Posts Tagged ‘science’

by Antonio Regalado

Human intelligence is one of evolution’s most consequential inventions. It is the result of a sprint that started millions of years ago, leading to ever bigger brains and new abilities. Eventually, humans stood upright, took up the plow, and created civilization, while our primate cousins stayed in the trees.

Now scientists in southern China report that they’ve tried to narrow the evolutionary gap, creating several transgenic macaque monkeys with extra copies of a human gene suspected of playing a role in shaping human intelligence.

“This was the first attempt to understand the evolution of human cognition using a transgenic monkey model,” says Bing Su, the geneticist at the Kunming Institute of Zoology who led the effort.

According to their findings, the modified monkeys did better on a memory test involving colors and block pictures, and their brains also took longer to develop—as those of human children do. There wasn’t a difference in brain size.

The experiments, described on March 27 in a Beijing journal, National Science Review, and first reported by Chinese media, remain far from pinpointing the secrets of the human mind or leading to an uprising of brainy primates.

Instead, several Western scientists, including one who collaborated on the effort, called the experiments reckless and said they questioned the ethics of genetically modifying primates, an area where China has seized a technological edge.

“The use of transgenic monkeys to study human genes linked to brain evolution is a very risky road to take,” says James Sikela, a geneticist who carries out comparative studies among primates at the University of Colorado. He is concerned that the experiment shows disregard for the animals and will soon lead to more extreme modifications. “It is a classic slippery slope issue and one that we can expect to recur as this type of research is pursued,” he says.

Research using primates is increasingly difficult in Europe and the US, but China has rushed to apply the latest high-tech DNA tools to the animals. The country was first to create monkeys altered with the gene-editing tool CRISPR, and this January a Chinese institute announced it had produced a half-dozen clones of a monkey with a severe mental disturbance.

“It is troubling that the field is steamrolling along in this manner,” says Sikela.

Evolution story

Su, a researcher at the Kunming Institute of Zoology, specializes in searching for signs of “Darwinian selection”—that is, genes that have been spreading because they’re successful. His quest has spanned such topics as Himalayan yaks’ adaptation to high altitude and the evolution of human skin color in response to cold winters.

The biggest riddle of all, though, is intelligence. What we know is that our humanlike ancestors’ brains rapidly grew in size and power. To find the genes that caused the change, scientists have sought out differences between humans and chimpanzees, whose genes are about 98% similar to ours. The objective, says, Sikela, was to locate “the jewels of our genome”—that is, the DNA that makes us uniquely human.

For instance, one popular candidate gene called FOXP2—the “language gene” in press reports—became famous for its potential link to human speech. (A British family whose members inherited an abnormal version had trouble speaking.) Scientists from Tokyo to Berlin were soon mutating the gene in mice and listening with ultrasonic microphones to see if their squeaks changed.

Su was fascinated by a different gene, MCPH1, or microcephalin. Not only did the gene’s sequence differ between humans and apes, but babies with damage to microcephalin are born with tiny heads, providing a link to brain size. With his students, Su once used calipers and head spanners to the measure the heads of 867 Chinese men and women to see if the results could be explained by differences in the gene.

By 2010, though, Su saw a chance to carry out a potentially more definitive experiment—adding the human microcephalin gene to a monkey. China by then had begun pairing its sizeable breeding facilities for monkeys (the country exports more than 30,000 a year) with the newest genetic tools, an effort that has turned it into a mecca for foreign scientists who need monkeys to experiment on.

To create the animals, Su and collaborators at the Yunnan Key Laboratory of Primate Biomedical Research exposed monkey embryos to a virus carrying the human version of microcephalin. They generated 11 monkeys, five of which survived to take part in a battery of brain measurements. Those monkeys each have between two and nine copies of the human gene in their bodies.

