A new study examined the galaxy cluster Abell 3827 and found indications that dark matter could be self-interacting. If confirmed, this would mark a significant step forward in the ongoing quest to understand the substance that helps structure the Universe.
The team used the MUSE instrument on the Very Large Telescope (VLT) along with images from the Hubble Space Telescope to map out the cluster. Because large masses such as galaxies and galaxy clusters bend the paths of light, they act as lenses, a process called (surprise!) gravitational lensing. The team made use of the complex web of lensing effects throughout the cluster to map out the dark matter there. The presence of strong gravitational lensing is fortunate for the study, as the dark matter would be invisible without it.
Every galaxy sits within a roughly spherical blob, called a halo, of dark matter. That halo makes up most of the galaxy’s mass. In normal situations this configuration is stable, but when multiple galaxies interact with each other, a process called tidal stripping can take place, in which gravity from one galaxy pulls in material from another. This can separate the dark matter from the stars in the galaxy.
SpaceX's trial-and-error process of learning to land one of its Falcon main stages continued this week. After successfully sending a Dragon capsule toward a rendezvous with the International Space Station, the Falcon reversed course, fired its thrusters, and made its way back into the atmosphere over the Atlantic. After a controlled plunge through the air, it attempted to land on a barge named "Just Read the Instructions." This time, conditions enabled the company to have had an aircraft in the area to film the results.
The video above shows the Falcon dropping at a rather healthy clip until it's quite close to the barge. At that point, the rocket's electronics appear to try to adjust its location; the craft tips while firing its main engines at a much higher level. This appears to be enough to set it down on the barge, but now tilting in the opposite direction. Thrusters at the top of the rocket attempt to correct the tilt but can't; it slowly falls over until it explodes while nearly horizontal.
SpaceX originally posted video footage of the crash landing, but it was taken down and marked private on YouTube on Wednesday afternoon.
The ability to walk upright is a defining characteristic of humans, one that emerged through a long evolutionary history. It's not just a matter of the right bones; our muscular, skeletal, and neural systems have evolved to enable our coordinated movements. The nerves allow us to develop a gait that is optimized to minimize the amount of energy necessary by modulating aspects of our movement such as our step length or arm motions.
Even with all that optimization, walking can be tiring; in fact, people expend more energy walking than any other daily activity. As we age, walking often becomes even more difficult. For decades researchers have explored ways to mitigate the energy cost associated with walking—studies that are typically aimed at helping those who are weaker or disabled.
Recently, scientists and engineers started to look at this issue from a new perspective; they questioned whether the human gait is as efficient as it can be. This interdisciplinary research team developed a device that behaves as an unpowered exoskeleton.
NASA researchers have spotted something weird on the surface of the dwarf planet Ceres—a pair of mysterious shiny patches that reflect sunlight.
The bright spots were imaged by the Dawn spacecraft, which is whizzing through space on its way to Ceres, and should arrive in orbit on March 6. It'll be the first spacecraft to study a protoplanet at such close range.
"As we slowly approach the stage, our eyes transfixed on Ceres and her planetary dance, we find she has beguiled us but left us none the wiser," said Chris Russell, principal investigator of the Dawn mission. "We expected to be surprised; we did not expect to be this puzzled."
In January Netflix, the online video streaming site, used its quarterly letter to shareholders (pdf) to take aim at a rival. Not premium pay TV channel HBO, with which it is locked in an increasingly bitter battle for the best shows and movies; nor cable provider Comcast, with which it has squabbled over the future of the internet. Rather, Netflix’s missive called out a new adversary. “Piracy continues to be one of our biggest competitors,” it reads. “Popcorn Time’s sharp rise relative to Netflix and HBO in the Netherlands, for example, is sobering.”
Popcorn Time is one of the most fascinating stories on the internet at the moment. It is a platform that allows people to access vast swathes of video content without paying for it, but with a clean, legitimate-looking (and somewhat Netflix-y) interface. In other words, it’s not a shady looking portal that makes you feel dirty for using it.
By some estimates, Popcorn Time’s user base in the Netherlands rivals that of Netflix. It also appears to be used quite a lot in the US. Bloomberg reported last week that usage of the service in the US more than trebled between July 2014 and January 2015, and it now accounts for one ninth of all torrent traffic in the country. Its rise reflects a sobering reality for the entertainment industry. Despite the widespread success of internet-based content smorgasbords with simple pricing models like Netflix, piracy endures. And TV and movie piracy, at least, is almost impossible to wipe out.
Unlike in music, where services like Spotify give you a single subscription for almost any track you might want, there is no one-stop shop for video. That’s partly because of the way licensing works: Movies are released at different times for theaters, video-on-demand, and then cable TV or streaming services. It’s partly also because, unlike in music, video streaming services have chosen to compete by each offering their own exclusive content rather than trying to have the most complete menu. As a result, the best video remains spread out across a confusing phalanx of outlets.
Popcorn Time, according to people who use it, lets you access just about everything on the internet. It operates using the BitTorrent protocol, a file-sharing method that breaks large files into small pieces, which are shared out across the network of its users’ computers. When a user wants to download a file, her computer assembles it from pieces stored on other people’s computers across the network. This makes it easier to download large files, and harder to pinpoint who is responsible for uploading them, and thus almost impossible to eliminate. (The main difference between Popcorn Time and traditional BitTorrent is that when you choose a file to watch, BitTorrent assembles it first and stores it on your computer’s hard drive; PopcornTime just streams it as its components come in).
The site emerged seemingly out of nowhere last year. The people claiming to be its creators wrote that it began as a challenge by “a group of geeks from Buenos Aires who wanted to see if they could create a better way to watch movies.” By March last year they had abandoned it because, they said, they “need[ed] to move on with our lives.”
