Month: April 2019

Enlarge / Some of the XENON1T hardware. (credit: XENON collaboration)

One of the ways we measure the age of the Earth is using the half-life of uranium. With a half-life of around four billion years, your typical atom of uranium only has even odds of having decayed during Earth's entire history. But it only takes a few hundred atoms to up the odds for us to see enough decays to be able to accurately measure the age of something, even though the decay itself may be rare. In fact, with enough atoms, it's possible to measure radioactive decays from events that have a half-life longer than the Universe's age.

Now, researchers have used a tank full of two tonnes of liquid xenon, put together to detect dark matter, to identify the rarest decay ever detected. The XENON1T detector picked up some xenon atoms being transformed into tellurium, an event with a half-life measured at 1.8 x 10²² years—or about a trillion times the age of the Universe.

Tonnes of xenon

What's the point of having two tonnes of liquid xenon in the first place? XENON1T was set up to detect a different but also extremely rare event: a dark matter particle bumping into one of the xenon atoms. This would impart enough energy to the atom to allow the event to be picked up by detectors that monitored the xenon tank. For this to work, however, the tank had to be shielded from any events that could also create a signal in the monitoring system. As a result, it was set up deep underground at Italy's Gran Sasso facility, and any potentially radioactive contaminants were eliminated from the liquid xenon.

Enlarge (credit: Ars Technica)

Greetings, Arsians! The Dealmaster is back with another round of deals to share. Today's list is led by one of the first genuine discounts on the latest version of Apple's AirPods, as Amazon currently has the little white wireless earbuds down to $140.

That's only good for a $20 discount, but discounts on the first-gen AirPods weren't terribly frequent this soon after they launched, and massive price cuts have been rare ever since. This deal is for the updated model Apple announced in March, however, which utilizes a more power-efficient "H1" wireless chip and supports a new wireless charging case. The listing here doesn't come with said case—that's currently going for $70 on Amazon or $199 as a bundle—and is currently backordered until mid-May, so you'll have to wait a bit for them to ship. But hey, it's nice to get newer things for less money, right?

As for the AirPods themselves, well, you probably know the deal with them at this point. They're actually priced competitively compared to other big-name truly wireless earbuds, but they don't sound that great, their design may not fit all ears, and their tiny, non-repairable design gives them a shorter lifespan than most wireless headphones. If you can look past all of that—and lots of people seem to have—they can be incredibly convenient when paired with an iPhone. If you need more details, most of the things we said in our review way back in 2016 still hold true today.

Enlarge / SpaceX's Crew Dragon approaches the International Space Station in March, 2019. (credit: NASA)

Since issuing a brief statement Saturday after a test of its Crew Dragon vehicle resulted in an "anomaly," SpaceX has not offered additional comment about its ongoing investigation. NASA, too, has not said much outside of saying it is assisting the investigation and that the agency has "full confidence in SpaceX" to understand and address the problem which appears to have destroyed the crew capsule.

A previously scheduled meeting of NASA's Aerospace Safety Advisory Panel on Thursday, however, did offer a little bit more insight into the problem that occurred with the Crew Dragon vehicle at SpaceX's Landing Zone 1 facility in Florida, near the company's two launch sites there.

"The event occurred during a static fire test conducted prior to the in-flight abort test," said Patricia Sanders, chairwoman of the panel charged with ensuring that NASA has a healthy safety culture and mitigates risks where possible during spaceflight.

Enlarge (credit: Elliot Margolies)

Recycling sounds great in principle (because it is), but a frustrating number of devils lurk in the details. For example, while some materials like aluminum can readily be melted down and turned right back into new aluminum cans, recovered plastics tend to be lower quality than “virgin” material. That’s because recycled plastic retains some of its previous properties—like Lego bricks that can’t be separated. The next plastic you make won’t be exactly the same type, and the recycled material won’t fit perfectly into its new spot.

To improve this situation, plastics engineers want to create new materials that can cleanly and easily break down to the most basic components—individual Lego bricks that can be reassembled into absolutely anything. The difficulty of this task is increased by all the pigments, flame retardants, and other additives used in plastics. But a group led by Lawrence Berkeley National Laboratory’s Peter Christensen has developed a new plastics process that conquers these challenges.

The basic building block of a plastic is called a “monomer”—connect monomers together and you create “polymers” with the useful physical properties you’re after. In this case, the researchers are using triketones and amines as building-block monomers. The process for putting them together sounds like minor sorcery (as chemistry often does): combining chemical ingredients causes different building blocks to form, which then spontaneously assemble.

Enlarge (credit: Getty / Aurich Lawson / Tesla)

There's an old joke in the software engineering world, sometimes attributed to Tom Cargill of Bell Labs: "the first 90 percent of the code accounts for the first 90 percent of the development time. The remaining 10 percent of the code accounts for the other 90 percent of the development time."

On Monday, Tesla held a major event to show off the company's impressive progress toward full self-driving technology. The company showed off a new neural network computer that seems to be competitive with industry leader Nvidia. And Tesla explained how it leverages its vast fleet of customer-owned vehicles to collect data that helps the company train its neural networks.

Elon Musk's big message was that Tesla was close to reaching the holy grail of fully self-driving cars. Musk predicts that by the end of the year, Tesla's cars will be able to navigate both surface streets and freeways, allowing them to drive between any two points without human input.