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New Study Says There’s a Way to Make Dyson Bubbles and Stellar Engines Stable
In addition to being a staple of science fiction, the concept of megastructures has long been the subject of serious scientific studies. As famed physicist Freeman Dyson originally proposed in 1960, “Malthusian pressures will ultimately drive an intelligent species” to occupy an “artificial biosphere which completely surrounds its parent star.” In short, he theorized that advanced civilizations would disassemble their planet (or planets) to create a structure (which has since come to be called a “Dyson Sphere” that would harness all the energy from their star and provide immense living space.
Over time, scientists have proposed many variations on this structure, collectively known as “Dyson Structures.” However, considerable research has countered these proposals, arguing that such megastructures would be unstable. In a new study, famed engineer Colin R. McInnes demonstrates how two specific megastructures – Dyson Bubbles and Stellar Engines – could be built in such a way that they would be passively stable over time. These findings could aid the Search for Extraterrestrial Intelligence (SETI) by constraining the technosignatures these structures could produce.
Colin R. McInnes is a Professor of Engineering Science at the University of Glasgow and the chair of the James Watt School of Engineering. His findings are presented in a paper that appeared in the Monthly Notices of the Royal Astronomical Society. While the concept is several decades old, megastructures have received renewed attention thanks to the discovery of Boyajian’s Star and other cases where stars exhibited periodic dimming, were low in luminosity, or were “missing.”
In addition to being a leading figure in the field of solar sails, reflectors, and satellites, McInnes has also previously authored a paper on the subject of megastructure stability. As he summarized in this latest study, megastructures have been proposed for a range of ventures, including asteroid orbit modification, climate engineering (i.e., solar shields), terraforming (a la Ken Roy’s Shell World concept), and planetary orbit modification (moving them into the star’s habitable zone).
At larger scales, scientists have considered how massive swarms of reflectors could enshroud a star, known as a Dyson Swarm, Bubble, or Matrioshka Brain, or be used to alter a star’s orbit, known as a Stellar Engine or Shkadov Thruster. In the case of the former, the reflective surface ensures that radiation pressure will levitate the swarm (which could support habitats) above the star. In the latter, a flat reflective disk remains bound to a star through gravitational coupling, causing the star to move.
Much like Dyson proposed in his original paper, these studies assume that advanced civilizations will experience exponential growth and rising energy demands as they age. “Freeman Dyson imagined a swarm of energy-collecting elements enveloping a central star as an endpoint for a civilisation with continuously growing energy demands,” McInnes told Universe Today via email. “It’s clearly difficult to infer motivations. However, the universality of the laws of physics means that we can at least speculate on how such structures could be engineered.”
While a popular idea among scientists, considerable research by physicists and structural engineers has cast doubt on the existence of megastructures. In short, they have argued that such structures would be, by their very nature, gravitationally unstable. But as McInnes explained, it is possible that megastructures could be built in a way that would ensure long-term passive stability:
Many concepts, such as a rigid Dyson sphere or Ringworld, are not in orbit, and so a small displacement can cause the structure to drift and collide with the central star. They would therefore need active control measures to stabilise them. However, my interest is in understanding ways in which ultra-large structures could be engineered so that they are passively stable. We can imagine that engineers, terrestrial or otherwise, would prefer passive stability to more complex active control measures.
The simplest design (he notes) for a Stellar Engine would likely be a flat reflective disk. Using an ultra-large disk as a starting point, he calculated the structure’s stability from first principles using a simplified model of a perfectly reflecting rigid disc. He then employed the functional forms of gravitational and radiation-pressure forces to investigate the stability of a stellar engine and of orbiting reflectors (making up a Dyson’ Bubble) in different configurations. Said McInnes:
Stability analysis involves adding a small displacement to the equations of motion describing such structures and then determining if the displacement grows with time. Then, by considering ways to engineer the structure’s properties, for example, its geometry or mass distribution, we can determine if it can be stabilized such that small displacements do not grow and are bounded. There isn’t a set process as such; it’s a case of looking at the equations of motion and considering how the forces acting could be modified, for example, through changes in the geometry or mass distribution of the structure.
