from the world's big
Physicists invent a new way to search for dark matter using lasers
Japanese physicists devise technology to discover axion dark matter.
- Physicists from the University of Tokyo plan to use lasers to discover axions.
- Axions are theoretical particles that may be components of dark matter.
- Dark matter is a mysterious substance that may compose up to 27% of the universe.
Japanese physicists propose modifications to existing equipment that could allow them to pinpoint axions, hypothetical particles that may be components of dark matter. Dark matter, a mysterious theoretical substance that is thought to make up about 27% of all matter in the universe, is yet to be directly observed.
The scientists hope to track down the elusive axions using experiments with lasers.
The difficulty in finding dark matter is that it is made of, as many physicists think, weakly interacting massive particles or WIMPs, produced in the early Universe. While we haven't figured out how to spot these particles directly, interacting with regular matter, but we've been able to predict their existence by the gravitational effects they have throughout the universe.
The celebrated Large Hadron Collider in Switzerland has been used to search for WIMPs, and now a new approach from Japan hopes to use the KAGRA Observatory to discover dark matter by tracking down axions.
KAGRA stands for the Kamioka Gravitational Wave Detector. This first major gravitational wave observatory in Asia is located deep under a mountain of the Kamioka mine in Japan's Gifu Prefecture.
The Assistant Professor Yuta Michimura from the Department of Physics at the University of Tokyo, which runs the KAGRA project, explained that because axions are light and don't interact with normal matter, they are good candidates for dark matter.
Interestingly, he also quantified how much dark matter is there, saying the amount of it inside our planet would weigh as much as a squirrel —
"We don't know the mass of axions, but we usually think it has a mass less than that of electrons, " said Michimura. "Our universe is filled with dark matter and it's estimated there are 500 grams of dark matter within the Earth, about the mass of a squirrel."
The proposed instrument that would hunt for axion dark matter.
Credit: 2019 Nagano et al | University of Tokyo Institute for Cosmic Ray Research
As you can imagine, spotting such particles is no easy task. Physicists have to figure out ways that can make the particles reveal themselves through their signatures.
Koji Nagano, a graduate student at the Institute for Cosmic Ray Research at the University of Tokyo, says that their models show that axions affect light polarization, which describes the geometrical orientation of oscillating electromagnetic waves.
Their method of finding axions relies on this finding.
"This polarization modulation can be enhanced if the light is reflected back and forth many times in an optical cavity composed of two parallel mirrors apart from each other, " further expounds their approach Nagano.
The best examples of such cavities, says the researcher, are the long tunnels of gravitational-wave observatories.
"There is overwhelming astrophysical and cosmological evidence that dark matter exists, but the question "What is dark matter?" is one of the biggest outstanding problems in modern physics," said Nagano. "If we can detect axions and say for sure they are dark matter, it would be a truly exciting event indeed. It's what physicists like us dream for."
The team proposes plans to inexpensively modify existing observatories like KAGRA or the Laser Interferometer Gravitational-Wave Observatory (LIGO) in the U.S. to search for the axions. The plan, according to Michimura, would be to add "polarization optics in front of photodiode sensors in gravitational-wave detectors."
The idea's additional benefit is that it doesn't require building entirely new facilities. Upgrading gravitational wave labs would not hamper their original missions — looking for gravitational waves. But the new functionality would open a new chapter in the search for dark matter.
The study involved Koji Nagano, Tomohiro Fujita, Yuta Michimura, and Ippei Obata.
Check out the their paper "Axion Dark Matter Search with Interferometric Gravitational Wave Detectors" in the journal Physical Review Letters.
Andy Samberg and Cristin Milioti get stuck in an infinite wedding time loop.
- Two wedding guests discover they're trapped in an infinite time loop, waking up in Palm Springs over and over and over.
- As the reality of their situation sets in, Nyles and Sarah decide to enjoy the repetitive awakenings.
- The film is perfectly timed for a world sheltering at home during a pandemic.
China moves to Russia and India takes over Canada. The Swiss get Bangladesh, the Bangladeshi India. And the U.S.? It stays where it is.
What if the world were rearranged so that the inhabitants of the country with the largest population would move to the country with the largest area? And the second-largest population would migrate to the second-largest country, and so on?
A recent analysis of a 76-million-year-old Centrosaurus apertus fibula confirmed that dinosaurs suffered from cancer, too.
- The fibula was originally discovered in 1989, though at the time scientists believed the damaged bone had been fractured.
- After reanalyzing the bone, and comparing it with fibulas from a human and another dinosaur, a team of scientists confirmed that the dinosaur suffered from the bone cancer osteosarcoma.
- The study shows how modern techniques can help scientists learn about the ancient origins of diseases.
Centrosaurus apertus fibula
Royal Ontario Museum<p>In the recent study, the team used a combination of techniques to analyze the fibula, including taking CT scans, casting the bone and studying thin slices of it under a microscope. The analysis suggested that the dinosaur likely suffered from osteosarcoma, a type of bone cancer that affects modern humans, typically young adults.</p><p>For further evidence, the team compared the damaged fibula to a healthy fibula from a dinosaur of the same species, and also to a fibula that belonged to a 19-year-old human who suffered from osteosarcoma. Both comparisons supported the osteosarcoma diagnosis.</p>
Evans et al.<p style="margin-left: 20px;">"The shin bone shows aggressive cancer at an advanced stage," Evans said in a <a href="https://www.rom.on.ca/en/about-us/newsroom/press-releases/rare-malignant-cancer-diagnosed-in-a-dinosaur" target="_blank">press release</a>. "The cancer would have had crippling effects on the individual and made it very vulnerable to the formidable tyrannosaur predators of the time."</p><p style="margin-left: 20px;">"The fact that this plant-eating dinosaur lived in a large, protective herd may have allowed it to survive longer than it normally would have with such a devastating disease."</p><p>The fossilized fibula was originally unearthed in a bonebed alongside the remains of dozens of other <em>Centrosaurus </em><em>apertus</em>, suggesting the dinosaur didn't die from cancer, but from a flood that swept it away with its herd.</p>
Dinosaur fibula; the tumor mass is depicted in yellow.
Royal Ontario Museum/McMaster University<p>The new study highlights how modern techniques can help scientists learn more about the evolutionary origins of modern diseases, like cancer. It also shows that dinosaurs suffered through some of the same terrestrial afflictions humans face today.</p><p style="margin-left: 20px;">"Dinosaurs can seem like mythical creatures, but they were living, breathing animals that suffered through horrible injuries and diseases," Evans said, "and this discovery certainly makes them more real and helps bring them to life in that respect."</p>
Join the lauded author of Range in conversation with best-selling author and poker pro Maria Konnikova!
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