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Paradox declares pulp strategy The Lamplighters League a $22m flop – Eurogamer.net
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The Lamplighters League a ‘Big Disappointment’ for Paradox as It Confirms $22 Million Write-Down – IGN
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Paradox Interactive and Harebrained Schemes announce turn-based strategy game The Lamplighters League for Xbox Series, PC – Gematsu
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Leonardo da Vinci’s paradox on the periodic motion of bubbles cracked
Prof. Miguel Ángel Herrada, from the University of Seville, and Prof. Jens G. Eggers, from the University of Bristol, have discovered a mechanism to explain the unstable movement of bubbles rising in water. According to the researchers, the results, which are published in the journal PNAS, may be useful to understand the motion of particles whose behavior is intermediate between a solid and a gas.
Leonardo da Vinci observed five centuries ago that air bubbles, if large enough, periodically deviate in a zigzag or spiral from straight-line movement. However, no quantitative description of the phenomenon or physical mechanism to explain this periodic motion had ever been found.
The authors of this new paper have developed a numerical discretization technique to characterize precisely the bubble’s air-water interface, which enables them to simulate its motion and explore its stability. Their simulations closely match high-precision measurements of unsteady bubble motion and show that bubbles deviate from a straight trajectory in water when their spherical radius exceeds 0.926 millimeters, a result within 2% of experimental values obtained with ultrapure water in the 90s.
The researchers propose a mechanism for the instability of the bubble trajectory whereby periodic tilting of the bubble changes its curvature, thus affecting the upward velocity and causing a wobble in the bubble’s trajectory, tilting up the side of the bubble whose curvature has increased.
Then, as the fluid moves faster and the fluid pressure falls around the high-curvature surface, the pressure imbalance returns the bubble to its original position, restarting the periodic cycle.
More information:
Miguel A. Herrada et al, Path instability of an air bubble rising in water, Proceedings of the National Academy of Sciences (2023). DOI: 10.1073/pnas.2216830120
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Leonardo da Vinci’s paradox on the periodic motion of bubbles cracked (2023, January 17)
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This Trait of Red Dwarf Star Systems Could Help Us Resolve The Red Sky Paradox : ScienceAlert
There’s something very peculiar about Earth, aside from all the organisms crawling all over it. It’s our star, the Sun, that’s weird: It’s a yellow dwarf.
Sun-like stars are a minority in the Milky Way. It’s estimated that fewer than 10 percent of the stars in our galaxy are G-type stars, like the Sun.
The most abundant stars are those we can’t even see with the naked eye: red dwarfs. They’re only up to about half the mass of the Sun, cool, dim, and with the longest lifespans of any stars.
These stellar lightweights account for up to 75 percent of all the stars in the Milky Way. One would therefore think, statistically, that if life were to emerge anywhere, it would be on a planet around a red dwarf.
Yet here we are, with our yellow Sun. This discrepancy between expectation and reality is known as the Red Sky Paradox, and scientists have yet to figure it out.
A new paper, accepted into The Astrophysical Journal Letters and uploaded to preprint server arXiv while it undergoes peer review and publication, could have a clue.
Basically, it seems like it might be much harder for life as we know it to get started in red dwarf planetary systems – because they lack the asteroid and gas giant architecture to deliver the ingredients for life to Earth-like worlds.
The results could have implications for our search for life outside the Solar System, especially since exoplanets defined as “potentially habitable” are often found in orbit around red dwarf stars.
Red dwarfs, in some respects, are some of the most promising targets in our search for habitable worlds. Because they are so small, they burn through their hydrogen fuel much more slowly than Sun-like stars do.
They can hang around for potentially trillions of years – much longer than the estimated 10 billion-year lifespan of the Sun and even the 13.8 billion-year age of the Universe. This means there’s more time available for life to emerge and potentially thrive.
