CLOSE
SXS Collaboration, University of Chicago
SXS Collaboration, University of Chicago

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.

nextArticle.image_alt|e
Department Of Classics, University Of Cincinnati
arrow
Stones, Bones, and Wrecks
Ancient Poop Contains First Evidence of Parasites Described by Hippocrates
Department Of Classics, University Of Cincinnati
Department Of Classics, University Of Cincinnati

The long-held mystery of Hippocrates and the parasitic worms has finally been solved, and it’s all thanks to a few samples of ancient poop.

Researchers don’t know much about the parasites that plagued the Greeks thousands of years ago, and what they do know is largely from the Hippocratic Corpus, the medical texts that the father of medicine and his students put together between the 4th and 3rd centuries BCE. Modern historians have spent years trying to figure out which diseases and parasites Hippocrates and his followers were referring to in their writing, relying solely on their descriptions to guess at what ailments the ancient Greeks might have suffered from. Now, they finally have concrete evidence of the existence of some of the intestinal worms Hippocrates mentioned, Helmins strongyle and Ascaris.

As part of a study in the Journal of Archaeological Science: Reports, an international group of researchers analyzed the ancient remains of feces in 25 prehistoric burials on the Greek island of Kea to determine what parasites the people were carrying when they died. Using microscopes, they looked at the soil (formed by the decomposed poop) found on the pelvic bones of skeletons dating back to the Neolithic, Bronze, and Roman periods.

A roundworm egg under the microscope
A roundworm egg
Elsevier

Around 16 percent of the burials they studied contained evidence of parasites. In these ancient fecal samples, they found the eggs of two different parasitic species. In the soil taken from the skeletons dating back to the Neolithic period, they found whipworm eggs, and in the soil taken from the Bronze Age skeletons, roundworm.

With this information, researchers deduced that what Hippocrates called the Helmins strongyle worm was probably what modern doctors would call roundworm. The Ascaris worm probably referred to two different parasites, they conclude, known today as pinworm (which was not found in this analysis) and whipworm (pictured below).

Whipworm under a microscope
A whipworm egg
Elsevier

Though historians already hypothesized that Hippocrates's patients on Kea had roundworm, the Ascaris finding comes as a particular surprise. Previous research based solely on Hippocrates’s writing rather than physical evidence suggested that what he called Ascaris was probably a pinworm, and another worm he mentioned, Helmins plateia, was probably a tapeworm. But the current research didn’t turn up any evidence of either of those two worms. Instead of pinworm eggs, the researchers found whipworm, another worm that’s similarly small and round. (Pinworms may very well have existed in ancient Greece, the researchers caution, since evidence of their fragile eggs could easily have been lost to time.) The soil analysis has already changed what we know about the intestinal woes of the ancient Greeks of Kea.

More importantly, this study provides the earliest evidence of ancient Greece’s parasitic worm population, proving yet again that ancient poop is one of the world’s most important scientific resources.

nextArticle.image_alt|e
iStock
arrow
science
Arctic Temperatures are Rising So Fast, They're Confusing the Hell Out of Computers
iStock
iStock

This past year was a brutal one for northern Alaska, which saw temperatures that soared above what was normal month after month. But you wouldn't know that by looking at the numbers from the weather station at Utqiaġvik, Alaska. That's because the recent heat was so unusual for the area that computers marked the data as incorrect and failed to report it for the entirety of 2017, leaving a hole in the records of the Climate Monitoring group at the National Centers for Environmental Information (NCEI), according to the Huffington Post.

The weather station in the northernmost tip of Alaska has been measuring temperatures for nearly a century. A computer system there is programed to recognize if the data has been influenced by artificial forces: Perhaps one of the instruments isn't working correctly, or something is making the immediate area unnaturally hot or cold. In these cases, the computer edits out the anomalies so they don't affect the rest of the data.

But climate change has complicated this failsafe. Temperatures have been so abnormally high that the Utqiaġvik station erroneously removed all its data for 2017 and part of 2016. A look at the region's weather history explains why the computers might have sensed a mistake: The average yearly temperature for the era between 2000 and 2017 has gone up by 1.9°F from that of the era between 1979 and 1999. Break it down by month and the numbers are even more alarming: The average temperature increase is 7.8°F for October, 6.9°F for November, and 4.7°F for December.

"In the context of a changing climate, the Arctic is changing more rapidly than the rest of the planet," Deke Arndt, chief of NOAA's Climate Monitoring Branch, wrote for climate.gov. The higher temperatures rise, the faster Arctic sea ice melts. Arctic sea ice acts as a mirror that reflects the Sun's rays back into space, and without that barrier, the sea absorbs more heat from the Sun and speeds up the warming process. “Utqiaġvik, as one of a precious few fairly long-term observing sites in the American Arctic, is often referenced as an embodiment of rapid Arctic change,” Arndt wrote.

As temperatures continue to grow faster than computers are used to, scientists will have to adjust their algorithms in response. The team at NCEI plans to have the Utqiaġvik station ready to record our changing climate once again within the next few months.

[h/t Huffington Post]

SECTIONS

arrow
LIVE SMARTER
More from mental floss studios