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What's the Matter with the Universe?

An artist's rendering shows a star called a white dwarf with a planet (upper right) and material in orbit around the star. Courtesy of Mark Garlick/UCLA/Handout via REUTERS.
An artist's rendering shows a star called a white dwarf with a planet (upper right) and material in orbit around the star. Courtesy of Mark Garlick/UCLA/Handout via REUTERS.
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What's the Matter with the Universe?

An artist's rendering shows a star called a white dwarf with a planet (upper right) and material in orbit around the star. Courtesy of Mark Garlick/UCLA/Handout via REUTERS.
An artist's rendering shows a star called a white dwarf with a planet (upper right) and material in orbit around the star. Courtesy of Mark Garlick/UCLA/Handout via REUTERS.

A team of US astrophysicists has produced one of the most precise measurements ever made of the total amount of matter in the Universe, a longtime mystery of the cosmos.

The answer, published in The Astrophysical Journal on Monday, is that matter accounts for 31.5 percent -- give or take 1.3 percent -- of the total amount of matter and energy that make up the Universe.

The remaining 68.5 percent is dark energy, a mysterious force that is causing the expansion of the Universe to accelerate over time, and was first inferred by observations of distant supernovae in the late 1990s.

Put another way, this means the total amount of matter in the observable Universe is equivalent to 66 billion trillion times the mass of our Sun, Mohamed Abdullah, a University of California, Riverside astrophysicist and the paper's lead author, told AFP.

Most of this matter -- 80 percent -- is called dark matter. Its nature is not yet known, but it may consist of some as-yet-undiscovered subatomic particle.

The latest measurements correspond well with values previously found by other teams using different cosmological techniques, such as measuring temperature fluctuations in the low-energy radiation left over from the Big Bang.

"This has been a long process over the course of 100 years where we're gradually getting more and more precise," Gillian Wilson, the study's co-author and a professor at UCR told AFP.

"It's just kind of cool to be able to make such a fundamental measurement about the Universe without leaving planet Earth," she added.

So how exactly do you weigh the Universe?

The team honed a 90-year-old technique that involves observing how galaxies orbit inside galaxy clusters -- massive systems that contain thousands of galaxies.

These observations told them how strong each galaxy cluster's gravitational pull was, from which its total mass could then be calculated.

In fact, explained Wilson, their technique was originally developed by the pioneering astronomer Fritz Zwicky, who was the first person to suspect the existence of dark matter in galaxy clusters, in the 1930s.

He noticed that the combined gravitational mass of the galaxies he observed in the nearby Coma galaxy cluster was insufficient to prevent those galaxies from flying away from one another, and realized there must be some other invisible matter at play.

The UCR team, whose research received money from the US National Science Foundation and NASA, refined Zwicky's technique, developing a tool they called GalWeight that determines more accurately which galaxies belong to a given cluster and which do not.

They applied their tool to the Sloan Digital Sky Survey, the most detailed three-dimensional maps of the Universe currently available, measuring the mass of 1,800 galaxy clusters and creating a catalog.

Finally, they compared the number of clusters observed per unit volume in their catalog against a series of computer simulations, each of which was fed a different value for the total matter of the Universe.

Simulations with too little matter had too few clusters, while those with too much matter had too many clusters.

The "Goldilocks" value they found fit just right.

Wilson explained that having a more precise measure of the total amount of matter in the Universe may take us a step closer to learning the nature of dark matter, because "we know just how much matter we should be looking for" when scientists carry out particle experiments, for example at the Large Hadron Collider.

What's more, "the total amount of dark matter and dark energy tells us the fate of the Universe," she added, with the current scientific consensus being that we are headed for a "Big Freeze" where galaxies move further and further apart, and the stars in those galaxies eventually run out of fuel.

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Varieties

Return of Swarming Moth Spectacle Has Australia in a Flutter

This picture taken on October 1, 2026 shows a Bogong moth among the leaves of a tree in Sydney. (Photo by David WILLIAMS / AFP)
This picture taken on October 1, 2026 shows a Bogong moth among the leaves of a tree in Sydney. (Photo by David WILLIAMS / AFP)
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Return of Swarming Moth Spectacle Has Australia in a Flutter

This picture taken on October 1, 2026 shows a Bogong moth among the leaves of a tree in Sydney. (Photo by David WILLIAMS / AFP)
This picture taken on October 1, 2026 shows a Bogong moth among the leaves of a tree in Sydney. (Photo by David WILLIAMS / AFP)

Moth swarms so thick they can blot out the stars are fluttering across Australia, heralding a migratory spectacle unseen since the creature's brush with extinction nearly 10 years ago.

