A mind-bending hypothesis is gaining traction among scientists: The universe may be teeming with microscopic black holes the size of an atom, but with the mass of a city-sized asteroid.

Created just a split second after the Big Bang, these hypothetical black holes would whip quietly through the solar system roughly once every few years, traveling over a hundred times faster than a bullet.

Some have even argued that an immense explosion that flattened a Siberian forest in 1908 could have been the result of one of these micro black holes impacting Earth.

Now, researchers say they’ve figured out a way to test whether these cosmic bullets truly exist.

In a study published Tuesday in the journal Physical Review D, physicists at MIT say the presence of a tiny black hole speeding through the solar system could be identified by the gentle gravitational nudge it exerted on the Earth and other planets, which would alter their orbital paths by no more than a few feet.

The possibility of proving the existence of micro black holes is generating excitement among some astrophysicists because it could help them to explain a mystery that has taunted them for almost a century: the nature and composition of dark matter.

In the 1930s, astronomers started noticing anomalies in the way galaxies were moving. Lurking in the dark and empty expanse of intergalactic space, something was generating tremendous amounts of gravity to tug on the galaxies — yet it seemingly refused to interact with light or any other force.

Scientists found this mysterious gravitational tugging everywhere. In order to account for it, they hypothesized that it was being caused by invisible mass, or dark matter, that made up roughly 85% of all matter in the universe.

Some physicists have suggested dark matter may be made up of exotic undiscovered particles. Others, such as the MIT researchers, think dark matter probably is just regular matter that is extremely hard to detect. And black holes, the researchers say, are a prime example of the properties of dark matter.

“It’s just fantastic that the most conceptually conservative response is to say, ‘It’s just super tiny black holes that were made a split second after the Big Bang,’” said David Kaiser, a physics professor at MIT and an author on the study.

“It’s not inventing new forms of matter that have not yet been detected. It’s not changing the laws of gravity,” he said.

Still, black holes are not the sole potential culprit and there remains a lot of debate in the field.

Physicists have, in their quest to find dark matter, searched for new exotic particles, as well as regular matter that may have been overlooked — such as black holes of varying sizes. So far, they have come up empty-handed.

Until now, astronomers have been unsure how to search for black holes of a particularly pesky size — those that are too small for their gravity to bend star light.

The MIT researchers determined, through modeling, that these tiny black holes may have formed from pockets of dense matter that collapsed on themselves immediately following the Big Bang.

The researchers simulated what might happen if one of these primordial black holes made a flyby within the orbit of Jupiter. They found that the orbits of Earth, Mars, Venus and Mercury could veer off their original course by up to 3 feet over a decade.

The researchers said they would expect to detect a black hole nudge somewhere between once a year to once every century — depending on the abundance and masses of the black holes.

To put their own minds at ease, the researchers also calculated the likelihood that one of these tiny black holes would strike Earth and found it would only happen roughly once in a billion years.

Even then, the black hole wouldn’t lead to an apocalypse.

Instead, it would pass straight through the Earth, leaving the planet relatively unbothered.

Scientists in the 1970s even showed that a black hole impact would look strikingly similar to an streaking light and explosion over Russia 116 years ago that scientists believe was caused by a small asteroid or comet. (Although, a black hole would also leave an “exit wound.”)

Detecting the existence of mini black holes will require extremely precise measurements of where planets are and models of where they’re supposed to be. Fortunately, scientists have the tools to accomplish this.

NASA’s Jet Propulsion Laboratory in La Cañada Flintridge, for example, has created a detailed model of the solar system that uses Albert Einstein’s general relativity theory of gravity to calculate the expected orbits of the planets and account for hundreds of asteroids in excruciating detail. (They even calculated how the Earth’s ocean tides affect the moon’s orbit.)

NASA scientists also have developed an extremely precise means of determining the distance between the Earth and Mars. By measuring the time it takes radio signals to travel from Earth to spacecraft orbiting Mars, or to rovers on its surface, scientists can calculate the red planet’s distance from Earth within two feet.

“It’s really only a few decades where we’ve had that level of accuracy,” Kaiser said. “From a series of space program missions, we can worry about if Mars is 50 centimeters off from where we expect it to be.”

To convince the skeptics, the scientists also would have to show that the nudge wasn’t caused by a passing asteroid.

