Latest news with #AmericanPhysicalSociety
Asia Times
25-05-2025
- Politics
- Asia Times
The many holes in Trump's Golden Dome
The Trump administration's recent announcement of a 'Golden Dome' strategic missile defense shield to protect the US is the most ambitious such project since President Ronald Reagan's Strategic Defense Initiative (SDI) of the 1980s. The SDI program – better known by its somewhat mocking nickname of 'Star Wars' – sparked a heated debate over its technical feasibility. Ultimately, it would never become operational. But do we now have the technologies to realize the Golden Dome shield – or is this initiative similarly destined to be shelved? A completed Golden Dome missile defense shield would supposedly defend the US against the full spectrum of air and missile threats, including long-range intercontinental ballistic missiles (ICBMs) and those with shorter ranges, any of which could be armed with nuclear warheads. But Golden Dome would also aim to work against cruise missiles and hypersonic weapons such as boost-glide vehicles, which use a rocket to reach hypersonic speeds (more than five times the speed of sound) before continuing their trajectory unpowered. The missile defense shield could theoretically also protect against warheads placed in space that can be commanded to re-enter the atmosphere and destroy targets on Earth, known as fractional orbital bombardment systems. Ballistic missiles arguably pose the biggest threat because of the sheer numbers in the hands of other nuclear-armed nations. ICBMs follow a three-phase trajectory: the boost, midcourse and terminal phases. The boost phase consists of a few minutes of powered flight as the missile's rocket engines propel it into space. In the midcourse phase, the missile travels unpowered through space for about 20-25 minutes. Finally, during the terminal phase, the missile re-enters the atmosphere and hits the target. Plans for the Golden Dome are likely to involve defensive weapons that target ballistic missiles during all three phases of their trajectory. Boost-phase missile defence is attractive because it would only require shooting down a single target. During the midcourse phase, the ballistic missile will deploy its warhead – the section that includes the explosive charge – but could also release several decoy warheads. Even with the best radar systems, discriminating between the real warhead from the decoys is incredibly difficult. One part of the Golden Dome will involve targeting ballistic missiles during their boost phase. US Air Force However, there are big questions over the technical feasibility of targeting ballistic missiles during their boost phase – and there is also a limited time window, given that this phase is relatively short. The weapons platforms designed to target a ballistic missile in its boost phase could consist of a large satellite in low-Earth orbit, armed with multiple small missiles called interceptors. An interceptor could be deployed if a nuclear-armed ballistic missile is launched at the US. One study conducted by the American Physical Society suggested that, under generous assumptions, a space-based interceptor platform might be able to destroy a target from 530 miles (850km) away. This measure is known as the weapon's 'kill radius.' Even with a kill radius of this size, a space-based interceptor system would require hundreds or even thousands of satellites, each armed with small missiles to achieve effective regional coverage. It might be possible to get around this constraint, though, by using directed-energy weapons such as powerful lasers or even particle beam weapons, which use high-energy beams of atomic or subatomic particles. A critical vulnerability of such a system, however, is that an adversary could use anti-satellite weapons – missiles launched from the ground – or other offensive actions such as cyberattacks to destroy or disable some of the interceptor satellites. This could establish a temporary corridor for an adversary's ballistic missile to pass through. An idea for a space-based boost-phase defense system called Brilliant Pebbles was proposed towards the end of the 1980s. Rather than having large satellites with multiple missiles, it entailed having around 1,000 small individual missiles in orbit. It would have also used about 60 orbiting sensors called Brilliant Eyes to detect launches. Brilliant Pebbles was cancelled by President Bill Clinton's administration in 1994. But it provides another template for technologies that could be used by Golden Dome. Options for destroying ballistic missiles during the midcourse of their trajectories include existing weapons systems such as the Ground-based Midcourse Defense system and the US Navy's ship-based Aegis platform. Unlike midcourse-phase missile defense (which must cover a large geographical area), terminal-phase interception is a last line of defense. It usually involves destroying incoming warheads that have re-entered the atmosphere from space. A plan for destroying single warheads during the terminal trajectory phase could use future versions of existing weapons platforms, such as the Patriot Advanced Capability 3 Missile Segment Enhancement or the Terminal High Altitude Area Defense. However, while there has been progress in this technology in the decades since Star Wars was proposed, the debate continues over whether these systems work effectively. Ultimately, it is the huge costs, as well as political opposition, that could pose the biggest hurdles to implementing an effective Golden Dome system. Trump's proposal has revived the idea of missile defense in the US. But it remains unclear whether its most ambitious components will ever be realized. Jack O'Doherty is a PhD Candidate in nuclear strategy, University of Leicester This article is republished from The Conversation under a Creative Commons license. Read the original article.