The great migration of the Bogong moth was once a yearly feature of the Australian spring, the insects humming down the nation's east coast in their billions as they searched for cooler climes.

But drought, pesticides and habitat destruction triggered an unprecedented collapse that began in 2017, eventually wiping out an estimated 99.5 percent of the Bogong moth population.

While vast clouds of flying bugs might not be everyone's cup of tea, scientists have been delighted to find that the Bogongs are back.

"There have been happy tears in my office because this is what nature should be," said conservation biologist Marissa Parrott.

"People are noticing those big swarms again. They can celebrate what I think is one of nature's great spectacles."

In a good year, four billion moths or more would escape the inland heat to seek shelter in the alpine caves of eastern Australia.

"So many Bogong moths would come through that they could block out the stars and the moon as they went overhead," said Parrott, from Zoos Victoria.

Photos showed how the endangered moths clustered together so densely inside their caves, it was impossible to see the rock beneath.

"They get up into the mountains and into these caves, where they make this beautiful tiling pattern," said Western Sydney University insect researcher Eleanor Drinkwater.

"They cover the walls in this very dense mat of moths.

"They hang out there until the weather starts getting cooler, and they come back down to their breeding grounds."

Their migration has long fascinated scientists, who have puzzled over how they found their way on a journey they only ever make once.

By placing a tether around captive moths and projecting stars on the wall, researchers last year showed how Bogongs used the Milky Way.

They were the first invertebrates -- a broad group of animals including spiders, snails and worms -- shown to use celestial navigation for such long trips.

Bogong moths are thought to help plants spread pollen and are also a key food source for the mountain pygmy possum, a critically endangered cave-dwelling marsupial.

"They are very, very important to Australian ecosystems," Drinkwater said.

Drawn towards the blazing stadium floodlights, Bogong swarms caused havoc at the 2000 Olympic Games in Sydney.

Forecasters warned that heavy rain was about to drench the event's closing ceremony -- only to realize the radar had picked up a cloud of Bogongs, AFP reported.

While the Bogong migration continued in the years following the population crash, scientists were aghast at how few moths were making the journey.

"People described going into the caves and finding barely any moths, and just kind of being in shock," Drinkwater said.

Researchers are still working to better understand what contributed to the Bogong bounce-back, but believe a spate of wetter weather has helped.

With a severe El Nino forecast to send temperatures soaring over summer, scientists hope the rebound is not short lived.

"It's great they're back, and we're really excited they're back," said Drinkwater.

Varieties

Heat-trapping Gas Once Frozen in Arctic Ground is Slowly Leaking, Warming the Planet

FILE - Permafrost melts on the coast in Newtok, Alaska, Aug. 16, 2024. (AP Photo/Rick Bowmer, File)
FILE - Permafrost melts on the coast in Newtok, Alaska, Aug. 16, 2024. (AP Photo/Rick Bowmer, File)
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Heat-trapping Gas Once Frozen in Arctic Ground is Slowly Leaking, Warming the Planet

FILE - Permafrost melts on the coast in Newtok, Alaska, Aug. 16, 2024. (AP Photo/Rick Bowmer, File)
FILE - Permafrost melts on the coast in Newtok, Alaska, Aug. 16, 2024. (AP Photo/Rick Bowmer, File)

As Ted Schuur stepped along the edges of Smith Lake, a bubble surfaced from the muck underfoot. And then another.

They're bubbles of methane, a potent heat-trapping gas made from decomposing plants and animals that had once been stuck in Alaska's frigid permafrost. But that frozen ground is thawing because the Arctic is warming four times faster than the rest of the globe. For thousands of years that frozen ground stored dead plants and animals, but the accelerating thaw is allowing them to decay into methane and carbon dioxide.

“Once you start leaking this carbon out, there’s so much in the ground that it’s not going to shut off,” said Schuur, an ecologist at Northern Arizona University, calling it one of climate change's scary tipping points. “Essentially every year is setting a permafrost record.”

There’s three times as much carbon still frozen in permafrost than what’s now in the air, but all over the Arctic those heat-trapping gases are escaping into the atmosphere. Their release adds to what's already in the air from humanity's burning coal, oil and natural gas, changing the delicate balance of how a warming world deals with the buildup of heat-trapping carbon, Schuur said.

Permafrost is ground that stays frozen — below 32 degrees Fahrenheit (zero degrees Celsius) — for at least two years and often for centuries and even millennia. That frozen ground — found in Alaska, Canada, Siberia, Antarctica and high mountain elevations elsewhere — has special advantages, trapping decaying matter, keeping it from turning into greenhouse gases and just being firm enough for communities and industries to build their lives upon.

But warming is undercutting that, The Associated Press reported.

