Science
Jeremiah Ostriker, Who Plumbed Dark Forces That Shape Universe, Dies at 86
Jeremiah Ostriker, an astrophysicist who helped set off a revolution in humankind’s view of the universe, revealing it to be a vaster, darker realm than the one we can see, ruled by invisible forms of matter and energy we still don’t understand, died on Sunday at his home on the Upper West Side of Manhattan. He was 87.
His daughter Rebecca Ostriker said the cause was end-stage renal disease.
Over more than four decades, mostly at Princeton University, Dr. Ostriker’s work altered our understanding of how galaxies form and evolve as he explored the nature of pulsars, the role of black holes in the evolution of the cosmos and what the universe is made of.
Before the 1970s, most astronomers believed that galaxies were made up mostly of stars.
“Ostriker was arguably the most important single figure in convincing the astronomical community that this natural and seductive assumption is wrong,” David Spergel, the president of the Simons Foundation, which supports scientific research, wrote in 2022, nominating Dr. Ostriker, his mentor, for the Crafoord Prize, the astronomical equivalent of a Nobel. He cited Dr. Ostriker’s “eloquent advocacy for the then-radical new model in which the visible stars in galaxies were only a minor pollutant at the center of a much larger halo of dark matter of unknown composition.”
Dr. Ostriker’s work, he said, was “the grandest revision in our understanding of galaxies” in half a century.
Jerry Ostriker, as he was known to friends and colleagues, a man with a prickly sense of humor and a soft but commanding voice, was willing to go wherever the data and scientific calculations led him, and was not shy about questioning assumptions — or having fun. Prominently displayed in his home was a youthful photo of himself, taken in Cambridge, Mass., driving a motor scooter as his wife, Alicia Ostriker, seated behind him, lifts a bottle of wine to her lips. (A close look shows the cork still in the bottle.)
“He had the quickest wit of any scientist I have encountered,” said James Peebles, a Nobel physics laureate and a colleague of Dr. Ostriker’s at Princeton. “And I don’t remember ever matching him in a spontaneous debate” on any issue.
Asked in a 1988 oral history interview for the American Institute of Physics if he had favored any of the models of the universe being batted about in the 1970s, when he entered the field — whether the universe was finite or infinite, whether it had a beginning or was somehow always here, whether it would expand forever or crash back down in a big crunch — he said he had not.
“Scientists have followed their own biases, and my principle bias at the time was being contemptuous and intolerant of all of these people who had specific models,” he answered. “How could they be so certain when the evidence was as confusing and inconclusive?”
A ‘Classic Nerd Child’
Jeremiah Paul Ostriker was born on April 13, 1937, on the Upper West Side, the second of four siblings. His father, Martin Ostriker, ran a clothing company, and his mother, Jeanne (Sumpf) Ostriker, was a public-school teacher. Babe Ruth lived around the corner, and the children used to chase his car for autographs.
“I must have been the classic nerd child,” Dr. Ostriker wrote in a memoir published in the Annual Review of Astronomy and Astrophysics in 2016. He first became interested in science when he was 4: His mother started reading science books aloud to get him to sit still for an oil portrait, and the readings stuck.
After graduating from the Ethical Culture Fieldston School in the Bronx, Jerry Ostriker went to Harvard University, where he planned to study chemistry. Instead, he switched to physics, which appealed to what he called his “cosmic perspective.”
“I probably spent more time on literature than I spent on science,” he said in the oral history interview.
He soon began commuting to Brandeis University to visit Alicia Suskin, a former Fieldston classmate who was an aspiring artist and poet. They were married in 1958, while they were still undergraduates.
Ms. Ostriker, a professor emerita of English at Rutgers University, became an award-winning poet and has often written her husband into her work. In turn, he found poetry in astrophysics. “As an astrophysicist, you get a perspective on humankind,” he said, describing it as “sweating on this little grain of spinning sand.”
In addition to his wife and his daughter Rebecca, an editor for the opinion section of The Boston Globe, Dr. Ostriker is survived by two other children, Eve Ostriker, an astrophysicist at Princeton, and Gabriel Ostriker, a data engineer; a sister, Naomi Seligman; two brothers, Jon and David; and three grandchildren.