Su’s monkeys raise some unusual questions about animal rights. In 2010, Sikela and three colleagues wrote a paper called “The ethics of using transgenic non-human primates to study what makes us human,” in which they concluded that human brain genes should never be added to apes, such as chimpanzees, because they are too similar to us. “You just go to the Planet of the Apes immediately in the popular imagination,” says Jacqueline Glover, a University of Colorado bioethicist who was one of the authors. “To humanize them is to cause harm. Where would they live and what would they do? Do not create a being that can’t have a meaningful life in any context.”

In an e-mail, Su says he agrees that apes are so close to humans that their brains shouldn’t be changed. But monkeys and humans last shared an ancestor 25 million years ago. To Su, that alleviates the ethical concerns. “Although their genome is close to ours, there are also tens of millions of differences,” he says. He doesn’t think the monkeys will become anything more than monkeys. “Impossible by introducing only a few human genes,” he says.

Smart monkey?

Judging by their experiments, the Chinese team did expect that their transgenic monkeys could end up with increased intelligence and brain size. That is why they put the creatures inside MRI machines to measure their white matter and gave them computerized memory tests. According to their report, the transgenic monkeys didn’t have larger brains, but they did better on a short-term memory quiz, a finding the team considers remarkable.

Several scientists think the Chinese experiment didn’t yield much new information. One of them is Martin Styner, a University of North Carolina computer scientist and specialist in MRI who is listed among the coauthors of the Chinese report. Styner says his role was limited to training Chinese students to extract brain volume data from MRI images, and that he considered removing his name from the paper, which he says was not able to find a publisher in the West.

“There are a bunch of aspects of this study that you could not do in the US,” says Styner. “It raised issues about the type of research and whether the animals were properly cared for.”

After what he’s seen, Styner says he’s not looking forward to more evolution research on transgenic monkeys. “I don’t think that is a good direction,” he says. “Now we have created this animal which is different than it is supposed to be. When we do experiments, we have to have a good understanding of what we are trying to learn, to help society, and that is not the case here.” One issue is that genetically modified monkeys are expensive to create and care for. With just five modified monkeys, it’s hard to reach firm conclusions about whether they really differ from normal monkeys in terms of brain size or memory skills. “They are trying to understand brain development. And I don’t think they are getting there,” says Styner.

In an e-mail, Su agreed that the small number of animals was a limitation. He says he has a solution, though. He is making more of the monkeys and is also testing new brain evolution genes. One that he has his eye on is SRGAP2C, a DNA variant that arose about two million years ago, just when Australopithecus was ceding the African savannah to early humans. That gene has been dubbed the “humanity switch” and the “missing genetic link” for its likely role in the emergence of human intelligence.

Su says he’s been adding it to monkeys, but that it’s too soon to say what the results are.

https://www.technologyreview.com/s/613277/chinese-scientists-have-put-human-brain-genes-in-monkeysand-yes-they-may-be-smarter/

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Beauty might only be skin deep, but for those wondering how to keep that skin young, scientists may have found an answer in the form of a protein that encourages cell competition.

The prosaically named COL17A1 might not sound like a fountain of youth, but the new study suggests it does the heavy lifting when it comes to keeping skin intact and unimpaired.

The protein works by encouraging cell competition, a key process to maintain tissue fitness. That effectively “drives out” weaker cells while encouraging replication of stronger ones.

“Damaged or stressed stem cells can be selectively eliminated by intact stem cells every day in our skin,” said Emi Nishimura, a professor at the Tokyo Medical and Dental University’s Stem Cell Biology department, who led the research.

But ageing results in a depletion of COL17A1, as do familiar enemies of youthful skin, like UV radiation and other stress factors.

And when that happens, weaker cells replicate, leaving the skin thinner, more prone to damage and slower to heal.

The research published Thursday in the journal Nature is based on investigations using mice tails, which share many of the same characteristics as human skin.

After confirming the importance of COL17A1, the team decided to investigate whether they could stimulate the protein once it was depleted—effectively looking for compounds that could kickstart the anti-ageing process in skin.

They isolated two chemical compounds—Y27632 and apocynin—and tested both on skin cells, with positive results.

“Application of these drugs to full-thickness skin wounds significantly promoted wound repair,” the study said.

