Physicists Spot Einstein's Gravitational Waves for the First Time

SXS Collaboration, University of Chicago
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.

10 Famous Siblings Who Conquered the World

The Williams sisters have won plenty of gold on their own and in doubles competition.
The Williams sisters have won plenty of gold on their own and in doubles competition.
Julian Finney/Getty Images

Whether you adore them or they drive you crazy, siblings play a major part in family dynamics. And while it’s noteworthy when one person in a family accomplishes great things, it’s doubly (or triply) remarkable when multiple siblings achieve greatness. To celebrate National Sibling Day, we’re taking a look at 10 sets of seriously accomplished siblings.

1. Jacob and Wilhelm Grimm

The Brothers Grimm.
A portrait of Jacob and Wilhelm Grimm.
Hulton Archive/Getty Images

Even if you know nothing about the Brothers Grimm, you’ve no doubt read versions of the fairy tales and folk stories they compiled. Born in modern-day Germany in 1785 and 1786, Jacob and Wilhelm Grimm were young boys when their father died. Their family struggled financially, but both brothers were able to study law at the University of Marburg. Jacob went to work as his professor’s library assistant, and he later became the royal librarian for the new King of Westphalia, Jerome-Napoleon Bonaparte (that Napoleon's younger brother).

Wilhelm worked as his brother’s library assistant, and because Napoleon had recently conquered much of Germany, the two brothers wanted to help their fellow Germans preserve their culture’s stories. After gathering folk tales from books and committing oral stories to paper, the Brothers Grimm published collections of these stories, including Snow White, Hansel and Gretel, and Rumpelstiltskin. Besides working together, Jacob also lived with Wilhelm and his wife, and Wilhelm named his first son Jacob. Before they died, the Brothers Grimm gave lectures and began work on a comprehensive German dictionary.

2. Louisa May and Abigail May Alcott

Louisa May Alcott
Louisa May Alcott
Culture Club/Getty Images

Louisa May Alcott is best known for her bestselling novel Little Women, which she based on her experience growing up with three sisters. But Louisa’s youngest sister—the inspiration for Amy March in Little Women—was an accomplished artist in her own right. Abigail (who went by May) had shown vast artistic promise as a child and young adult, even covering the walls and window frames in the family home with sketches of people and animals, and Louisa used a portion of her new-found fortune to further May's training.

After studying art in Boston, London, Rome, and Paris, May lived in France and earned spots for her still life and oil paintings in the Paris Salon’s exhibitions. The two sisters were so close that May named her baby daughter Louisa (nicknamed "Lulu"), and just before May died in 1879 (a month after childbirth), she told her husband to send baby Lulu to Louisa in Massachusetts. Louisa raised her niece until her own death eight years later, at which point Lulu went back to Europe to live with her father.

3. Wolfgang and Maria Mozart

Leopold Mozart, Wolfgang Amadeus, and Maria Anna Mozart.
Left to right: Leopold Mozart; his son, Wolfgang Amadeus; and his daughter, Maria Anna Mozart.
Art Media/Print Collector/Getty Images

We remember musical wunderkind Wolfgang Amadeus Mozart for his instantly recognizable symphonies and concertos, but his older sister paved the way for him to become one of history’s most famous classical composers. Born in 1751, five years before her brother, Maria Anna Mozart (nicknamed Nannerl) played piano to audiences across Europe before she hit her teens. Her technical skills earned her a reputation as a prodigy and one of the best pianists in Europe.

Nannerl and her younger brother also toured together, wowing audiences with their harpsichord performances. Nannerl wrote down (or possibly collaborated on) her brother’s first symphony, but her father made her stop performing once she turned 18. Still, Nannerl continued to compose music, and Mozart praised his sister’s work. Although some scholars dismiss Nannerl’s talent, others stress that her early interest (and success) in music deeply influenced and inspired her younger brother’s career.

4. Venus and Serena Williams

Venus and Serena Williams.
Venus and Serena Williams.
Scott Barbour/Getty Images

There aren't many athletes more decorated than the Williams sisters. Serena currently holds tennis's Open Era record for the most Grand Slam singles titles (for a man or woman) with 23, while Venus has won seven on her own, and, in 2000, became the first African American woman to win a single's title at Wimbledon since 1957. The sisters both have four Olympic gold medals to their name, three of which they won together in doubles play.

The two were born just 15 months apart, with Venus being the oldest. Despite Serena's otherworldly success, she knows to respects her sister's seniority in doubles play.

"She’s definitely the boss out there," Serena joked during an interview with BBC. To which Venus added: "Well I’m the older sister, so it kind of falls on me."

