Three progressively heavier copies of each type of matter particle exist, and no one knows why. A new paper by Steven Weinberg takes a stab at explaining the pattern. From a report: Electrons and two types of quarks, dubbed "up" and "down," mix in various ways to produce every atom in existence. But puzzlingly, this family of matter particles -- the up quark, down quark and electron -- is not the only one. Physicists have discovered that they make up the first of three successive "generations" of particles, each heavier than the last. The second- and third-generation particles transform into their lighter counterparts too quickly to form exotic cats, but they otherwise behave identically. It's as if the laws of nature were composed in triplicate. "We don't know why," said Heather Logan, a particle physicist at Carleton University. In the 1970s, when physicists first worked out the Standard Model of particle physics -- the still-reigning set of equations describing the known elementary particles and their interactions -- they sought some deep principle that would explain why three generations of each type of matter particle exist. No one cracked the code, and the question was largely set aside.

Now, though, the Nobel Prize-winning physicist Steven Weinberg, one of the architects of the Standard Model, has revived the old puzzle. Weinberg, who is 86 and a professor at the University of Texas, Austin, argued in a recent paper in the journal Physical Review D that an intriguing pattern in the particles' masses could lead the way forward. "Weinberg's paper is a bit of lightning in the dark," said Anthony Zee, a theoretical physicist at the University of California, Santa Barbara. "All of a sudden a titan in the field is suddenly working again on these problems." "I'm very happy to see that he thinks it's important to revisit this problem," said Mu-Chun Chen, a physicist at the University of California, Irvine. Many theorists are ready to give up, she said, but "we should still be optimistic."

An anonymous reader shares a report: The Intel Core i5-8210Y delivers a multi-core score of 1544 which compares poorly with the Qualcomm Snapdragon 8cx multi-core score of 2745. Yet, despite fitting the MacBook Air with a 49.9 Wh battery, Apple claims it will deliver just 13 hours of continuous video playback. However, because of the superior performance-per-watt of the Snapdragon 8cx when paired with the smaller 42 Wh battery in the Galaxy Book S, it delivers up to 25 hours (claimed) of continuous video playback. You can probably also argue that Microsoft has done an excellent job of optimizing Windows on ARM so that it works so harmoniously in this WinARM union. The MacBook Air weighs 1.25 kg (2.75 pounds) and is 15.6 mm (0.61-inches) at its thickest point. This compares with the Galaxy Book S which weighs 0.96 kg (2.11 pounds) and measures 11.8 mm (0.46-inches). Given that buyers of the slightly more expensive MacBook Air (US$1,099) are also only going to be doing relatively light-weight tasks on it like internet browsing and running Microsoft's Office suite on it, why would anyone choose the MacBook Air over the Galaxy Book S (US$999)? Like the MacBook Air, the Galaxy Book S runs its operating system, pre-installed apps and the Office suite natively while also giving users the option to use 32-bit x86 apps for those occasions where you might want to use other apps.

"Present laptop dying, battery of course," writes long-time Slashdot reader ClarkMills. It uses proprietary pouch Lithium cells. Wouldn't it be great to just swap in a new set of 18650s? Okay, it may not be a thin laptop but it would save me from turfing a perfectly good laptop otherwise...
The original submission drew some interesting comments -- including one from long-time Slashdot reader thegreatbob suggesting a used laptop might be the only option. "This seems to be due to the notion that 'thinner!' and 'lighter!' are more important than 'doesn't periodically turn into an incendiary pillow!' "

But are there other options? Share your own thoughts in the comments.

Is there a laptop that uses rechargeable 18650 cell batteries?

The world's first fully electric commercial aircraft has taken its inaugural test flight, taking off from the Canadian city of Vancouver and flying for 15 minutes. From a report: "This proves that commercial aviation in all-electric form can work," said Roei Ganzarski, chief executive of Australian engineering firm magniX. The company designed the plane's motor and worked in partnership with Harbour Air, which ferries half a million passengers a year between Vancouver, Whistler ski resort and nearby islands and coastal communities. Ganzarski said the technology would mean significant cost savings for airlines and zero emissions. "This signifies the start of the electric aviation age," he said. Civil aviation is one of the fastest-growing sources of carbon emissions as people increasingly take to the skies, and new technologies have been slow to get off the ground. The International Civil Aviation Organization (ICAO) has encouraged greater use of efficient biofuel engines and lighter aircraft materials, as well as route optimization.