Red dwarfs also represent an opportunity for our current detection methods. Because they burn so slowly, they are cooler and dimmer than the Sun. This means that the habitable zone – the distance range from the star in which habitable temperatures can be found – is much closer. Recently, astronomers discovered an exoplanet in the habitable zone of a red dwarf star with an orbit of just 8.4 days.
But it seems like life’s emergence and continued existence might be a tricky thing.
Previous studies have suggested that red dwarfs might not present the most hospitable environment. For example, such stars tend to be very active, frequently erupting with flares that would lash any close planets with radiation.
The authors of the new paper – astronomers Anna Childs, Rebecca Martin, and Mario Livio of the University of Nevada, Las Vegas – wanted to determine if red dwarf systems had enough of the ingredients that we think kick-started life on Earth.
Current studies suggest that asteroid and comet bombardment relatively late in the Solar System’s youth altered Earth’s crust in ways that made it more hospitable to life and delivered many of the chemical ingredients necessary for it.
Without an asteroid belt, therefore, the terraforming and chemical delivery systems for life are significantly reduced.
Models suggest that the formation of a stable asteroid belt, and late asteroid bombardment, requires the presence of a gas giant beyond a distance from the star known as the snow line, beyond which volatile compounds condense into solid ice. This is because such a gas giant can gravitationally interact with the asteroid belt, causing instabilities that pelt asteroids inwards towards the habitable zone.
So the researchers looked at red dwarf systems to see if they could find one of these gas giants.
There are currently 48 red dwarf stars with confirmed, rocky exoplanets orbiting in the habitable zone. Of these, 27 have more than one exoplanet. Of that group, 16 have mass measurements for the exoplanets in the system.
Defining a gas giant as a planet between 0.3 and 60 times the mass of Jupiter and calculating the position of the snow line for those systems, the team went looking for gas giants.
They found that none of the systems with a rocky, Earth-like planet in the habitable zone had a known gas giant as well.
Statistically, the team calculated, that there is a population of giant exoplanets orbiting red dwarf stars beyond the snow line. This means that, theoretically, red dwarf stars can have asteroid belts.
It’s just that none of the known red dwarf systems with habitable zone rocky worlds are likely among that category, suggesting that red dwarf planetary system architecture can be wildly different from the Solar System we know and love.
There are a lot of assumptions at play. For example, maybe asteroid impacts aren’t all that important. Maybe life on red dwarf exoplanets doesn’t look at all like life on Earth. Maybe we’re overestimating the significance of the habitable zone.
However, based on our current knowledge and understanding of life, things aren’t looking great for red dwarf planets.
“The lack of giant planets in the (so far) observed systems containing habitable zone exoplanets suggests that these systems are unlikely to harbor an asteroid belt and the mechanism required for late-stage asteroid delivery to the habitable zone,” the researchers write.
“Therefore, if asteroid impacts are indeed necessary for life, it is unlikely that the observed planets in the habitable zone harbor life.”
And, in turn, that might be at least partially why our home planet isn’t orbiting one of these cranky little red stars.
The research has been accepted into The Astrophysical Journal Letters and is available on arXiv.
Best of Last Week – Solving Hawking’s black hole paradox, a new form of ice, bad cholesterol may not be so bad
It was a good week for physics research as work by two teams of theorists working independently may have solved Stephen Hawking’s black hole paradox. The first demonstrated that black holes are more complex than thought, while the second followed up on work by the first suggesting that their proposed “quantum hair” resolves the paradox. Also, a team at Pennsylvania State University developed a novel theory of entropy that may solve materials design issues. Called Zentropy, it involves predicting the change of volume as a function of temperature at a multiscale level. And a team at the University of Nevada, Las Vegas discovered a new form of ice, adding to the 20 known solid forms.
