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.”
Science
Can fire-resistant homes be sexy? ‘You be the judge,’ says this Palisades architect
At first glance, it looks like nothing more than a charming Spanish-revival, quintessentially Californian home — but this Pacific Palisades rebuild is constructed like a tank.
Every exterior wall of the steel-framed home is a foot-thick, fire-resistant barricade. The home is connected to a satellite fire monitoring service. Should a fire start in town, sturdy metal shutters descend to cover every window. An exterior sprinkler system can pump 40,000 gallons of water from giant tanks hidden behind the shrubs in the property’s yard. If the cameras and heat sensors around the house detect danger, the system can envelop the home in over 1,000 gallons of fire retardant and hundreds of gallons of fire-suppressing foam.
Palisades resident and architect Ardie Tavangarian is so confident in his design that he even asked the fire department if they could start a controlled fire on the property to test it all out. (They said no.)
Tavangarian built a career designing multimillion-dollar luxury homes in Los Angeles, but after the Palisades fire destroyed 13 of his works — including his family’s home — he found another calling: how to design a house that can handle what the Santa Monica Mountains throw at it. And how to do it quickly and affordably.
Water tanks form part of a backup water supply in a newly built fire-resistant home in Pacific Palisades.
“Nature is so powerful,” he said, sitting on a couch in the new house, which he built for his adult twin daughters. “We are guests living in that environment and expecting, ‘Oh, nature is going to be really kind to me.’ No, it’s not. It does what it’s supposed to do.”
Tavangarian watched the Jan. 1 Lachman fire from his property not far from here; a week later that fire rekindled, grew into the Palisades fire, and burned through his house. But the painful details of the fire — the missteps of the fire department, the empty reservoir — didn’t matter when it came to deciding how to rebuild, he said. The reality is, many fires have burned in these mountains. Many more will.
A sprinkler on the roof is part of a house-wide sprinkler system.
For the architect, who has spent much of his 45-year career designing for luxury, hardening a home against wildfire has brought a new kind of luxury to his homes: peace of mind.
It’s a sentiment that resonates with fire survivors: Tavangarian says he’s received considerable interest from other property owners in the Palisades looking to rebuild their houses.
The metal shutters and advanced outdoor sprinkler system are the flashiest parts of Tavangarian’s home hardening project, and the efficacy of these adaptations is still up for debate. Because the measures have not yet been widely adopted, there are few studies exploring how much or little they protect homes in real-world fires.
Architect Ardie Tavangarian inside the house he designed.
Anecdotal evidence has indicated the effectiveness of sprinklers can vary significantly based on the setup and the conditions during the fire. Extreme wind, for example, can make them less effective. Lab studies have generally found shutters can reduce the risk of windows shattering.
These measures aren’t cheap, either. Sprinkler systems can cost north of $100,000, for example. However, Tavangarian said when all was said and done, the home he built for his daughters cost around $700 per square foot — less than what Palisades residents said they expected to pay, but more than what Altadena residents expected for their rebuilds.
Tavangarian also hopes to see insurers increasingly consider the home-hardening measures property owners take when writing policies, which he said could potentially offset the extra cost in a decade or less. As he explored getting insurance for the new home, one insurer quoted him $80,000 a year. After he convinced the company to visit the property, it lowered the quote to just $13,000, he said.
The house includes metal heat shields that can drop down if a fire approaches.
The home also has essentially all of the other less flashy — but much cheaper and well-proven — home hardening measures recommended by fire professionals: The underside of the roof’s overhang is closed off — a common place embers enter a home. The roof, where burning embers can accumulate, is made of fire-resistant material. The windows, vulnerable to shattering in extreme heat, are made of a toughened glass. There is virtually no vegetation within the first five feet of the home.
When asked if he felt he had compromised on design, comfort or aesthetics for the extra protection — one of the many concerns Californians have with the state’s draft “Zone Zero” requirements that may significantly limit vegetation within five feet of a home — Tavangarian simply said, “You be the judge.”
Science
Commentary: My toothache led to a painful discovery: The dental care system is full of cavities as you age
I had a nagging toothache recently, and it led to an even more painful revelation.
If you X-rayed the state of oral health care in the United States, particularly for people 65 and older, the picture would be full of cavities.
