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New class of gravitational waves may come from clusters of massive black holes – The Globe and Mail

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An artist’s interpretation shows an array of pulsars being affected by gravitational ripples produced by a supermassive black hole binary in a distant galaxy.Handout

Somewhere, far away, the universe is humming, and for the first time, scientists are picking up the tune.

But that hum is not audible; rather, it consists of unimaginably long waves of gravitational energy that alternately stretch and squeeze space as they propagate in all directions. Their suspected source: hundreds of thousands of supermassive black holes swinging around each other like vigorous couples shaking the floor at a cosmic barn dance.

Such is the world of low frequency gravitational wave astronomy – a search for undulations so vast that, even thought they are coming at us at the speed of light, any single wave might take a decade or more to crest as it passes by Earth. The change is so subtle that scientists must employ special techniques just to demonstrate that the waves are there at all.

“These truly are among the lowest notes in the cosmic symphony. It’s an amazing feat to have found evidence for signals like this,” said Ingrid Stairs, an astronomer at the University of British Columbia and member of the NANOGrav collaboration, a North America-wide effort to search for the elusive low frequency waves.

The project’s latest measurements were published Thursday in the Astrophysical Journal Letters, in co-ordination with teams in Europe, India, Australia and China that have been independently looking for the same signal. All the findings are consistent with the existence of low frequency gravitational waves, though NANOGrav team members said the data are close but not yet at the 3.5 million-to-one-certainty level considered the gold standard for reporting new discoveries in physics.

“We’re not saying the word ‘detection,’ ” Dr. Stairs said.

If their interpretation is correct, researchers have used gravity to open up a new window into the unseen depths of the universe and shed light on the formation and evolution of the heaviest objects we know – or it could mean the discovery of something entirely new and unexpected.

Distant black hole caught in the act of annihilating a star

Long predicted by Einstein’s theory of general relativity, gravitational waves are disturbances in space that are produced whenever massive objects move very quickly. Their existence was first confirmed in 2015 by the Laser Interferometer Gravitational-Wave Observatory. The U.S.-based facility uses laser light reflecting back and forth between mirrors that are four kilometres apart to pick up slight vibrations that occur when gravitational waves are traversing through the experiment.

Since acquiring the sensitivity to detect the waves, LIGO has recorded many signals that come from colliding black holes a few dozen times the sun’s mass. Those signals appear as short-lived chirps in the data that momentarily jiggle the detector before fading away.

This week, scientists are reporting something quite different: not high-pitched chirps but a deep and continuous drone that permeates all of space. Such a drone would be expected to arise not from one collision but from the collective motion of many of the largest black holes in the universe – each one carrying the mass of millions of suns. Black holes of such extreme mass are known to form at the centres of distant galaxies. And while they may form separately, two such black holes can find themselves bound together in a tight orbit after their host galaxies merge.

Neither LIGO nor any other detector on Earth is large enough to sense the gravitational waves emanating from such a massive duo. However, by checking Earth’s position relative to other objects in space, astronomers have shown that our planet is acting very much like a cork bobbing around in slow motion exactly as would be expected from the low frequency waves.

“This is really compelling evidence for a background of gravitational waves,” said Steve Taylor, an astronomer at Vanderbilt University in Tennessee and current chair of NANOGrav during a briefing on the find. The collaboration harnessed researchers and facilities across North America to search for the effect.

To conduct its search, the team used radio telescopes in multiple locations to carefully monitor pulsars – compact, rotating objects scattered around our Milky Way galaxy that are left behind when stars exhaust their fuel and explode as supernovas. Some pulsars can spin as much as 1000 times per second, which makes then ideal natural timers because their rotations are so precise and consistent. As Earth is buffeted by gravitational waves, the planet’s back and forth motion can be spotted by comparing pulsars in different directions and checking for slight discrepancies in timing. The hitch is that it takes years of measurements to see the gradual change caused by passing low frequency gravitational waves.

Achieving that result reliably “has taken a small army of people to do everything right,” Dr. Stairs said.

Other teams used the same pulsar-timing approach to arrive at comparable results. And while the existence of low frequency gravitational waves has long been suspected, the details include a few puzzles. For example, if the background hum is produced solely by close pairs of supermassive black holes circling each other, then the pairs are more common and somewhat more massive on average than standard theories predict.

This had some researchers this week pointing to even more exotic possibilities for explaining the cause of the gravitational waves, including cosmic strings: hypothetical defects in spacetime that some theories predict could have formed during the Big Bang.

Luis Lehner, a researcher at the Perimeter Institute for Theoretical Physics in Waterloo, Ont., who was not part of the collaboration, said that theorists may have difficulty explaining how pairs of supermassive can get close enough to each other often enough to match what observers are now finding in their data.