After graduating from Harvard in 1959, Dr. Ostriker worked at the United States Naval Research Laboratory for a year before enrolling in graduate school at the University of Chicago, splitting his time between the university’s Yerkes Observatory and the physics department, where he worked under the future Nobel laureate Subrahmanyan Chandrasekhar.
He earned his Ph.D. in 1964. After a postdoctoral year at the University of Cambridge in England, where he rubbed elbows with future black hole eminences like Stephen Hawking and Martin Rees, Dr. Ostriker joined Princeton as a research scientist. He remained there for 47 years, rising through the ranks to become chairman of the astronomy department and provost of the university.
The Dark Side of the Universe
At Princeton, Dr. Ostriker wrote a series of papers that would lead astronomy to the dark side.
He wondered whether galaxies, like stars, could break apart if they rotated too fast. The question was particularly relevant to so-called disc galaxies like the Milky Way, which are shaped sort of like a fried egg, with a fat, yolky center surrounded by a thin, white flat of stars.
Working with Dr. Peebles, he constructed a computer simulation and found that disc galaxies were indeed unstable. They would fall apart unless there was something we couldn’t see, a halo of some additional invisible mass, lending gravitational support.
Whatever this stuff called dark matter was — dim stars, black holes, rocks, exotic subatomic particles left over from the Big Bang — there could be a lot of it, as much as 10 times the mass of ordinary atomic matter.
It was one of the first theoretical arguments that there must be more to galaxies than could be seen in starlight. In the 1930s, the astronomer Fritz Zwicky had suggested that most of the mass in galaxies was “dark.” His idea was largely ignored until Dr. Ostriker and Dr. Peebles published their paper in 1973.
The reaction from the scientific community was predominantly hostile, Dr. Ostriker said. “I couldn’t see particularly why,” he said in the oral history. “It was just a fact.”
A year later, incorporating more data from galaxy clusters and other star systems, he and his colleagues argued that, in fact, most of the mass in the universe was invisible.
By the early 1980s, the idea of dark matter had become an accepted part of cosmology, but there remained conundrums, including calculations that suggested that stars were older than the universe in which they lived.
The missing ingredient, Dr. Ostriker and the theoretical physicist Paul Steinhardt, then at the University of Pennsylvania, suggested in 1995, was a fudge factor known as the cosmological constant. Einstein had come up with this concept in 1917, but had later abandoned it, considering it a blunder.
As Dr. Steinhardt recalled, he and Dr. Ostriker were “convinced that a universe with only dark and ordinary matter could not explain the existing observations.” But once they added the cosmological constant, everything came out right.
They were not the only ones with this idea. The cosmologists Michael Turner, now retired from the University of Chicago, and Lawrence Krauss, now retired from Arizona State University, also argued in favor of bringing back the constant. “To say Jerry was a giant in the field is an understatement,” Dr. Turner wrote in an email, adding, “Sparring with Jerry over science was a privilege and often a learning experience.”
Three years later, two competing teams of astronomers discovered that the expansion of the universe was being accelerated by a “dark energy” acting as the cosmological constant, pushing galaxies apart. The cosmological constant then became part of a standard model of the universe, as Dr. Ostriker and others had predicted.
In another series of papers, he and various collaborators transformed astronomers’ view of what was going on in the space between stars.
Dr. Ostriker and Renyue Cen, also of Princeton, concluded in 1999 that most ordinary atomic matter in the nearby universe was invisible, taking the form of intergalactic gas heated to millions of degrees by shock waves and explosions.
A Passion That Never Waned
At Princeton, Dr. Ostriker helped set up the Sloan Digital Sky Survey, a collaboration — initially of Princeton, the University of Chicago and the Institute for Advanced Study in Princeton, N.J. — aimed at remapping the entire sky in digital form with a dedicated telescope at Apache Point Observatory in Sunspot, N.M.
“The survey is going to increase our knowledge and our understanding of the universe a hundredfold,” he told The New York Times in 1991. “The map is not going to show us how the universe began, but it will show us the nature and origin of large-scale structure, the most interesting problem in astrophysics today. With an answer to this problem, we will be able to better approach the question of how it all began.”