The two compounds point to ways of “facilitating skin regeneration and reducing skin ageing,” the study added.

In a review of the study commissioned by Nature, two professors from the University of Colorado said cell competition had previously only been studied extensively in fruit flies.

The research “provides evidence that healthy cells in mammals can also efficiently repopulate adult tissues, replacing unfit or damaged cells,” wrote professors Ganna Bilousova and James DeGregori.

And they said the research offered “proof-of-principle” that the two chemical compounds could combat ageing.

“Future studies are needed to determine the mechanisms of cell competition in other tissues, and to identify compounds capable of reversing ageing in other organs,” they said.

Nishimura told AFP that the work could eventually lead to products like creams or tablets that could stop skin deterioration and promote repair.

“We are going to collaborate with pharmaceutical or cosmetic companies for the clinical use of the chemicals,” she said.

She said additional research would investigate whether the same process might also be at work in other parts of the body that have so-called epithelial cells like skin does.

“We are working on other epithelial organs as well to find out (whether) similar competition may underlie long-term tissue maintenance as well as organ ageing,” she said.

https://medicalxpress.com/news/2019-04-young-uncovers-protein-skin-youthful.html

by CARLY CASSELLA

Scientists are closing in on a blood test for fibromyalgia, and the result could save patients from what is currently a lengthy and vague process of diagnosis.

Researchers at Ohio State University are now aiming to have a diagnostic blood test available for widespread use within the next five years.

Their confidence stems from a recently discovered biomarker – a “metabolic fingerprint” as the researchers put it – traceable in the blood of those with the disorder.

“We found clear, reproducible metabolic patterns in the blood of dozens of patients with fibromyalgia,” says lead author Kevin Hackshaw, a rheumatologist at Ohio State University.

“This brings us much closer to a blood test than we have ever been.”

Fibromyalgia is a common, debilitating, and poorly understood disorder, marked by widespread pain and fatigue, with no known cause and absolutely no cure.

In the United States, it’s the most common cause of chronic widespread pain, and that’s not even counting the thousands of patients who go undiagnosed every year.

Without a reliable way to detect this disorder, it’s estimated that up to three out of four people with the condition remain undiagnosed. And on average it can take five years from when a person’s symptoms first appear to them actually receiving a diagnosis.

In total, the US Centers for Disease Control and Prevention estimates that about two percent of the population – around four million adults – have fibromyalgia, with women making up a disproportionate slice.

Left with few options, many patients are simply forced to live with their pain.With nowhere to go, many become desperate and turn to potentially harmful treatments.

“When you look at chronic pain clinics, about 40 percent of patients on opioids meet the diagnostic criteria for fibromyalgia,” says Hackshaw.

“Fibromyalgia often gets worse, and certainly doesn’t get better, with opioids.”

It was Hackshaw’s goal to intervene sooner. Using vibrational spectroscopy, a technique which measures the energy of molecules, his team analysed blood samples from 50 people with fibromyalgia, 29 with rheumatoid arthritis, 19 with osteoarthritis, and 23 with lupus.

Despite the fact these disorders can present with similar symptoms, the blood of those participants with fibromyalgia was distinct.

Using these unique patterns, the researchers then tried to blindly predict participants’ diagnoses. Even without knowing their true disorder, the researchers were able to accurately diagnose every study participant based on that molecular fingerprint in the blood.

“These initial results are remarkable,” says co-author Luis Rodriguez-Saona, an expert in vibrational spectroscopy at Ohio State University.

“If we can help speed diagnosis for these patients, their treatment will be better and they’ll likely have better outlooks. There’s nothing worse than being in a grey area where you don’t know what disease you have.”

While the sample size is undoubtedly small, the results are promising. If the team can replicate their results on a larger scale, with a couple hundred diverse participants, then a blood test in five years might not seem so far-fetched.

Not to mention what that would mean for treatment. If the researchers can prove they really have identified a biological fingerprint for fibromyalgia, this could give us new drug targets in the future.