“They take too long to merge, but we’re not seeing that,” he said. “Somehow they get together … it’s nature reminding us that it’s always going to be smarter than we are.”

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Here’s how Helene and other storms dumped a whopping 40 trillion gallons of rain on the South

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More than 40 trillion gallons of rain drenched the Southeast United States in the last week from Hurricane Helene and a run-of-the-mill rainstorm that sloshed in ahead of it — an unheard of amount of water that has stunned experts.

That’s enough to fill the Dallas Cowboys’ stadium 51,000 times, or Lake Tahoe just once. If it was concentrated just on the state of North Carolina that much water would be 3.5 feet deep (more than 1 meter). It’s enough to fill more than 60 million Olympic-size swimming pools.

“That’s an astronomical amount of precipitation,” said Ed Clark, head of the National Oceanic and Atmospheric Administration’s National Water Center in Tuscaloosa, Alabama. “I have not seen something in my 25 years of working at the weather service that is this geographically large of an extent and the sheer volume of water that fell from the sky.”

The flood damage from the rain is apocalyptic, meteorologists said. More than 100 people are dead, according to officials.

Private meteorologist Ryan Maue, a former NOAA chief scientist, calculated the amount of rain, using precipitation measurements made in 2.5-mile-by-2.5 mile grids as measured by satellites and ground observations. He came up with 40 trillion gallons through Sunday for the eastern United States, with 20 trillion gallons of that hitting just Georgia, Tennessee, the Carolinas and Florida from Hurricane Helene.

Clark did the calculations independently and said the 40 trillion gallon figure (151 trillion liters) is about right and, if anything, conservative. Maue said maybe 1 to 2 trillion more gallons of rain had fallen, much if it in Virginia, since his calculations.

Clark, who spends much of his work on issues of shrinking western water supplies, said to put the amount of rain in perspective, it’s more than twice the combined amount of water stored by two key Colorado River basin reservoirs: Lake Powell and Lake Mead.

Several meteorologists said this was a combination of two, maybe three storm systems. Before Helene struck, rain had fallen heavily for days because a low pressure system had “cut off” from the jet stream — which moves weather systems along west to east — and stalled over the Southeast. That funneled plenty of warm water from the Gulf of Mexico. And a storm that fell just short of named status parked along North Carolina’s Atlantic coast, dumping as much as 20 inches of rain, said North Carolina state climatologist Kathie Dello.

Then add Helene, one of the largest storms in the last couple decades and one that held plenty of rain because it was young and moved fast before it hit the Appalachians, said University of Albany hurricane expert Kristen Corbosiero.

“It was not just a perfect storm, but it was a combination of multiple storms that that led to the enormous amount of rain,” Maue said. “That collected at high elevation, we’re talking 3,000 to 6000 feet. And when you drop trillions of gallons on a mountain, that has to go down.”

The fact that these storms hit the mountains made everything worse, and not just because of runoff. The interaction between the mountains and the storm systems wrings more moisture out of the air, Clark, Maue and Corbosiero said.

North Carolina weather officials said their top measurement total was 31.33 inches in the tiny town of Busick. Mount Mitchell also got more than 2 feet of rainfall.

Before 2017’s Hurricane Harvey, “I said to our colleagues, you know, I never thought in my career that we would measure rainfall in feet,” Clark said. “And after Harvey, Florence, the more isolated events in eastern Kentucky, portions of South Dakota. We’re seeing events year in and year out where we are measuring rainfall in feet.”

Storms are getting wetter as the climate change s, said Corbosiero and Dello. A basic law of physics says the air holds nearly 4% more moisture for every degree Fahrenheit warmer (7% for every degree Celsius) and the world has warmed more than 2 degrees (1.2 degrees Celsius) since pre-industrial times.

Corbosiero said meteorologists are vigorously debating how much of Helene is due to worsening climate change and how much is random.

For Dello, the “fingerprints of climate change” were clear.

“We’ve seen tropical storm impacts in western North Carolina. But these storms are wetter and these storms are warmer. And there would have been a time when a tropical storm would have been heading toward North Carolina and would have caused some rain and some damage, but not apocalyptic destruction. ”

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Follow AP’s climate coverage at https://apnews.com/hub/climate

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Follow Seth Borenstein on Twitter at @borenbears

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Associated Press climate and environmental coverage receives support from several private foundations. See more about AP’s climate initiative here. The AP is solely responsible for all content.

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‘Big Sam’: Paleontologists unearth giant skull of Pachyrhinosaurus in Alberta

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It’s a dinosaur that roamed Alberta’s badlands more than 70 million years ago, sporting a big, bumpy, bony head the size of a baby elephant.

