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<ul class="summary-list"><li>The US and China are in a race to develop the most advanced submarines. </li><li>Chinese researchers say they have made a breakthrough in laser propulsion technology that could one day be used on submarines and missiles.</li></ul>Submarines have long been known as the silent hunters of the deep, lurking undetected under the surface.But as sonar systems have improved, minimizing sound on all on board components has become crucial to avoiding detection — not least the mechanical noises of propellers, generators, and nuclear reactor coolant systems that help propel submarines forward.A team of engineers at China's Harbin University claim to have taken a step forward in developing technology that could make submarines almost silent and ultrafast, the <a target="_blank" href="https://www.scmp.com/news/china/science/article/3259875/chinese-scientists-close-laser-propulsion-superfast-silent-submarines">South China Morning Post</a> reported.Rather than relying on nuclear or battery power, the scientists say they have found a way to use lasers to propel submarines — known as underwater laser propulsion.Theoretically, submarines could be coated in a web of minuscule optical fibers that emit laser pulses, the scientists wrote in the journal <a target="_blank" href=" https://m.researching.cn/articles/OJe5f22f467839a111">Acta Optica Sinica</a>.The small laser pulses emitted by the fibers would vaporize seawater and generate <a target="_blank" href="https://www.businessinsider.com/image-first-supermassive-black-hole-spews-jets-of-plasma-2023-4">plasma</a>, the substance created when gas is heated.In turn, the plasma would expand, creating a detonation wave that would act as an opposite force to the submarine, propelling it forward.<div type="image" title="Lasers submarines propulsion" height="373" width="1049" msid="109665819" hostid="261" sizebytes="15166"></div>A large number of high-powered laser beams positioned around the submarine at various angles could produce nearly 70,000 newtons of thrust and would drive it forward at speeds almost as fast as a commercial jet, according to SCMP.Ge Yang, the leading researcher on the project, said the technology could also be used on underwater missiles or torpedoes, "significantly increasing the underwater range," the outlet reported.<h2>Stealth and speed</h2>The team of scientists say this process would deliver not just speed but enhanced stealth as well.Using lasers may also induce a process known as "supercavitation" — a coating of bubbles forms around an object in water, reducing drag resistance and making it travel faster.This technology has already been used in Russian Shkval torpedoes since the 1970s, using rocket exhaust rather than laser power.<div type="image" title="Submarine shooting missile" height="3001" width="4000" msid="109665821" hostid="261" sizebytes="57048"></div>But Professor Andrew Higgins, who leads a team at McGill University developing laser propulsion technology for space travel, doesn't believe that lasers could be powerful enough to induce this "bubble" effect around torpedos, let alone submarines."Cavitation can be induced on the front of the torpedo by a spike or forward-facing rocket exhaust. I am doubtful a torpedo can carry enough of a power supply to power a laser that would continuously perform this operation," he told Business Insider.And for a laser to produce enough thrust to propel an entire submarine?"I am even more skeptical," Higgins said. "The average overall thrust is low and the jet power cannot exceed the power supply of the laser.""Even with the high efficiencies of today's lasers, this approach would never be as efficient as a propeller, so there is no net propulsive gain."As the SCMP notes, Japanese researchers first proposed this sort of laser propulsion methodology 20 years ago, but for decades the technology has only been able to produce thrust powers of one-millionth of a newton thrust.Controlling the direction of the plasma detonation wave to steer the submarine is another issue.The Chinese researchers say the unique design of the microcavities in the optical fibers has increased the efficiency of thrust and channels the direction of force, according to SCMP.<div type="image" title="Advanced space transportation concepts, such as antimatter, laser propulsion, solar sails and fusion-driven vehicles as shown in this artist's concept could lead to human exploration of the Solar System and beyond." height="1680" width="2100" msid="109665823" hostid="261" sizebytes="65900"></div>However, they admit there are many challenges to overcome before the technology can be applied to submarines.Higgins says they also avoid a key issue in their claim that the technology would reduce noise — cavitation is an "acoustic dead giveaway.""It would not be feasible or desirable to propel a nuclear submarine in this way.""For nuclear submarines, acoustic stealth is the entire purpose, and great effort is expended in avoiding cavitation."<h2>Race to advance military capabilities</h2>While laser propulsion technologies for submarines remain in the theoretical stage for now, the US is locked in a race with China to develop advanced military capabilities.Harbin University, where the researchers are based, is a hub of Chinese military development and is listed as "very high risk/top secret" in Australia's <a target="_blank" href="https://www.aspi.org.au/report/china-defence-universities-tracker">China Defense Universities Tracker</a>.According to the tracker, 52% of the university's total research budget was spent on defense research in 2018.China currently operates 60 submarines, compared to the 67 operated by the US. But while US numbers are stagnating, China's submarine count is expected to rise to 80 by 2035.China's navy is numerically the largest in the world, but analysts say it is <a target="_blank" href="https://www.businessinsider.com/us-navy-shrinking-china-biggest-fleet-shipbuilding-taiwan-2024-4">not as technologically advanced</a> and lacks experience compared to the US.

