Geophysicist John Vidale noticed something striking while tracking the way seismic waves move from Earth’s crust through its core.

The very center of the planet, a solid ball of iron and nickel floating in a sea of molten rock, appears to be slowing down in relation to the movement of Earth itself. The inner core has slowed so much that it has essentially kicked into reverse.

The finding by Vidale and his counterpart Wei Wang of the Chinese Academy of Sciences, published recently in the journal Nature, offers the most convincing evidence yet that the core seems to operate with a mind of its own.

“It might be cycling back and forth but it might also be on a random walk,” Vidale said. “It went one way for a while, then it’s going back the other way. Who knows what it’s going to do next?”

The fluctuations happening 3,000 miles beneath us won’t affect life on the planet’s surface in any noticeable way — at least not for now, Vidale said.

“There’s essentially no effect on people, from what we’ve seen,” said Vidale, who is Dean’s Professor of Earth Sciences at the USC Dornsife College of Letters, Arts and Sciences. “It’s a part of basically understanding the evolution of the planet. What we’d also like to know in more detail is what are the forces that are moving the inner core.”

Scientists first had a hunch that the inner core was moving in the 1990s, he said. It has taken years to back up that theory with hard evidence, mainly because of the difficulty of studying a mass located so far out of reach — and suspended inside a hellish sea of liquid iron that’s between 8,000 and 10,000 degrees.

Instead, Vidale, who was director of the Southern California Earthquake Center at USC from 2017 to 2018, peered into the planet by tracking seismic waves from quakes occurring off the lower tip of South America. As the waves passed through the heart of the planet, they were recorded on 400 seismometers positioned at the other end of the globe in Alaska and Northern Canada. The sensors were the same kind used to measure ground vibrations during nuclear tests.

He compared those refined readings to quake signals recorded in past years to see where they matched. That’s how he determined that the rotation has been decreasing since 2010. Prior to that, the core’s spin had been accelerating.

The findings add to the mystique of the most inscrutable part of our world, Vidale said. Literature and lore involving Earth’s core have filled the knowledge void with all sorts of fanciful ideas.

“I’m not such a philosopher but we’ve all had nightmares of what’s going on down in the planet,” Vidale said. “Just a couple hundred years ago, people thought the planet was hollow and that there were people living down there. It’s pretty exotic — exotic like Jupiter, but it’s just right under our feet.”

In Jules Verne’s 1864 science-fiction classic “Journey to the Center of the Earth,” a German professor, his nephew and their guide descend into the planet through a volcano in Iceland — along the way encountering caverns, a subterranean ocean, living dinosaurs, strange sea creatures and even a prehistoric giant herding mastodons — and are finally spat out through a volcano off the coast of Sicily.

The 2003 disaster film “The Core” imagines that the rotation of Earth’s center has stalled, damaging the magnetic field that envelops the planet — and triggering a violent lightning storm that destroys Rome and “invisible microwaves” that melt the Golden Gate Bridge. A hotshot crew of scientists burrows down through Earth’s layers to jump-start the core with a nuclear bomb.

In the real world, no human could survive the unimaginable heat and bone-crushing pressure, even if there were a vehicle capable of tunneling to the core, Vidale said.

It is true that the outer core generates electrical currents that sustain the planet’s magnetic field, but Vidale says shifts in the Texas-size inner core are too minuscule to have an impact.

While the planet’s subterranean reality is less fantastical than novels and Hollywood movies make it out to be, it is still fascinating to those like Vidale whose job is to counter conjecture with facts.

What is increasingly clear is that the inner core is susceptible in different ways to activity in the layers of Earth that encircle it.

“The mechanics are that the outer core is circulating and making a magnetic field, and so it’s kind of pulling the inner core back and forth,” Vidale said.

The latest discoveries about the inner core have fueled vigorous disagreements among the world’s top Earth scientists, USC’s John Vidale says. Some don’t believe the core turns at all.

(Christina House/Los Angeles Times)

Another player in the endless tug-of-war taking place inside the planet is the lower level of the planet’s mantle, whose mix of hard and less-dense matter results in its own peculiar magnetic pull, Vidale said.

“We sort of think the outer core is stirring up the inner core, but the mantle’s trying to keep it aligned — maybe that’s why it’s oscillating,” he said.

The latest discoveries about the inner core have fueled vigorous disagreements among the world’s top Earth scientists and given rise to competing theories of varying credibility, Vidale says. Some don’t believe the core turns at all. Some insist that forces on the surface, such as quakes, briefly alter the rotation.