India.com
23-05-2025
- Business
- India.com
The golden dome: A bold vision or an overpriced dream?
The golden dome: A bold vision or an overpriced dream? Donald Trump has unveiled an ambitious plan to shield America from missile attacks with a space-based defense system called the 'Golden Dome.' Inspired by Ronald Reagan's vision from decades ago, Trump claims today's advanced technology makes this dream achievable. Unlike Israel's Iron Dome, which protects against short-range rockets, the Golden Dome aims to cover the entire United States using thousands of satellites. These satellites would detect enemy missiles and destroy them before they reach American soil. During his campaign, Trump promised to fund this project through a 'big and beautiful' tax bill, allocating $25 billion to kickstart it, with total costs estimated at $175 billion. However, Congress has yet to approve this funding, and experts warn the price tag could balloon to over $500 billion, taking decades to complete. Trump's timeline of two and a half to three years is also considered overly optimistic. The promise of 'close to 100% protection' sounds reassuring, but it's not that simple. A recent study by the American Physical Society highlights the challenge: to stop just ten North Korean Hwasong-18 missiles, the U.S. would need around 16,000 defensive missiles in space. Why so many? Hitting a missile in space is like shooting a bullet with another bullet at incredible speeds. Even the best systems aren't perfect, so multiple interceptors are needed for each incoming threat. Add to that the vastness of space, unpredictable missile paths, and enemy decoys, and the numbers grow quickly. The challenge gets tougher with time and territory. If decision-makers want just 30 seconds to think before launching interceptors, the number of defensive missiles jumps to 36,000. Protecting additional areas like Alaska or the Midwest would require thousands more. It's like guarding a massive fence line that stretches in every direction—each new section needs its own network of defenders. The Golden Dome is a response to a rapidly changing threat. For years, U.S. defenses focused on missiles coming over the North Pole from places like Russia. But new hypersonic missiles can change direction mid-flight, and 'fractional orbital' missiles circle the Earth before striking. Intelligence reports now show potential attacks from all directions—north, south, east, and west. Canada, a close ally, is even considering joining the project, as it faces similar risks. But the Golden Dome isn't just about defense—it's part of a larger battle for control of space. Russia and China are developing weapons to destroy satellites, which the Golden Dome would rely on. Russia's Cosmos 2553 satellite, for instance, is suspected to be a test for a nuclear bomb that could wipe out satellites across vast areas. China, meanwhile, is building anti-satellite weapons at an alarming pace, according to U.S. Space Command. Space is no longer just for exploration or communication. It's a new battleground where nations are racing to build defenses while creating weapons to disable each other's satellites. This creates a dangerous cycle: America plans to deploy thousands of satellites for the Golden Dome, while Russia and China develop tools to take them out. The stakes are higher than military defense. Satellites power everyday life—phone calls, internet, GPS navigation, even banking and power grids rely on precise timing from space. Attacks like jamming (blocking GPS signals) or spoofing (sending fake signals) are already on the rise. If space weapons destroy these satellites, it could disrupt everything from ATMs to traffic lights. The competition in space is getting intense. Russia's Cosmos 2576 satellite recently shadowed an American spy satellite, raising fears of a potential space weapon. China's TJS-4 satellite cleverly used the sun's shadow to hide from an American surveillance satellite. France is now exploring 'bodyguard' systems to protect its satellites with robots or lasers. Even the U.S. is playing this game—last month, an American satellite 'buzzed' two Chinese satellites, coming dangerously close in a provocative move. This cat-and-mouse game in space shows how nations are using satellites to stalk, intimidate, and outsmart each other. What was once a peaceful frontier is now a high-tech battlefield, with each side accusing the other of the same aggressive tactics they use themselves. The Golden Dome is a bold idea, but it comes with big questions. Can America afford a project that could cost half a trillion dollars? Will it deliver the near-perfect protection Trump promises? And how will it fare in a space increasingly crowded with threats? As the U.S. pushes forward, it must balance ambition with reality, ensuring this shield doesn't become a golden dream too costly to achieve. ( Girish Linganna is an award-winning science communicator and a Defence, Aerospace & Geopolitical Analyst. He is the Managing Director of ADD Engineering Components India Pvt. Ltd., a subsidiary of ADD Engineering GmbH, Germany. Contact: girishlinganna@
WIRED
20-03-2025
- Science
- WIRED
Evidence Grows That Dark Energy Changes Over Time