Ford will soon start using coffee chaff from McDonald's to manufacture auto parts like headlamp housings and other interior and exterior components. "In addition to making Ford vehicles a little bit 'greener,' the coffee chaff -- or the waste produced by coffee during the roasting process -- will apparently also help the company make parts that are 20 percent lighter," reports Engadget. From the report: Ford already uses various sustainable materials like soy and tree cellulose in an effort to only use recycled and renewable plastics in its vehicles. It has added coffee chaff to the list after its research team discovered that it can be turned into a durable product by heating it to high temperatures under low oxygen and mixing it with additives like plastic. The material will then be turned into pellets that can be formed into various shapes. During the team's tests, they found that the chaff-based material has "significantly better" heat properties than the current material Ford is using. They also discovered that it'll allow the company to enjoy 25 percent energy savings during the molding process. McDonald's is expected to earmark a significant portion of the coffee chaff its North American operations produce for this project. While it's not entirely clear how much chaff that is, McD's generates 62 million pounds of chaff a year in the continent alone, which is currently just used to make coal and garden mulch.

Oxis Energy, of Abingdon, UK, says it has a battery based on lithium-sulfur chemistry that can greatly increase the ratio of watt-hours per kilogram, and do so in a product that's safe enough for use even in an electric airplane. Specifically, a plane built by Bye Aerospace, in Englewood, Colo., whose founder, George Bye, described the project in this 2017 article for IEEE Spectrum. From a report: The two companies said in a statement that they were beginning a one-year joint project to demonstrate feasibility. They said the Oxis battery would provide "in excess" of 500 Wh/kg, a number which appears to apply to the individual cells, rather than the battery pack, with all its packaging, power electronics, and other paraphernalia. That per-cell figure may be compared directly to the "record-breaking energy density of 260 watt-hours per kilogram" that Bye cited for the batteries his planes were using in 2017.

This per-cell reduction will cut the total system weight in half, enough to extend flying range by 50 to 100 percent, at least in the small planes Bye Aerospace has specialized in so far. If lithium-sulfur wins the day, bigger planes may well follow. [...] One reason why lithium-sulfur batteries have been on the sidelines for so long is their short life, due to degradation of the cathode during the charge-discharge cycle. Oxis expects its batteries will be able to last for 500 such cycles within the next two years. That's about par for the course for today's lithium-ion batteries. Another reason is safety: Lithium-sulfur batteries have been prone to overheating. Oxis says its design incorporates a ceramic lithium sulfide as a "passivation layer," which blocks the flow of electricity -- both to prevent sudden discharge and the more insidious leakage that can cause a lithium-ion battery to slowly lose capacity even while just sitting on a shelf. Oxis also uses a non-flammable electrolyte.

According to a report by The Information, Apple is planning to launch an augmented reality (AR) headset in 2022, followed by a sleeker pair of AR glasses in 2023. From a report: While we've heard loads of similar reports over the years, this one -- if accurate -- is different. First, The Information claims that Apple CEO Tim Cook spoke about the project at an internal gathering of as many as 1,000 Apple employees, which is an uncommonly large number. Second, the report contains loads of details, not only about the AR headset/glasses hardware, but also about Apple's plans and ideas about the concept of wearable augmented reality devices.

First, the headset. It's code-named N301 and will be a virtual reality and augmented reality hybrid. On the outside, it will look like a "sleeker" Oculus Quest, with cameras mounted on the outside (important for AR, which must include a way to view reality in order to mix virtual elements into it). It will be lightweight and comfortable enough to be worn for extended periods of time, the report says. Inside, the headset will have a high-resolution display and 3D-mapping capabilities, as well as the ability to detect humans. Perhaps the more interesting gadget of the two are the AR glasses, which are code-named N421. These will be meant to worn all day, meaning they'll have to be slimmer, lighter and more comfortable than the headset. Apple's current prototypes are essentially sunglasses with "thick frames" with the electronics stuffed inside, the report says -- perhaps (my guess) something similar to Snap's Spectacles.