In the end, his analysis showed that while an ideal stellar engine comprising a uniform, reflective, rigid disc is unstable, a reflective disc whose mass is concentrated at its edge can (in principle) be passively stable. By balancing the gravitational and radiation pressure forces, such a design would also maximize the stellar engine’s propulsion. Meanwhile, a self-stabilizing Dyson Bubble or Swarm would avoid (or minimize) collisions among the cloud’s elements and maintain equilibrium, provided the right configuration and design considerations were taken into account.
These structures would also produce telltale technosignatures that SETI researchers could look for in the future. While a Stellar Engine would scatter light reflected from its star, a Dyson Bubble would appear as a dense cloud enclosing a star, thus modifying its spectral characteristics. For a static cloud, there would be no flickering apparent to observers, unlike a swarm of orbiting reflectors, which would pass in front of the stellar disc. And as Dyson first predicted, e a solid Dyson sphere would be discernible from the infrared excess produced by radiated heat.
However, as McInnes added, this study is not the final word on megastructures and their potential stability. “The analysis in the paper is simplified and makes a number of assumptions,” he said. “However, it’s a starting point to begin to understand how ultra-large structures could be engineered to be passively stable. For example, a dense Dyon bubble can apparently be self-stabilising due to light pressure falling faster than gravity as we move out through the cloud of elements. Perhaps by understanding how such structures can be engineered to be passively stable, we can better predict the technosignatures associated with them.”
Further Reading: MNRAS
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Riverside wants to fire three cops over disability claims, lawyer says
The city of Riverside is trying to fire three of its police officers because they’re using license plates for disabled veterans on their personal vehicles despite having no apparent problems performing their jobs, the officers’ attorney has claimed.
The department’s logic for firing the officers, their attorney Matthew McNicholas said, was that they must have lied to the California Department of Motor Vehicles in order to obtain the specialized plates, which exempt drivers from paying registration fees and allow them to use disabled parking spots and park in metered spots for free.
That logic is broken, McNicholas said, because under federal law, to get a 100% disability rating — which each of the officers obtained — a veteran doesn’t have to be fully disabled. A veteran can get that disability status through a combination of partial disabilities, such as partial hearing loss, post-traumatic stress disorder or a back injury. To obtain plates for veterans rated as 100% disabled, a person must submit a certificate from a medical professional or a county, state or federal veterans’ agency confirming their disability.
“The department said it’s a bad look” for the officers to come to work in their personal cars carrying plates for veterans with a 100% disability rating, McNicholas said in an interview Tuesday.
The Riverside Police Department declined to comment on the case or the officers’ status with the agency, citing employee confidentiality. But McNicholas said that the department is acting out of concern about public perception and to punish the officers for refusing to remove the plates when asked to do so by their superiors.
Officers Timothy Popplewell, Richard Cranford and Raymond Olivares were put on administrative leave and informed of an internal investigation into their use of veteran plates on May 21. They sued the agency about two months later, claiming in a complaint filed July 17 in Riverside County Superior Court that it had discriminated against them and harassed them based on their veteran and disability status. On Feb. 24, the Riverside City Council met in closed session to discuss whether to settle the case and voted against doing so, said Saku Ethir, the Riverside Police Officers’ Assn. attorney representing the officers. The day after that vote, the officers received notices of termination, Ethir said.
The city moved to fire the officers because despite having special veteran plates stemming from their war injuries, they “showed up to work” and “were completely fit and satisfactory,” McNicholas said in a video posted to Instagram March 2. All three had been asked by their superiors to replace the plates on their cars but refused, McNicholas said. A fourth officer with veteran plates agreed to remove them and has not faced termination, he said.
Through a spokesperson, the Riverside Police Department declined to answer questions about the officers, “due to the confidential nature of the personnel action which has not completed its process.”
In an Oct. 16 response to the officers’ lawsuit, the department said it “acted in good faith with reasonable belief that its actions were lawful and further did not directly or indirectly perform any acts whatsoever which would constitute a breach of any duty owed to Plaintiffs.”