Jennifer Ouellette, Ars Technica Mar 20, 2025 6:00 PM The latest Dark Energy Spectroscopic Instrument results fall short of the discovery threshold but strengthen evidence for dynamical dark energy. Last year, we reported on an exciting hint of new physics in the first data analysis results from the Dark Energy Spectroscopic Instrument (DESI)—namely that the dark energy, rather than being constant, might vary over time. Granted, those hints were still below the necessary threshold to claim discovery and hence fell under the rubric of 'huge, if true.' But now we have more data from DESI, combined with other datasets, and those hints have gotten significantly stronger—so much so that Mustapha Ishak-Boushaki of the University of Texas at Dallas, who co-chairs one of the DESI working groups, said that 'we are getting to the point of no return' for confirming dynamical dark energy. Ishak-Boushaki and several other DESI team members presented their results at the American Physical Society's Global Physics Summit today in Anaheim, California. Several relevant papers have also been posted to the physics arXiv. This story originally appeared on Ars Technica, a trusted source for technology news, tech policy analysis, reviews, and more. Ars is owned by WIRED's parent company, Condé Nast. Einstein's cosmological constant (lambda) implied the existence of a repulsive form of gravity. (For a more in-depth discussion of the history of the cosmological constant and its significance for dark energy, see our 2024 story.) Quantum physics holds that even the emptiest vacuum is teeming with energy in the form of 'virtual' particles that wink in and out of existence, flying apart and coming together in an intricate quantum dance. This roiling sea of virtual particles could give rise to dark energy, giving the universe a little extra push so that it can continue accelerating. The problem is that the quantum vacuum contains too much energy: roughly 10120 times too much. So the universe should be accelerating much faster than it is if the dark energy is, essentially, the cosmological constant. Still, all the observations to date indicate that it's constant. The best theoretical fit thus far is known as the Lambda CDM model, which incorporates both a weakly interacting cold dark matter and dark energy. One alternative theory proposes that the universe may be filled with a fluctuating form of dark energy dubbed 'quintessence.' There are also several other alternative models that assume the density of dark energy has varied over the history of the universe. In its earliest days, the universe was a hot, dense soup of subatomic particles, including hydrogen and helium nuclei, aka baryons. Tiny fluctuations created a rippling pattern through that early ionized plasma, which froze into a three-dimensional place as the universe expanded and cooled. Those ripples, or bubbles, are known as baryon acoustic oscillations (BAO). It's possible to use BAOs as a kind of cosmic ruler to investigate the effects of dark energy over the history of the universe. DESI is a state-of-the-art instrument that can capture light from up to 5,000 celestial objects simultaneously. Courtesy of Marilyn Sargent/Berkeley Lab That's what DESI was designed to do: take precise measurements of the apparent size of these bubbles (both near and far) by determining the distances to galaxies and quasars over 11 billion years. That data can then be sliced into chunks to determine how fast the universe was expanding at each point of time in the past, the better to model how dark energy was affecting that expansion. An Upward Trend Last year's results were based on analysis of a full year's worth of data taken from seven different slices of cosmic time and include 450,000 quasars, the largest ever collected, with a record-setting precision of the most distant epoch (between 8 to 11 billion years back) of 0.82 percent. While there was basic agreement with the Lamba CDM model, when those first-year results were combined with data from other studies (involving the cosmic microwave background radiation and Type Ia supernovae), some subtle differences cropped up. Essentially, those differences suggested that the dark energy might be getting weaker. In terms of confidence, the results amounted to a 2.6-sigma level for the DESI's data combined with CMB datasets. When adding the supernovae data, those numbers grew to 2.5-sigma, 3.5-sigma, or 3.9-sigma levels, depending on which particular supernova dataset was used. It's important to combine the DESI data with other independent measurements because 'we want consistency,' said DESI co-spokesperson Will Percival of the University of Waterloo. 'All of the different experiments should give us the same answer to how much matter there is in the universe at present day, how fast the universe is expanding. It's no good if all the experiments agree with the Lambda-CDM model, but then give you different parameters. That just doesn't work. Just saying it's consistent to the Lambda-CDM, that's not enough in itself. It has to be consistent with Lambda-CDM and give you the same parameters for the basic properties of that model.' These latest results cover the first three years of collected data, spanning almost 15 million galaxies and quasars. Once again, the DESI data alone was consistent with Lambda CDM, i.e., the dark energy is constant. And once again, when combined with other datasets—from CMB, supernovae, and weak gravitational lensing studies—strong hints emerged that dark energy might be changing over time. The confidence level ranges from 2.8 to 4.2 sigma, depending on the combination of datasets—just shy of the five-sigma threshold. This might strike the average citizen as an incremental advance, but the reality is more complicated. 'The DESI data itself is not incremental,' said Percival. 'We now have three years of data rather than one year of data. That is substantial, not just because of an increased area but because we've increased the overlap. The way we do the survey is we build up plates on the sky, and, after three years rather than one year of operations, we have a lot more of those overlaps filled in. So our data is a lot more complete in the sense that we've gone down to the full depth that we expect to get to in more patches. Consequently, our BAO measurements themselves are a lot better. They're between a factor of two and three better depending on exactly this balance between area versus depth.' A slice of the DESI data mapping celestial objects from Earth (center) to billions of light years away. Courtesy of Claire Lamman/DESI Collaboration Catherine Heymans, astronomer royal of Scotland, told Ars that these new results give scientists much more confidence in DESI's analysis. She was surprised at the excitement over last year's first results, since, 'whenever there's a first data release, the scientific community always takes the results with a pinch of salt,' she said. But DESI made its data public, and other scientists have been making their own analyses over the last year; it has stood up to that close scrutiny. 