dryriver shares a report from CNN: Several rival companies may be hard at work trying to get Elon Musk's Hyperloop concept off the ground, but hurtling across country -- maybe even across continents -- at 600 miles per hour in a low-pressure steel tube still feels far from reality. But 13-year-old New York student Caroline Crouchley may have invented a more economically viable and eco-friendly Hyperloop solution. Crouchley's idea, which just won second place in the annual 3M Young Scientist Challenge, is to build pneumatic tubes next to existing train tracks. Magnetic shuttles would travel through these vacuum tubes, connected via magnetic arm to trains traveling on the existing tracks. This system would utilize current train tracks, thereby cutting infrastructure costs and, Crouchley says, eradicating the potential safety risk posed by propelling passengers in a vacuum. There'd be no need for trains to use diesel or electric motors, making the trains lighter and more fuel-efficient. This is important to Crouchley, who aims to devise active solutions to the climate crisis. "I pinpointed transportation as something I wanted to work on because if we can make trains more efficient, then we can eliminate the amount of cars, trucks and buses on the road," Crouchley tells CNN Travel.

The streaming giant is having to navigate different political and moral landscapes, and calls for government oversight, as it seeks subscribers worldwide. From a report: In September, Netflix released a trailer for the "Breaking Bad" sequel "El Camino." In it, a character sits in a car, lights a cigarette and holds it out the window, its orange tip glowing. The next day, Netflix Turkey released its own version. In it, the character sparks a lighter and puts his hand out of the window. But there's a difference: The cigarette has been edited out. It wasn't the first time Netflix had censored one of its trailers here. In January, the streaming giant edited one for "Sex Education," a series about a teenage sex therapist, to blur a character's hands so you couldn't see the raised middle fingers. These changes may seem small, but they are a sign of Netflix trying to get ahead of regulation it could soon face in Turkey.

[...] In Turkey, and in other countries, Netflix must navigate different political and moral landscapes, and calls for censorship, as it expands worldwide. Its 2018 annual report lists both "censorship" and "the need to adapt our content and users interfaces for specific cultural and language differences" as business risks. India is another country where Netflix has been embroiled in debates around regulation and censorship. In 2017, the company offered viewers "Angry Indian Goddesses," a movie that had been released in Indian theaters in a censored form to avoid offending religious sensibilities.ï Netflix, which is not subject to India's movie theater code, initially showed the censored version anyway, to avoid a backlash from religious viewers. But complaints came instead from viewers who wanted to see the movie uncut. Netflix made that version available and released a statement: "Our members reached out to us and we listened."

Camera bumps on smartphones may soon go away thanks to a team of researchers at the University of Utah who've developed a radically thin camera lens. Gizmodo reports: For comparison, the lens elements used in today's smartphone cameras, which gather and focus light onto a tiny sensor, are a few millimeters thick. It might not sound like much, but the best smartphone cameras use multiple elements, which quickly add up, resulting in a thin phone simply not having enough room to house all of them: hence the camera bump trend. But a team of electrical and computer engineering researchers at the University of Utah have succeeded in creating a new type of optical lens that measures just a few microns thick, or about a thousand times thinner and one hundred times lighter than what you'll find in smartphones today.

The lens the researchers created is actually made up of innumerable tiny microstructures, imperceptible to the human eye, and strategically positioned so that each one bends and redirects light towards a camera's sensor. When they're all working together, they produce the same results as a single curved element does. Manufacturing the lenses also required the team to develop a new fabrication process, a new polymer, and custom algorithms to calculate the shape and position of each microstructure. But the resulting lens can be completely flat, and made of lightweight plastic. If you've ever spent a day carrying around a camera with a big lens hanging off the front, you'll appreciate that benefit alone. The study has been published in the Proceedings of the National Academy of Sciences.

"The best way to get oneself somewhere with the least impact on the climate is a lot more complex than it may seem at first glance," writes Slashdot reader Dan Drollette (who is also the deputy editor of The Bulletin of the Atomic Scientists).

Slashdot reader Lasrick also submitted their report. A few excerpts: - For a short distance taking a train may be better than flying, but there is some ambiguity for long-distance travel. But no matter what mode of travel we choose, the distance traveled strongly determines emissions.

- Trends suggest that ground transportation is increasingly being electrified (with the potential for using renewable sources). However, there is likely no such technological breakthrough on the horizon for planes. Thus, flying less is an important long-term commitment because it helps to make sure there are more alternative transportation options, and shows where we want government and industry to prioritize efforts toward efficiency and transit... [I]f you choose to drive because it is more climate-friendly than flying short-haul, you are adding an extra car on the road while the plane would have flown anyway. However, in the long run, if many people choose to drive (hopefully in a full car), it is likely there will be fewer short-haul flights.
Obviously, fewer passengers per vehicle will also increase the per-passenger carbon count, and right now short economy flights "generally have higher occupancy and lighter fuel loads," placing them just below a U.S. grid-powered electric car. And mode of transportation is still less important than distance traveled, though very short flights less than 1000 kilometres (621 miles) are more carbon intensive than longer flights "as they spend little time cruising, and are often not very direct."