The researchers say that the speed of the black holes — which would be traveling more than two times faster than anything else in our solar system — would create an unmistakably unique wobble in the planets’ orbits.

And astronomers are pretty good at spotting objects with a mass similar to that of the hypothetical black holes. In 2017, researchers identified the first object from another star to enter our solar system, which had far less mass than a microscopic black hole would.

Whether or not they detect a passing black hole, the scientists say it will push forward humanity’s understanding of dark matter.

“Of course I’d love to discover dark matter in the solar system,” said Benjamin Lehmann, a postdoctoral student at MIT and an author of the study. However, “if this kind of observation is what helps us to close this window and say dark matter is not in the form of these primordial black holes, that’s really important information.”

By proposing a method for simply testing this possibility, “they’ve done … exactly what we should be doing in dark matter searches,” said Vera Gluscevic, a cosmology professor at USC who was not involved with the study. “We should not leave any stone unturned.”

Although the scientists plan to keep refining planetary motion models and dig through historical observations from the last few decades for signs of the black holes, the main test will be to simply watch and wait.

Eight years after an independent state watchdog agency harshly criticized the state for failing to provide dental care to low-income children, California has failed to remedy the problem or fully implement the commission’s recommendations, according to a follow-up review published last week.

The Little Hoover Commission found that less than half of the children in Medi-Cal received an annual dental visit in 2022 — 3% higher than when the initial report was released in 2016, which implored the state to do more to ensure that children have access to needed care.

“California is still doing a miserable job,” said Pedro Nava, chair of the commission and a former member of the state Assembly. “We have failed generations of children. We and they deserve better.”

The 2016 report was one of the most scathing reports that the commission had generated in years, Nava said. It found that only 44.5% of children in the Medi-Cal program had a visit with a dentist in 2016, a key indicator of whether children are receiving the care they need to prevent painful dental decay, and recommended that the state increase the rate to 66%. Lawmakers responded with a law requiring the health department to set a target of at least 60% of children.

Last fall, after the publication of an L.A. Times story on high rates of dental disease among California children, the commission initiated a follow-up review of the state’s progress.

It found that the state had fallen far short of the goal; in 2022, the most recent data provided in the report, 47.6% of children with Medi-Cal visited a dentist, a 3-percentage-point increase from 2016.

“If you were an investor in a private company, and that was the best they could do, you’d sell your stock and invest it somewhere else,” Nava said. “It is a disappointment that low-income families with children have to shoulder the burden of this every day.”

California has made some improvements since 2016, the report said, fully implementing one recommendation and partially implementing seven of the commission’s eight others.

The state health department, however, disputes those findings and said they have fully implemented all of the recommendations from the 2016 report. The percentage of kids going to the dentist had been increasing significantly, they said — up to 49.6% in 2019 — but the pandemic interrupted that growth.

“California, along with every other state in the nation, was profoundly impacted by the effects of the COVID-19 pandemic. Virtually every state within the U.S. decreased and had a recovery period that lasted at least two years to return to pre-COVID figures,” the Department of Health Care Services wrote in a statement provided to The Times.

Since 2016, the department has made a number of important changes, the department wrote, including expanding the use of tele-dentistry to reach members across the state, increasing provider networks and creating a public education and outreach media campaign for Medi-Cal patients and providers.

In 2023 the percentage of children who visited the dentist “recovered to 2019 levels. Even higher utilization is projected in 2024,” the health department said, although data have not been been released on this upward trend.

“I don’t think this response really questions the fact that they have not come close to reaching the recommendation set by the Legislature of 60% of kids getting in to see the dentist, let alone our rate of 66%,” said Ethan Rarick, executive director of the Little Hoover Commission. “Kids’ dental health is among the worst in the country, and much more needs to be done.”

California children have among the worst rates of dental disease in the nation. A national survey from 2020 to 2021 found that 14.8% of the state’s children ages 1 to 17 had decayed teeth or cavities in the last 12 months studied — ranking 47th out of 51 among all the states and the District of Columbia, with only Louisiana and Wyoming faring worse. “I don’t understand,” Nava said. “If you’re the fifth-largest economy in the world, you ought to be a leader in children’s health.”

Nationwide, more than half of children develop cavities by the age of 8, usually because of poor nutrition, bad hygiene habits or a lack of dental care.

