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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.
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Construction of the $500 billion dollar tech city-state of the future is moving ahead.
- The futuristic megacity Neom is being built in Saudi Arabia.
- The city will be fully automated, leading in health, education and quality of life.
- It will feature an artificial moon, cloud seeding, robotic gladiators and flying taxis.
The Red Sea area where Neom will be built:
Saudi Arabia Plans Futuristic City, "Neom" (Full Promotional Video)<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="c646d528d230c1bf66c75422bc4ccf6f"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/N53DzL3_BHA?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span>
Frequent shopping for single items adds to our carbon footprint.
- A new study shows e-commerce sites like Amazon leave larger greenhouse gas footprints than retail stores.
- Ordering online from retail stores has an even smaller footprint than going to the store yourself.
- Greening efforts by major e-commerce sites won't curb wasteful consumer habits. Consolidating online orders can make a difference.
A pile of recycled cardboard sits on the ground at Recology's Recycle Central on January 4, 2018 in San Francisco, California.
Photo by Justin Sullivan/Getty Images<p>A large part of the reason is speed. In a competitive market, pure players use the equation, <em>speed + convenience</em>, to drive adoption. This is especially relevant to the "last mile" GHG footprint: the distance between the distribution center and the consumer.</p><p>Interestingly, the smallest GHG footprint occurs when you order directly from a physical store—even smaller than going there yourself. Pure players, such as Amazon, are the greatest offenders. Variables like geographic location matter; the team looked at shopping in the UK, the US, China, and the Netherlands. </p><p>Sadegh Shahmohammadi, a PhD student at the Netherlands' Radboud University and corresponding author of the paper, <a href="https://www.cnn.com/2020/02/26/tech/greenhouse-gas-emissions-retail/index.html" target="_blank">says</a> the above "pattern holds true in countries where people mostly drive. It really depends on the country and consumer behavior there."</p><p>The researchers write that this year-and-a-half long study pushes back on previous research that claims online shopping to be better in terms of GHG footprints.</p><p style="margin-left: 20px;">"They have, however, compared the GHG emissions per shopping event and did not consider the link between the retail channels and the basket size, which leads to a different conclusion than that of the current study."</p><p>Online retail is where convenience trumps environment: people tend to order one item at a time when shopping on pure player sites, whereas they stock up on multiple items when visiting a store. Consumers will sometimes order a number of separate items over the course of a week rather than making one trip to purchase everything they need. </p><p>While greening efforts by online retailers are important, until a shift in consumer attitude changes, the current carbon footprint will be a hard obstacle to overcome. Amazon is trying to have it both ways—carbon-free and convenience addicted—and the math isn't adding up. If you need to order things, do it online, but try to consolidate your purchases as much as possible.</p><p>--</p><p><em>Stay in touch with Derek on <a href="http://www.twitter.com/derekberes" target="_blank">Twitter</a>, <a href="https://www.facebook.com/DerekBeresdotcom" target="_blank">Facebook</a> and <a href="https://derekberes.substack.com/" target="_blank">Substack</a>. His next book is</em> "<em>Hero's Dose: The Case For Psychedelics in Ritual and Therapy."</em></p>
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