Energy sources also matter, since trains in Europe are largely electrified, while North America's trains burn fossil fuels. "In Europe, trains are by far the best choice in terms of climate benefits, even if that's not as true elsewhere." Thus the three worst choices right now are a large car (getting 15 miles per gallon), followed by a long (non-economy) business flight, and a "medium" car (getting 25 miles per gallon), while the three best choices are a solar-powered electric car (#3), a crowded U.S. school bus, and Eurostar rail.

But it's important to remember that the majority of people don't fly, Dan Drollette reminds us, "And we should not be so focused on the carbon contributions of air travel (which only account for 2 percent of all carbon emissions) that we take our eyes off the causes of the other 98 percent of carbon emissions."

Speaking of Dropbox, the online storage cloud service has enabled support for ZFS and XFS on 64-bit Linux systems, and eCryptFS and Btrfs on all Linux systems. The move comes after it recently pulled support for all file storage systems on Linux except Ext4. From a report: Dropbox stopped supporting folder syncing to drives with filesystems it deemed "uncommon", which on Linux meant anything but Ext4, upsetting quite a few users. The reason cited for this was that "a supported file system is required as Dropbox relies on extended attributes (X-attrs) to identify files in the Dropbox folder and keep them in sync", which doesn't really make sense since there are many filesystems that support xattr (extended attributes) on Linux. After this change was announced, various workarounds started to appear online, including one that I posted on Linux Uprising. There was even a new unofficial, open source Dropbox client developed for this reason (which is also much lighter than the official client by the way). But this didn't last long though, as last week, the Dropbox 77.3.127 beta changelog says that Dropbox has added back support for ZFS (on 64-bit systems only), XFS (on 64bit systems only), Btrfs and eCryptFS.

Harry Barnes runs a Twitter account called The State of LinkedIn with more than 100,000 followers. On it, he tweets a curated selection of the most egotistical, self-unaware, jargon-ridden posts from LinkedIn members [Editor's note: the link may be paywalled]. From a report: Recent gems range from the boastful "You call it luck, I call it 80 hours a week", to the baffling "How easy is it to hire me? I interviewed myself", as well as the awful-wonderful morning routine which begins "I wake up. Instantly. From the fogginess of dreams, to the readiness of full consciousness..." Humble brags, including Mr Barnes's favourite, in which a man is pictured playing pool while a supercar just happens to be parked in the background, also feature regularly. Mr Barnes, who has worked in social media but runs the account as a hobby, says the idea is to poke fun at the ridiculous world of workplace self-promotion, rather than individuals. "All the content is sent to me," he says. "I don't trawl LinkedIn looking for it."

Mr Barnes is not the only one enjoying the lighter side of LinkedIn. There is also the @CrapOnLinkedIn Twitter feed and parody LinkedIn accounts, such as the "demotivational speaker" Mike Winnet. Unlike other social networks, however, humour is not the norm for LinkedIn, which has always been a more grown-up, professional place. For better or for worse, that may be changing.

Apple has stopped selling the 12-inch MacBook just four years after introducing the laptop as the slimmest in its lineup. From a report: The previous generation MacBook Air -- the one without a Retina display -- is no longer available in Apple Stores either. The 12-inch MacBook hadn't been updated in two years, but it still filled a spot that stood out from other models: it was thinner and lighter, though that also came with being less powerful. At $1,299, its price put it directly up against the entry-level MacBook Pro, which outperformed it, with only a small gain in weight and size.

Slashdot's gotten over 17,000 votes in its poll about which web browser people use on their desktop. (The current leader? Firefox, with 53% of the vote, followed by Chrome with 30%.)

But Slashdot reader koavf asks an interesting follow-up question: "What's everyone's go-to Plan B browser and why?"

To start the conversation, here's how James Gelinas (a contributor at Kim Komando's tech advice site) recently reviewed the major browsers:

• He calls Chrome "a safe, speedy browser that's compatible with nearly every page on the internet" but also says that Chrome "is notorious as a resource hog, and it can drastically slow your computer down if you have too many tabs open."
  