The reality of dental disease can be devastating to children, causing pain and difficulty eating, sleeping and focusing in school, and low-income children of color are at greatest risk. L.A. County’s Smile Survey, which was conducted by the public health department, found that on any given day, more than 4,500 Los Angeles County kindergarten and third-grade children need urgent dental care, which means they may be experiencing mouth pain or a serious infection.

The state increased the payment rate for evaluating a child’s teeth, for example, from $15 to $45, and up to $100 if a dentist sees the same child two years in a row, according to the California Dental Assn. The reimbursement for a filling increased from $48 to $67.20. These rate increases were funded by Proposition 56, a 2016 tobacco tax that raised money for Medi-Cal payments, and by CalAIM, a state initiative to transform Medi-Cal. The Proposition 56 money was also used to fund county oral health plans and repay student loans for new dentists.

The state has made it easier for dentists to enroll as Medi-Cal providers by simplifying the enrollment forms and putting them online, the report said. It also began a pilot program for telehealth to help bring care to healthcare deserts through the Dental Transformation Initiative.

Between the Medi-Cal payment rate and fewer administrative burdens, dentists appear to have taken note: 40% of all California dentists in the state now take Medi-Cal, a 34% increase since 2017, according to the dental association.

“The program had such a huge hole to dig out of, and COVID really derailed everything,” said Brianna Pittman-Spencer, senior director of government affairs at the California Dental Assn. “There have been improvements but obviously still a long way to go for the impact we want.”

Eileen Espejo, who leads the oral health project at Children Now, said she was pleased to see that the state had at least started to implement most of the recommendations, but that the numbers suggest the approach may not be working. “If we’re going to do better, it doesn’t seem like we should do more than the same,” she said.

In particular, she worries about children in far northern counties and those bordering Nevada, where dentists are hard to find. Twenty-one counties have five or fewer dental providers that take Medi-Cal, the report found. “How are we going to get providers to live in parts of the state where they aren’t yet?” she asked, adding that using more telehealth dentistry and allowing dental hygienists to provide more care could be part of the solution.

“Hopefully this report will light a fire and get more people engaged,” Espejo said. “I certainly think it opens the pathway for advocates to ask for more resources to help improve the program.”

This article is part of The Times’ early childhood education initiative, focusing on the learning and development of California children from birth to age 5. For more information about the initiative and its philanthropic funders, go to latimes.com/earlyed.

An industrial chemical used in plastic products has been cropping up in illegal drugs from California to Maine, a sudden and puzzling shift in the drug supply that has alarmed health researchers.

Its name is bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, commonly abbreviated as BTMPS. The chemical is used in plastic for protection against ultraviolet rays, as well as for other commercial uses.

In an analysis released Monday, researchers from UCLA, the National Institute of Standards and Technology (NIST) and other academic institutions and harm reduction groups collected and tested more than 170 samples of drugs that had been sold as fentanyl in Los Angeles and Philadelphia this summer. They found roughly a quarter of the drugs contained BTMPS.

Researchers called it the most sudden change in the U.S. illegal drug supply in recent history, based on chemical prevalence. They found that BTMPS sometimes dramatically exceeded the amount of fentanyl in drug samples and, in some cases, had made up more than a third of the drug sample.

It was also a growing presence in fentanyl over the summer: In June, none of the L.A. fentanyl samples tested by the team contained BTMPS, the analysis found. By August, it was detected in 41% of them.

“This is effectively unprecedented,” said Morgan Godvin, one of the authors of the study and project director for Drug Checking Los Angeles, a UCLA project that works in partnership with the L.A. County Department of Public Health to analyze illicit drugs.

“We have no idea just how many people have been exposed,” Godvin said, but if the high prevalence among drug samples tested so far is any indication, “that translates to tens of thousands of fentanyl users being exposed to BTEMPS, sometimes at very high volume.”

The findings were publicly released as a preprint — research that has not been peer reviewed — on the website of Drug Checking Los Angeles and have been submitted to medRxiv, a website where scientists share preliminary findings.

BTMPS has been studied in rats for its potential to reduce withdrawal symptoms from morphine and affect nicotine use, but it can be toxic and even deadly to rodents at sufficient doses, and health researchers say there is an urgent need for more studies on its effects on the human body.

The PubChem database lists a number of possible hazards associated with BTMPS, including skin irritation and eye damage. Godvin was alarmed by animal studies indicating dangers from inhaling BTMPS — such as tremors and shortness of breath — because smoking is now common in L.A. among people who use fentanyl.

