Showing posts with label Scientific American. Show all posts
Showing posts with label Scientific American. Show all posts
Friday, February 23
Minds Blown by Quantum Physics
The quantum world defies common sense at every turn. Shaped across hundreds of thousands of years by biological evolution, our modern human brain struggles to comprehend things outside our familiar naturalistic context.
Understanding a predator chasing prey across a grassy plain is easy; understanding most anything occurring at subatomic scales may require years of intense scholarship and oodles of gnarly math.
It’s no surprise, then, that every year physicists deliver mind-boggling new ideas and discoveries harvested from reality’s deep underpinnings, well beyond the frontiers of our perception. Here, Scientific American highlights some of our favorites from 2022. READ MORE...
Friday, December 29
Sterile Neutrinos Unlocking Secrets
The neutrino is perhaps the most fascinating inhabitant of the subatomic world. Nearly massless, this fundamental particle experiences only the weak nuclear force and the much fainter force of gravity. With no more than these feeble connections to other forms of matter, a neutrino can pass through the entire Earth with just a tiny chance of hitting an atom. Ghosts, who are said to be able to pass through walls, have nothing on neutrinos.
The neutrinos’ phantom properties are not the only thing that sets them apart from other fundamental particles. They are unique in that they don’t have a fixed identity. The three known forms of neutrinos are able to transform into one another through a cyclical process called neutrino oscillation. In addition to being subatomic specters, they are also quantum chameleons. READ MORE...
Friday, September 1
Brain Reading Devices Using Thoughts
A brain-computer interface translates the study participant’s brain signals into the speech and facial movements of an animated avatar. Credit: Noah Berger
Brain-reading implants enhanced using artificial intelligence (AI) have enabled two people with paralysis to communicate with unprecedented accuracy and speed.
In separate studies, both published on 23 August in Nature, two teams of researchers describe brain–computer interfaces (BCIs) that translate neural signals into text or words spoken by a synthetic voice. The BCIs can decode speech at 62 words per minute and 78 words per minute, respectively.
Natural conversation happens at around 160 words per minute, but the new technologies are both faster than any previous attempts.
“It is now possible to imagine a future where we can restore fluid conversation to someone with paralysis, enabling them to freely say whatever they want to say with an accuracy high enough to be understood reliably,” said Francis Willett, a neuroscientist at Stanford University in California who co-authored one of the papers, in a press conference on 22 August. READ MORE...
Wednesday, May 3
Pioneerng Nuclear Fusion
To achieve fusion, the U.S. National Ignition Facility focuses its lasers onto a gold cylinder containing a diamond capsule filled with hydrogen isotopes. NIF could need safety upgrades, if its energy yields continue to climb. Credit: UPI/Alamy Stock Photo
Last month, the US National Ignition Facility (NIF) fired its lasers up to full power for the first time since December, when it achieved its decades-long goal of ‘ignition’ by producing more energy during a nuclear reaction than it consumed. The latest run didn’t come close to matching up: NIF achieved only 4% of the output it did late last year. But scientists didn’t expect it to.
Building on NIF’s success, they are now flexing the programme’s experimental muscles, trying to better understand the nuclear-fusion facility’s capabilities. Here, Nature looks at what’s to come for NIF, and whether it will propel global efforts to create a vast supply of clean energy for the planet.
WHAT WAS THE GOAL OF THE LATEST EXPERIMENT?
NIF, based at Lawrence Livermore National Laboratory (LLNL) in California, is a stadium-sized facility that fires 192 lasers at a tiny gold cylinder containing a diamond capsule. Inside the capsule sits a frozen pellet of the hydrogen isotopes deuterium and tritium. The lasers trigger an implosion, creating extreme heat and pressure that drive the hydrogen isotopes to fuse into helium, releasing additional energy.
One of the main challenges in getting this scheme to work is fabricating the diamond capsule. Even the smallest defects — bacterium-sized pockmarks, metal contamination or variations in shape and thickness — affect the implosion, and thus the pressure and heat that drive the fusion reactions.
