Astrophysicists Detect Gravitational Waves Once Again

The hat-shaped Sombrero galaxy was not involved in the gravitational wave research, but it is lovely. Seen edge-on, it features an unusually large and extended central bulge composed of billions of old stars, while its dust rings harbor many younger and brighter stars. Its center is thought to house a large black hole. Image credit: NASA/Hubble Heritage Team

Just four months after the announcement of the first detection of gravitational waves, physicists say they’ve recorded another burst of these elusive ripples in space-time, again coming from a merging pair of black holes, far beyond our galaxy.

The first gravitation wave detection, announced with great fanfare in February, was sparked by a signal recorded at the twin LIGO detectors on September 14 of last year; this latest signal tripped the detectors on December 26. (The acronym stands for Laser Interferometer Gravitational-wave Observatory.)

“We now know that the first detection wasn’t just luck,” LIGO team member Duncan Brown, of Syracuse University, tells mental_floss. The odds of the earlier signal being a false alarm were on the order of a million to one—but, notes Brown, “people do win the lottery sometimes.” This second detection clinches it, he says. “This tells us that we will be making regular detections of binary black holes” in the coming years.

The LIGO team announced the discovery today at a meeting of the American Astronomical Society in San Diego. Their paper will be published in the journal Physical Review Letters

The paper, which examines data collected by LIGO from September 2015 to January 2016, also hints at a third gravitational wave event, recorded last October, although that event is less certain (and is being described only as a “candidate signal,” and not necessarily a “detection”).

Black holes form when massive stars collapse in the final stage of their evolution. Occasionally black holes end up orbiting other black holes, their orbits gradually shrinking as the system loses energy. Eventually they accelerate and merge, sending a blast of gravitational waves out across the universe.

Until this year, gravitational waves were purely theoretical, a prediction of Einstein’s general theory of relativity, published 100 years ago.

NASA created this visualization of two black holes merging when the discovery of gravitational waves was announced earlier this year.

The black holes that caused the December signal are smaller than those responsible for the earlier event; in this case their masses are believed to have been about 14 and about 17.5 times the mass of the Sun (in the earlier case, they were 29 and 36 times as massive as the Sun). Because of their smaller size, they took longer to execute their final orbits, Brown says. As a result, while the earlier signal was a mere blip, lasting about one-tenth of a second, this event lasted for a relatively leisurely 1.5 seconds. During that time, the two ultra-dense stars, having orbited each other for perhaps 100,000,000 years, performed their final loops. “This time we saw about 30 orbits, before they finally crashed into each other and merged,” Brown says.

The result is an even bigger black hole—though not quite as large as you’d expect by just adding up the masses of the two black holes that gave rise to it. That’s because roughly one solar mass was converted into energy, via Einstein’s famous equation, E = mc2. The magnitude of the explosion boggles the imagination. “When a nuclear bomb explodes, you’re converting about a gram of matter—about the weight of a thumbtack—into energy,” Brown explains. “Here, you’re converting the equivalent of the mass of the Sun into energy, in a tiny fraction of a second.”

As powerful as the blast was—for an instant, it would have produced more energy than all the stars in the universe—the ripples it unleashed were almost vanishingly small by the time they reached the Earth, having traveled across some 1.4 billion light years of space.            

For now, scientists can only estimate what direction these signals have come from; however, their ability to “triangulate” locations will greatly improve when another gravitational wave detector, Italy’s Virgo facility, is incorporated into the network of detectors, possibly as early as this autumn. India and Japan are also set to bring gravitational wave detectors online in the years ahead.

LIGO began operation in 2002, but with only a fraction of its current sensitivity. The detectors, located in Louisiana and in Washington state, were upgraded last fall in an effort known as “Advanced LIGO.” The facility is still operating at just one-third of its potential maximum sensitivity, Brown says.

As gravitational wave observations become routine, physicists will be able to tackle some of the outstanding problems in astrophysics and cosmology—many of which involve the puzzling properties of black holes, as University of Florida physicist Clifford Will tells mental_floss: “Where do black holes come from? Were they born small, and then grow? Or are there mechanisms that can produce 30 or 40 stellar mass black holes from the get-go? Did they form within binary systems? Or did one black hole capture another, later in life? These are the questions that astronomers and astrophysicists will be thinking about.”