5. Emily and Austin Dickinson

Emily Dickinson and her siblings.
Left to right: Emily, Austin, and Lavinia Dickinson.
Culture Club/Getty Images

Emily Dickinson’s poetry, as well as her mysteriously reclusive later life, continues to enchant readers more than a century after her death. But most people aren’t as familiar with her brother, Austin. Born a year and a half before Emily, Austin graduated from Amherst College and Harvard Law School before working as an attorney. A prominent member of the Amherst community, Austin served as the treasurer of Amherst College, founded the town’s private cemetery, and held leadership roles in civic organizations.

Austin and his wife lived next door to Emily and had a close relationship with the poet—who never had anything published under her own name in her lifetime. After Emily’s death, her sister Lavinia found the poems and was determined to get them published, ultimately enlisting Austin’s longtime mistress, Mabel Loomis Todd, who got her poetry shared with the world.

6. The Jackson Siblings

Jermaine, Tito, Jackie, Michael, and Marlon Jackson
Left to right: Jermaine, Tito, Jackie, Michael, and Marlon Jackson, with Randy up top.
William Milsom/Getty Images

From their home base in Gary, Indiana, Joe and Katherine Jackson raised nine children. In 1969, the five eldest brothers (Jackie, Tito, Jermaine, Marlon, and Michael) hit it big as the Jackson 5, delighting audiences with catchy hits such as "I Want You Back" and "ABC." Since then, the members of the Jackson family have continued to make music, both together and separately.

Although Michael and youngest sister Janet achieved the most success with their music careers, each one of the couple’s seven other children—including sisters Rebbie and La Toya, and youngest brother Randy—achieved musical success in their own right. In fact, all nine Jackson siblings have released solo songs that charted on Billboard charts.

7. William and Caroline Herschel

William Herschel.
William Herschel was appointed court astronomer by King George III.
The Print Collector via Getty Images

Astronomer Sir William Herschel gets the credit for discovering, in March 1781, that Uranus was in fact a planet and not a star, as other astronomers had thought. Herschel also served as King George III’s official Court Astronomer, became president of the Royal Astronomical Society, and identified thousands of star clusters. But Herschel’s younger sister Caroline, born a dozen years after her brother, was also a seriously accomplished astronomer. As a young woman, she moved from her family’s home in Hanover to join her brother in England.

The two siblings shared a love of music and science, and Caroline worked as her brother’s assistant, providing technical support for the telescopes he built. She also was the first woman to be credited as the discoverer a comet (it’s called Comet C/1786 P1) and, after King George III began paying her, the first female scientist to ever be paid for her work. Caroline was awarded a Gold Medal from London’s Royal Astronomical Society and a Gold Medal for Science from Prussia’s King Frederick William IV.

8. The Wright Siblings

Wilbur Wright and his sister, Katherine.
A photo of Wilbur and Katherine Wright in 1909.
Historica Graphica Collection/Heritage Images/Getty Images

We know that Wilbur and Orville Wright were the inventors of the first successful airplane. But Katharine, the Wright brothers’ youngest sibling, played a huge role in facilitating her brothers’ aviation success. After graduating from Oberlin, Katharine worked as a Latin teacher in Dayton, Ohio. Although she wasn’t an engineer, she frequently corresponded with her brothers when they were in Kitty Hawk, North Carolina, testing airplane prototypes. The brothers bounced ideas off of her, and she gave them emotional support and encouragement when they worried that flight simply wasn’t possible. Katharine also helped run her brothers’ bicycle company, which provided the funds that the brothers used to finance their airplane experiments.

Additionally, Katharine played an integral role in publicizing the Wright Brothers’ success, encouraging them to give speeches and do public flight demonstrations. Katharine even learned French, so she could hobnob with European royalty and aristocracy, spreading the word of her brothers’ aeronautical achievement.

9. Harriet and Catharine Beecher

Harriet Beecher Stowe
Though most of the world knows Harriet Beecher Stowe, her sister, Catharine, made tremendous strides for women's education.
Culture Club/Getty Images

Harriet Beecher Stowe's famous novel Uncle Tom’s Cabin was a landmark piece of work for the anti-slavery movement, but she also had 12 siblings, many of whom also worked tirelessly for causes like abolitionism and women’s suffrage. Catharine, the oldest sibling, was passionate about seeing young girls become educated, and she opened the Hartford Female Seminary in Hartford, Connecticut, in 1824. Working from textbooks she wrote herself, Catharine taught groups of young girls everything from philosophy and art to chemistry and algebra. During her life, she opened schools in Ohio, Wisconsin, Iowa, and Illinois.

10. The Brontë Sisters

Anne, Emily, and Charlotte Bronte
Anne, Emily, and Charlotte Bronte
Rischgitz/Getty Images

Decades before J.R.R. Tolkien would create Middle-Earth, Charlotte, Emily, and Anne Brontë wrote stories together in childhood that revolved around fantasy worlds with names like Angria and Gondal. After a brief separation when they reached young adulthood, the sisters eventually reunited in 1845, following the death of their aunt Elizabeth, and began writing together once again. The next year, they published a book of poems under pen names titled Poems by Currer, Ellis and Acton Bell. Soon, each sister would write her own defining work: Charlotte published Jane Eyre in 1847, while Emily penned Wuthering Heights the same year, and in 1848, Anne Brontë published The Tenant of Wildfell Hall.