Record-breaking experiments in 2021 and 2022 used the best capsules available, but in March, while waiting for a new batch, NIF scientists ran an experiment with a capsule that was thicker on one side than the other. Modelling suggested that they could offset this imperfection by adjusting the beams coming from the lasers, to produce a more uniform implosion. This was a test of their theoretical predictions, says Richard Town, a physicist who heads the lab’s inertial-confinement fusion science programme at the LLNL.
The results fell short of their predictions, and researchers are now working to understand why. But if this line of investigation pays off, Town says, “it opens up more capsules for us to use and will improve our understanding of implosion”. READ MORE...
NIF, based at Lawrence Livermore National Laboratory (LLNL) in California, is a stadium-sized facility that fires 192 lasers at a tiny gold cylinder containing a diamond capsule. Inside the capsule sits a frozen pellet of the hydrogen isotopes deuterium and tritium. The lasers trigger an implosion, creating extreme heat and pressure that drive the hydrogen isotopes to fuse into helium, releasing additional energy.
One of the main challenges in getting this scheme to work is fabricating the diamond capsule. Even the smallest defects — bacterium-sized pockmarks, metal contamination or variations in shape and thickness — affect the implosion, and thus the pressure and heat that drive the fusion reactions.
Record-breaking experiments in 2021 and 2022 used the best capsules available, but in March, while waiting for a new batch, NIF scientists ran an experiment with a capsule that was thicker on one side than the other. Modelling suggested that they could offset this imperfection by adjusting the beams coming from the lasers, to produce a more uniform implosion. This was a test of their theoretical predictions, says Richard Town, a physicist who heads the lab’s inertial-confinement fusion science programme at the LLNL.
The results fell short of their predictions, and researchers are now working to understand why. But if this line of investigation pays off, Town says, “it opens up more capsules for us to use and will improve our understanding of implosion”. READ MORE...
Sunday, April 16
Is There Really a Multiverse?
The notion of parallel universes leapt out of the pages of fiction into scientific journals in the 1990s. Many scientists claim that mega-millions of other universes, each with its own laws of physics, lie out there, beyond our visual horizon. They are collectively known as the multiverse.- The trouble is that no possible astronomical observations can ever see those other universes. The arguments are indirect at best. And even if the multiverse exists, it leaves the deep mysteries of nature unexplained.
In the past decade an extraordinary claim has captivated cosmologists: that the expanding universe we see around us is not the only one; that billions of other universes are out there, too. There is not one universe—there is a multiverse.
In Scientific American articles and books such as Brian Greene’s latest, The Hidden Reality, leading scientists have spoken of a super-Copernican revolution. In this view, not only is our planet one among many, but even our entire universe is insignificant on the cosmic scale of things. It is just one of countless universes, each doing its own thing.
The word “multiverse” has different meanings. Astronomers are able to see out to a distance of about 42 billion light-years, our cosmic visual horizon. We have no reason to suspect the universe stops there. Beyond it could be many—even infinitely many—domains much like the one we see.
The word “multiverse” has different meanings. Astronomers are able to see out to a distance of about 42 billion light-years, our cosmic visual horizon. We have no reason to suspect the universe stops there. Beyond it could be many—even infinitely many—domains much like the one we see.
Each has a different initial distribution of matter, but the same laws of physics operate in all. Nearly all cosmologists today (including me) accept this type of multiverse, which Max Tegmark calls “level 1.” Yet some go further. They suggest completely different kinds of universes, with different physics, different histories, maybe different numbers of spatial dimensions.
Most will be sterile, although some will be teeming with life. A chief proponent of this “level 2” multiverse is Alexander Vilenkin, who paints a dramatic picture of an infinite set of universes with an infinite number of galaxies, an infinite number of planets and an infinite number of people with your name who are reading this article.
Similar claims have been made since antiquity by many cultures. What is new is the assertion that the multiverse is a scientific theory, with all that implies about being mathematically rigorous and experimentally testable. I am skeptical about this claim.
