The average jump height of a person on different planets

 

The average jump height of a person on earth and its equivalent in other worlds of the solar system

Experts Say Vegetable Oil May Not Be As Healthful As We Thought

JOHN TURNER VIA GETTY IMAGES

Data from an unpublished trial reveals replacing saturated fats with corn oil doesn’t help reduce cardiovascular disease or death. 

Never-published data on vegetable oil and heart health reveals some disturbing trends.

Anna Almendrala

The American Heart Association, U.S. Dietary Guidelines and most doctors and nutritionists say that if you eat more “healthy fats” from vegetable and seed oils and less “bad fats” from red meat and dairy products, you’re on your way to better cardiovascular health. 

It turns out that may not be supported by the highest standards of scientific evidence. A new analysis of never-before-published trial data from the 1960s and ‘70s pokes holes at the notion that we can stave off heart attack and stroke by eating more polyunsaturated fat (the “healthy” kind). Instead, it suggests that some people who eat more of this fat from vegetable and and seed oils — specifically, those that are high in omega-6 fatty acids — actually have a higher risk of death than those who have a diet high in saturated fat. 

The study’s findings were never published in full, perhaps because they went against the emerging and increasingly popular hypothesis that saturated fat in foods like red meat and dairy causes cholesterol levels in blood to rise, increasing the risk of cardiovascular disease and death. This hypothesis, called the Lipid Hypothesis, is currently a generally accepted piece of conventional wisdom in the nutrition science community. With help from the son of one of the original investigators, two researchers recently unearthed and re-analyzed the previously unpublished data. What they found contradicts the Lipid Hypothesis, and could change the way we view “healthy” polyunsaturated fats.  

The analysis, published Tuesday in the British medical journal BMJ, is a sequel of sorts for lead researchers Daisy Zamora of the University of North Carolina, Chapel Hill and Christopher Ramsden of the National Institutes of Health. Back in 2013, they performed a similar analysis on another set of previously unpublished data, known as the Sydney Diet Heart Study, and came to similar conclusions: Substituting saturated fat with oils high in omega-6 acids, also known as linoleic acids, actually increases the risk of death from all causes, coronary heart disease and cardiovascular disease.

“Our research highlights the paucity of evidence supporting the dietary replacement of saturated fat with vegetable oils rich in linoleic acid for heart health,” Zamora told The Huffington Post.

Experts say that, combined, these two trials could upend the way we view healthy eating — especially when it comes to our relationship with so-called “healthy” oils. 

This new finding is based on data from 1968 

Back in 1968, the U.S. Public Health Service and National Heart Institute funded a five-year study called the Minnesota Coronary Experiment to see whether replacing saturated fat with vegetable oil would prevent heart attacks, stroke and death. To have complete control over what study participants ate and didn’t eat, researchers Ivan Frantz and Ancel Keys — who famously made the connection between a Mediterranean diet and better heart health — divided over 9,000 adults in nursing homes and mental hospitals into two groups in a double blind, randomized trial.

The intervention group reduced their saturated fat intake about 50 percent compared to their normal diet, and upped their vegetable oil intake more than 280 percent in the form of corn oil. The control group was put on a diet much lower in polyunsaturated fats and higher in saturated fat — in other words, more typical of the average American diet. 

These experimental diets lasted between 41 to 56 months, depending on the institution. Then Frantz and Keys followed up with roughly 2,403 participants who stayed on their new diets for a year or more, and measured their cholesterol levels several times over an average of three years. They also conducted autopsies participants who died during the experiment to see whether there were any differences in their arterial or heart health at death.

The unexpected (and perhaps unwanted) results

Frantz and Keys found that the intervention group participants, who swapped more corn oil for saturated fat, did indeed lower the levels of cholesterol in their blood compared to the control group and baseline levels. The intervention worked as they predicted.

However, later analyses reported in a 1981 master’s thesis paper by now-retired biostatistician Steven K. Broste found that the though the intervention group lowered their cholesterol levels, they didn’t lower their risk of death. In fact, participants who were over 65 when they started the experiment actually had a higher risk of death if they had been part of the group eating more vegetable oils.

