Posts Tagged ‘science’

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/

Advertisements

Birds do it, bees do it, even educated fleas do it: No, they don’t fall in love, they sleep. However, exactly why all animals with a nervous system evolved to sleep has been a longstanding scientific mystery. Slumber certainly feels great, but it doesn’t exactly make sense — why should we spend a third of our lives passed out?

In a study published Tuesday in Nature Communications, scientists say they’ve figured out why on the cellular level. The core cellular function of sleep, they explain, is to combat the neuronal DNA damage that accumulates during waking hours. Sleep allows neurons to perform the efficient DNA maintenance that’s essential to a healthy life: Scientists already know that less sleep means greater vulnerability to anxiety, frustration, and ill health, but now they’re closer to understanding exactly why that’s the case.

“We’ve found a causal link between sleep, chromosome dynamics, neuronal activity, and DNA damage and repair with direct physiological relevance to the entire organism,” study lead Lior Appelbaum, Ph.D., said Tuesday. “Sleep gives an opportunity to reduce DNA damage accumulated in the brain during wakefulness.”

Applebaum and his team examined how sleep is linked to nuclear maintenance by examining one of the most frequently used model organisms for genetic and developmental studies: the zebrafish. These transparent zebrafish were genetically engineered so that the chromosomes in their neurons carried colorful chemical tags. While the fish were awake and asleep, the scientists observed the movement of DNA and nuclear proteins inside the fish with a high-resolution microscope, which can be seen in the video above.

They witnessed that when the fish were awake, the chromosomes were relatively inactive, and broken strands of DNA accumulated in the neurons. However, when the fish were asleep the chromosomes became more active, and the DNA damage that had accumulated began to be repaired. Subsequent analysis confirmed that in order to perform nuclear maintenance, single neurons need an animal to go to sleep.

The accumulation of DNA damage, says Appelbaum, is the “price of wakefulness.” During wakefulness, chromosomes are less active, leaving them vulnerable to DNA damage caused by radiation, oxidative stress, and neuronal activity. Sleep kickstarts chromosomal activity and synchronizes nuclear maintenance within individual neurons, allowing the brain to be repaired while it’s not being used to the extent that it is during the day.

“It’s like potholes in the road,” Applebaum says. “Roads accumulate wear and tear, especially during daytime rush hours, and it is most convenient and efficient to fix them at night, when there is light traffic.”

Anecdotally, we know that a good night’s sleep can be restorative. Now it appears that it’s quantifiably restorative for the brain as well, allowing it to naturally mend the damage of the day.

Abstract:

Sleep is essential to all animals with a nervous system. Nevertheless, the core cellular function of sleep is unknown, and there is no conserved molecular marker to define sleep across phylogeny. Time-lapse imaging of chromosomal markers in single cells of live zebrafish revealed that sleep increases chromosome dynamics in individual neurons but not in two other cell types. Manipulation of sleep, chromosome dynamics, neuronal activity, and DNA double-strand breaks (DSBs) showed that chromosome dynamics are low and the number of DSBs accumulates during wakefulness. In turn, sleep increases chromosome dynamics, which are necessary to reduce the amount of DSBs. These results establish chromosome dynamics as a potential marker to define single sleeping cells, and propose that the restorative function of sleep is nuclear maintenance.

By David Freeman

No one is ditching the night-vision goggles just yet, but scientists working in the United States and China have developed a technique that they say could one day give humans the ability to see in the dark.

The technique involves injecting the eyes with particles that act like tiny antennae that take infrared light — wavelengths that are invisible to humans and other mammals — and convert it to visible wavelengths. Mammals can see wavelengths in just a sliver of the electromagnetic spectrum, and the new technique is designed to widen that sliver.

The nanoparticle injections haven’t been tried on humans, but experiments on mice show that they confer the ability to see infrared light without interfering with the perception of light in the visible range. The effect worked during the day and at night and lasted for several weeks. The rodents were left unharmed once it wore off.

Gang Han, a chemist at the University of Massachusetts Medical School and a co-author of a new paper describing the research, said in a statement that the technique could lead to a better understanding of visual perception and possibly lead to new ways to treat color blindness.

But those are far from the only possible applications if the technique can be made to work safely in other mammals, including humans. In an email to NBC News MACH, Han said it might be possible to use nanoparticle injections to create “superdogs” that could make it easier to apprehend lawbreakers in darkness.

“For ordinary people,” he added, “we may also see our sky in a completely different way” both at night and during the day because many celestial objects give off infrared light.