“Thus,” the authors conclude, “our studies have great importance both from development of a reproducible biomarker as well as identifying potential new therapeutic targets for treatment.”

This study has been published in the Journal of Biological Chemistry.

https://www.sciencealert.com/scientists-have-devised-a-blood-test-that-can-accurately-diagnose-fibromyalgia


The mathematically designed, 3D-printed acoustic metamaterial is shaped in such a way that it sends incoming sounds back to where they came from, Ghaffarivardavagh and Zhang say. Inside the outer ring, a helical pattern interferes with sounds, blocking them from transmitting through the open center while preserving air’s ability to flow through.

Boston University researchers, Xin Zhang, a professor at the College of Engineering, and Reza Ghaffarivardavagh, a Ph.D. student in the Department of Mechanical Engineering, released a paper in Physical Review B demonstrating it’s possible to silence noise using an open, ringlike structure, created to mathematically perfect specifications, for cutting out sounds while maintaining airflow.

“Today’s sound barriers are literally thick heavy walls,” says Ghaffarivardavagh. Although noise-mitigating barricades, called sound baffles, can help drown out the whoosh of rush hour traffic or contain the symphony of music within concert hall walls, they are a clunky approach not well suited to situations where airflow is also critical. Imagine barricading a jet engine’s exhaust vent — the plane would never leave the ground. Instead, workers on the tarmac wear earplugs to protect their hearing from the deafening roar.

Ghaffarivardavagh and Zhang let mathematics — a shared passion that has buoyed both of their engineering careers and made them well-suited research partners — guide them toward a workable design for what the acoustic metamaterial would look like.

They calculated the dimensions and specifications that the metamaterial would need to have in order to interfere with the transmitted sound waves, preventing sound — but not air — from being radiated through the open structure. The basic premise is that the metamaterial needs to be shaped in such a way that it sends incoming sounds back to where they came from, they say.

As a test case, they decided to create a structure that could silence sound from a loudspeaker. Based on their calculations, they modeled the physical dimensions that would most effectively silence noises. Bringing those models to life, they used 3D printing to materialize an open, noise-canceling structure made of plastic.

Trying it out in the lab, the researchers sealed the loudspeaker into one end of a PVC pipe. On the other end, the tailor-made acoustic metamaterial was fastened into the opening. With the hit of the play button, the experimental loudspeaker set-up came oh-so-quietly to life in the lab. Standing in the room, based on your sense of hearing alone, you’d never know that the loudspeaker was blasting an irritatingly high-pitched note. If, however, you peered into the PVC pipe, you would see the loudspeaker’s subwoofers thrumming away.

The metamaterial, ringing around the internal perimeter of the pipe’s mouth, worked like a mute button incarnate until the moment when Ghaffarivardavagh reached down and pulled it free. The lab suddenly echoed with the screeching of the loudspeaker’s tune.

“The moment we first placed and removed the silencer…was literally night and day,” says Jacob Nikolajczyk, who in addition to being a study co author and former undergraduate researcher in Zhang’s lab is a passionate vocal performer. “We had been seeing these sorts of results in our computer modeling for months — but it is one thing to see modeled sound pressure levels on a computer, and another to hear its impact yourself.”

By comparing sound levels with and without the metamaterial fastened in place, the team found that they could silence nearly all — 94 percent to be exact — of the noise, making the sounds emanating from the loudspeaker imperceptible to the human ear.

Now that their prototype has proved so effective, the researchers have some big ideas about how their acoustic-silencing metamaterial could go to work making the real world quieter.

“Drones are a very hot topic,” Zhang says. Companies like Amazon are interested in using drones to deliver goods, she says, and “people are complaining about the potential noise.”

“The culprit is the upward-moving fan motion,” Ghaffarivardavagh says. “If we can put sound-silencing open structures beneath the drone fans, we can cancel out the sound radiating toward the ground.”

Closer to home — or the office — fans and HVAC systems could benefit from acoustic metamaterials that render them silent yet still enable hot or cold air to be circulated unencumbered throughout a building.