On Wednesday, paleontologists near Grande Prairie pulled its 272-kilogram skull from the ground.

They call it “Big Sam.”

The adult Pachyrhinosaurus is the second plant-eating dinosaur to be unearthed from a dense bonebed belonging to a herd that died together on the edge of a valley that now sits 450 kilometres northwest of Edmonton.

It didn’t die alone.

“We have hundreds of juvenile bones in the bonebed, so we know that there are many babies and some adults among all of the big adults,” Emily Bamforth, a paleontologist with the nearby Philip J. Currie Dinosaur Museum, said in an interview on the way to the dig site.

She described the horned Pachyrhinosaurus as “the smaller, older cousin of the triceratops.”

“This species of dinosaur is endemic to the Grand Prairie area, so it’s found here and nowhere else in the world. They are … kind of about the size of an Indian elephant and a rhino,” she added.

The head alone, she said, is about the size of a baby elephant.

The discovery was a long time coming.

The bonebed was first discovered by a high school teacher out for a walk about 50 years ago. It took the teacher a decade to get anyone from southern Alberta to come to take a look.

“At the time, sort of in the ’70s and ’80s, paleontology in northern Alberta was virtually unknown,” said Bamforth.

When paleontogists eventually got to the site, Bamforth said, they learned “it’s actually one of the densest dinosaur bonebeds in North America.”

“It contains about 100 to 300 bones per square metre,” she said.

Paleontologists have been at the site sporadically ever since, combing through bones belonging to turtles, dinosaurs and lizards. Sixteen years ago, they discovered a large skull of an approximately 30-year-old Pachyrhinosaurus, which is now at the museum.

About a year ago, they found the second adult: Big Sam.

Bamforth said both dinosaurs are believed to have been the elders in the herd.

“Their distinguishing feature is that, instead of having a horn on their nose like a triceratops, they had this big, bony bump called a boss. And they have big, bony bumps over their eyes as well,” she said.

“It makes them look a little strange. It’s the one dinosaur that if you find it, it’s the only possible thing it can be.”

The genders of the two adults are unknown.

Bamforth said the extraction was difficult because Big Sam was intertwined in a cluster of about 300 other bones.

The skull was found upside down, “as if the animal was lying on its back,” but was well preserved, she said.

She said the excavation process involved putting plaster on the skull and wooden planks around if for stability. From there, it was lifted out — very carefully — with a crane, and was to be shipped on a trolley to the museum for study.

“I have extracted skulls in the past. This is probably the biggest one I’ve ever done though,” said Bamforth.

“It’s pretty exciting.”

This report by The Canadian Press was first published Sept. 25, 2024.

The Canadian Press. All rights reserved.

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The ancient jar smashed by a 4-year-old is back on display at an Israeli museum after repair

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TEL AVIV, Israel (AP) — A rare Bronze-Era jar accidentally smashed by a 4-year-old visiting a museum was back on display Wednesday after restoration experts were able to carefully piece the artifact back together.

Last month, a family from northern Israel was visiting the museum when their youngest son tipped over the jar, which smashed into pieces.

Alex Geller, the boy’s father, said his son — the youngest of three — is exceptionally curious, and that the moment he heard the crash, “please let that not be my child” was the first thought that raced through his head.

The jar has been on display at the Hecht Museum in Haifa for 35 years. It was one of the only containers of its size and from that period still complete when it was discovered.

The Bronze Age jar is one of many artifacts exhibited out in the open, part of the Hecht Museum’s vision of letting visitors explore history without glass barriers, said Inbal Rivlin, the director of the museum, which is associated with Haifa University in northern Israel.

It was likely used to hold wine or oil, and dates back to between 2200 and 1500 B.C.

Rivlin and the museum decided to turn the moment, which captured international attention, into a teaching moment, inviting the Geller family back for a special visit and hands-on activity to illustrate the restoration process.

Rivlin added that the incident provided a welcome distraction from the ongoing war in Gaza. “Well, he’s just a kid. So I think that somehow it touches the heart of the people in Israel and around the world,“ said Rivlin.

Roee Shafir, a restoration expert at the museum, said the repairs would be fairly simple, as the pieces were from a single, complete jar. Archaeologists often face the more daunting task of sifting through piles of shards from multiple objects and trying to piece them together.

Experts used 3D technology, hi-resolution videos, and special glue to painstakingly reconstruct the large jar.

Less than two weeks after it broke, the jar went back on display at the museum. The gluing process left small hairline cracks, and a few pieces are missing, but the jar’s impressive size remains.

The only noticeable difference in the exhibit was a new sign reading “please don’t touch.”

The Canadian Press. All rights reserved.

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