In technical news, a combined team from the University of Cambridge and the University of Oslo showed that a mathematical paradox can demonstrate the limits of AI, helping to explain why AI systems have difficulty “knowing” when they are making errors. Also, a team at Carnegie Mellon University created a system that allows users to control robotic hands and arms remotely by demonstrating movements in front of a camera. And a team at Sinhgad Institute of Technology Lonavala developed a new model to automatically detect and filter spam emails. Also, an international team of materials scientists discovered why perovskite solar cells degrade in sunlight and an easy fix for it, one that involves using a different surface treatment to resolve defects.
In other news, a team with members from Karolinska Institutet, the Helmholtz Center Munich and the Technical University of Munich, found that elevated inflammation can persist in immune cells for months after a mild COVID-19 infection. Also, an international team of researchers found evidence of the effects of ancient carbon releases on the planet, suggesting possible scenarios for Earth’s future climate.
And finally, a team at The Royal College of Surgeons in Ireland’s University of Medicine and Health Sciences found the link between high cholesterol and heart disease to be “inconsistent.”
Scientists may have solved Stephen Hawking’s black hole paradox
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A spiderweb of wormholes could solve a fundamental paradox first proposed by Stephen Hawking
A seemingly intractable black hole paradox first proposed by physicist Stephen Hawking could finally be resolved — by wormholes through space-time.
The “black hole information paradox” refers to the fact that information cannot be destroyed in the universe, and yet when a black hole eventually evaporates, whatever information was gobbled up by this cosmic vacuum cleaner should have long since vanished. The new study proposes that the paradox could be resolved by nature’s ultimate cheat code: wormholes, or passages through space-time.
“A wormhole connects the interior of the black hole and the radiation outside, like a bridge,” Kanato Goto, a theoretical physicist at the RIKEN Interdisciplinary Theoretical and Mathematical Sciences Program in Japan, said in a statement.
Under Goto’s theory, a second surface appears inside the event horizon of a black hole, the boundary beyond which nothing can escape. Threads from a wormhole connect that surface to the outside world, entangling information between the interior of the black hole and the radiation leaks at its edges.
Black hole information paradox
In the 1970s, Hawking discovered that black holes aren’t exactly black, but at first, he didn’t realize the giant problem he had created. Before his discovery, physicists had assumed that black holes were exceedingly simple. Sure, all sorts of complicated stuff fell into them, but the black holes locked all that information away, never to be seen again.
But Hawking found that black holes release radiation, and can eventually evaporate entirely, in a process now known as Hawking radiation But that radiation didn’t carry any information itself. Indeed, it couldn’t; by definition, the event horizon of a black hole prevents information from leaving. So, when a black hole finally evaporates and disappears from the universe, where did all its locked-up information go?
Related: 4 bizarre Stephen Hawking theories that turned out to be right
This is the black hole information paradox. One possibility is that information can be destroyed, which seems to violate everything we know about physics. (For instance, if information can be lost, then you can’t reconstruct the past from present events, or predict future events.) Instead, most physicists try to solve the paradox by finding some way — any way — for the information inside the black hole to leak out through the Hawking radiation. That way, when the black hole disappears, the information is still present in the universe.
Either way, describing this process requires new physics.
“This suggests that general relativity and quantum mechanics as they currently stand are inconsistent with each other,” Goto said. “We have to find a unified framework for quantum gravity.”
A tale of two entropies
In 1992, physicist Don Page, a former graduate student of Hawking, viewed the information paradox problem another way. He started by looking at quantum entanglement, which is when distant particles have their fates linked. This entanglement acts as the quantum mechanical connection between the Hawking radiation and the black hole itself. Page measured the amount of entanglement by calculating the “entanglement entropy,” which is a measure of the amount of information contained in the entangled Hawking radiation.
In Hawking’s original calculation, no information escapes, and the entanglement entropy always increases until the black hole finally disappears. But Page found that if black holes do indeed release information, the entanglement entropy initially grows; then, halfway through the black hole’s lifetime, it decreases before finally reaching zero, when the black hole evaporates (meaning all the information inside the black hole has finally escaped).