'The really strong significance for dynamical dark energy comes from the combination of the DESI standard ruler, the BAO plus the supernova data,' she added. 'That's two different ways of measuring the expansion rate of the universe. By combining those two things together, you get this strong detection of dynamical dark energy.' The next step for the DESI collaboration is to analyze five years' worth of data to see if the upward trend toward the 5-sigma threshold for discovery holds—perhaps even surpassing that threshold, which would be very exciting indeed. That will likely not happen for another two years, per Percival. Should 5 sigma be reached, Heymans said astronomers should expect to see similar results in data from the Euclid Space Telescope, which is slated to do a similar experiment to DESI, at higher redshift, in the near future. 'It opens up a huge range of possibilities,' said Percival of the implications should it be confirmed that dark energy changes over time. 'It will keep theorists happy for many years to come. As a scientist you want to sit a little bit on the fence. But if this is right, this is the next step after the discovery of dark energy. Lambda works. Now, Lambda doesn't work. It means there's a lot more information that's accessible about this process. I think people were worried that everything would show that it just exactly agrees with Lambda. But if there's actually things happening to how the acceleration is changing within detail, that's exciting because we can get a handle on the physics.' 'There's no fundamental underpinning for what could be causing that dynamical dark energy, and that does make me anxious,' said Heymans. 'It's like the observers are throwing the gauntlet back to the theorists. It'd be nice to be able to explain two dark entities with one fell swoop. I am excited about cracks in the cosmological model, because this way is pushing the theoretical community to think outside the box, to think of new ideas. And maybe that will solve the whole dark entity conundrum, which is why we're all here.' This story originally appeared on Ars Technica.
NBC News
20-03-2025
- Science
- NBC News
How will the universe end? A changing understanding of dark energy may provide a new answer
Scientists are homing in on the nature of a mysterious force called dark energy, and nothing short of the fate of the universe hangs in the balance. The force is enormous — it makes up nearly 70% of the universe. And it is powerful — it is pushing all the stars and galaxies away from each other at an ever faster rate. And now scientists are getting a little closer to understanding how it behaves. The big question is whether this dark energy is a constant force, which scientists have long thought, or whether the force is weakening, a surprising wrinkle tentatively proposed last year. Results presented at a meeting of the American Physical Society Wednesday bolster the case that the force is weakening, though scientists are not yet certain and they still haven't worked out what this means for the rest of their understanding of the universe. The updated findings come from an international research collaboration that is creating a three-dimensional map to see how galaxies have spread and clustered over 11 billion years of the universe's history. Carefully tracking how galaxies move helps scientists learn about the forces that are moving them around. Called the Dark Energy Spectroscopic Instrument, the collaboration released its first analysis of 6 million galaxies and quasars last year and has now added more data, bringing the count to nearly 15 million. Their updated results, taken with other measurements — exploding stars, leftover light from the young universe and distortions in galaxy shape — support the idea presented last year that dark energy may be waning. 'It's moving from a really surprising finding to almost a moment where we have to throw out how we've thought about cosmology and start over,' said Bhuvnesh Jain, a cosmologist with the University of Pennsylvania who was not involved with the research. It's not time to completely rule out the idea that dark energy is constant because the new results are still shy of the gold standard level of statistical proof physics requires. The collaboration aims to map around 50 million galaxies and quasars by the end of its survey in 2026. And other efforts around the globe have an eye on dark energy and aim to release their own data in the coming years, including the European Space Agency's Euclid mission and the Vera C. Rubin Observatory in Chile. 'We want to see several different collaborations having similar measurements' at that gold standard to be sure that dark energy is weakening, said cosmologist Kris Pardo with the University of Southern California who was not involved with the new research. If dark energy is constant, scientists say our universe may continue to expand forever, growing ever colder, lonelier and still. If dark energy ebbs with time, which now seems plausible, the universe could one day stop expanding and then eventually collapse on itself in what's called the Big Crunch. It might not seem like the cheeriest fate, but it offers some closure, said cosmologist and study collaborator Mustapha Ishak-Boushaki of the University of Texas at Dallas. 'Now, there is the possibility that everything comes to an end,' he said. 'Would we consider that a good or bad thing? I don't know.'