Similar claims have been made since antiquity by many cultures. What is new is the assertion that the multiverse is a scientific theory, with all that implies about being mathematically rigorous and experimentally testable. I am skeptical about this claim.
I do not believe the existence of those other universes has been proved—or ever could be. Proponents of the multiverse, as well as greatly enlarging our conception of physical reality, are implicitly redefining what is meant by “science.” READ MORE...
Monday, March 20
Alien Life Being Obliterated by Moons
The moon crashing into Earth may sound like an unrealistic doomsday scenario or the stuff of sci-fi disasters. But for some planets in other star systems, such catastrophic collisions may be common.
New research published in the journal Monthly Notices of the Royal Astronomical Societyuses computer simulations to show that collisions between exoplanets and their moons (called exomoons) may actually be a regular occurrence, which could be disastrous for any budding alien life on those planets.
While astronomers have yet to make a confident detection of an exomoon, scientists expect them to be plentiful in the universe.
"We know of lots of moons in our own solar system, so naturally we'd expect to see moons in exoplanet systems," Jonathan Brande, a University of Kansas astrophysicist who was not associated with the new study, told Live Science in an email. Therefore, theorists such as Brad Hansen, an astronomer at the University of California, Los Angeles and author of the new study, are interested in exploring how alien moons and exoplanets may interact, and how these interactions affect the potential for life in distant star systems.
Runaway moons
Gravity rules the interactions between a planet and its moons, manifesting as tides and other effects, like the slow recession of our own moon. Every year, Earth's moon creeps a little over an inch farther away from our planet, its orbit growing larger each year. At the same time, Earth spins a little more slowly every year. These two effects are directly related: Earth is giving some of the angular momentum from its spin to the moon's orbit.
If this trade-off were to continue long enough, the moon could eventually become unbound from Earth. Thankfully for us, this process would take so long that the sun would explode long before the moon could fully escape. But around some exoplanets, particularly those much closer to their stars than Earth is to the sun, this situation could evolve much faster, with planets and their "unstable" moons colliding within the first billion years of their formation, according to Hansen's calculations. (For comparison, Earth and its moon are about 4.5 billion years old).
In his simulations, moons that wandered away from their host planets often returned with a bang, smashing into the planet and creating huge dust clouds. These dust clouds glowed in the infrared, as they were illuminated and warmed by the star's light. But they lasted only about 10,000 years before fading away — a cosmic blink of an eye.
Observations from NASA's Wide-field Infrared Survey Explorer space telescope suggest that every star will undergo one such event at some point in its lifetime, Hansen said. It's plausible that these dust emissions represent the collisions between planets and their moons, he added. READ MORE...
Tuesday, November 8
Mysteries of King Tut
It is one of the most iconic discoveries in all of archaeology—the treasure-filled tomb of the young Egyptian pharaoh Tutankhamun, better known as King Tut. One hundred years ago today British archaeologist Howard Carter and an Egyptian excavation team found the boy king’s final resting place. Scholars have been studying the royal tomb and its owner ever since.
From this work the broad outlines of the life and times of Tut have emerged. Many mysteries remain, however, including how the young pharaoh was related to Queen Nefertiti (herself a subject of debate), how influential he was as a ruler and how he died. Now new findings are emerging that could fill in some of the missing details. But as ever, debates rage over how to interpret them.
The key to Tut’s discovery was dogged perseverance. By November 4, 1922, Carter and his team had spent five futile years searching for an undiscovered royal tomb in Egypt’s Valley of the Kings. The prevailing wisdom said that everything the valley had to offer had already been found. Carter decided to spend what was to be his final field season digging beneath a group of huts that housed the ancient tomb builders.
The key to Tut’s discovery was dogged perseverance. By November 4, 1922, Carter and his team had spent five futile years searching for an undiscovered royal tomb in Egypt’s Valley of the Kings. The prevailing wisdom said that everything the valley had to offer had already been found. Carter decided to spend what was to be his final field season digging beneath a group of huts that housed the ancient tomb builders.