Over the phone, Vidale reads a review from a scientist in Australia who greeted Vidale’s recent findings with much skepticism. The Australian proclaims that the analysis will lead to “the erosion of seismology as a credible branch of science and the destruction of seismologists as credible researchers.”

“I think he’s just frustrated — he knows he’s lost,” Vidale said, gently ribbing his peer.

“It’s exciting because the core is pretty big, it’s moving by measurable amounts and it’s a mystery,” Vidale said. “We’re making progress and seeing more things, arguing with people around the world and trying to get more data … What our paper’s done is it’s convinced most of the community.”

In a typical presidential election year, voters might wonder how the candidates’ views stack up on issues such as abortion, tax cuts, gun rights and immigration policy.

But this year, as a 78-year-old Republican Party nominee campaigned to replace an 81-year-old Democratic incumbent, a different question rose to the forefront of many voters’ minds: What’s in their medical files?

That issue eclipsed all others after President Biden’s blundering performance in last month’s debate against Donald Trump, triggering widespread concern about Biden’s physical and cognitive health. It became even more salient after Trump sustained a gunshot wound to his ear and Biden came down with COVID-19.

When Biden withdrew from the presidential race Sunday, House Speaker Mike Johnson (R-La.) kept the health question alive by calling on the commander in chief to resign.

“If Joe Biden is not fit to run for President, he is not fit to serve as President,” Johnson wrote on the social media platform X.

Biden’s doctors have denied speculation that the president is being treated for Parkinson’s disease or another neurological disorder. Meanwhile, Trump’s campaign has released limited information about the former president’s condition after he was grazed by a rifle round.

Is the public entitled to know more than either man has willingly disclosed?

“In the ideal world, it would be great if there were full transparency,” said Dr. Robert Klitzman, a psychiatrist and bioethicist at Columbia University. But no patient — not even a president — should be forced to share medical information they’d rather keep between themselves and their doctor, he and other experts said.

The reason is simple: A successful relationship between a doctor and patient relies on trust, and that includes trusting a doctor to not share information that might be considered embarrassing, unflattering or stigmatizing.

“To be able to help a patient as much as possible, we need the whole story,” Klitzman said. “We need to know if the patient is depressed, if the patient can’t pee, if the patient’s in pain, if the patient is forgetting things. We need that information to make an accurate diagnosis and figure out the best treatment to help.”

Without the assurance of confidentiality, a president might well decide he’s better off steering clear of doctors altogether, said George Annas, a professor of health law, bioethics and human rights at Boston University.

“You want him to have access to whatever treatment there is, and he ain’t going to get it if he’s not going to get tested,” Annas said. “That’s why we keep this stuff confidential, and why it makes perfect sense to do it even though everything in you screams, ‘I want to know what’s the matter with him.’”

The principle of doctor-patient confidentiality goes back to ancient Greece and is enshrined in the Hippocratic oath: “Whatever I see or hear in the lives of my patients, whether in connection with my professional practice or not, which ought not to be spoken of outside, I will keep secret, as considering all such things to be private.”

About 2,400 years later, the notion that a patient’s medical information should remain private was codified into federal law as part of the Health Insurance Portability and Accountability Act of 1996, better known as HIPAA.

There are limited circumstances where doctors have a duty to disclose a certain amount of information about their patients.

For example, if a patient presents a danger to himself or others, a doctor has a duty to warn law enforcement or potential victims of the threat, said Dr. Bandy X. Lee, a forensic psychiatrist and educator in Harvard Medical School’s program on psychiatry and the law.

If a patient has a reportable sexually transmitted infection such as syphilis or HIV, that diagnosis must be shared with a public health department, along with the names of the patient’s past partners so they can be informed and get tested, Klitzman said.

And if doctors notice a spike in cancer cases among people clustered in a geographic area, that too is passed along for public health officials to investigate.

Beyond cases such as these, the consensus fades, Annas said.

Congress could try to carve out an exception to HIPAA and require presidents and presidential candidates to release their medical records to the public. But in the unlikely event that the law were to change, it’s unclear whether it would survive a challenge in court, said Bert A. Rockman, a professor emeritus of political science at Purdue University who specializes in the American presidency.

“It raises a lot of questions to which we don’t know the answers,” he said.

Besides, forcing sitting and would-be presidents to waive their right to doctor-patient confidentiality wouldn’t guarantee that voters learn the truth, Rockman said. A president could simply shop around for a doctor willing to obfuscate in a medical report, for instance.

“There are always going to be ways to get a work-around,” he said.