Ghaffarivardavagh and Zhang also point to the unsightliness of the sound barriers used today to reduce noise pollution from traffic and see room for an aesthetic upgrade. “Our structure is super lightweight, open, and beautiful. Each piece could be used as a tile or brick to scale up and build a sound-canceling, permeable wall,” they say.

The shape of acoustic-silencing metamaterials, based on their method, is also completely customizable, Ghaffarivardavagh says. The outer part doesn’t need to be a round ring shape in order to function.

“We can design the outer shape as a cube or hexagon, anything really,” he says. “When we want to create a wall, we will go to a hexagonal shape” that can fit together like an open-air honeycomb structure.

Such walls could help contain many types of noises. Even those from the intense vibrations of an MRI machine, Zhang says.

According to Stephan Anderson, a professor of radiology at BU School of Medicine and a coauthor of the study, the acoustic metamaterial could potentially be scaled “to fit inside the central bore of an MRI machine,” shielding patients from the sound during the imaging process.

Zhang says the possibilities are endless, since the noise mitigation method can be customized to suit nearly any environment: “The idea is that we can now mathematically design an object that can block the sounds of anything,” she says.

https://www.sciencedaily.com/releases/2019/03/190307103109.htm

by Jonathan O’Callaghan

You might be forgiven for thinking our understanding of classical physics had reached its peak in the four centuries since Isaac Newton devised his eponymous laws of motion. But surprising new research shows there are still secrets waiting to be found, hidden in plain sight—or, at least in this case, within earshot.

In a paper published in Physical Review Letters, a group of scientists has theorized that sound waves possess mass, meaning sounds would be directly affected by gravity. They suggest phonons, particlelike collective excitations responsible for transporting sound waves across a medium, might exhibit a tiny amount of mass in a gravitational field. “You would expect classical physics results like this one to have been known for a long time by now,” says Angelo Esposito from Columbia University, the lead author on the paper. “It’s something we stumbled upon almost by chance.”

Esposito and his colleagues built on a previous paper published last year, in which Alberto Nicolis of Columbia and Riccardo Penco from Carnegie Mellon University first suggested phonons could have mass in a superfluid. The latest study, however, shows this effect should hold true for other materials, too, including regular liquids and solids, and even air itself.

And although the amount of mass carried by the phonons is expected to be tiny—comparable with a hydrogen atom, about 10–24 grams—it may actually be measurable. Except, if you were to measure it, you would find something deeply counterintuitive: The mass of the phonons would be negative, meaning they would fall “up.” Over time their trajectory would gradually move away from a gravitational source such as Earth. “If their gravitational mass was positive, they would fall downward,” Penco says. “Because their gravitational mass is negative, phonons fall upwards.” And the amount they would “fall” is equally small, varying depending on the medium the phonon is traveling through. In water, where sound moves at 1.5 kilometers per second, the negative mass of the phonon would cause it to drift at about 1 degree per second. But this corresponds to a change of 1 degree over 15 kilometers, which would be exceedingly difficult to measure.

Difficult it might be, but such a measurement should still be possible. Esposito notes that to distinguish the phonons’ mass, one could look for them in a medium where the speed of sound was very slow. That might be possible in superfluid helium, where the speed of sound can drop to hundreds of meters per second or less, and the passage of a single phonon might shift an atom’s equivalent of material.

Alternatively, instead of seeking minuscule effects magnified by exotic substances, researchers might look for more obvious signs of mass-carrying phonons by closely studying extremely intense sound waves. Earthquakes offer one possibility, Esposito says. According to his calculations, a magnitude 9 temblor would release enough energy so that the resulting change in the gravitational acceleration of the earthquake’s sound wave might be measurable using atomic clocks. (Although current techniques are not sensitive enough to detect the gravitational field of a seismic wave, future advancements in technology might make this possible.)