The survey, started in 1998, is now in its fifth iteration and has generated some 10,000 research papers and archived measurements of a half-billion stars and galaxies, all free to any astronomer in the world.
As provost, Dr. Ostriker led the effort to vastly expand the university’s financial aid program, changing many loans to grants that would not need to be repaid, making a Princeton education more egalitarian. In 2000, he was awarded the National Medal of Science by President Bill Clinton.
Dr. Ostriker retired from Princeton in 2012, just as his daughter Eve was joining the astronomy faculty there. He took a part-time position at Columbia University, returning to his childhood neighborhood.
“Growing up in New York City, I couldn’t see the stars,” he once told The Times. He found them anyway, and a whole lot more that we can’t see with or without the glare of streetlights.
It was a passion that never waned. Encountered recently by a reporter on the sidewalk in front of Columbia, Dr. Ostriker launched into an enthusiastic description of a promising new theory of dark matter.
Early in 2023, by then ailing, he took to his bed at home. But he kept up with his research by email and had regular pizza lunches with colleagues.
Apprised recently of results from the James Webb Space Telescope that seemed to reinforce his ideas about dark matter, he wrote in an email to his colleagues, “Keep up the good work.”
The dark universe he helped conjure half a century ago has developed a few small cracks, leading to new ideas about the nature of that dark matter.
“It’s a very, very, very specific and clear theory. So therefore, God bless it, it can be wrong,” Dr. Ostriker said in a recent interview. “That’s the way science proceeds. And what we know about it is that it is a little bit wrong, not a lot wrong.”
Dr. Rees, a cosmologist at the University of Cambridge and the Astronomer Royal, summed up Dr. Ostriker’s life this way: “Some scientists come up with pioneering ideas on novel themes; others write definitive ‘last words’ on already-established topics. Jerry was in the first category.”
“He wrote among the earliest papers — now classics — on the nature of pulsars, the evidence for dark matter and on galaxy formation and cosmology. His flow of papers continued into his 80s,” Dr. Rees added. “He enthusiastically engaged in new data and in computational techniques. He inspired younger colleagues and collaborators, not just at Princeton but around the world.”
The contract for management and operation of NASA’s Jet Propulsion Laboratory will be opened up to a competitive bidding process for the first time in its history, the space agency announced on Friday.
The action forces Caltech to compete for control of the La Cañada Flintridge institution it has managed since NASA’s inception in 1958.
“The rapid growth of the U.S. space economy indicates there may now be a viable competitive market for programmatic and institutional elements,” NASA said in a statement. “This decision is part of a broader governmentwide and agency effort to find efficiencies, strengthen performance, and drive mission outcomes faster and more affordably.”
In a joint statement, Caltech President Thomas F. Rosenbaum and JPL Director Dave Gallagher said that the announcement came as “no surprise” and that it already had a team in place “to ensure we are positioned for success” in the bidding process.
“Over the course of our nearly seven-decade-long partnership with NASA, Caltech and JPL have led humanity’s exploration and understanding of the universe — and our place within it,” the Pasadena university said. “The ambitions ahead — no less bold than those we have already realized— are ones we are fully prepared to meet.”
The competition for the contract is part of a slate of changes NASA Administrator Jared Isaacman announced on Friday, including a massive reorganization of the space agency intended “to concentrate resources towards the highest priority objectives in the National Space Policy and liberate the best and brightest from needless bureaucracy and obstacles that impede progress,” Isaacman wrote in a letter to the agency’s roughly 18,000 employees.
JPL was founded by Caltech researchers in 1936, and became part of NASA when the space agency was formed in 1958. Its current 10-year contract with NASA, which is valued at up to $30 billion, runs through Sept. 30, 2028.
Times staff writer Noah Haggerty contributed to this report.
Despite finding nearly one in five homes had excessive levels of lead, the U.S. Environmental Protection Agency this week claimed that recent soil testing in Altadena proved that expedited federal cleanup efforts had effectively removed toxic ash and debris from homes destroyed by the deadly Eaton fire.