The autopsies Frantz and Keys conducted were even more disquieting. Among the 149 autopsies for which there was complete information, 41 percent of the intervention group showed signs of at least one heart attack, while only 22 percent of the participants in the control group — the high saturated fat group — showed the same. Deceased people from the intervention group also had similar levels of fatty plaque buildup in the arteries and hardened arteries compared to the control group.

After collecting all the data from the Minnesota trial, Zamora and Ramsden combined it with four published randomized, controlled trials that also substituted saturated fat with vegetable oils high in linoleic acid. Like the Minnesota trial, this additional meta-analysis found there was no benefit to switching to these oils when it came to death by coronary heart disease or death by any cause.

“It’s truly a shame that Americans are being recommended to consume these industrial seed oils, as it’s in direct contradiction to the highest level of evidence in the literature,” observed James DiNicolantonio, a cardiovascular research scientists at St. Luke’s Mid America Heart Institute who wasn’t involved in these studies. 

For unknown reasons, Frantz and Keys never published the full results of this experiment. Their study has the distinction of being one of the very few randomized, controlled trials — considered the highest standard of medical evidence — to evaluate the effects of lowering saturated fat on heart health.

In their 2016 re-analysis, Zamora and Ramsden speculate that perhaps the researchers didn’t publish the findings in full because they were so “contrary” to the popular scientific beliefs of the time.

“There would have been little or no scientific or clinical trial literature at the time to support findings that were so contrary to prevailing beliefs and public policy,” they wrote. “And, finally, it is possible that medical journal reviewers would not have accepted study results for the reasons cited above.”

Some vegetable oils are better for you than others

It’s important to note that Frantz and Keys’ trial was conducted when Americans were eating more corn oil and margarine made from corn oil, and that corn oil was the only polyunsaturated fat that was used in the experiment. Corn oil is high in omega-6 fatty acids, and while our bodies need some amount of omega-6 fatty acids to function properly, Zamora and Ramsden note that too much of it could have a “wide range of biochemical consequences” that could perhaps be negative. This nuance isn’t reflected in the most up-to-date nutritional advice in the federal dietary guidelines, which state simply we should eat less saturated fat and more polyunsaturated fat without mention of omega-6 acids.

Rebecca Blake, a registered dietitian and administrative director for medicine at Mt. Sinai-Beth Israel, put it this way: “We don’t usually consider corn oil the gold standard of healthy oils.

“It’s fine — it’s a vegetable oil,” she continued. “But it’s not olive oil, and it’s not like having a diet that’s high in healthy fats like fatty fish.”

 

Some other sources of polyunsaturated fats, like fatty fish, contain both omega-6 and omega-3 fatty acids. It’s this combination that could be the key to protecting people’s hearts, rather than just consuming polyunsaturated fats as a class, notes Tom Brenna, a professor of human nutrition at Cornell University.

“This gives us strong reason to think carefully about the composition of polyunsaturated fatty acids,” said Brenna. “The analysis does not say that polyunsaturated fatty acids in general are a bad substitute, but that they’re seeing negative things exclusively with omega-6 fatty acids.”

He also expressed regret that nutrition experts have not been able to effectively communicate this to the general public. Brenna, who served on the committee of scientists who helped create the 2015-2020 U.S. Dietary Guidelines, says it isn’t as simple as rattling off the names of certain plant oils. Different types of oils have different fatty acid profiles, which all act on your body in different ways. 

“You can no longer just say eat one kind of oil or another kind of oil,” he said. “You have to specify which one it is, and we have not, as a society, figured out how to talk about that yet.” 

For the record, the only oils that Brenna can wholeheartedly recommend are olive oil, avocado oil and high-oleic sunflower oil. 

“It gets so confusing for people, but it shouldn’t be,” Brenna concluded. “We should figure out a way to deal with this behind the scenes, so that people don’t have to become chemists in order to eat.”