If Page’s calculations are correct, this suggests that if black holes do allow information to escape, then something special has to happen around the halfway point of their lives. While Page’s work didn’t solve the information paradox, it did give physicists something juicy to work on. If they could give black holes a midlife crisis, then that solution might just resolve the paradox.
Through the wormhole
More recently, several teams of theorists have been applying mathematical techniques borrowed from string theory — one approach to unifying Einstein’s relativity with quantum mechanics — to examine this problem. They were examining how space-time near an event horizon might be more complex than scientists initially thought. How complex? As complex as possible, allowing any sort of curving and bending at the microscopic scale.
Their work led to two surprising features. One was the appearance of a “quantum extremal surface” just below the event horizon. This interior surface moderates the amount of information leaving the black hole. Initially, it doesn’t do much. But when the black hole is halfway through its life, it begins to dominate the entanglement, reducing the amount of information released) so that the entanglement entropy follows Page’s predictions.
Secondly, the calculations revealed the presence of wormholes — a lot of them. These wormholes appeared to connect the quantum extremal surface to the exterior of the black hole, allowing the information to bypass the event horizon and be released as Hawking radiation.
But that previous work was only applied to highly simplified “toy” models (such as one-dimensional versions of black holes). With Goto’s work, that same result has now been applied to more realistic scenarios — a major advance that brings this work closer to explaining reality.
Still, there are a lot of questions. For one, it’s not clear yet if the wormholes that appear in the mathematics are the same wormholes that we think of as shortcuts in time and space.
They are so deeply buried in the math that it’s difficult to determine their physical meaning. On one hand, it could mean that literal wormholes thread in and out of an evaporating black hole. Or it could just be a sign that space-time near a black hole is nonlocal, which is a hallmark of entanglement — two entangled particles do not need to be in causal contact in order to influence each other.
One of the other major issues is that, while physicists have identified a possible mechanism to relieve the paradox, they don’t know how it actually works. There’s no known process that actually performs the work of taking the information that’s inside a black hole and encoding it in the Hawking radiation. In other words, physicists have built a possible road to solving the information paradox, but they haven’t found any way to build the trucks that travel down that road.
“We still don’t know the basic mechanism of how information is carried away by the radiation,” Goto said. “We need a theory of quantum gravity.”
Originally published on Live Science.
Scientists may have solved Stephen Hawking’s black hole paradox
Researchers may have solved Professor Stephen Hawking’s famous black hole paradox—a mystery that has puzzled scientists for almost half a century.
According to two new studies, something called “quantum hair” is the answer to the problem.
In the first paper, published in the journal Physical Review Letters, researchers demonstrated that black holes are more complex than originally thought and have gravitational fields that hold information about how they were formed.
The researchers showed that matter collapsing into a black hole leaves a mark in its gravitational field—an imprint referred to as a “quantum hair.”
In a follow-up paper, published in a separate journal, Physics Letters B, Professor Xavier Calmet from the University of Sussex’s School of Mathematical and Physical Sciences and Professor Stephen Hsu from Michigan State University said quantum hairs resolve Hawking’s Black Hole Information Paradox.
In 1976, Hawking suggested that, as black holes evaporate, they destroy information about what had formed them.
That idea goes against a fundamental law of quantum mechanics which states any process in physics can be mathematically reversed.
In the 1960s, physicist John Archibald Wheeler, discussing black holes’ lack of observable features beyond their total mass, spin, and charge, coined the phrase “black holes have no hair”—known as the no-hair theorem.
However, the newly discovered “quantum hair” provides a way for information to be preserved as a black hole collapses and, as such, resolves one of modern science’s most famous quandaries, experts say.
Prof Calmet said: “Black holes have long been considered the perfect laboratory to study how to merge Einstein’s theory of general relativity with quantum mechanics.
“It was generally assumed within the scientific community that resolving this paradox would require a huge paradigm shift in physics, forcing the potential reformulation of either quantum mechanics or general relativity.
“What we found—and I think is particularly exciting—is that this isn’t necessary.”