Popplewell, Cranford and Olivares will still have a chance to argue to the department that they shouldn’t be fired, Ethir said. They’ve already been provided with documents the department relied on in its decision to fire them, but a hearing to appeal their termination has not yet been scheduled, she said. Ethir said she believes the department has not provided all the records it is legally obligated to give the officers.
Popplewell served in the military from 2008 to 2011 and was deployed in Iraq, McNicholas said. Olivares was in the Marines from 2013 to 2019 and was deployed in the Middle East and Africa. Cranford served in the Army from 2010 to 2014 and was deployed to Iraq. All three joined the Riverside Police Department in 2019, according to the lawsuit.
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Why Did the UK Police Repeatedly Decline to Investigate Claims About Epstein and Prince Andrew?
The police in London interviewed Virginia Giuffre three times over her allegations about Jeffrey Epstein, Andrew Mountbatten-Windsor and Ghislaine Maxwell, but never began a criminal investigation.
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AI Could Make Alien Contact More Likely for SETI’s ‘Project Hail Mary’
“Project Hail Mary,” a science-fiction novel that’s just been turned into a big-budget, big-screen movie, tells the story of an unlikely astronaut who unexpectedly encounters an alien during a desperate mission to save their respective civilizations.
The astronaut (played by Ryan Gosling in the movie) and the alien have to figure out on the spot whether they’re friends or foes. They also have to come up with a translation system that can accommodate two completely different ways of communicating.
That all makes for a do-or-die space drama reminiscent of “Apollo 13” — but the day is fast approaching when advances in astronomy and artificial intelligence could take a lot of the drama out of alien contact.
Seth Shostak, senior astronomer for the SETI Institute, says he wouldn’t be at all surprised if our first encounter with aliens came in the form of AI-to-AI contact.
“My guess is that the aliens are going to be machines, because that’s what we’re doing, right?” he says in the latest episode of the Fiction Science podcast. “We’re just in the early days of building machines that can do things that humans have had to do in the past. I’m sure that 100 years from now, the most capable intelligence on this planet will not be some sort of soft and squishy biological thing. That’s going to be a machine. And so, if we hear the aliens, I suspect that it’s more than likely that they, too, will be machines.”
If you’re worried that talking about AI and the search for aliens will require delving deeply into spoilers, never fear: Artificial intelligence doesn’t really play a role in the “Project Hail Mary” movie. It’s mentioned only once in the Andy Weir novel on which the movie is based — merely to explain why the planners of the do-or-die mission opted not to use AI. (We do get into spoilers toward the end of this post, however, so consider yourselves warned.)
For more than 65 years, astronomers have been searching the skies for radio signals that might have been sent out by extraterrestrial civilizations. “The usual approach is to build a receiver that can monitor thousands — well, today, millions of different channels simultaneously,” Shostak says. “And you can just look at how that capability has improved over time. It turns out it follows what’s called Moore’s Law … which says that the speed of electronics more or less doubles every two years.”
It takes a lot of computing power to monitor millions of channels, and Shostak says he’s certain that AI will accelerate the search for extraterrestrial intelligence, better known as SETI.
There’s already evidence of that: Last November, the Breakthrough Listen Initiative reported that an AI system developed in partnership with NVIDIA could process real-time data from telescopes searching for fast radio bursts at a rate more than 600 times faster than the current data pipeline. The system improved detection accuracy by 7% and reduced false positives by nearly an order of magnitude.
“This technology doesn’t just make us faster at finding known types of signals — it enables us to discover completely unexpected signal morphologies,” Andrew Siemion, principal investigator for the Breakthrough Listen Initiative, said in a news release. “An advanced civilization might use burst-like communications, modulated signals or transmission schemes we haven’t even imagined. This AI system can learn to recognize patterns that a human might miss entirely.”
Several years ago, another team of astronomers used a machine language algorithm to identify potential alien signals that were overlooked by other data-processing systems. (But don’t get too excited: Follow-up observations didn’t confirm that the signals came from extraterrestrial civilizations. You would have heard if they did.)