CORRECTION: A previous version of this story incorrectly stated that the researchers added data from an additional five randomized controlled trials. In fact, they added data from four trials. Also, a portion of a quote from an outside researcher that appeared to misinterpret Zamora and Ramsden’s analysis has been removed.

No Such Thing as a Black Hole?

New theories question just about everything we thought we knew about nature’s bottomless pits.

By Corey S. Powell

The black hole from Interstellar is based on current theory, but that theory may not match reality.

Double Negative/Paramount/Warner Brothers

It takes a special kind of personality to argue passionately about the nature of objects that are hundreds of trillions of miles away, impossible to see and impossible even to describe using the known laws of physics. And yet, in the woolly world of modern astrophysics, such personalities are not in short supply. Lately they’ve engaged in a full-on debate about the nature of black holes, with some of the most fundamental notions about these strange objects suddenly under attack.

Despite what you saw in the movie Interstellar, black holes may not be black, and they may not be holes, either. Some theorists argue that the event horizon of a black hole — the boundary where light, matter and Matthew McConaughey vanish from our universe — is actually a brilliant, blistering inferno. Others propose that black holes are more properly described as “gray holes” with fuzzy, leaky outer boundaries. And a few agitators argue that the whole debate is off track because nature makes it impossible for black holes to form in the first place.

All of which might seem like so much theoretical navel-gazing, except that the debate over black holes is a proxy in a much grander battle. Right now, physics is split in two: Quantum mechanics describes small, fast phenomena while general relativity describes large, slow ones.

But in the extreme conditions around a black hole, time and space get so stretched that the two theories are forced to overlap. Making sense of what happens at that intersection is crucial for developing a “theory of everything”— a unified set of physical laws that describe the entire cosmos, from the Big Bang to a Big Mac.

As material (dust in this illustration) falls toward a black hole, it heats up and emits radiation. No one knows what happens next.

Richard Kail/Science Source

Fire in the Hole!

The trouble began, like so many confounding concepts in modern physics, in the brain of Stephen Hawking. Four decades ago, he realized that a black hole’s event horizon is inherently leaky; quantum processes allow a slow but steady flow of particles away from the black hole, a process now known as Hawking radiation. Given enough time, a black hole can evaporate completely. The idea of matter escaping the alleged point-of-no-return was surprising (it’s a central plot point in that other recent movie about black holes, the biographical The Theory of Everything), but the fate of information that falls into the black hole was what really troubled Hawking’s colleagues.

In the current view, which Hawking helped formulate, every event in the universe contains quantum information. When objects fall into a black hole, they take their information with them. That’s fine so long as the information stays in there, but if the black hole evaporates, things go all wonky. Coherent information goes in, but what comes out is just noise — Hawking radiation is 100 percent content-free.

Falling into a black hole seems to destroy a slice of reality, which just makes no sense. Hawking and other theorists began searching desperately for ways to prevent information from getting into the black hole in the first place, for ways to let it back out, or even for ways to make peace with the possibility that some information really can be lost forever.

In 2012, Joseph Polchinski of the University of California, Santa Barbara, offered a novel solution: As soon as an object gets pulled across the event horizon, it hits a firewall — an inferno so intense that it erases all the quantum information that object contained. No information gets lost because no information actually makes it through to the black hole’s interior. Polchinski pictures the event horizon as a kind of quantum eraser that neatly makes the information paradox go away.

If you think that sounds like a dodgy answer, rest assured that many of Polchinski’s colleagues (and even Polchinski himself) thought so, too — though perhaps not for the reasons you’d expect. The problem is that the rules of general relativity mandate physical continuity everywhere in the universe, even around a black hole. There should be no gap in the experience of, say, a doomed astronaut falling across the event horizon.

Or think of it this way: In relativity, the laws of physics look the same from all perspectives. The astronaut may get squished and stretched on the way in, but should still observe physics operating normally. The firewall, on the other hand, is about as abnormal and discontinuous as it gets. Now we’ve got a new paradox to deal with.