Sound waves having mass are unlikely to have a major impact on day-to-day life, but the possibility something so fundamental has gone unnoticed for so long is intriguing. “Until this paper, it was thought that sound waves do not transport mass,” says Ira Rothstein from Carnegie Mellon University, who was not involved in this research. “So in that sense it’s a really remarkable result. Because anytime you find any new result in classical physics, given that it’s been around since Newton, you would have thought it would be completely understood. If you look carefully enough, you can find fresh [ideas] even in fields which have been covered for centuries.”

As for why this has never been spotted before, Esposito is uncertain. “Maybe because we are high-energy physicists, gravity is more our language,” he says. “It’s not some theoretical mumbo jumbo kind of thing. In principle people could have discovered it years ago.”

https://www.scientificamerican.com/article/sound-by-the-pound-surprising-discovery-hints-sonic-waves-carry-mass/

by PETER DOCKRILL

When bad things happen, we don’t want to remember. We try to block, resist, ignore – but we should perhaps be doing the opposite, researchers say.

A new study led by scientists in Texas suggests the act of intentionally forgetting is linked to increased cerebral engagement with the unwanted information in question. In other words, to forget something, you actually need to focus on it.

“A moderate level of brain activity is critical to this forgetting mechanism,” explains psychologist Tracy Wang from the University of Texas at Austin.

“Too strong, and it will strengthen the memory; too weak, and you won’t modify it.”

Trying to actively forget unwanted memories doesn’t just help prevent your brain from getting overloaded.

It also lets people move on from painful experiences and emotions they’d rather not recall, which is part of the reason it’s an area of active interest to neuroscientists.

“We may want to discard memories that trigger maladaptive responses, such as traumatic memories, so that we can respond to new experiences in more adaptive ways,” says one of the researchers, Jarrod Lewis-Peacock.

“Decades of research has shown that we have the ability to voluntarily forget something, but how our brains do that is still being questioned.”

Much prior research on intentional forgetting has focussed on brain activity in the prefrontal cortex, and the brain’s memory centre, the hippocampus.

In the new study, the researchers monitored a different part of the brain called the ventral temporal cortex, which helps us process and categorise visual stimuli.

In an experiment with 24 healthy young adults, the participants were shown pictures of scenes and people’s faces, and were instructed to either remember or forget each image.

During the experiment, each of the participants had their brain activity monitored by functional magnetic resonance imaging (fMRI) machines.

When the researchers examined activity in the ventral temporal cortex, they found that the act of forgetting effectively uses more brain power than remembering.

“Pictures followed by a forget instruction elicited higher levels of processing in [the] ventral temporal cortex compared to those followed by a remember instruction,” the authors write in their paper.

“This boost in processing led to more forgetting, particularly for items that showed moderate (vs. weak or strong) activation.”

Of course, forgetting specific images on demand in a contrived laboratory experiment is very different to moving on from painful or traumatic memories of events experienced in the real world.

But the mechanisms at work could be the same, researchers say, and figuring out how to activate them could be a huge benefit to people around the world who need to forget things, but don’t know how.

Especially since this finding in particular challenges our natural intuition to suppress things; instead, we should involve more rather than less attention to unwanted information, in order to forget it.

“Importantly, it’s the intention to forget that increases the activation of the memory,” Wang says.

“When this activation hits the ‘moderate level’ sweet spot, that’s when it leads to later forgetting of that experience.”

The findings are reported in JNeurosci.

https://www.sciencealert.com/to-forget-something-you-need-to-think-about-it-neuroscientists-reveal

Back in 1961, the Nobel Prize–winning physicist Eugene Wigner outlined a thought experiment that demonstrated one of the lesser-known paradoxes of quantum mechanics. The experiment shows how the strange nature of the universe allows two observers—say, Wigner and Wigner’s friend—to experience different realities.

Since then, physicists have used the “Wigner’s Friend” thought experiment to explore the nature of measurement and to argue over whether objective facts can exist. That’s important because scientists carry out experiments to establish objective facts. But if they experience different realities, the argument goes, how can they agree on what these facts might be?

