didn’t always support his Jewish colleagues against the Nazis—he chastised Einstein for not returning to Germany after Hitler came to power and eventually dismissed Jewish members of the Kaiser Wilhelm Society (later the Max Planck Society) due to pressure from the Third Reich [PDF]—he did make several stands against Nazi policies. He fought against the inclusion of Nazi party members in the Prussian Academy and, as president of the Kaiser Wilhelm Society, met with Hitler and appealed to the Führer to let certain Jewish scientists keep their jobs.

It didn't work. In 1935, one in five German scientists had been dismissed from their posts (as many as one in four in the field of physics) and supporting Jewish scientists became increasingly risky. Still, in 1935, Planck convened a commemorative meeting of the Kaiser Wilhelm Society to honor the late Jewish chemist Fritz Haber despite an explicit government ban on attending the event. His prominent support of Jewish scientists like Haber and Einstein and refusal to join the Nazi Party eventually resulted in the government forcing him out of his position at the Prussian Academy of Sciences and blocking him from receiving certain professional awards.

13. BUT HE HAD A COMPLICATED RELATIONSHIP WITH THE NAZIS.

He was one of many apolitical civil servants in German academia who hoped that the worst effects of anti-Semitic nationalism would eventually pass, and who wanted to maintain Germany’s importance on the world scientific stage as much as possible in the meantime. When Hitler began demanding that speeches open with “Heil Hitler,” Planck begrudgingly complied. As physicist Paul Ewald described of his address at the opening of the Kaiser Wilhelm Institute of Metals in the 1930s, “… we were all staring at Planck, waiting to see what he would do at the opening, because at that time it was prescribed officially that you had to open such addresses with ‘Heil Hitler.’ Well, Planck stood on the rostrum and lifted his hand half high, and let it sink again. He did it a second time. Then finally the hand came up and he said ‘Heil Hitler.’ … Looking back, it was the only thing you could do if you didn’t want to jeopardize the whole [Kaiser Wilhelm Society].” As science writer Philip Ball describes, for Planck, the rise of Hitler and Nazi Germany was a “catastrophe that had engulfed him, and which in the end destroyed him.”

14. HIS SON WAS LINKED TO A PLOT TO ASSASSINATE HITLER.

Erwin Planck was a high-ranking government official before the Nazis came to power, and although he resigned from political life in 1933, he secretly helped craft a constitution for a post-Nazi government. In 1944, he was arrested and accused of taking part in Claus Stauffenberg’s assassination attempt on Adolf Hitler, in which the Nazi leader was wounded by an exploding briefcase. While it seems that Erwin didn’t directly take part in the bombing plot, he did recruit supporters for the conspirators, and he was sentenced to death for treason. Trying to save his favorite son’s life, the 87-year-old Max Planck wrote personal letters begging for clemency to both Hitler and the head of the SS, Heinrich Himmler. Erwin was executed in 1945.

15. HIS MOTTO WAS “PERSEVERE AND CONTINUE WORKING.”

After World War I, Planck encouraged his fellow scientists to ignore the turbulence of politics to focus on the greater importance of their scientific achievements. “Persevere and continue working” was his slogan.

16. HE CALLED PHYSICS “THE MOST SUBLIME SCIENTIFIC PURSUIT IN LIFE.”

In his autobiography, Planck described why he chose to pursue physics. “The outside world is something independent from man, something absolute, and the quest for the laws which apply to this absolute appeared to me as the most sublime scientific pursuit in life,” he wrote.

17. THERE ARE MANY THINGS NAMED AFTER HIM.

Several discoveries by Planck were eventually named after him, including Planck’s law, Planck’s constant (h, or 6.62607004 × 10^-34 joule-seconds), and Planck units. There is the Planck era (the first stage of the Big Bang), the Planck particle (a tiny black hole), the lunar crater Planck, and the European Space Agency spacecraft Planck, among others. Not to mention the Max Planck Society and its 83 Max Planck Institutes.

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