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Science

Physicists make progress towards developing an extremely accurate ‘nuclear’ clock

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Scientists have made significant progress in developing a novel clock that relies on minute changes in energy within an atomic nucleus. Conceptually, a nuclear clock has the potential to surpass the precision of the world’s most accurate timekeeping devices, referred to as optical clocks, while also being less susceptible to disruptions.

Additionally, a nuclear chronometer could enable physicists to investigate the fundamental forces of nature using novel approaches. “We will have the capability to investigate situations involving dark matter and fundamental physics that are presently unattainable through alternative means,” states Elina Fuchs, a theoretical physicist at CERN, the particle-physics laboratory in Europe located near Geneva, Switzerland.

The highly anticipated discovery, achieved through a partnership between the Vienna University of Technology and Germany’s national metrology institute, the PTB, in Braunschweig, utilized an ultraviolet laser to induce a transition in the energy levels of a nucleus of the radioactive element thorium-229. The frequency of light that is absorbed and emitted by the nucleus serves as the mechanism for the clock’s ticking. The researchers disseminated their findings in the scientific journal Physical Review Letters on the 29th of April.

“This is significant,” states Adriana Pálffy-Buß, a theoretical physicist affiliated with the University of Würzburg in Germany. Using a laser to drive the transition is a crucial step that signifies the ability to construct a clock.”The achievement represents the combined efforts of numerous scientific organizations over a period of almost fifty years,” states Olga Kocharovskaya, a physicist affiliated with Texas A&M University in College Station.

Exactly on time
So well do optical clocks keep time that they only go off by one second every 30 billion years. To change an electron’s energy state around an atom like strontium, they need a certain frequency of visible light. This frequency controls how fast they tick.

But a nuclear clock would work better. To make the transition more energetic, the protons and neutrons in the nucleus would be raised to a higher energy level. This would use a slightly higher frequency of radiation, which would allow time to be cut even more precisely, making the clock more accurate. A clock like this would also be much more stable than an optical clock, since particles in the nucleus are not as affected by outside fields or temperature as electrons are.

But it has been hard to find a material with the right nucleus. Most nuclei have big energy changes that need a lot more than the push of a tabletop laser. Scientists found out in the 1970s that thorium-229 is different because its first energy state is very close to its ground state. In 2003, physicists suggested using thorium-229 as the building block of a super-stable clock. But they had to find the exact energy of the transition and the laser frequency that went with it, which could not have been predicted with any degree of accuracy using theory. The numbers have been narrowed down in a number of different ways since then.

To see the change, scientists put radioactive thorium atoms into calcium fluoride crystals that were only a few millimeters wide. They used a custom-built laser to scan the expected area and finally found the right frequency: about 2 petahertz (1015 oscillations per second). They were able to identify this frequency by observing the photons released by the nuclei as they returned to a lower-energy state. Thorsten Schumm, an atomic physicist at the Vienna University of Technology and co-author, remembers writing “found it” in big red letters in his lab book at a meeting the next day to talk about the signal that looked promising. He says, “It was very clear.”

The team was 800 times more accurate than the next best attempt when they found the frequency. According to co-author and PTB physicist Ekkehard Peik, since then, a team at the University of California, Los Angeles, has used the same frequency to achieve the same result. He calls it “a very nice confirmation.”

Help with basic physics
Scientists will have to greatly lower the laser’s resolution in order to make the system work as a real clock. This is so that it can reliably stimulate the nucleus at just the right frequency, according to Peik. “Building such a laser remains a big challenge,” says Kocharovskaya. “But there are little doubts that it will be possible in the near future.”

The group says that a thorium-based nuclear clock might be about 10 times more accurate than the best optical clocks if everything goes as planned. “This will be a better clock because it will be more resistant to changes in the outside world,” says Schumm. The clock might be smaller and easier to carry around if the nuclei are in a solid crystal instead of an optical system.

Help with basic physics
Scientists will have to greatly lower the laser’s resolution in order to make the system work as a real clock. This is so that it can reliably stimulate the nucleus at just the right frequency, according to Peik. “Building such a laser remains a big challenge,” says Kocharovskaya. “But there are little doubts that it will be possible in the near future.”