Explaining the discovery of the “quantum hair,” Roberto Casadio, professor of Theoretical Physics at the University of Bologna, said: “A crucial aspect is that black holes are formed by the collapse of compact objects and then, according to the quantum theory, there is no absolute separation between the interior and the exterior of the black hole.
“In the classical theory, the horizon acts as a perfect one-way membrane which does not let anything out and the exterior is therefore the same for all black holes of a given mass. This is the classical no-hair theorem,” Casadio added.
“However, in the quantum theory, the state of the matter that collapses and forms the black hole continues to affect the state of the exterior, albeit in a way that is compatible with present experimental bounds. This is what is known as ‘quantum hair.'”
Wormholes help resolve black hole information paradox
More information:
Xavier Calmet et al, Quantum hair and black hole information, Physics Letters B (2022). DOI: 10.1016/j.physletb.2022.136995
Xavier Calmet et al, Quantum hair and black hole information, Physics Letters B (2022). DOI: 10.1016/j.physletb.2022.136995
Xavier Calmet et al, Quantum Hair from Gravity, Physical Review Letters (2022). DOI: 10.1103/PhysRevLett.128.111301
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‘Quantum hair’ could resolve Hawking’s black hole paradox, say scientists | Black holes
Stephen Hawking’s black hole information paradox has bedevilled scientists for half a century and led some to question the fundamental laws of physics. Now scientists say they may have resolved the infamous problem by showing that black holes have a property known as “quantum hair”.
If correct, this would mark a momentous advance in theoretical physics.
Prof Xavier Calmet, of the University of Sussex, who led the work, said that after working on the mathematics behind the problem for a decade, his team made a rapid advance last year that gave them confidence that they had finally cracked it.
“It was generally assumed within the scientific community that resolving this paradox would require a huge paradigm shift in physics, forcing the potential reformulation of either quantum mechanics or general relativity,” said Calmet. “What we found – and I think is particularly exciting – is that this isn’t necessary.”
Hawking’s paradox boils down to the following: the rules of quantum physics state that information is conserved. Black holes pose a challenge to this law because once an object enters a black hole, it is essentially gone for good – along with any information encoded in it. Hawking identified this paradox and for decades it has continued to confound scientists.
There have been innumerable proposed solutions, including a “firewall theory” in which information was assumed to burn up before entering the black hole, the “fuzzball theory” in which black holes were thought to have indistinct boundaries, and various exotic branches of string theory. But most of these proposals required rewriting of the laws of quantum mechanics or Einstein’s theory of gravity, the two pillars of modern physics.
By contrast, the quantum hair theorem claims to resolve the paradox by bridging the gap between general relativity and quantum mechanics using a new mathematical formulation.
The name is a nod to the view, based on classical physics, that black holes can be viewed as surprisingly simple objects, defined only by their mass and speed of rotation. The prediction of bald, featureless black holes has been nicknamed the “no-hair theorem” since the 1970s.
Calmet and his collaborators think the black hole is more complex – or hairy. As matter collapses into a black hole, they suggest, it leaves a faint imprint in its gravitational field. This imprint is referred to as “quantum hair” and, the authors say, would provide the mechanism by which information is preserved during the collapse of a black hole. Under this theory, two black holes with identical masses and radii, but with different internal composition, would have very subtle differences in their gravitational fields.
“Our solution doesn’t require any speculative idea; instead our research demonstrates that the two theories can be used to make consistent calculations for black holes and explain how information is stored without the need for radical new physics,” said Calmet.
There is no obvious way to test the theory through astronomical observations – the gravitational fluctuations would be too tiny to be measurable. But the theory is likely to come under robust scrutiny from the theoretical community.
“When you have a big claim you have to back it up,” said Calmet. He added: “It’s going to take some time for people to fully accept this. The paradox has been around for a long time and you’ve got very famous people all over the world who’ve been working on this for years.”
The work is published in the journal Physical Review Letters.