Even if a president is forthcoming, knowing their diagnosis wouldn’t necessarily tell you much about their ability to function. A White House occupant could have a mild case of Parkinson’s but be able to carry out the job just fine with proper treatment, Klitzman said.

Voters should also keep in mind that there’s a difference between the president and the presidency, Rockman said.

“The presidency can work even if the president is diminished,” he said. “In all likelihood, unless the president is completely out to lunch for some reason or another, either physically or mentally, the office itself functions.”

Indeed, U.S. history is rife with examples of presidents concealing serious medical problems from the public.

John F. Kennedy was taking narcotic painkillers, amphetamines and steroids to treat his Addison’s disease and other ailments while trying to avert a nuclear crisis with the Soviet Union in the early 1960s.

Grover Cleveland said he was going on a four-day fishing trip when he boarded a yacht in 1893 to have a malignant tumor — along with part of his jaw and five teeth — surgically removed from the roof of his mouth.

Woodrow Wilson suffered a stroke in 1919 that left him partially paralyzed, bedridden and unable to feed himself for the remainder of his presidency. When pressed for details about Wilson’s condition, his doctor said “the President’s mind is not only clear but very active.”

It’s not OK to lie to preserve a patient’s privacy, Klitzman said, but that doesn’t necessarily mean a doctor must reveal “the truth, the whole truth, and nothing but the truth.”

“You can say, ‘The President’s not feeling well today,’ or you can say, ‘The President has COVID,’” he said. “You want people to trust the government, and if people feel the government is lying all the time and we can’t trust anything they say, that’s not good.”

The young whale was seen off Southern California, struggling, its tail flukes dangerously entangled in rope. The animal may have been injured for as long as half a year.

After a week of tracking and near-misses, a crew from the National Oceanic and Atmospheric Administration freed the juvenile humpback whale Friday.

On July 13, a whale-watching boat encountered the rope-snarled animal and reported it to NOAA. For the next week, crews from its large whale entanglement response network made near-daily excursions to find the injured whale, said Justin Viezbicke, the agency’s California marine mammal response stranding coordinator.

On July 15, the team spotted the whale off Dana Point, but the weather turned bad before they could attempt to free it. The next day they found the animal in the same area, but nearby jet skiers accidentally scared it away before rescuers could get close enough to help.

It was seen near Newport Beach on Wednesday and Thursday, then returned to Dana Point on Friday. The rescue attempt was on.

For several hours, the NOAA boat traveled alongside the animal as it surfaced for air and dove back into the sea. The mammal was about 30 feet long, with rope from fishing equipment wrapped tightly around both tail flukes.

“Being in the right place at the right time was very difficult,” Viezbicke said. “This whale was super skittish and wasn’t comfortable with us being around it.”

At last the crew got close enough to cut through the rope. For the next 60 to 90 minutes, the whale swam, dove and slapped its tail against the water in an effort to dislodge the remaining equipment, Viezbicke said. Once it had, it slipped back into the water and swam off. Whale-watching boats in Orange County have spotted it swimming in the days since.

Though the rope is gone, there is still concern for the animal’s future. NOAA estimated that the mammal had been entangled in the fishing line for at least three to six months, causing “some serious damage” to the flukes, Viezbicke said. It also appeared to have a significant amount of whale lice, which is often an indicator of poor health.

“We are hopeful that with the gear off it will make a full recovery,” he said.

Instances of humpback whale entanglements with fishing gear have climbed sharply in the last decade, thanks to a chain of events sparked by warming seas.

From 2014 to 2016, a Pacific Ocean heat wave forced anchovies and other humpback prey closer to shore and into the path of Dungeness crab fishing equipment. The same heat wave also delayed the crab fishing season to a time that coincided with the whales’ migration season.

Statewide, NOAA typically receives 15 to 20 reports per year of whales trapped in fishing lines or other human-made debris in the ocean, Viezbicke said. Yet such reports are likely only a small percentage of total cases.

“Unfortunately, most whale entanglements go undetected,” said Ashley Blacow-Draeger, Pacific policy and communications manager for Washington, D.C.-based nonprofit Oceana. Researchers who have tracked observation of entanglement scars on whales estimate that only 5% to 10% of such incidents are recorded.

Oceana has been working with fisheries to test ropeless fishing gear that vastly reduces the risk of wildlife entanglement, Blacow-Draeger said. California issued experimental permits for the pop-up, ropeless equipment in 2023, and permitted fishermen started selling crabs caught with the new gear that season.

Oceana is pressing for the state to authorize widespread commercial use of the whale-safe equipment by spring 2025, Blacow-Draeger said.