The group says that a thorium-based nuclear clock might be about 10 times more accurate than the best optical clocks if everything goes as planned. “This will be a better clock because it will be more resistant to changes in the outside world,” says Schumm. The clock might be smaller and easier to carry around if the nuclei are in a solid crystal instead of an optical system.

Very accurate optical clocks have made it possible for scientists to do things like measure differences in clock speeds to look into Earth’s gravitational field. Kocharovskaya says that these methods “could get a major boost.”

On a deeper level, physics could also use some help. Says Fuchs that a nuclear clock would be 10,000 times more aware of changes in fundamental constants, like the strength of the strong nuclear and electromagnetic forces. This means they could find possible types of dark matter, an invisible substance that physicists believe makes up 85% of the universe’s matter and is thought to cause tiny changes in the strength of these forces.

Fuchs says, “It’s possible that there’s very “light” dark matter that moves around, which could make these fundamental constants move.” She says that nuclear clocks might be able to pick up on that wiggle because these forces control the energy of their transition, and any change in their strength would change the tick in a way that can be measured. She also says that nuclear clocks could find out if the masses of some particles change over time. Fuchs and her colleagues are already working on their first paper, which is based on the measurement of frequency. She says, “This is pretty exciting for us.”

As Editor here at GeekReply, I'm a big fan of all things Geeky. Most of my contributions to the site are technology related, but I'm also a big fan of video games. My genres of choice include RPGs, MMOs, Grand Strategy, and Simulation. If I'm not chasing after the latest gear on my MMO of choice, I'm here at GeekReply reporting on the latest in Geek culture.

Medicine and Health

Toxic chemicals leak out of plastic bottles when they are exposed to sunlight

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If you don’t want to drink a bunch of chemicals that could be harmful, keep your water bottle out of the sun. Plastic water bottles that are left out in the sun break down and release many different types of volatile organic compounds (VOCs).

VOCs are chemicals that evaporate quickly at room temperature. They are found in a lot of different products, like paints, cleaners, fuels, and solvents. They’re also made of plastic, like those used to make water bottles and food trucks. Many of them are safe, but some may be bad for your health in the short and long term.

In the most recent study, UV-A light and sunlight were used to test six different kinds of plastic water bottles in China. They discovered that this process let out a wide range of VOCs, such as acids, alcohols, aldehydes, and alkanes.

Some signs pointed to “highly toxic” VOCs, such as n-hexadecane, which is known to cause cancer.

A single sip of contaminated water doesn’t pose much of a health risk, but the researchers found that long-term exposure may pose a greater risk.

“Our results are strong proof that plastic bottles can release harmful chemicals into the air when they are exposed to sunlight.” “Consumers need to be aware of these risks, especially in places where bottled water is left out in the sun for long periods of time,” said Dr. Huase Ou, lead researcher from China’s Jinan University’s Guangdong Key Laboratory of Environmental Pollution and Health.

However, the researchers were quick to point out that the risk seems to be pretty low since the bottle only releases a small amount of chemicals.

“Given that a container weighs about 20 grams on average, the VOCs that were released from a single container were only a few nanograms.” So, even after long-term exposure, opening a bottle and drinking water from it doesn’t pose many health risks to people, the study’s authors write in the conclusion.

The bottles in the study were all made of polyethylene terephthalate (PET), which is one of the most common types of plastic. However, the VOC composition and concentration of the different bottles were very different. The different production methods and additives seem to have something to do with this.

Most likely, the chemicals leaked out of the bottle because of a process called photodegradation. This is when light breaks down the structure of the plastic.

There are more things than just sunlight that you should think about when it comes to your plastic bottle’s “health.” A study from the past found that leaving water in a plastic bottle for just one day could let hundreds of chemicals get into your drink. Several of these chemicals are thought to be harmful to health, such as those that cause cancer or mess with the hormone system (endocrine disruptors).

In the same way, there is some evidence that heating plastic bottles might not be a good idea. A study done in 2020 found that the sterilization process recommended by the World Health Organization put between 1.3 and 16.2 million microplastic particles per liter into child bottles.

In the 21st century, plastic is found everywhere, from penises to ice in Antarctica. It was once thought to be mostly harmless, but it’s becoming clearer that it’s having a bad effect on us and the planet, and we’re only just beginning to understand how bad it is.