“We had almost made up our minds that we were beaten...,” he and archaeologist Arthur Cruttenden Mace wrote in The Discovery of the Tomb of Tutankhamen, their account of the expedition. “Hardly had we set hoe to ground in our last despairing effort than we made a discovery beyond our wildest dreams.”
Beneath those huts, the excavation team uncovered a step cut into the rock. Within days the team had dug out a steep staircase and a 30-foot-long passageway that ended in a door sealed with plaster and stamped with the royal necropolis seal. Carter waited to open the door until his benefactor George Edward Stanhope Molyneux Herbert, fifth earl of Carnarvon, who had funded his work in the valley for all those years, could travel to the site.
Beneath those huts, the excavation team uncovered a step cut into the rock. Within days the team had dug out a steep staircase and a 30-foot-long passageway that ended in a door sealed with plaster and stamped with the royal necropolis seal. Carter waited to open the door until his benefactor George Edward Stanhope Molyneux Herbert, fifth earl of Carnarvon, who had funded his work in the valley for all those years, could travel to the site.
The next day the team dug out a steep staircase and a door sealed with plaster and stamped with the royal necropolis seal. Carter waited to open the door until his benefactor George Edward Stanhope Molyneux Herbert, fifth earl of Carnarvon, who had funded his work in the valley for all those years, could travel to the site. On November 24, 1922, it was cleared to reveal a corridor, followed by a 30-foot-long passageway that ended in another door. On November 26, 1922, Carter broke open a small hole in the door and stuck a candle through, casting the first light into the chamber in nearly 3,300 years.
The sight held him speechless as his eyes adjusted. “Details of the room emerged slowly from the mist, strange animals, statues, and gold—everywhere the glint of gold,” Carter wrote in The Discovery of the Tomb of Tutankhamen. He was looking into the antechamber of the tomb of Tutankhamun, a ruler who sat his throne for only around 10 years but did so at a pivotal time in Egyptian history. READ MORE...
Wednesday, July 27
Searching for Meaning
Summary: Appreciating the beauty in the smaller things in everyday life can contribute to a more meaningful existence, a new study reports.
Source: Texas A&M
Appreciating the intrinsic beauty in life’s everyday moments can contribute to a more meaningful existence, according to new research.
In a paper recently published in Nature Human Behavior, Joshua Hicks, a professor in the Texas A&M University Department of Psychological and Brain Sciences, says this may be a previously unaccounted for factor tied to perceptions of meaning.
“It might not relate to whether you matter in the grand scheme of things, but we’ve shown people who value the little things, like your cup of coffee in the morning or being mindful in conversations with others, tend to have a high sense of meaning in life,” he said.
Hicks studies existential psychology. Put simply, he aims to understand the “big questions” in life. He describes his main focus as the experience of life—studying people’s subjective feeling that their life has meaning.
Scholars like Hicks generally agree there are three main sources of a subjectively meaningful existence: coherence, or the feeling that one’s life “makes sense”; the possession of clear, long-term goals and sense of purpose; and existential mattering. This last factor, he says, is the belief that one’s actions matter to others.
What Hicks and his co-authors argue in their latest research is that appreciating and finding value in experiences, referred to as experiential appreciation, is a fourth fundamental pathway toward finding meaning in life.
Researchers measured this factor by asking study participants how strongly they identified with statements linked to finding beauty in life and appreciating a wide variety of experiences.
They were also asked to recall the most meaningful event of the past month, among other questions, with the goal of measuring experiential appreciation. Hicks described this series of experiments in a recent article he co-authored for Scientific American.
In each case, the results confirmed the original theory that appreciating small moments can make for a more meaningful life. READ MORE...
Wednesday, July 20
The Aliens are Us
On a geologic timescale, the emergence of the human “dataome” is like a sudden invasion by extraterrestrials or an asteroid impact that precipitates a mass extinction...