Adds Brown: “The field of 'gravitational wave astronomy' is now open for business.”

job secrets
10 Secrets of Hotel Room Service

Guests visiting New York City's Waldorf Astoria hotel in the 1930s enjoyed an amenity that was unheard of at the time: waiters delivering meals directly to their rooms. While the Astoria’s reputation for luxury has endured, room service is no longer exclusive to five-star stays. Roughly 22 percent of the country’s 54,000 hotels [PDF] are willing and able to bring breakfast, lunch, or dinner to people who prefer to eat while splayed out on a large and strange bed.

To get the scoop on what goes into getting food from the kitchen to your floor, Mental Floss spoke with Matt, a hospitality specialist who spent a total of 10 years working in and around room service for a major San Francisco hotel. Matt preferred not to use his last name; since his stories sometimes involved naked people, undercooked chicken, and Oprah, you can understand why. Below, check out a few things you should know before you dig into that tray.


When a room service delivery employee takes a tray from the kitchen to your room, it’s typically covered in a metal lid to retain heat and to prevent other guests from sneezing on it. The higher up you are, the longer it has to travel—and the more that lid traps steam, soaking your food in moisture. “Food sweats in there,” Matt says. “Instead of having crispy, toasted bread, you get wet toast. The longer it stays in there, the worse it gets.” If you want crunchy fries, you’d better be on the first couple of floors.


A seafood dinner is presented on a plate

That lid is a nuisance in other ways. Because it traps heat, it’s effectively cooking your food in the time it takes to get from the chef’s hands to yours. “If you order a steak medium, it will probably be medium well by the time it gets to you,” Matt says. While you can try to outsmart the lid by requesting meat be cooked a notch lower than your preference, it's not so easy to avoid overcooked fish—which will probably also stink up your room. Instead, stick with burgers, club sandwiches, or salads. According to Matt, it’s hard to mess any of them up.


Just because you see a menu in your room, it doesn’t mean the hotel has a kitchen or chef on-site. To cut costs, more hotels are opting to out-source their room service to local eateries. “It might be ‘presented’ by the hotel, but it’s from a restaurant down the street,” Matt says. Alternately, hotels might try to save money by eliminating an overnight chef and having food pre-prepped so a desk clerk or other employee can just heat it up. That’s more likely if sandwiches or salads are the only thing available after certain hours.


Two coffee cups sit on a hotel bed

No, not for the reason you’re thinking. Because so many hotel guests are business travelers who are away from home for weeks or months at a time, some of them get tired of eating alone. When that happens, they turn to the first—and maybe only—person who could offer company: the room service waiter. “People are usually traveling alone, so they’ll offer you food,” Matt explains. Sometimes the traveler is a familiar face: According to Matt, he once sat down to eat with Oprah Winfrey, who was eating by herself despite her suite being filled with her own employees. He also says he had a bite with John F. Kennedy Junior, who wanted to finish watching Fast Times at Ridgemont High before heading for his limo.


Busy hotel kitchens aren’t always paying attention to whether the chicken wings they buy in bulk are frozen raw, frozen cooked, or somewhere in between. “Ask for them extra crispy,” Matt says. That way, they’ll be cooked thoroughly regardless of their freezer status. “I recommend that to everyone.”


A hotel guest pours milk into a bowl of cereal

Breakfast is undoubtedly the busiest time for room service, and those little cards that allow you to check off your menu items the night before are a huge help. “It’s great for everybody involved,” Matt says. “The kitchen can pace themselves and you can get your food on time.”


Yes, guests answer the door barely clothed. No, this is not optimal. “We don’t want to see it,” Matt says. “It's something we dealt with numerous times.” While it's likely your waiter will use discretion, any combination of genitalia, drugs, or illicit activity is best kept out of their sight.


A hotel room service tray sits in a hallway

That move where you stick your soggy fries outside your door? It can lead to some awkward encounters. Matt says he’s seen other guests stop, examine trays, and then pick up discarded food from them. Other times, people leave unimaginably gross items on the trays. “I’ve found condoms on there. Divorce paperwork. All kinds of things.”


Weird people aside, “We don’t really want it out there,” Matt says. “It stinks.” Instead, dial 0 for the front desk and let them know you’re done eating. They’ll dispatch someone to come and get it.