The study was published in the magazine Eco-Environment & Health.

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Astronomy

There Is A Hotly Debatable Twin To The Search For Extraterrestrial Intelligence

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Humanity has been trying to find signals from extraterrestrial civilizations for more than a century. Prior to focusing our eyes and ears on the galaxy and universe beyond, early efforts in the Search for Extraterrestrial Intelligence (SETI) concentrated on listening for messages from within the Solar System.

There have been no alien signals found thus far in these searches. While one signal remains enigmatic, it most likely stems from a human or natural source. But given that we (aside from our stray signals) don’t broadcast ourselves on a regular basis, is it unreasonable to assume that alien civilizations would do the same?

Messaging for Extraterrestrial Intelligence, or METI, is introduced. While it wouldn’t be accurate to state that humanity hasn’t communicated with the cosmos, there have undoubtedly been a few. The Golden Records are audio and visual files that NASA’s Voyager I and Voyager II spacecraft “selected to portray the diversity of life and culture on Earth.” Aliens will probably never find these. However, we have also sent other signals, like the Arecibo Message, which was directed about 21,000 light-years from Earth toward the globular star cluster M13. With only 210 bytes of data, the message was small but contained information about the 4 billion people that lived on Earth at the time, a stick figure of a person, a double helix, and a drawing of the Arecibo radio telescope that sent the message.

The organization METI International was founded in 2015 with the intention of communicating with extraterrestrial civilizations. They delivered a similar message to the super-Earth exoplanet GJ273b in October 2017, which is only 19 light-years away from Earth and may be habitable.

This is where METI becomes a little contentious. A map of the solar system was also included in the Arecibo message, and there are (very speculative) reasons why we might not want to communicate with aliens in our cosmic backyard or even send a return address.

The explanation of the Fermi paradox offered by what is now widely referred to as the “Dark Forest Hypothesis” is one of the reasons METI is controversial.

In short, it looks like the universe is full of planets that might be habitable, but we have never picked up a signal from an alien civilization.

The very dark Dark Forest Hypothesis, which is explained in Liu Cixin’s Remembrance of Earth’s Past trilogy, says that alien civilizations hide their existence because you can’t be sure what other civilizations want. There’s no way for you to know if they are hostile or friendly, or what their intentions are.

It’s possible that you, as a friendly civilization, find an alien civilization that is also friendly and about the same level of development as yours. You know you’re nice, but you don’t know if they’re also calm. Even worse, because of how far away these civilizations are and how long it takes to receive light and signals from them, you have no idea how their society has changed since the signal from them reached yours. In the meantime, they may have made huge technological leaps. This means that even if the planet you are looking at seems peaceful and not too far ahead of yours, everything could have changed by the time the light gets to you.

On top of that, there is the pressure of resources. According to the books, you also know from your own planet that life uses and spreads all the resources it can find. But there are only so many resources in the universe.

You still have to deal with the fact that you don’t know if they know that you are peaceful if you decide that they are peaceful. Since they think or even just suspect that you are bad, it makes sense that they would try to kill you before you could kill them. You could talk to them, just like you can here on Earth, to reassure them even more of your plans. In space, though, it could take hundreds or even thousands of years for your new message to get there. During that time, they could have began an attack to destroy you. With this many red flags, Liu comes to the conclusion that the only smart thing for a civilization that wants to stay alive is to hide in the forest and kill any civilizations that make noise, before they kill you.

Scientists are serious about the idea of hostile aliens, even though the idea became popular in fiction. In 2015, Stephen Hawking started a project to look for alien civilizations. He talked about why it might not be a good idea to say hello back.

According to Space.com, Hawking told the crowd, “We don’t know much about aliens, but we know a lot about humans.” “If you look at history, interactions between humans and less intelligent creatures have often been terrible for them, and interactions between civilizations with advanced and primitive technologies have also been bad for the less advanced.” If someone reads one of our messages, they might be billions of years ahead of us. They will be much stronger if that’s the case, and they might not value us more than we value bacteria.