Something very old, very powerful and very special has been unleashed on Earth.
Humans are strange. For a global species, we’re not particularly genetically diverse, thanks in part to how our ancient roaming explorations caused “founder effects” and “bottleneck events” that restricted our ancestral gene pool. We also have a truly outsize impact on the planetary environment without much in the way of natural attrition to trim our influence (at least not yet).
But the strangest thing of all is how we generate, exploit, and propagate information that is not encoded in our heritable genetic material, yet travels with us through time and space. Not only is much of that information represented in purely symbolic forms—alphabets, languages, binary codes—it is also represented in each brick, alloy, machine, and structure we build from the materials around us. Even the symbolic stuff is instantiated in some material form or the other, whether as ink on pages or electrical charges in nanoscale pieces of silicon.
Altogether, this “dataome” has become an integral part of our existence. In fact, it may have always been an integral, and essential, part of our existence since our species of hominins became more and more distinct some 200,000 years ago. This idea, which I also pursue in my upcoming book, The Ascent of Information, leads to a number of quite startling and provocative proposals.
For example, let’s consider our planetary impact. Today we can look at our species’ energy use and see that of the roughly six to seven terawatts of average global electricity production, about 3 percent to 4 percent is gobbled up by our digital electronics, in computing, storing and moving information.
That might not sound too bad—except the growth trend of our digitized informational world is such that it requires approximately 40 percent more power every year. Even allowing for improvements in computational efficiency and power generation, this points to a world in some 20 years where all of the energy we currently generate in electricity will be consumed by digital electronics alone.
And that’s just one facet of the energy demands of the human dataome. We still print onto paper, and the energy cost of a single page is the equivalent of burning five grams of high-quality coal. Digital devices, from microprocessors to hard drives, are also extraordinarily demanding in terms of their production, owing to the deep repurposing of matter that is required.
And that’s just one facet of the energy demands of the human dataome. We still print onto paper, and the energy cost of a single page is the equivalent of burning five grams of high-quality coal. Digital devices, from microprocessors to hard drives, are also extraordinarily demanding in terms of their production, owing to the deep repurposing of matter that is required.
We literally fight against the second law of thermodynamics to forge these exquisitely ordered, restricted, low-entropy structures out of raw materials that are decidedly high-entropy in their messy natural states. It is hard to see where this informational tsunami slows or ends. READ MORE...
Tuesday, May 10
Molten Salt Battery & Energy
Close-up of the freeze-thaw battery developed by the PNNL team.
Credit: Andrea Starr/Pacific Northwest National Laboratory
During spring in the Pacific Northwest, meltwater from thawing snow rushes down rivers and the wind often blows hard. These forces spin the region’s many power turbines and generate a bounty of electricity at a time of mild temperatures and relatively low energy demand. But much of this seasonal surplus electricity—which could power air conditioners come summer—is lost because batteries cannot store it long enough.
Researchers at Pacific Northwest National Laboratory (PNNL), a Department of Energy national laboratory in Richland, Wash., are developing a battery that might solve this problem. In a recent paper published in Cell Reports Physical Science, they demonstrated how freezing and thawing a molten salt solution creates a rechargeable battery that can store energy cheaply and efficiently for weeks or months at a time.
Researchers at Pacific Northwest National Laboratory (PNNL), a Department of Energy national laboratory in Richland, Wash., are developing a battery that might solve this problem. In a recent paper published in Cell Reports Physical Science, they demonstrated how freezing and thawing a molten salt solution creates a rechargeable battery that can store energy cheaply and efficiently for weeks or months at a time.
Such a capability is crucial to shifting the U.S. grid away from fossil fuels that release greenhouse gases and toward renewable energy. President Joe Biden has made it a goal to cut U.S. carbon emissions in half by 2030, which will necessitate a major ramp-up of wind, solar and other clean energy sources, as well as ways to store the energy they produce.