AI tools could help astronomers overcome some of the obstacles facing the SETI quest. For example, one group of researchers recently reported that signals from alien civilizations could be scrambled by stormy space weather. Improved pattern-recognition software just might be able to pick out the signal hidden in the cosmic noise.
AI models could also come into play for interpreting alien messages once they’re found. But Shostak isn’t focusing so much on that challenge. “Even if we never understand what the aliens are saying, just the fact that we pick up the signal and can tell that it’s an artificial signal — in other words, made by some technology — that’s very interesting, because we’ve proved that they’re there,” Shostak says.
Understanding what the aliens are saying “would be interesting to know, but I would consider that a secondary benefit of finding their presence,” he says.
Seth Shostak is senior astronomer at the SETI Institute. (SETI Institute Photo)
Shostak compares the challenge of deciphering alien messages to the challenge that archaeologists faced when they unearthed Egyptian hieroglyphs. “The best way to decipher the hieroglyphics is to have lots of people working on the problem, so just make them known,” he says. “I think the same sort of logic applies here.”
Douglas Vakoch, the president of METI International, has spent a lot of time working on the message translation problem. You can tell that from his organization’s acronym, which stands for “Messaging Extraterrestrial Intelligence.” He says AI can play a supporting role in detecting and decoding alien messages, but not the starring role.
“We need to realize that when we humans try to find patterns hidden in radio static, we may start out with some cut-and-dried guidelines that are very similar to the clear rules used by AI. But often we fail to realize exactly how our rules fall short, because we don’t lay them out clearly,” Vakoch told me via email. “AI forces us to get clear about how we are attempting to solve problems, and simply learning from AI how it is attempting to solve a problem can make us say, ‘You’ve missed something critical. You need to do this instead.’ ”
In his view, discovering an alien message is only half the battle.
“An even greater challenge will be understanding what it means. And that’s where humans will continue to play a role, even as AI becomes more computationally sophisticated in the years to come,” Vakoch said. “Deciphering a message from extraterrestrials will be much more ambiguous. AI might help us detect patterns in alien messages that humans would miss, but we’ll still need people to figure out what the message means.”
How long will it take to make alien contact? Will we need to wait for a do-or-die mission to a faraway star system? More than 20 years ago, Shostak predicted that we’d find evidence of aliens by 2025 or so. And for more than 15 years, he’s been betting a cup of coffee on it.
Now Shostak is acknowledging that he might have to pay up. “Next time I see you, I’ll buy you a cup of coffee,” he says. “We haven’t found them yet. … Maybe it was just wishful thinking, but honestly, I think that it was more based on the known rate of improvement in the experiments to find the aliens.”
Maybe SETI astronomers just need more time to take advantage of Moore’s Law and AI. Maybe it’ll take another 20 years, or 200 years, to follow through on the promise of “Project Hail Mary” and connect with alien travelers. But in the meantime, I’ll take that cup of coffee.
Here come the spoilers
If you haven’t already read “Project Hail Mary,” it can be tricky to keep track of the movie’s scientific twists and turns. Some of those plot twists have interesting parallels to real-world science, and I can’t resist pointing them out.
“Project Hail Mary” is scheduled for theatrical release on March 20, and it’s already getting rave reviews. For more from Seth Shostak, check out Big Picture Science, the podcast he co-hosts; and look for his columns in Astronomy magazine.
My co-host for the Fiction Science podcast is Dominica Phetteplace, an award-winning writer who is a graduate of the Clarion West Writers Workshop and lives in San Francisco. To learn more about Phetteplace, visit DominicaPhetteplace.com.
This report was originally posted on Cosmic Log, the home base for the Fiction Science podcast. Stay tuned for future episodes of Fiction Science via Apple, Spotify, Player.fm, Pocket Casts and Podchaser. Fiction Science is included in FeedSpot’s 100 Best Sci-Fi Podcasts. If you like Fiction Science, please rate the podcast and subscribe to get alerts for future episodes.
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