However, the Dark Forest theory is still a long way from being proven. It is important to think about hostile aliens when deciding whether to contact other species and who should make that decision. David Brin, an American author and scientist, asked “whether small groups of zealots should bypass all institutions, peer critique, risk appraisal, or public opinion, to shout ‘yoohoo’ into a potentially dangerous cosmos.”

In a way, the fact that METI exists could be used to show that the Dark Forest Hypothesis is wrong. Let’s say there are very advanced societies out there. Assuming that some people in these advanced civilizations have access to advanced broadcast technology is a reasonable thing to do. Another reasonable guess is that if they were that advanced, they would have built this civilization with science instead of magic.

The civilizations would probably gather information about other star systems in the same way that we do, unless they have a good reason for not wanting to know about life beyond their own planet. Assuming that this information and broadcast technology aren’t somehow limited across all civilizations, there must be some people who would be crazy enough to try to get in touch with other civilizations. While obviously speculating wildly, it’s possible that an alien METI species that likes to take risks might try to warn other, younger civilizations about how the universe is like a dark forest. Also, we haven’t heard from these actors, which could mean that the long silence has a different cause than the Dark Forest Hypothesis.

That, or the METI problem, might only happen in new civilizations that send out messages every so often before we learn about the universe’s dark side and do everything we can to stay quiet.

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Engineering

Content creators on the platform YouTube have constructed a remarkable and “potentially hazardous” retractable lightsaber

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A group of YouTubers have created a remarkable retractable lightsaber that they classify as “potentially hazardous.”.

HeroTech recently released a video outlining their intention to develop a lightsaber that mimics the retractable nature of the lightsabers seen in the Star Wars movies, as opposed to the currently available models with fixed extended blades.

The team stated on YouTube that they were well aware of the challenges they would face when embarking on the project to create an actual retractable lightsaber. “Our primary obstacles were evident: achieving complete containment of blade extension and retraction, creating a compact hilt design that is proportional to the original, and producing a blade and sound that closely resemble reality.”

Creating a retractable lightsaber proved challenging, but the team successfully accomplished this by utilizing a magician’s cane, a tool that can contract to a compact size and extend to a length of over 0.9 meters (3 feet). After extensive tinkering, the outcome is a remarkable lightsaber that elongates upon activation.

The team clarifies on their website that this lightsaber showcases a dazzling blade of light that genuinely extends from and retracts into the hilt. “Equipped with a 12V COB LED strip, 4S LiPo battery, the Proffieboard V3.9, and a high-performance speaker, this lightsaber delivers authentic lighting effects and lifelike sound effects.”

The team also aimed to enable others to construct the lightsaber in their own homes, by furnishing their subscribers with comprehensive instructions on how to do so. Nevertheless, they have strongly cautioned against attempting it.

“This lightsaber is an experimental model and has the potential to be hazardous if attempted to be made by oneself,” they mention on their YouTube channel. “Although I am actively working towards improving this situation, I am unable to currently endorse this product for individuals lacking engineering proficiency and the determination to spend several hours resolving technical issues.”

Disney has developed its own collapsible lightsabers specifically for use in performances at Disney World, although they are probably not produced at a low cost.

Neither of the blades is capable of cutting through stormtroopers, as they are purely ornamental. Nevertheless, an inexperienced YouTuber successfully constructed a functional lightsaber with the ability to retract, earning a place in the Guinness Book of World Records in 2022.

Alex Burkan, the proprietor of the YouTube channel Alex Lab, engineered a contraption capable of generating a plasma blade measuring 1 meter (equivalent to 3.28 feet) in length upon activation. The blade, which reaches a temperature of 2,800°C (5,072°F), possesses the ability to effortlessly slice through steel.

“An electrolyser is the crucial element of my lightsaber,” Burkan informed Guinness World Records. An electrolyser is a device capable of producing a substantial quantity of hydrogen and oxygen, and it can compress the gas to any desired pressure without the need for a mechanical compressor.

However, in contrast to an authentic lightsaber or the ones demonstrated by Disney, the blade has a limited operational duration of approximately 30 seconds at maximum intensity. Consequently, lightsaber duels are brief unless they occur in close proximity to charging stations.

Burkan also mentioned that occasionally the lightsaber may explode in your hand due to a hydrogen flashback.

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