At this point, the story circles back to Hawking, who decided there must be a better way out. In a short paper presented last year, he suggests that the event horizon is not a defined boundary at all, but rather a zone of chaos where space and time are completely scrambled. No specific physical event occurs there — no Polchinski firewall — but any information passing through is rendered completely meaningless. Although Hawking dispenses with the traditional idea of the event horizon, he doesn’t dispute that black holes exist (as some breathless news stories claimed). Rather, he proposes that black holes are more like gray holes, defined by fuzzy edges that shed energy and garbled information.

My brain was starting to hurt, so I called on Juan Maldacena of the Institute for Advanced Study, a leading black hole theorist and a neutral third party. He doesn’t think much of the firewall concept because it fails miserably at the key task of reconciling quantum mechanics and relativity. “It’s telling us how not to do it,” he says. Does he like the Hawking approach, then? “No. He did not propose anything concrete,” Maldacena replies tersely.

When you are trying to solve the riddle of the black hole, nobody gets special treatment, not even Stephen Hawking.

Event Horizon Denialists

Here is where the deniers come in: If black holes keep sprouting paradoxes, the thinking goes, maybe the problem lies with our understanding of the black hole itself. I first encountered black hole denialism during a cosmology conversation with Laura Mersini-Houghton of the University of North Carolina, who mentioned, as a casual aside, “Oh, I also proved black holes don’t exist.” Over the past year, she has written two papers (one published, one in press) laying down the gauntlet.

Even Stephen Hawking can’t quite explain how black holes actually work in our universe.

Karwai Tang/Getty Images

Mersini-Houghton is flipping around Hawking’s old ideas. He considered the radiation released by black holes after they form. She looks instead at the radiation generated by a massive, collapsing object before it ever crosses the event horizon. In Mersini-Houghton’s analysis, the resulting energy and opposing pressure become so intense that it stops the infall, reverses it, and flings everything outward. The result is “fireworks, not firewalls,” as she puts it. 

Event horizons, and the paradoxes that go with them, do not exist because the laws of physics guarantee that imploding stars self-destruct before they can become black holes. Cenalo Vaz, a physicist at the University of Cincinnati, recently came to similar conclusions by looking at outward pressure exerted by the structure of space around a collapsing object.

If black holes don’t exist, I ask Mersini-Houghton, what are those things at the hearts of most galaxies? Astronomers have found clear evidence of tiny but supermassive objects there, pulling on stars and stirring up hot disks of gas. Her answer cuts to the heart of one of the weirdest aspects of a black hole. As matter moves closer to the event horizon, time slows down from the perspective of an outside observer — that is, from the perspective of us and everyone else on the outside. At the horizon itself, time appears to us to come to a dead halt.

Even if matter never quite reaches the horizon, as in Mersini-Houghton’s theory, time could be stretched so drastically that a sudden rebound or explosion (from the collapsing object’s perspective) might look like a single, motionless moment (from ours).

Laura Mersini-Houghton thinks the laws of physics prevent black holes' forming.

Dan Sears/the University of North Carolina at Chapel Hill

Put plainly: To a human observer, black holes do not exist because we can never see them form. In the traditional view, a star keeps collapsing past the event horizon down to a dot known as a singularity. In the dissenting view, the star collapses to the edge of the event horizon and then hovers there, or rebounds and explodes. But from our outside perspective, there is essentially no difference. All we see is a frozen frame when the star is infinitesimally close to the event horizon. An astronaut falling toward the star would know the answer instantly, but any message that he or she sent would take a near-infinite amount of time to reach us.

Nevertheless, because such an experience is possible, there must be a theory to describe it.

Maldacena, like most mainstream physicists, dismisses black hole denialism. The real way to make sense of all this black hole madness, he insists, is to address the underlying clashes between relativity and quantum physics. “A full theory of quantum gravity must resolve them,” he emphasizes. And that is, perhaps, the ultimate paradox of black holes: They embody our very deepest scientific understanding of how the universe works, and yet in many ways we do not understand them at all.