CBS News
20-03-2025
- Science
- CBS News
Dark energy findings could rewrite our understanding of the universe and its fate: "Cusp of a major discovery"
Scientists are homing in on the nature of a mysterious force called dark energy , and nothing short of the fate of the universe hangs in the balance. The force is enormous - it makes up nearly 70% of the universe. And it is powerful - it is pushing all the stars and galaxies away from each other at an ever faster rate. And now scientists are getting a little closer to understanding how it behaves. The big question is whether this dark energy is a constant force, an idea first introduced by Albert Einstein in his theory of relativity, or whether the force is weakening, a surprising wrinkle tentatively proposed last year. Results presented at a meeting of the American Physical Society Wednesday bolster the case that the force is weakening, though scientists are not yet certain and they still haven't worked out what this means for the rest of their understanding of the universe. The updated findings come from an international research collaboration that is creating a three-dimensional map to see how galaxies have spread and clustered over 11 billion years of the universe's history. Carefully tracking how galaxies move helps scientists learn about the forces that are moving them around. Called the Dark Energy Spectroscopic Instrument (DESI), the collaboration released its first analysis of 6 million galaxies and quasars last year and has now added more data, bringing the count to nearly 15 million. Their updated results, taken with other measurements - exploding stars, leftover light from the young universe and distortions in galaxy shape - support the idea presented last year that dark energy may be waning. "It's moving from a really surprising finding to almost a moment where we have to throw out how we've thought about cosmology and start over," said Bhuvnesh Jain, a cosmologist with the University of Pennsylvania who was not involved with the research. Alexie Leauthaud-Harnett, a spokesperson for the DESI collaboration, called the new observations "deeply intriguing." "It is exciting to think that we may be on the cusp of a major discovery about dark energy and the fundamental nature of our universe," she said in a statement. It's not time to completely rule out the idea that dark energy is constant because the new results are still shy of the gold standard level of statistical proof physics requires. The collaboration aims to map around 50 million galaxies and quasars by the end of its survey in 2026. "We want to see several different collaborations having similar measurements" at that gold standard to be sure that dark energy is weakening, said cosmologist Kris Pardo with the University of Southern California who was not involved with the new research. If dark energy is constant, scientists say our universe may continue to expand forever, growing ever colder, lonelier and still. If dark energy ebbs with time, which now seems plausible, the universe could one day stop expanding and then eventually collapse on itself in what's called the "Big Crunch." It might not seem like the cheeriest fate, but it offers some closure, said cosmologist and study collaborator Mustapha Ishak-Boushaki of the University of Texas at Dallas. "Now, there is the possibility that everything comes to an end," he said. "Would we consider that a good or bad thing? I don't know." Other efforts around the globe have an eye on dark energy and aim to release their own data in the coming years, including the European Space Agency's Euclid mission and the Vera C. Rubin Observatory in Chile. Launched in 2023, the ESA's $1.5 billion Euclid space telescope is equipped with a near-perfect 3-feet 11-inch-wide primary mirror and two instruments: a 600 megapixel visible light camera and a 64-megapixel infrared imaging spectrometer. The telescope's field of view is roughly twice the size of the full moon. It will take Euclid six years to complete its map of the sky, generating on the order of 100 gigabytes of compressed data per day, or an estimated, difficult-to-imagine 70,000 terabytes over the course of the mission. Agence France-Presse contributed to this report. William Harwood contributed to this report.