That’s provided some entertaining fodder for after-dinner conversation, but Wigner’s thought experiment has never been more than that—just a thought experiment.

Last year, however, physicists noticed that recent advances in quantum technologies have made it possible to reproduce the Wigner’s Friend test in a real experiment. In other words, it ought to be possible to create different realities and compare them in the lab to find out whether they can be reconciled.

And today, Massimiliano Proietti at Heriot-Watt University in Edinburgh and a few colleagues say they have performed this experiment for the first time: they have created different realities and compared them. Their conclusion is that Wigner was correct—these realities can be made irreconcilable so that it is impossible to agree on objective facts about an experiment.

Wigner’s original thought experiment is straightforward in principle. It begins with a single polarized photon that, when measured, can have either a horizontal polarization or a vertical polarization. But before the measurement, according to the laws of quantum mechanics, the photon exists in both polarization states at the same time—a so-called superposition.

Wigner imagined a friend in a different lab measuring the state of this photon and storing the result, while Wigner observed from afar. Wigner has no information about his friend’s measurement and so is forced to assume that the photon and the measurement of it are in a superposition of all possible outcomes of the experiment.

Wigner can even perform an experiment to determine whether this superposition exists or not. This is a kind of interference experiment showing that the photon and the measurement are indeed in a superposition.

From Wigner’s point of view, this is a “fact”—the superposition exists. And this fact suggests that a measurement cannot have taken place.

But this is in stark contrast to the point of view of the friend, who has indeed measured the photon’s polarization and recorded it. The friend can even call Wigner and say the measurement has been done (provided the outcome is not revealed).

So the two realities are at odds with each other. “This calls into question the objective status of the facts established by the two observers,” say Proietti and co.

That’s the theory, but last year Caslav Brukner, at the University of Vienna in Austria, came up with a way to re-create the Wigner’s Friend experiment in the lab by means of techniques involving the entanglement of many particles at the same time.

The breakthrough that Proietti and co have made is to carry this out. “In a state-of-the-art 6-photon experiment, we realize this extended Wigner’s friend scenario,” they say.

They use these six entangled photons to create two alternate realities—one representing Wigner and one representing Wigner’s friend. Wigner’s friend measures the polarization of a photon and stores the result. Wigner then performs an interference measurement to determine if the measurement and the photon are in a superposition.

The experiment produces an unambiguous result. It turns out that both realities can coexist even though they produce irreconcilable outcomes, just as Wigner predicted.

That raises some fascinating questions that are forcing physicists to reconsider the nature of reality.

The idea that observers can ultimately reconcile their measurements of some kind of fundamental reality is based on several assumptions. The first is that universal facts actually exist and that observers can agree on them.

But there are other assumptions too. One is that observers have the freedom to make whatever observations they want. And another is that the choices one observer makes do not influence the choices other observers make—an assumption that physicists call locality.

If there is an objective reality that everyone can agree on, then these assumptions all hold.

But Proietti and co’s result suggests that objective reality does not exist. In other words, the experiment suggests that one or more of the assumptions—the idea that there is a reality we can agree on, the idea that we have freedom of choice, or the idea of locality—must be wrong.

Of course, there is another way out for those hanging on to the conventional view of reality. This is that there is some other loophole that the experimenters have overlooked. Indeed, physicists have tried to close loopholes in similar experiments for years, although they concede that it may never be possible to close them all.

Nevertheless, the work has important implications for the work of scientists. “The scientific method relies on facts, established through repeated measurements and agreed upon universally, independently of who observed them,” say Proietti and co. And yet in the same paper, they undermine this idea, perhaps fatally.

The next step is to go further: to construct experiments creating increasingly bizarre alternate realities that cannot be reconciled. Where this will take us is anybody’s guess. But Wigner, and his friend, would surely not be surprised.

Ref: arxiv.org/abs/1902.05080 : Experimental Rejection of Observer-Independence in the Quantum World

https://www.technologyreview.com/s/613092/a-quantum-experiment-suggests-theres-no-such-thing-as-objective-reality/