  "Additionally, the perks of having your Google Account connected to your browser can quickly turn into downsides for the privacy-minded among is. If you're uncomfortable with your browser knowing your searching and spending behaviors, Chrome may not be the best choice for you."

• He calls Firefox "the choice for safety".
  
  "Predating Chrome by 6 years, Firefox was the top choice for savvy Netizens in the early Aughts. Although Chrome has captured a large segment of its user base, that doesn't mean the Fox is bad. In fact, Mozilla is greatly appreciated by fans and analysts for its steadfast dedication to user privacy... Speedwise, Firefox isn't a slouch either. The browser is lighter weight than Chrome and is capable of loading some websites even faster."

• He calls Apple's Safari and Microsoft Edge "the default choice...because both of these browsers come bundled with new computers."
  
  "Neither one has glaring drawbacks, but they tend to lack some of the security features and extensions found in more popular browsers. Speedwise, however, both Edge and Safari are able to gain the upper hand against their competition. When it comes to startup time and functions, the apps are extremely lightweight on your system's resources. This is because they're part of the Mac and Window's operating systems, respectively, and are optimized for performance in that environment."

Finally, he gives the Tor browser an honorable mention. ("It's still one of the best anonymous web browsers available. It's so reliable, in fact, that people living under repressive governments often turn to it for their internet needs -- installing it on covert USB sticks to use on public computers.") And he awards a "dishonorable mention" to Internet Explorer. ("Not only is the browser no longer supported by Microsoft, but it's also vulnerable to a host of malware and adware threats.")

But what do Slashdot's readers think? Putting aside your primary desktop browser -- what's your own go-to "Plan B" web browser, and why? Leave your best answers in the comments.

What's your "backup" browser?

Magic Leap, a secretive U.S. startup that makes a $2,295 augmented-reality headset, filed a lawsuit Monday accusing one of its former engineers of stealing its technology to create his own AR device for China. Bloomberg reports: In a lawsuit filed Monday, Magic Leap alleges that Chi Xu, who left in 2016, exploited its confidential information to "quickly develop a prototype of lightweight, ergonomically designed, mixed reality glasses for use with smart phones and other devices that are strikingly similar" to the Florida-based startup's designs. The lawsuit marks the latest accusation from an American firm of intellectual property theft by Chinese companies, a perennial sore point that's helped escalate tensions between the world's two largest economies. With more than $2 billion in financing, Magic Leap is one of the better-funded startups delving into so-called augmented or mixed reality, a technology that gives users the illusion that fantastical, three-dimensional digital objects exist in the physical world.

Xu, who founded Beijing-based Hangzhou Tairuo Technology Co., also known as Nreal, unveiled his own augmented reality glasses at a major Las Vegas trade show in January, touting them as lighter than the Magic Leap One, Forbes has reported. Magic Leap released its headset last August after seven years of secretive work and more than $2 billion of investment. The startup alleges that Xu plotted during his roughly 13 months working there to launch his own competing company in China and "neglected his work duties" to acquire proprietary information. Xu is accused in the suit of breach of contract, fraud and unfair competition.

Lenovo is launching a new AR-and-VR system targeted at businesses. It's called ThinkReality, and from the looks and description of the device and platform, it looks like a competitor for Microsoft's HoloLens. Engadget reports: There are two parts to the new ThinkReality system -- the AR headset and a software platform. The ThinkReality A6 is a comfortable 380-gram headset with two fisheye cameras on the front, as well as depth sensors and a 13-megapixel RGB sensor. There's also microphones onboard for voice control, and the headset can also detect where you're gazing to optimize resolution or navigation. You'll also be able to interact with your virtual environments using an included 3DoF controller. Untethered, the A6 can last up to four hours with its 6,800mAh battery, and you can still use the device while it's plugged in and charging.

The headset connects to an SSD-sized compute box that contains a Snapdragon 845 CPU running an Android-based platform. There's also an Intel Movidius chips powering waveguide optics here, and each eye on the A6 offers a 40-degree diagonal field of view and 1080p resolution. By comparison, the HoloLens 2 uses a Snapdragon 850 CPU and packs two 2K MEMS displays. Microsoft also squeezes all the computing components into the headset rather than in a separate box like Lenovo does. While I'm not a fan of having to carry around an additional accessory to power a headset, this setup does make the ThinkReality A6 lighter, so it's a compromise I'm willing to make. You can wear the box on a belt clip or an armband, which should make it easy to move around when wearing this setup at work. Lenovo claims this is "one of the lightest fully featured AR headsets in its class," and during a brief trial with a non-working model, I certainly found the A6 lightweight.