Most conventional batteries store energy as chemical reactions waiting to happen. When the battery is connected to an external circuit, electrons travel from one side of the battery to the other through that circuit, generating electricity. To compensate for the change, charged particles called ions move through the fluid, paste or solid material that separates the two sides of the battery.
Most conventional batteries store energy as chemical reactions waiting to happen. When the battery is connected to an external circuit, electrons travel from one side of the battery to the other through that circuit, generating electricity. To compensate for the change, charged particles called ions move through the fluid, paste or solid material that separates the two sides of the battery.
But even when the battery is not in use, the ions gradually diffuse across this material, which is called the electrolyte. As that happens over weeks or months, the battery loses energy. Some rechargeable batteries can lose almost a third of their stored charge in a single month. READ MORE...
Friday, April 29
Einstein's First Wife
A photograph of Mileva Marić and her husband, Albert Einstein in 1912.
While Mileva Marić was married to Albert Einstein, many believe she greatly contributed to his world-changing discoveries — only to be denied credit later on.
In 1896, a young Albert Einstein walked into the Polytechnic Institute in Zurich. The 17-year-old student was beginning a four-year program in the school’s physics and mathematics department. Of the five scholars admitted to the department that year, only one of them — Mileva Marić — was a woman.
Soon, the two young physics students were inseparable. Mileva Marić and Albert Einstein conducted research and wrote papers together, and soon began falling in love. “I’m so lucky to have found you,” Einstein wrote to Marić in a letter, “a creature who is my equal, and who is as strong and independent as I am! I feel alone with everyone else except you.”
But Einstein’s family never approved of Mileva Marić. And when their relationship soured, Einstein turned against his wife, and may have robbed her of crucial credit for her work on “his” groundbreaking discoveries.
Who Was Mileva Marić?
Mileva Marić was born in Serbia in 1875. A bright student from her early years, she quickly moved to the top of hlber class. According to Scientific American, in 1892, Marić became the only woman allowed to attend physics lectures at her Zagreb high school after her father petitioned the Minister of Education for an exemption.
According to her classmates, Marić was a quiet but brilliant student. Later, she became just the fifth woman at the Polytechnic Institute to study physics. READ MORE...
Friday, March 25
A Unified Theory of Math
Within mathematics, there is a vast and ever expanding web of conjectures, theorems and ideas called the Langlands program. That program links seemingly disconnected subfields. It is such a force that some mathematicians say it—or some aspect of it—belongs in the esteemed ranks of the Millennium Prize Problems, a list of the top open questions in math. Edward Frenkel, a mathematician at the University of California, Berkeley, has even dubbed the Langlands program “a Grand Unified Theory of Mathematics.”
The program is named after Robert Langlands, a mathematician at the Institute for Advanced Study in Princeton, N.J. Four years ago, he was awarded the Abel Prize, one of the most prestigious awards in mathematics, for his program, which was described as “visionary.”
Langlands is retired, but in recent years the project has sprouted into “almost its own mathematical field, with many disparate parts,” which are united by “a common wellspring of inspiration,” says Steven Rayan, a mathematician and mathematical physicist at the University of Saskatchewan. It has “many avatars, some of which are still open, some of which have been resolved in beautiful ways.”
Increasingly mathematicians are finding links between the original program—and its offshoot, geometric Langlands—and other fields of science. Researchers have already discovered strong links to physics, and Rayan and other scientists continue to explore new ones. He has a hunch that, with time, links will be found between these programs and other areas as well. “I think we’re only at the tip of the iceberg there,” he says. “I think that some of the most fascinating work that will come out of the next few decades is seeing consequences and manifestations of Langlands within parts of science where the interaction with this kind of pure mathematics may have been marginal up until now.” Overall Langlands remains mysterious, Rayan adds, and to know where it is headed, he wants to “see an understanding emerge of where these programs really come from.” READ MORE...
Wednesday, March 16
Quantum Mechanics and Free Will
Credit: francescoch/Getty Images
A conjecture called superdeterminism, outlined decades ago, is a response to several peculiarities of quantum mechanics: the apparent randomness of quantum events; their apparent dependence on human observation, or measurement; and the apparent ability of a measurement in one place to determine, instantly, the outcome of a measurement elsewhere, an effect called nonlocality.