The technique doesn’t confer the ability to see the longer-wavelength infrared light given off by living bodies and other warm objects, Tian Xue, a neuroscientist at the University of Science and Technology of China and a co-author of the paper, said in an email. But at least theoretically, it could give humans the ability to see bodies and objects in darkness without the use of night-vision gear — though an infrared light would still be needed.

For their research, Han, Xue and their collaborators injected the rodents’ eyes with nanoparticles treated with proteins that helped “glue” the particles to light-sensitive cells in the animals’ retinas. Once the tiny antennae were in place, the scientists hypothesized, the nanoparticles would convert infrared light into shorter wavelengths, which the animals would then perceive as green light.

To make sure the mice were actually seeing the converted infrared light, the scientists subjected the animals to a number of tests, including one in which they were given a choice of entering a totally dark box or one illuminated only with infrared light. (Mice are nocturnal, and ordinarily they prefer darkness.) Control animals showed no preference — because both boxes appeared dark to them — while treated mice showed a distinct preference for the dark box.

Other scientists praised the research while expressing doubts about trying the technique in humans.

Harvard neuroscientist Michael Do said in an email that the experiments were “sophisticated” and that the technique was likely to work in humans as well as in mice. But he said it was unclear just how sharp the infrared vision would be in humans, and he cautioned that the injections might damage delicate structures in the eye.

Glen Jeffery, a neuroscientist at the University College London, expressed similar praise for the research — but even graver doubts. “Injecting any material under the retina is risky and should never be done unless there is a clear and justifiable clinical reason…” he said in an email. “I have no idea how you could use this technology to human advantage and would never support its application on healthy humans.”

But the researchers are moving ahead. Han said the team planned to test the technique in bigger animals — possibly dogs.

https://www.nbcnews.com/mach/science/scientists-create-super-mice-can-see-dark-here-s-what-ncna977966

Thanks to Kebmodee for bringing this to the It’s Interesting community.

by CHRISTIAN COTRONEO

If the startling results of a recent Austrian study are any indication, we should all get better acquainted with ashitaba.

In fact, we might even want to make a little room for this ancient Japanese plant beside the basil and lavender in the windowsill.

Ashitaba may have a bright future in Western households because the so-called “Tomorrow’s Leaf” promises just that: A future.

In a paper published this month in the journal Nature, researchers at the University of Graz, suggest a key component of the plant — called 4,4′-dimethoxychalcone, or DMC — may act as an anti-aging mechanism.

In experiments, the substance was found to prolong the lives of worms and fruit flies by as much as 20 percent.

Keeping the cellular process tidy
Researchers suggest DMC acts as a kind of “cellular garbage collector.” It basically speeds along the natural process by which frail and damaged cells are shed to be replaced by shiny new ones.

Normally, the crusty old cells are removed regularly through a process called autophagy. But as we age, the body’s trash collector starts missing appointments, allowing the damaged cells to accumulate, opening the door for a wide range of diseases and disorders.

In the experiments, DMC kept the process whirring along.

So what exactly is this humble hero — and more importantly, why haven’t we carpeted the planet with it yet?

Well, it’s not much to look at, and its leaves are said to be rather bitter — but that likely just gives adds more cred for its centuries-long use as a traditional medicine.

Let’s face it, practitioners of traditional medicine were probably the first to offer the cheerful slogan, “It tastes awful and it works.”

And those ancient chemists stood by the myriad benefits of Angelica keiskei — the plant’s botanical name — touting its powers of increasing breast milk flow, easing blood pressure and even calming the savage ulcer.

Samurai, too, were notorious nibblers— not so much for the plant’s breast milk-boosting ways, but rather its reputation for adding years to one’s life.

But does it really work? Or does it get a pass from traditional medicine because it tastes awful?

Keep in mind that Austrian researchers developed an intensive process to isolate the DMC, administering concentrated dosages to subjects. You’re not likely to be overwhelm your anti-aging genes by chewing on a bale of ashitaba, or making it into a nice tea.

Also, although this was the first time DMC was tested on living animals, there’s a wide chasm between worms and human beings. Countless promising experiments involving animals have crashed hard against the very different reality of human biology.

“The experiments indicate that the effects of DMC might be transferable to humans, although we have to be cautious and wait for real clinical trials,” Frank Madeo, lead author of the study, tells Medical News Today.

Human testing, he adds, will follow, only after researchers see how DMC fares at torquing the hearts of mice.

Of course, that doesn’t mean you can’t get a headstart on what could well become the ultimate opiate for the age-obsessed masses — and grow your own little ashitaba garden.

“Angelicas [another name for the plant] like to be cold stratified,” San Francisco Botanical Garden curator Don Mahoney tells Modern Farmer.

That means keeping the seeds outside at night, preferably in 30-degree temperatures, to help them germinate. As an alternative, Mahoney suggests, a couple of weeks in the fridge could kickstart the process.