Earlier this year, the EPA announced it would perform a limited soil sampling at 100 destroyed homes across the burn zone in order to verify that contractors had thoroughly mitigated toxic substances. In a recent news release, the EPA said that testing revealed median lead concentrations below federal standards, and “confirmed that cleanup methods successfully addressed contamination and verified cleanup protocols.”
The EPA soil sampling comes amid mounting pressure from residents and environmentalists who claim that a hasty federal cleanup effort had left behind or spread hazardous fire debris. Internal government reports also raised questions about the thoroughness of the cleanup.
The EPA did not release its report to the public, but it said 95 of 100 soil samples collected near the surface of the home’s building footprint were below the federal lead screening level.
“I think for the folks in Altadena who maybe had some concerns about the adequacy of the work that was performed by the federal government in removing ash and debris — I think they should feel confident that those areas of their property are safe to use now,” said Mike Montgomery, EPA Superfund and emergency management director.
In announcing its findings, the EPA cited federal lead standards only, and not California’s more stringent thresholds. Of the 100 homes sampled, 17 had lead levels above 80 milligrams per kilogram, California’s benchmark for residential properties. The highest concentration of lead was 705 milligrams per kilogram — nearly nine times higher than the state standard and triple the federal threshold, according to a copy of the report that was reviewed by The Times.
The results unnerved some Altadena residents, who see more and more fire-destroyed homes being rebuilt. Joy Chen, executive director of Eaton Fire Survivors Network, called on federal officials to release the full report and provide additional resources to address elevated contamination.
“From the beginning, people have been very worried that they [federal workers] did not thoroughly clear these sites. Now 16 months later, people are taking it upon themselves to test or bioremediate to ensure it’s safe to rebuild. Most of us don’t have the resources to make those decisions,” Chen said.
“It would’ve been much easier if homes had been cleared to safe levels the first time around.”
EPA officials said the agency had notified Altadena property owners of their soil test results and encouraged them to review local public health guidance. Montgomery said EPA officials would proactively reach out to property owners whose lots had lead levels above the federal benchmark of 200 milligrams per kilogram.
Federal disaster officials say that some toxic substances within the burn zone could have been deposited there long before the fire — the result perhaps of decades of burning leaded gasoline or lead paint.
The Federal Emergency Management Agency had refused repeatedly to pay for post-cleanup soil testing and broke from long-standing California fire recovery protocols that are intended to protect returning residents from toxic substances. FEMA, along with the U.S. Army Corps of Engineers and the EPA, had touted the fire recovery as the fastest in modern history.
Disaster crews removed millions of tons of fire debris from nearly 9,700 properties affected by the Eaton and Palisades fires in roughly eight months.
But hundreds of disaster victims had complained about substandard work from federal cleanup workers, and internal government reports said crews had left debris behind and, in at least one instance, dumped ash on a neighbor’s property.
In January — shortly after the one-year anniversary of the fires — the EPA announced that it would perform soil testing for lead at 100 randomly-selected homes that were destroyed in the Eaton fire and later cleared of debris by federal contractors. The announcement followed months of criticism that federal cleanup workers had mishandled debris — including dumping fire debris and contaminated pool water on neighboring properties.
The Los Angeles Times collected soil samples in March 2025 and published the first evidence that already-remediated home sites retained elevated levels of toxic substances. Los Angeles County, UCLA, USC and several other organizations launched their own soil testing efforts, and all found elevated levels of lead at homes that had already been remediated by federal cleanup crews.
Lead is a potent neurotoxin that can stunt the brain development and lead to behavioral issues in young children that inhale or ingest it. When the Eaton fire burned through Altadena’s historic neighborhoods, it destroyed many homes that were coated in toxic lead paint. Plumes of smoke and ash then deposited the heavy metal across the burn zone.
Dr. Nichole Quick, chief medical advisor for the Los Angeles County Department of Public Health, encouraged property owners to seek further testing if they have concerns about contamination, including free testing services provided by local universities.
Quick said residents can take steps to limit their exposure, such as washing dusty equipment and keeping cleaning floors and other surfaces clean.