A tip is placed near a hotel check

People pay out the nose for room service, with hotels adding surcharges for “service” and “in-room” dining that can turn a $5 club sandwich into a $15 expense. That’s not great news for guests, but it does mean you don’t need to feel bad about not offering a cash tip. Those service fees usually go straight to the employees who got your food to your room. “I never tip,” Matt says. “Most of the time, the service and delivery charges are given to the waiter or split between the people who answered the phone and pick up the tray. It’s better to leave it all on paper to make sure it gets divided up.”

Big Questions
What is Mercury in Retrograde, and Why Do We Blame Things On It?

Crashed computers, missed flights, tensions in your workplace—a person who subscribes to astrology would tell you to expect all this chaos and more when Mercury starts retrograding for the first time this year on Friday, March 23. But according to an astronomer, this common celestial phenomenon is no reason to stay cooped up at home for weeks at a time.

"We don't know of any physical mechanism that would cause things like power outages or personality changes in people," Dr. Mark Hammergren, an astronomer at Chicago's Adler Planetarium, tells Mental Floss. So if Mercury doesn’t throw business dealings and relationships out of whack when it appears to change direction in the sky, why are so many people convinced that it does?


Mercury retrograde—as it's technically called—was being written about in astrology circles as far back as the mid-18th century. The event was noted in British agricultural almanacs of the time, which farmers would read to sync their planting schedules to the patterns of the stars. During the spiritualism craze of the Victorian era, interest in astrology boomed, with many believing that the stars affected the Earth in a variety of (often inconvenient) ways. Late 19th-century publications like The Astrologer’s Magazine and The Science of the Stars connected Mercury retrograde with heavy rainfall. Characterizations of the happening as an "ill omen" also appeared in a handful of articles during that period, but its association with outright disaster wasn’t as prevalent then as it is today.

While other spiritualist hobbies like séances and crystal gazing gradually faded, astrology grew even more popular. By the 1970s, horoscopes were a newspaper mainstay and Mercury retrograde was a recurring player. Because the Roman god Mercury was said to govern travel, commerce, financial wealth, and communication, in astrological circles, Mercury the planet became linked to those matters as well.

"Don’t start anything when Mercury is retrograde," an April 1979 issue of The Baltimore Sun instructed its readers. "A large communications organization notes that magnetic storms, disrupting messages, are prolonged when Mercury appears to be going backwards. Mercury, of course, is the planet associated with communication." The power attributed to the event has become so overblown that today it's blamed for everything from digestive problems to broken washing machines.


Though hysteria around Mercury retrograde is stronger than ever, there's still zero evidence that it's something we should worry about. Even the flimsiest explanations, like the idea that the gravitational pull from Mercury influences the water in our bodies in the same way that the moon controls the tides, are easily deflated by science. "A car 20 feet away from you will exert a stronger pull of gravity than the planet Mercury does," Dr. Hammergren says.

To understand how little Mercury retrograde impacts life on Earth, it helps to learn the physical process behind the phenomenon. When the planet nearest to the Sun is retrograde, it appears to move "backwards" (east to west rather than west to east) across the sky. This apparent reversal in Mercury's orbit is actually just an illusion to the people viewing it from Earth. Picture Mercury and Earth circling the Sun like cars on a racetrack. A year on Mercury is shorter than a year on Earth (88 Earth days compared to 365), which means Mercury experiences four years in the time it takes us to finish one solar loop.

When the planets are next to one another on the same side of the Sun, Mercury looks like it's moving east to those of us on Earth. But when Mercury overtakes Earth and continues its orbit, its straight trajectory seems to change course. According to Dr. Hammergren, it's just a trick of perspective. "Same thing if you were passing a car on a highway, maybe going a little bit faster than they are," he says. "They're not really going backwards, they just appear to be going backwards relative to your motion."

Embedded from GIFY

Earth's orbit isn't identical to that of any other planet in the solar system, which means that all the planets appear to move backwards at varying points in time. Planets farther from the Sun than Earth have even more noticeable retrograde patterns because they're visible at night. But thanks to astrology, it's Mercury's retrograde motion that incites dread every few months.

Dr. Hammergren blames the superstition attached to Mercury, and astrology as a whole, on confirmation bias: "[Believers] will say, 'Aha! See, there's a shake-up in my workplace because Mercury's retrograde.'" He urges people to review the past year and see if the periods of their lives when Mercury was retrograde were especially catastrophic. They'll likely find that misinterpreted messages and technical problems are fairly common throughout the year. But as Dr. Hammergren says, when things go wrong and Mercury isn't retrograde, "we don't get that hashtag. It's called Monday."

This story originally ran in 2017.


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