Chinese scientists want to use lasers to power ultrafast, stealthy submarines. A laser expert says there's a major flaw in their plan.

<ul class="summary-list"><li>Armies around the world are testing high-energy laser weapons to intercept targets. </li><li>If successful, the weapons could change warfare, as they travel near the speed of light.</li></ul>Chinese scientists claim they have found a way to build a laser weapon that can be fired indefinitely, which would dramatically increase its effectiveness over other laser weapons.If their claims are true, it means that China has leapfrogged over the US in developing <a href="https://www.businessinsider.com/lockheed-martin-laser-can-disable-boats-2014-5">high-energy laser weapons</a> that could be used on the battlefield.The capability China's military scientists claim to have developed, however, has not yet been seen in action.Researchers at the <a href="https://www.scmp.com/news/china/science/article/3230589/chinese-military-scientists-claim-have-achieved-huge-breakthrough-laser-weapon-technology" target="_blank" rel="noopener">National University of Defense Technology</a>, a military-research institution in Hunan, said they developed a cooling system that allowed high-energy lasers to remain powered up without getting too hot, the South China Morning Post reported.The system is a "huge breakthrough in improving the performance of high-energy laser systems," the scientists said in a paper published in Acta Optica Sinica, a Chinese-language peer-reviewed journal, on August 4, the South China Morning Post reported. "High-quality beams can be produced not only in the first second but also maintained indefinitely," they added.Laser beams can heat up gas in the air, which can reduce the quality of the beam and cause damage inside the laser chamber, the report said. To bypass this issue, the scientists said, they developed a system that could blow clean gas through the chamber and remove waste heat. This allowed them to make the laser more compact and efficient, the South China Morning Post said. "So far, many advanced designs and research progress on dynamic air-blowing thermal management in China have not been reported," the scientists said, the South China Morning Post reported. "This is the first time that some of the designs and test results [have gone] to the public," they said.China and the US, among other nations, are looking to develop combat-ready high-energy laser weapons that can generate beams <a href="https://www.gao.gov/products/gao-23-106717">strong enough to melt steel</a>.<a href="https://www.businessinsider.com/video-plane-armed-with-laser-downs-drones-israeli-military-test-2021-6">High-powered laser weapons</a> have the potential to be a game-changing technology for warfare and defense because they could shoot targets such as drones, missiles, and small aircraft at nearly the speed of light at lower costs than interceptor missiles. A challenge, though, has been cooldown time.In a <a href="https://twitter.com/SteveWeaverTEFL/status/1689952097351983104" target="_blank" rel="noopener">tweet about the reports</a>, Steve Weaver, a former British military official, said that if the news on the achievement by the Chinese scientists was true, it would put China ahead of the US in more ways than one."This is a big breakthrough considering the US failures in this area," he said, highlighting a section of the South China Morning Post report pointing to US military systems that didn't quite meet expectations.<div type="image" title="An artist's impression of a High Energy Laser weapon shows a laser beam being shot at an aircraft in a sandy landscape." height="915" width="1220" msid="102729708" hostid="261"></div>Major defense companies in the US have also been pushing forward the development of laser-based weapons as part of projects including the US Department of Defense's High Energy Laser Scaling Initiative. The beams could be used <a href="https://www.army-technology.com/projects/300kw-high-energy-laser-weapon-system-helws-us/">to defend sites from incoming threats</a>.The US military has in recent years embraced these systems.The Army, for example, has mounted 50-kilowatt lasers on its Stryker armored fighting vehicles, while the Navy's amphibious warship USS Portland, building on earlier testing, has tested a 150-kilowatt laser against a surface target. The Marines have tested a Compact Laser Weapons System in the range of 2 to 10 kilowatts, and the Air Force has received high-energy laser pods for its fighter jets.Lockheed Martin announced last year it had delivered a <a href="https://interestingengineering.com/innovation/lockheed-martin-breaks-own-record">300-kilowatt laser</a> to the Defense Department. It's now working on a more powerful, <a href="https://www.lockheedmartin.com/en-us/capabilities/directed-energy.html">500-kilowatt laser</a>, the company's website says. While there has been renewed interest in this technology, there are major limitations to its use.Laser weapons are usually less powerful the farther away they are from the target and can be foiled by bad weather such as fog and storms, which can reduce the beam's range and quality, the US Government Accountability Office said, adding that cooling requirements could also limit their effectiveness.

China's military claims to have found a way to build a laser weapon that can fire indefinitely

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Chinese scientists want to use lasers to power ultrafast, stealthy submarines. A laser expert says there's a major flaw in their plan.

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China's military claims to have found a way to build a laser weapon that can fire indefinitely

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