dryriver writes: The BBC reports on a 50ft long and only 120kg heavy blimp-like UAV aircraft that is designed to fly at 70,000 feet, is entirely solar powered, uses variable-buoyancy for propulsion, and can essentially stay airborne in a self-powered way until it experiences mechanical or electrical failure. The Phoenix varies its buoyancy continuously using a helium-filled fuselage that also has an interior air sack that works a bit like a lung. It can inhale air and compress it on demand, making the aircraft temporarily heavier than air, and expel the inhaled air through a nozzle at the back of the aircraft, making the aircraft lighter than air again, creating some extra forward propulsion in the process.

The Phoenix -- which is a simple, cheap-to-build aircraft that its designers describe as "almost a disposable aircraft" -- could one day act as a satellite replacement flying at 70,000 feet. It may also be used for surveillance purposes or to release micro-satellites into earth orbit. The Phoenix has already completed short test-flights of 120m inside the hangar it was built in. This YouTube video shows just how gently the Phoenix rises into the air, hovers in place, and lands again. Unlike drones that need to land, refuel and then take to the skies again, the Phoenix may stay in the air for very long periods of time, landing only for periodic maintenance of its electrical and mechanical components.

Yesterday, Tesla launched the next generation Supercharger V3 with higher charging capacity, better efficiency, and more. The biggest new feature is the ability to deliver a new 250 kW of peak power thanks to an "all-new liquid cooled cable design." Electrek reports: According to the company, the cable is "significantly lighter, more flexible, and more efficient" than their current air-cooled cable found on the V2 Superchargers. Other than the cable, the Supercharger V3 should be undifferentiated from V2 at the station. The company didn't even release new pictures for V3. The new 250 kW peak at the station is also enabled by a new 1 MW power cabinet. Instead of using onboard chargers staked together, the new Supercharger is built using technology Tesla developed for its massive grid energy storage system. With the new technology, there will be no power share between stalls like in the current version.

On Tesla's most efficient vehicles, like the Long Range Model 3, the company says that the new Supercharger V3 can add up to 75 miles of range in 5 minutes and charge at a peak rage of 1,000 miles per hour of range. A new 'On-Route Battery Warmup' software feature was also announced. When entering a Supercharger station in your navigation system, the vehicle's software will "intelligently heat the battery to ensure you arrive at the optimal temperature to charge." That's assuming you have enough charge in the battery when you come in. The new feature alone should reduce "average charge times for owners by 25%," according to the automaker. Model S and X owners may be disappointed to hear that the new peak charging rates won't be available for their vehicles at launch. Instead, they will have to wait for a software update "in the coming months." Model 3 vehicles will be the first to receive the software update to support the new speeds.

sciencehabit shares a report from Science Magazine: Chemists have stumbled across a new way to separate reflected light into the colors of the rainbow -- a phenomenon known as iridescence. The surprisingly simple technique, which is something of a hybrid of previously known ones, could have applications both scientific and aesthetic. In iridescence, an object reflects different colors at different angles, separating white light into its constituent colors.

Now, [researchers] at Pennsylvania State University in State College report producing iridescence in a new way. They happened across the effect in early 2017, when they cooked up micron-size spherical droplets containing two types of oil in which the lighter oil formed a lentil-shaped upper layer the researchers hoped to use as a lens. But surprisingly, when illuminated from above, the edges of the lentils glowed with a color that depended on their size and the angle at which they were viewed, the team reports today in Nature. Clarity came only with the computer simulations performed [the researchers]. Their analysis showed the iridescence emerges through a new mechanism that blends certain elements of the previously known ones. [...] Engineers already use thin-films and refractive particles to create iridescence in video displays, paints, and decorative wall coverings. With its simplicity and adjustability, the new effect could open ways to color the world. The effect can be explained in a much simpler system: "water droplets that condense and hang from the underside of the lid of a petri dish. Light waves entering near one edge of a droplet can bounce two or more times off the dome of the droplet before emerging near the other edge -- much as light reflects off the back of a raindrop in a rainbow. However, the light waves entering at slightly different distances from the center of the droplet can bounce different numbers of times. And waves bouncing different numbers of times can interfere and reinforce each other, as in diffraction or thin-film interference. As a result, different colors emerge at different angles, which can be controlled by changing the size of the droplet."