“Nearly all of my last batch of seeds germinated,” he explains.

From there, it’s all in the hands of quality soil, while you gradually increase the pot size until the seedling are ready for the ground.

Ashitaba is partial to cool, damp conditions. So in the summer, it might seem like you messed up yet another gardening gambit. But then, when things cool down, “Tomorrow’s Leaf” rises mightily to the occasion.

The plants generally grow to around four feet high. Not only that, but they have a remarkable knack for rejuvenating themselves — a leaf cut off in the morning will start growing back the next day.

As far as looks go, ashitaba, which is a relative of the carrot, isn’t going to make your begonias blush. But its leaves, stems and yellow sap still course with nutrients. Even if the age-torquing upside doesn’t work out, it still packs promise for ulcers and breast milk and even blood pressure.

At the very least, all that promise of extending life will be a nice conversation piece — even if all it ever ends up enlivening is your salad.

And remember: Even the samurai died of old age at some point.

https://www.mnn.com/your-home/organic-farming-gardening/stories/ashitaba-plant-antiaging-properties-how-to-grow

by Fiona MacDonald

Most of us know that at some point in our evolutionary history around 600 million years ago, single-celled organisms evolved into more complex multicellular life.

But knowing that happened and actually seeing it happen in real-time in front of you is an entirely different matter altogether.

And that’s exactly what researchers from the George Institute of Technology and University of Montana have witnessed – and captured in the breathtaking, time-lapse footage below.

The evolution took just 50 weeks, and was triggered by the introduction of a simple predator.

In this incredible experiment, the team was trying to figure out exactly what drove single-celled organisms to become multicellular all those years ago.

One hypothesis is that it was predation that put selective pressure on single-celled organisms, causing them to become more complex.

So to test the validity of this in the lab, the team led by evolutionary biologist William Ratcliff, took populations of single-celled green alga Chlamydomonas reinhardtii.

They then put a single-celled filter-feeding predator in the mix, Paramecium tetraurelia and watched what happened.

Incredibly, the researchers watched as in just 50 weeks – less than the span of a year – two out of five experimental populations of the single-celled creatures evolved into multicellular life.

“Here we show that de novo origins of simple multicellularity can evolve in response to predation,” the team write in their paper.

Fifty weeks is a relative blink of an eye on the evolutionary scale. For the algae it was a little longer – 750 generations. But that’s still quite impressive when you think that they evolved entirely new life cycles.

Being able to witness something like this is not only absolutely mind-blowing, but it also suggests that predation could have played some kind of role in at least part of the evolution of multicellularity.

Not only that, but the resulting multicellular organisms were all incredibly varied. Just like you’d expect in natural evolution.

“Considerable variation exists in the evolved multicellular life cycles, with both cell number and propagule size varying among isolates,” the team write in their paper.

“Survival assays show that evolved multicellular traits provide effective protection against predation.”

The research has been published in Scientific Reports and the full paper is freely available.

https://www.nature.com/articles/s41598-019-39558-8

by Mike McRae

Earth might have a dizzying array of life forms, but our biology ultimately remains a solitary data point – we simply don’t have a reference for life based on DNA different from our own. Now, scientists have taken matters into their hands to push the boundaries on what life could be like.

Research funded by NASA and led by the Foundation for Applied Molecular Evolution in the US has led to the creation of an entirely new flavour of the DNA double helix, one that has an additional four nucleotide bases.

It’s being called hachimoji DNA (from the Japanese words for ‘eight letters’) and it includes two new pairs to add to the existing partnerships of adenine (A) paired with thymine (T), and guanine (G) with cytosine (C).

This work to expand on nature’s own genetic recipe might sound a little familiar. The same scientists already successfully squeezed in two new letters in 2011. Only last year yet another version of an extended alphabet, also with six letters, was made to function inside a living organism.

Now, in what might seem like a case of overachievement, researchers have gone back to the drawing board to develop even more non-standard nucleotides.

They have a purpose for doubling the number of codes in the recipe book, though.

“By carefully analysing the roles of shape, size and structure in hachimoji DNA, this work expands our understanding of the types of molecules that might store information in extraterrestrial life on alien worlds,” says chemist Steven Benner.

We already know a lot about the stability and functionality of ‘natural’ DNA under a range of environmental conditions, and are slowly teasing apart possible scenarios describing its evolution from simpler organic materials to living chemistry.

But to really get a good sense of how a genetic system could evolve, we need to test the limits of its underlying chemistry.

Hachimoji DNA certainly allows for that. The new codes, labelled P, B, Z and S, are based on the same kind of nitrogenous molecules as existing ones, categorised as purines and pyrimidines.