“It’s probably worse than you can even imagine,” said Elizabeth Mertz, a UC San Francisco professor and Healthforce Center researcher who studies barriers to dental care for seniors.
Mertz once referred to the snaggletoothed, gap-filled oral health care system — which isn’t really a system at all — as “a mess.”
But let me get back to my toothache, while I reach for some painkiller. It had been bothering me for a couple of weeks, so I went to see my dentist, hoping for the best and preparing for the worst, having had two extractions in less than two years.
Let’s make it a trifecta.
My dentist said a molar needed to be yanked because of a cellular breakdown called resorption, and a periodontist in his office recommended a bone graft and probably an implant. The whole process would take several months and cost roughly the price of a swell vacation.
I’m lucky to have a great dentist and dental coverage through my employer, but as anyone with a private plan knows, dental insurance can barely be called insurance. It’s fine for cleanings and basic preventive routines. But for more complicated and expensive procedures — which multiply as you age — you can be on the hook for half the cost, if you’re covered at all, with annual payout caps in the $1,500 range.
“The No. 1 reason for delayed dental care,” said Mertz, “is out-of-pocket costs.”
So I wondered if cost-wise, it would be better to dump my medical and dental coverage and switch to a Medicare plan that costs extra — Medicare Advantage — but includes dental care options. Almost in unison, my two dentists advised against that because Medicare supplemental plans can be so limited.
Sorting it all out can be confusing and time-consuming, and nobody warns you in advance that aging itself is a job, the benefits are lousy, and the specialty care you’ll need most — dental, vision, hearing and long-term care — are not covered in the basic package. It’s as if Medicare was designed by pranksters, and we’re paying the price now as the percentage of the 65-and-up population explodes.
So what are people supposed to do as they get older and their teeth get looser?
A retired friend told me that she and her husband don’t have dental insurance because it costs too much and covers too little, and it turns out they’re not alone. By some estimates, half of U.S. residents 65 and older have no dental insurance.
That’s actually not a bad option, said Mertz, given the cost of insurance premiums and co-pays, along with the caps. And even if you’ve got insurance, a lot of dentists don’t accept it because the reimbursements have stagnated as their costs have spiked.
But without insurance, a lot of people simply don’t go to the dentist until they have to, and that can be dangerous.
“Dental problems are very clearly associated with diabetes,” as well as heart problems and other health issues, said Paul Glassman, associate dean of the California Northstate University dentistry school.
There is one other option, and Mertz referred to it as dental tourism, saying that Mexico and Costa Rica are popular destinations for U.S. residents.
“You can get a week’s vacation and dental work and still come out ahead of what you’d be paying in the U.S.,” she said.
Tijuana dentist Dr. Oscar Ceballos told me that roughly 80% of his patients are from north of the border, and come from as far away as Florida, Wisconsin and Alaska. He has patients in their 80s and 90s who have been returning for years because in the U.S. their insurance was expensive, the coverage was limited and out-of-pocket expenses were unaffordable.
“For example, a dental implant in California is around $3,000-$5,000,” Ceballos said. At his office, depending on the specifics, the same service “is like $1,500 to $2,500.” The cost is lower because personnel, office rent and other overhead costs are cheaper than in the U.S., Ceballos said.
As we spoke by phone, Ceballos peeked into his waiting room and said three patients were from the U.S. He handed his cellphone to one of them, San Diegan John Lane, who said he’s been going south of the border for nine years.
“The primary reason is the quality of the care,” said Lane, who told me he refers to himself as 39, “with almost 40 years of additional” time on the clock.
Ceballos is “conscientious and he has facilities that are as clean and sterile and as medically up to date as anything you’d find in the U.S.,” said Lane, who had driven his wife down from San Diego for a new crown.
“The cost is 50% less than what it would be in the U.S.,” said Lane, and sometimes the savings is even greater than that.
Come this summer, Lane may be seeing even more Californians in Ceballos’ waiting room.
“Proposed funding cuts to the Medi-Cal Dental program would have devastating impacts on our state’s most vulnerable residents,” said dentist Robert Hanlon, president of the California Dental Assn.
Dental student Somkene Okwuego smiles after completing her work on patient Jimmy Stewart, 83, who receives affordable dental work at the Ostrow School of Dentistry of USC on the USC campus in Los Angeles on February 26, 2026.