People who use drugs have said that BTMPS can smell like bug spray or plastic and have reported blurred vision, nausea and coughing after ingesting it. One told researchers that “it smelled so bad I could barely smoke it.” The UCLA and NIST researchers warned that “with such a sudden and sustained prevalence in the drug supply, users are at risk of repeated, ongoing exposures, which may compound health effects.”

A 35-year-old man in Los Angeles said that in recent months, he had noticed a rubbery or synthetic taste in the fentanyl he used. “I was asking my friend that I buy from, ‘What the hell is this?’” said the man, who requested anonymity to speak about his drug use.

When he took samples that were supposed to be fentanyl to Drug Checking Los Angeles to analyze, he learned that some contained the strange chemical. The 35-year-old said he now tries to avoid BTMPS, but “a lot of people are just trying to get anything to keep from being sick” from opioid withdrawal.

Whatever clandestine labs are doing, he said, “we’re the guinea pigs.”

L.A. and Philadelphia are far from the only places where the chemical has popped up: The team also detected BTMPS in trace amounts of drugs left behind on drug paraphernalia from other locations, including Delaware, Maryland and Nevada.

As of last week, a University of North Carolina program that tests drug samples from across the country had also found BTMPS in more than 200 samples from a dozen states stretching from the West Coast to Maine. UNC senior scientist Nabarun Dasgupta said the chemical began showing up in drug samples that it tested this summer, most often mingled with fentanyl, both in powder form and in fake pills.

Alex Krotulski, a director at the nonprofit Center for Forensic Science Research and Education in Pennsylvania, said the amount of BTMPS found in drug samples it has tested varies dramatically — sometimes making up a small amount, sometimes amounting to the “primary component” in the sample.

Unlike other adulterants added to fentanyl for their psychoactive effects, “it’s not like it’s something that you go out and you use a bunch of to get high,” Krotulski said. The UCLA and NIST team found that people who use drugs rated samples high in BTMPS as “bunk” — low in quality — and broadly saw it as “highly undesirable.”

Yet another oddity is that BTMPS has not followed a familiar path for new drugs in the U.S. Instead of showing up in one area and spreading to others, “this one has hit all at once across the U.S. within a two-week period,” said Tara Stamos-Buesig, founder and chief executive of the Harm Reduction Coalition of San Diego.

Stamos-Buesig, whose group helps analyze the contents of illegal drugs in San Diego to inform and protect people, said that “I’ve told people for a while — we can’t hyper-focus on fentanyl” as if it were the only threat.

“There’s a lot of other stuff coming on board,” Stamos-Buesig said.

The UCLA and NIST analysis suggested one possible scenario: Illegal drug manufacturers might be adding BTMPS to fentanyl precursors or to the final product “at a high level in the supply chain,” possibly to stabilize them from degrading from light or heat exposure as illicit drugs are made, stored and transported, they wrote.

UCLA assistant professor Chelsea Shover added that the team had found BTMPS for sale on online platforms like Amazon and Alibaba with similar wording to what Chinese chemical companies had used in the past to market to fentanyl producers, with sellers touting their “experience getting through Mexican customs.”

“This is clearly implying that this is to be used to make illicit drugs,” Shover said. “It’s stuff you wouldn’t expect to see if it was just selling an industrial chemical in a standard way.”

As it stands, there is no test strip that can quickly detect BTMPS as there is for fentanyl. Nor is the chemical routinely tested for by doctors or medical examiners, which means that if someone has been harmed by BTMPS they took accidentally, “clinicians would have no way of knowing,” the UCLA and NIST team wrote.

The UNC Street Drug Analysis Lab likewise said that much remains unknown at this point, including whether BTMPS poses an overdose risk, although the lab cautions that “EVERY substance at some volume will be toxic.”

Dasgupta said the detection of BTMPS represents the first example of the burgeoning network of drug checking programs working together to find a substance “before any health authorities or any law enforcement did.” Godvin said that “just a few years ago, we wouldn’t have even known about this” and urged Angelenos to get drugs analyzed through Drug Checking Los Angeles if they are able.

In a drug supply already riddled with threats like fentanyl and the animal tranquilizer xylazine, “this gives us a whole other thing to worry about,” Godvin said.