Similarly, they link up with hydrogen bonds to form their own base pairs – S bonding with B, and P with Z.

That’s where the similarities fade out. These new ‘letters’ introduce dozens of new chemical parameters to the double helix structure that potentially affect how it zips and twists.

By devising models that predict the molecule’s stability and then observing actual structures made of this ‘alien’ DNA, researchers are better equipped what’s truly important when it comes to the fundamentals of a genetic template.

The researchers constructed hundreds of hachimoji helices made up of different configurations of natural and synthetic bases and then subjected them to a range of conditions to see how well they held up.

While there were a few minor differences in how the new letters behaved, there was no reason to believe hachimoji DNA wouldn’t work well as an information-carrying template that could mutate and evolve.

The team not only showed their synthetic letters could contribute to new codes without swiftly disintegrating, the sequences were also translated into synthetic RNA versions.

Their work falls well short of a second genesis. But a novel DNA format such as this is a step towards determining what living chemistry might – and might not – look like elsewhere in the Universe.

“Life detection is an increasingly important goal of NASA’s planetary science missions, and this new work will help us to develop effective instruments and experiments that will expand the scope of what we look for,” says NASA’s Planetary Science Division’s acting director, Lori Glaze.

Devising new bases that can operate alongside our own DNA also has applications closer to home, not only as a way to reprogram life with a different code base, but in our effort to build new kinds of nanostructures.

The sky really isn’t the limit with synthetic DNA. This is going to take us to the stars and back again.

This research was published in Science.

https://www.sciencealert.com/scientists-made-synthetic-dna-using-8-letters-and-it-could-help-us-find-aliens

by David Nield

Scientists are genetically modifying mosquitoes in a high-security lab – and they’re hoping the insects will help wipe out some of the mosquito-borne diseases that continue to plague communities worldwide.

It’s known as a gene drive: where mosquitoes modified to be incapable of passing on a particular virus are used to replace the existing population of insects over several generations, with the modified genes being passed on to all their offspring.

The idea has attracted controversy because it messes with the fundamentals of nature, but it’s now under consideration by the World Health Organisation (WHO). This particular testing has entered a new phase, NPR reports, with a large-scale release of genetically modified mozzies inside a facility in Terni, Italy.

“This will really be a breakthrough experiment,” entomologist Ruth Mueller, who runs the lab, told Rob Stein at NPR. “It’s a historic moment. It’s very exciting.”

Using the ‘molecular scissor’ editing technique CRISPR, a gene known as “doublesex” in the bugs has been altered. The gene transforms female mosquitoes, taking away their biting ability and making them infertile.

At the moment, the bugs are being released in cages designed to replicate their natural environments, with hot and humid air, and places to shelter. Artificial lights are used to simulate sunrise and sunset.

The idea is to see if the mosquitoes with CRISPR-edited genetic code can wipe out the unmodified insects inside the cages. It follows on from previous proof-of-concept studies that we’ve seen before.

Ultimately these mosquitoes could be released in areas hit by malaria, bringing the local mozzie population crashing down and saving human lives. The disease is responsible for more than 400,000 deaths every year – mostly young children.

Reducing those figures sounds like a great idea, so why the controversy? Well, many scientists are urging caution when it comes to altering genetic code at this fundamental level – we just don’t know what impact these genetically edited mosquitoes will have on the world around them.

For that reason the lab has been designed to minimise any chance that the specially engineered mosquitoes could escape. The testing has also been specifically located in Italy, where this mosquito species – Anopheles gambiae – wouldn’t be able to survive outside in the natural climate.

“This is a technology where we don’t know where it’s going to end,” Nnimmo Bassey, director of the Health of Mother Earth Foundation in Nigeria, told NPR. “We need to stop this right where it is. They’re trying to use Africa as a big laboratory to test risky technologies.”

Some experts think adding genetically modified mosquitoes to natural ecosystems could harm other plants and animals that depend on them. There are a lot of unknowns.

The team behind the new experiments counters the critique by saying they’re working slowly and methodically – and that the potential side effects are outweighed by the benefits of eradicating malaria.

At the moment scientists are targeting just one species of mosquito out of hundreds, and several more years of research and consultation are planned before genetically edited mozzies would ever be released.

“There’s going to be concerns with any technology,” one of the research team, Tony Nolan from Imperial College London in the UK, told NPR.

“But I don’t think you should throw out a technology without having done your best to understand what its potential is to be transformative for medicine. And, were it to work, this would be transformative.”

https://www.sciencealert.com/scientists-take-first-step-in-controversial-mosquito-gene-drive-experiment