Einstein, who derided nonlocality as “spooky action at a distance,” insisted that quantum mechanics must be incomplete; there must be hidden variables that the theory overlooks. Superdeterminism is a radical hidden-variables theory proposed by physicist John Bell. He is renowned for a 1964 theorem, now named after him, that dramatically exposes the nonlocality of quantum mechanics.
Bell said in a BBC interview in 1985 that the puzzle of nonlocality vanishes if you assume that “the world is superdeterministic, with not just inanimate nature running on behind-the-scenes clockwork, but with our behavior, including our belief that we are free to choose to do one experiment rather than another, absolutely predetermined.”
In a recent video, physicist Sabine Hossenfelder, whose work I admire, notes that superdeterminism eliminates the apparent randomness of quantum mechanics. “In quantum mechanics,” she explains, “we can only predict probabilities for measurement outcomes, rather than the measurement outcomes themselves. The outcomes are not determined, so quantum mechanics is indeterministic. Superdeterminism returns us to determinism.”
“The reason we can’t predict the outcome of a quantum measurement,” she explains, “is that we are missing information,” that is, hidden variables. Superdeterminism, she notes, gets rid of the measurement problem and nonlocality as well as randomness. Hidden variables determine in advance how physicists carry out the experiments; physicists might think they are choosing one option over another, but they aren’t. Hossenfelder calls free will “logically incoherent nonsense.”
Hossenfelder predicts that physicists might be able to confirm superdeterminism experimentally. “At some point,” she says, “it’ll just become obvious that measurement outcomes are actually much more predictable than quantum mechanics says. Indeed, maybe someone already has the data, they just haven’t analyzed it the right way.” Hossenfelder defends superdeterminism in more detail in a technical paper written with physicist Tim Palmer.
A conjecture called superdeterminism, outlined decades ago, is a response to several peculiarities of quantum mechanics: the apparent randomness of quantum events; their apparent dependence on human observation, or measurement; and the apparent ability of a measurement in one place to determine, instantly, the outcome of a measurement elsewhere, an effect called nonlocality.
Einstein, who derided nonlocality as “spooky action at a distance,” insisted that quantum mechanics must be incomplete; there must be hidden variables that the theory overlooks. Superdeterminism is a radical hidden-variables theory proposed by physicist John Bell. He is renowned for a 1964 theorem, now named after him, that dramatically exposes the nonlocality of quantum mechanics.
Bell said in a BBC interview in 1985 that the puzzle of nonlocality vanishes if you assume that “the world is superdeterministic, with not just inanimate nature running on behind-the-scenes clockwork, but with our behavior, including our belief that we are free to choose to do one experiment rather than another, absolutely predetermined.”
In a recent video, physicist Sabine Hossenfelder, whose work I admire, notes that superdeterminism eliminates the apparent randomness of quantum mechanics. “In quantum mechanics,” she explains, “we can only predict probabilities for measurement outcomes, rather than the measurement outcomes themselves. The outcomes are not determined, so quantum mechanics is indeterministic. Superdeterminism returns us to determinism.”
“The reason we can’t predict the outcome of a quantum measurement,” she explains, “is that we are missing information,” that is, hidden variables. Superdeterminism, she notes, gets rid of the measurement problem and nonlocality as well as randomness. Hidden variables determine in advance how physicists carry out the experiments; physicists might think they are choosing one option over another, but they aren’t. Hossenfelder calls free will “logically incoherent nonsense.”
Hossenfelder predicts that physicists might be able to confirm superdeterminism experimentally. “At some point,” she says, “it’ll just become obvious that measurement outcomes are actually much more predictable than quantum mechanics says. Indeed, maybe someone already has the data, they just haven’t analyzed it the right way.” Hossenfelder defends superdeterminism in more detail in a technical paper written with physicist Tim Palmer.
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