(Genaro Molina / Los Angeles Times)
Under Proposition 56’s tobacco tax in 2016, supplemental reimbursements to dentists have been in place, but those increases could be wiped out under a budget-cutting proposal. Only about 40% of the state’s dentists accept Medi-Cal payments as it is, and Hanlon told me a CDA survey indicates that half would stop accepting Medi-Cal patients and many others will accept fewer patients.
“It’s appalling that when the cost of providing healthcare is at an all-time high, the state is considering cutting program funding back to 1990s levels,” Hanlon said. “These cuts … will force patients to forgo or delay basic dental care, driving completely preventable emergencies into already overcrowded emergency departments.”
Somkene Okwuego, who as a child in South L.A. was occasionally a patient at USC’s Herman Ostrow School of Dentistry clinic, will graduate from the school in just a few months.
I first wrote about Okwuego three years ago, after she got an undergrad degree in gerontology, and she told me a few days ago that many of her dental patients are elderly and have Medi-Cal or no insurance at all. She has also worked at a Skid Row dental clinic, and plans after graduation to work at a clinic where dental care is free or discounted.
Okwuego said “fixing the smiles” of her patients is a privilege and boosts their self-image, which can help “when they’re trying to get jobs.” When I dropped by to see her Thursday, she was with 83-year-old patient Jimmy Stewart.
Stewart, an Army veteran, told me he had trouble getting dental care at the VA and had gone years without seeing a dentist before a friend recommended the Ostrow clinic. He said he’s had extractions and top-quality restorative care at USC, with the work covered by his Medi-Cal insurance.
I told Stewart there could be some Medi-Cal cuts in the works this summer.
“I’d be screwed,” he said.
Him and a lot of other people.
steve.lopez@latimes.com
Science
Diablo Canyon clears last California permit hurdle to keep running
Central Coast Water authorities approved waste discharge permits for Diablo Canyon nuclear plant Thursday, making it nearly certain it will remain running through 2030, and potentially through 2045.
The Pacific Gas & Electric-owned plant was originally supposed to shut down in 2025, but lawmakers extended that deadline by five years in 2022, fearing power shortages if a plant that provides about 9 percent the state’s electricity were to shut off.
In December, Diablo Canyon received a key permit from the California Coastal Commission through an agreement that involved PG&E giving up about 12,000 acres of nearby land for conservation in exchange for the loss of marine life caused by the plant’s operations.
Today’s 6-0 vote by the Central Coast Regional Water Board approved PG&E’s plans to limit discharges of pollutants into the water and continue to run its “once-through cooling system.” The cooling technology flushes ocean water through the plant to absorb heat and discharges it, killing what the Coastal Commission estimated to be two billion fish each year.
The board also granted the plant a certification under the Clean Water Act, the last state regulatory hurdle the facility needed to clear before the federal Nuclear Regulatory Commission (NRC) is allowed to renew its permit through 2045.
The new regional water board permit made several changes since the last one was issued in 1990. One was a first-time limit on the chemical tributyltin-10, a toxic, internationally-banned compound added to paint to prevent organisms from growing on ship hulls.
Additional changes stemmed from a 2025 Supreme Court ruling that said if pollutant permits like this one impose specific water quality requirements, they must also specify how to meet them.
The plant’s biggest water quality impact is the heated water it discharges into the ocean, and that part of the permit remains unchanged. Radioactive waste from the plant is regulated not by the state but by the NRC.
California state law only allows the plant to remain open to 2030, but some lawmakers and regulators have already expressed interest in another extension given growing electricity demand and the plant’s role in providing carbon-free power to the grid.
Some board members raised concerns about granting a certification that would allow the NRC to reauthorize the plant’s permits through 2045.
“There’s every reason to think the California entities responsible for making the decision about continuing operation, namely the California [Independent System Operator] and the Energy Commission, all of them are sort of leaning toward continuing to operate this facility,” said boardmember Dominic Roques. “I’d like us to be consistent with state law at least, and imply that we are consistent with ending operation at five years.”
Other board members noted that regulators could revisit the permits in five years or sooner if state and federal laws changes, and the board ultimately approved the permit.
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