“Guidance is really geared towards how you interrupt that ingestion exposure, so we’re talking about a high-risk group, our kids with developing brains, pregnant women,” Quick said. “Kids also happen to be the ones that crawl around on all sorts of stuff and hands directly into mouth, so a lot of what we’re talking about is stopping that sort of exposure.”
Environmental experts quickly questioned the EPA’s soil sampling approach, which drastically differed from soil testing procedures from California environmental agencies. Andrew Whelton, a Purdue University researcher who has studied environmental risk following disaster, said the EPA sampling — which only tested one mixed sample — would likely mask heavily polluted areas of the home. The agency also only tested for lead — one of 17 toxic metals typically tested for following wildfires.
“It’s apples and oranges,” Whelton said. “They [the EPA] only looked for lead and didn’t look for hot spots. The approach that EPA differs from everything that California has done for fire cleanup for the last 15 years.
“My advice to property owners who haven’t tested soil or are adjacent to the fire area is conduct soil testing as it has always been done.”
The EPA and L.A. County health department are expected to discuss the soil testing results at the Altadena town council meeting on June 16.
One of NASA’s most valuable assets is a Southern Californian.
Following the space agency’s successful Artemis II mission around the moon last month, Victor Glover — who grew up primarily in the Inland Empire and has spent much of his career at Southern California’s many military and aerospace hubs — is now the only pilot to have flown NASA’s Orion capsule.
As the crew finishes its international victory lap before the media, Glover is preparing to put his head down and get to work training the Artemis generation of moon-faring astronauts.
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“I think Artemis is going to demand us to change the paradigm,” he told The Times.
The International Space Station, which has been continuously inhabited by a revolving crew of astronauts in low Earth orbit for over 25 years, has a “very well-worn” training program, he said. But developing a new instructional regimen for complex high-stakes moon missions as the agency tries to aggressively ramp up Artemis launches from once every 3 1/2 years to every six months is a different beast.
“Until we get really ramped up and have a solid training program, I think astronauts need to take more ownership of the training and be involved so we can share this experience,” Glover said.
As of today, the list of Artemis astronauts is only four people long. And the list of Artemis pilots has only one name: Victor Glover.
Glover, 50, was born in Pomona, graduated from Ontario High School and lived “all over” Southern California’s urban sprawl, including Baldwin Village (which he instinctively referred to by its pre-1988 name, “The Jungle”). He completed his undergraduate studies at Cal Poly San Luis Obispo and received graduate degrees (plural) from the Naval Postgraduate School in Monterey and the Air Force Test Pilot School at Edwards Air Force Base.
He cut his teeth as a test pilot at Naval Air Weapons Station China Lake, in the Mojave. After NASA selected him as an astronaut, he learned to fly SpaceX’s Dragon capsule at the company’s then-headquarters in Hawthorne before riding it to the ISS.
Glover particularly misses those test pilot days, when he was pushing the limits of the F/A-18 Hornet and Super Hornet in China Lake while completing a master’s degree on the side.
“That was actually maybe one of the best times of my career. We had our fourth daughter while we lived in China Lake,” he said. “I was … working really hard but having a ton of fun at a house full of kids.”
In one of Glover’s favorite pictures, snapped by his wife, he is sitting at his desk in his tan desert flight suit, focused on graduate school work while holding one of his daughters.
Glover sees himself as just one example of how the Golden State’s deserts and coastal cities have left a lasting mark on America’s space program.
“Southern California is very uniquely postured to help NASA,” Glover said. “Southern California has the combination of culture and technology — and it doesn’t hurt to have Hollywood” to help share NASA’s mission and values.
(Glover fondly recalled his joy seeing the “Iron Man” production crew, including actor and rapper Terrence Howard, roll through Edwards Air Force Base during his tenure.)
Glover, who now lives in Texas near NASA’s Johnson Space Center, is focused on bringing that SoCal sensibility and invaluable experience piloting the Orion capsule to the agency’s astronaut training program.
When asked if he hopes to fly again on an Artemis mission, he gave a simple answer: “No.”
There was one other thing on his to-do list, though.
“Tell L.A. I love them and all of Southern California — and I can’t wait to get back out there and visit my home state and my hometown.”
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