Two different studies project that by the end of this century, those previously trapped gases in permafrost will add nearly half a degree of warming (about a quarter degree Celsius) in addition to warming from the burning of fossil fuels. Over that time period, that'll warm the Earth about as much as a major industrialized country like the United States or the whole of Europe, scientists said.

A sleeping giant awakens “The permafrost system is really like a sleeping giant,” said Gustaf Hugelius, a permafrost expert at Stockholm University.

For thousands of years, when the climate was somewhat stable, the Arctic helped Earth's delicate carbon cycle by acting as a sink. That means plants in the cold areas used to pull some heat-trapping gas out of the air and capture it in the frozen ground, with the Arctic essentially withdrawing more carbon from the air than it added, benefiting the entire globe.

A few years ago, warming caused that balance to shift so that once-frozen ground is venting more heat-trapping gases than it takes in. Instead of reducing climate change, the Arctic is now adding to the problem, said Columbia University ecologist Duncan Menge.

Permafrost thaw, along with other “warming-induced emissions” from fires and changes to wetlands and lakes, are likely to increase warming by 20% by the end of the century, according to a September study co-authored by Arctic ecologist Sue Natali of the Woodwell Climate Research Center.

It may be a small amount, not worthy of scenarios of doom, but it’s something “that we’re going to have to deal with” on top of everything else, said University of Victoria climate scientist Andrew Weaver, who first calculated the half-a-degree of expected permafrost warming in a 2012 study.

What’s troublesome is that when politicians and scientists talk about future warming, they’re usually not accounting for the extra greenhouse gases from permafrost thawing, said Natali and Hugelius. So while the UN says without policy changes the world will warm 2.6 degrees C (4.7 degrees F) above pre-industrial times by the end of the century, it leaves out a few tenths of a degree from thawing permafrost, they said.

Thawing permafrost is not just messing with the planet's carbon balance, it's destabilizing the very land underfoot, making once-rigid ground collapse and sink, Natali said.

Frozen ground that's no longer firm became deadly this summer. Flooding in Nepal killed more than 1,000 people after part of a glacier collapsed, which happened after a heat wave that set records for the location and time of year, according to Berkeley Earth climate scientist Robert Rohde.

Ground that’s solidly frozen holds up mountains and skyscrapers, but once the permafrost thaws, it’s no longer strong enough. That was likely one of several still-to-be-determined factors in the Nepal disaster, said George Washington University permafrost scientist Dmitry Streletskiy, lead author of an August study that found significant permafrost thawing in most of the Northern Hemisphere.

Permafrost in Alaska and other Arctic areas has long supported homes, roads and pipelines, but it’s no longer so reliable. For example, in Galbraith on Alaska’s North Slope, a recently formed 10-foot (3-meter) deep, craterlike hole was visible during a recent foray by scientists.

These holes, known as slumps, occur when ice melts and the land collapses, releasing methane, Natali said. A Woodwell team has identified more than 40,000 of these slumps across the Arctic using satellites, according to scientist Kyle Arndt.

University of Alaska Fairbanks geophysicist Vladimir Romanovsky said when he first started studying permafrost in the 1970s, “everybody believed permafrost was very stable. People thought it was forever.”

Not anymore, he said.

“It took some thousands and tens of thousands of years to sequester this carbon into permafrost,” Romanovsky said. “You need a new ice age to put back this ice into the ground.”

A time capsule to the last ice age is visible under a Fairbanks hill where the US Army drilled a massive permafrost research tunnel. Artificially cooled and used for training, the tunnel's icy walls are dotted with bones of bison and mammoths, producing a sewage-like odor that vividly illustrates where the Arctic methane comes from.

“Every time I go there, I'm reminded of the magnitude of the problem. You smell it. You see it. You feel it all around you,” Natali said. “You see how deep the ice is and just how the carbon is buried and then when you go on top and you see these large thaw features. ... This isn't a problem of 100 years from now. This is a problem of right now.”

Varieties

When the World Saw van Gogh as ‘a Madman,’ she Saw his Genius

“Four Sunflowers Gone to Seed” Credit...Ilvy Njiokiktjien for The New York Times
“Four Sunflowers Gone to Seed” Credit...Ilvy Njiokiktjien for The New York Times
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When the World Saw van Gogh as ‘a Madman,’ she Saw his Genius

“Four Sunflowers Gone to Seed” Credit...Ilvy Njiokiktjien for The New York Times
“Four Sunflowers Gone to Seed” Credit...Ilvy Njiokiktjien for The New York Times

By Nina Siegal

It was April 1912, and Helene Kröller-Müller was on a shopping spree. She wasn’t interested in the latest shoes or fashions. She was on the hunt for Vincent van Gogh’s portrait of Madame Augustine Roulin.