Some People Can Control When They Get Goosebumps—and Scientists Are Stumped

This woman might be controlling her goosebumps with her mind.
This woman might be controlling her goosebumps with her mind.
MyetEck/iStock via Getty Images

Travis Carrasco, 29, is a mechanical engineer in Las Vegas, Nevada. For all intents and purposes, he’s a normal individual. He loves coloring with colored pencils; likes leadership books and the color green.

But in youth, his relatives took notice of Carrasco’s peculiar tendency to sway his head back and forth. He told them he was giving himself goosebumps. They didn’t believe him.

They were wrong.

According to the low end of informal estimates, about one in every 1500 people have something called Voluntarily Generated Piloerection (VGP)—the ability to consciously give themselves goosebumps. The weird thing is, VGP shouldn’t exist. The phenomenon both perplexes and intrigues neurophysiologists by defying conventional understanding of how the unconscious nervous system operates.

A mammal’s hair follicle clings to the skin via a tiny muscle. When this muscle contracts, the hair will stand, the skin around it will undergo bump-shaped distortion, and voilagoosebumps.

For the 1499 people in this statistical metaphor, goosebumps are completely involuntary. The tiny muscle, called the arrector pili, is made of smooth muscle fibers. And like other smooth muscles of the body—those that handle digestion, blood flow, respiration, and so on—they are unconsciously regulated. The nerves attached to them lie in the autonomic nervous system, the part of the nervous system dedicated to managing bodily functions you aren’t supposed to control consciously, like heart rate or pupil dilation.

Voluntary Generated Piloerection "Shouldn't Be Possible"

When James Heathers, a physiologist at Northeastern University, came across an engineering paper referencing the only three single-individual case studies of VGP in medical history, he couldn’t believe it. 

“That was catnip for me,” Heathers tells Mental Floss, his voice cracking with excitement. “[VGP] shouldn’t be possible. That’s not how the autonomic nervous system works; what it does. This reason that it’s called autonomic—autonomos—it means ‘without thought.’”

Heathers, who normally spends his time in data science and patient-centered electronic health development, got to work on goosebumps as a scientific side-hustle. In 2018, he authored a paper in the journal PeerJ making the first published attempt at defining the prevalence and properties of VGP.

He wanted to know exactly how it works. What do people think about when they give themselves goosebumps? In what situations are they deployed? What personality traits are common in people with VGP?

Heathers sifted through obscure internet forums and sent out surveys, and ended up evaluating 32 participants with VGP using standardized personality tests. He found that those with VGP who responded to his survey had unusually ‘open’ personalities compared to the average person.

“They seem to be more creative; they imagine more,” Heathers says. “They pay more attention to themselves. They track their emotions more closely. They have a preference for new stuff … That’s either an artifact of people who are more open being more likely to answer a survey on the internet for fun, because they want to know about themselves; or it’s a component of the experience itself.”

A "Sixth Sense"

You may be thinking, Wait, I’m open-minded, and I can give myself goosebumps just by thinking of nails scratching a chalkboard. But Heathers is clear; that’s not VGP. 

“VGP has no mental or cognitive component,” Heathers says. “The vast majority of people who do it, in the way that we’ve defined it, simply have a really straightforward pathway. A lot of the time, they focus on a point, behind their ear or on their neck or at the back of the head. They don’t have to think of anything.”

In other words, those with VGP need only think about getting goosebumps—not about the situations that would, under normal circumstances, give them goosebumps.

“Basically, it starts at the base of my neck, the bottom of my head and the backside,” Carrasco, the engineer with VGP, tells Mental Floss. “When I trigger it, it feels like a bunch of sparks travel throughout my entire body, and I can do it repetitively, over and over and over and over and over. However, the strongest sensation is only the first couple times.”

While the induced goosebumps are stronger than those generated unconsciously, Carrasco says he can maximize the strength and resolution of his goosebumps by swaying his head from side to side.

“It’s a weird rhythm, but if I sway my neck, it triggers a really strong response,” Carrasco says. “You know when you squeeze your eyes really tight, and sometimes you hear pressure building, and it’s really just squeezing a muscle in your ears or your eyes. It’s similar to that, but when [the goosebumps] happen, sometimes I can hear that same pressure … it feels relaxing. It feels good.”

Carrasco likes to think it’s a sixth sense. He’s never met anyone else with VGP. But he notices that his son of 19 months sways his head a lot, too. And Carrasco can’t help but wonder, “Does he have the same ability I have?”

Maybe it’s genetic; scientists don't know. Whatever the cause, 30 to 40 times a week, you’ll catch Carrasco exercising his hidden superpower—a thought that just might give you goosebumps.

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