She managed to find “La Berceuse,” as the painting is known, at a Paris gallery, and bought it on the spot. The next day, she went from gallery to gallery, looking for more van Gogh paintings, and took home a great haul: 15 in a single trip.

Kröller-Müller, a German heiress, had made it her life’s goal to establish a great public collection of modern art. She became one of the first major collectors to recognize van Gogh’s genius.

Now, more than a century after that Paris shopping spree, the entire collection of van Gogh paintings she assembled is on view together at the museum she built in the middle of a Dutch forest — for the first time since 1984.

It is the second-largest trove of van Gogh’s works anywhere, after the Van Gogh Museum in Amsterdam, and it was assembled by a woman who took great risks in buying his art at a time when few others dared.

The exhibition “Van Gogh: All Our Paintings” includes works like “La Berceuse,” hanging on the left side of the rear wall. Credit...Ilvy Njiokiktjien for The New York Times

The exhibition at the Kröller-Müller Museum in Otterlo, the Netherlands, called “Van Gogh: All Our Paintings” and running through Jan. 3, presents the whole collection as Kröller-Müller conceived it: an expression of the artist’s development, range and spiritual aspirations.

“This is a rare moment that all the paintings are in the house,” said Benno Tempel, the museum’s director. “It hasn’t happened for such a long time.”

The show is organized around three themes — faith, hope and love — reflecting the spiritual dimension that Kröller-Müller saw in van Gogh’s work. It includes many of his popular works, scattered throughout these broad categories, such as “Café Terrace at Night,” “Portrait of Joseph Roulin” and “The Sower.”

Kröller-Müller, the daughter of a German industrialist, had an early interest in art but had to end her formal education at age 16. At 18, she married one of her father’s employees, who would later take over the family business. Her husband, Anton Müller, encouraged her intellectual pursuits, including her interest in art, a socially acceptable hobby for wealthy women of the era.

“If you were married at the time, you gave all your money and assets to your husband," said the exhibition’s curator, Renske Cohen Tervaert. “So it was quite open-minded of him, in a way, to allow her to follow her dream in this way.”

But Kröller-Müller didn’t collect as a hobbyist. She embraced art with a kind of religious fervor.
She bought her first van Gogh painting in 1908 for 110 guilders — about the price of an exquisite dress, said Eva Rovers, her biographer. Four months later, she bought his “Four Sunflowers Gone to Seed” for 4,000 guilders.

Prices were rising in large part because she was buying so much.

“Bridge at Arles” Credit...Ilvy Njiokiktjien for The New York Times

Kröller-Müller’s collecting philosophy was largely shaped by the art historian Henk Bremmer, with whom she took an art appreciation class, Tervaert said. She added that for Bremmer, the key component of good art was that it made the viewer feel an emotion or experience something spiritual.

Kröller-Müller went looking for art that stirred her spirit and found van Gogh.

Rovers said that van Gogh was not well regarded in the early 20th century. “If the general public knew him at all, they really considered him a madman who could not paint,” she said.

But because van Gogh had been a preacher before becoming an artist, Kröller-Müller regarded him as a man who had found a connection to faith through his art.

“She understood his wish to transcend suffering, and his aim to use art to transcend suffering,” Rovers said.

While most collectors in the Netherlands were buying old masters and 19th-century Dutch painting, Kröller-Müller focused on Cubism, Pointillism and De Stijl artists, including Piet Mondrian, Fernand Léger and Pablo Picasso.

Van Gogh’s work dominated the collection for a simple reason, Rovers said: He “stood at the cradle of the beginning of avant-garde art.” Kröller-Müller built a collection, Rovers added, “that could show the broad variety of his work — landscapes, portraits, cityscapes.”

A van Gogh self-portrait from 1887. The show is organized around the themes of faith, hope and love. Credit...Ilvy Njiokiktjien for The New York Times

In the late 1930s, as Europe was approaching World War II, Kröller-Müller’s health was declining, along with her family fortune.

She decided to offer her art collection, worth about 4 million guilders at the time, along with family property in the Veluwe forest, to the Dutch state, as long as it would agree to build a museum to display it. She imagined the museum, with a 62-acre sculpture garden, as a retreat for spiritual and philosophical inquiry.

The result was a rare trove in a remote Dutch forest — now a national park — built around her collection.

The Van Gogh Museum in Amsterdam has more than 200 paintings, but its collection has a different history: It was established to show the collection of the van Gogh family, who owned the artist’s unsold works. The Kröller-Müller represents a collector’s eye.

“The Van Gogh Museum is just what was left over,” Tempel said. “This is a chosen collection.”

The New York Times