Yet others quickly took up the baton. There are multiple Popcorn Time sites now; popcorntime.io is the biggest, it has the most likes on Facebook (it passed 100,000 recently) and appears at the top of Google searches. It has a desktop client for both Mac and Windows computers, plus a Linux version and an Android app.
So who is behind this slick operation? Last month I spoke to a person who claims to be Popcorn Time’s official spokesperson, a 20-something from Ontario, called Robert “Red” English. He said that there are about 20 people—programmers and designers—scattered across the planet, working on Popcorn Time in their free time. It is an open-source project, so anyone can submit changes to the code, add features, and fix bugs. If he and the rest of the team think a contributor is helping, they will ask him or her to join on a more formal basis. Contributors change frequently.
“We are a community… I don’t think it will be ever turned into a proper business.” Popcorn Time has no funding—it’s run out of the pockets of the small community behind it—and no business model, English says. Unlike other platforms used for piracy it doesn’t even carry advertising.”We are a community and we are not really driven by the money of it,” he says. “I don’t think it will be ever turned into a proper business.” In other words, there are no plans to emulate Napster or BitTorrent and seek legitimacy. Napster, the first file sharing site to gain prominence, had a string of legitimate business owners after being shut down, including German Media conglomerate Bertelsmann, US retailer Best Buy, and is now part of streaming music provider Rhapsody. BitTorrent (the company, not the protocol) is backed by venture capital funds including Accel Partners.
So if there’s no money in it, why do the people behind Popcorn Time bother? Fun mainly, English says. “A lot of the project is about showing… other companies like Netflix that having the content that’s currently on air—the new stuff, not last season—that’s what drives people to watch. It’s a way of showing the media that you can do better.” (No doubt the fact that this gives them and others the ability to watch anything they want for free is also a motivating factor.)
The team behind the original Popcorn Time insisted they had checked “Four Times” with lawyers that the service was legal. English says his team has been in contact with lawyers, “but for the most part there is not a lot we need to speak to them about.” Popcorn Time does not control or manage any of the content that is accessible through the service; it just provides the method of access. “We are not selling you a product, we are not ripping you off, we are just giving something out for free,” he says.
The video and music industry see it differently, of course. There have been countless lawsuits against BitTorrent services and their users. Some, notably in Sweden, have been successful, even ending up in convictions. But in the US, as Mother Jones reported a year ago, judges have been getting more skeptical about the evidence copyright holders present. Basically, an IP address—a number that identifies each computer connected to a network—is no longer considered such a reliable indicator of who has been actually downloading or uploading files.
“If it’s used to infringe copyright, that may itself be a violation, but that doesn’t make the tool illegal.” The Motion Picture Association of America (MPAA), a trade association for Hollywood studios which has been involved in many lawsuits against copyright offenders, declined to comment on Popcorn Time to Quartz. So did Netflix. But Parker Higgins from the Electronic Frontier Foundation, a consumer digital rights group, argues that Popcorn Time is no more illegal than photocopiers or videocassette recorders. The US Supreme Court ruled in 1984 that Sony’s Betamax video recorder wasn’t illegal because it was capable of “significant non-infringing use.” Similarly, Popcorn Time can be used to navigate vast swathes of non-copyrighted material, Higgins explains. “If it’s used to infringe copyright, that may itself be a violation, but that doesn’t make the tool illegal.”
The Betamax defense isn’t iron-clad. At least two file-sharing sites that tried to use it—Grokster and Streamcast—lost, because the court ruled that they actively encouraged piracy. But that case also marked out a territory within which file-sharing is legal, making it easier for sites like Popcorn Time to stay (just) on the right side of the law.
English said the team behind Popcorn Time is aware that the platform is being used extensively in places like the Netherlands and “had a general idea that people were beginning to talk about us.” But what he did not realize it was stating to get noticed on Wall Street.
Investment analysts are concerned about its impact on Netflix and big entertainment companies that produce and own content. BTIG analyst Rich Greenfield for one, has repeatedly warned that “Hollywood should be very afraid” of apps like Popcorn Time, which he says could threaten the financial strength of the entertainment business. “The reality is TV everywhere [i.e., online services from US cable TV providers and channels such as HBO Go] has gone nowhere while the piracy sites such as Popcorn Time have continued to innovate,” Greenfield says in an email.
Popcorn Time does not track usage and is not particularly concerned about the imitators it has spawned. “In general we don’t care,” English says, “but when it comes to the ones that install viruses on your computer it pisses us off because it ruins a good name.” To think that a group of earnest freelancers working in their spare time could pose challenge to Netflix, a $30 billion company, not to mention media giants that have been around for decades, is staggering. But as long as the big TV and movie studios continue to limit their content to certain online platforms, there’ll be demand for a service that provides it all—especially if that service is also free.
Explore the history of the frame rate - the engine that gives motion to the motion picture from their earliest versions in silent pictures to the frame rates of broadcast television.
This lesson is proudly sponsored by RØDE Microphones:
The evolution of human culture is often compared to biological evolution, and it’s easy to see why: both involve variation across a population, transmission of units from one generation to the next, and factors that ensure the survival of some variants and the death of others. However, sometimes this comparison fails. Culture, for instance, can be transmitted “horizontally” between members of the same generation, but genes can’t.
“Little is known about whether human demographic history generates patterns in linguistic data that are similar to those found in genetic data,” write the authors of a recent paper in PNAS. Both linguistic and genetic data can be used to draw conclusions about human history, but it's vital to understand how the forces affecting them differ in order to be sure that the conclusions we're drawing are accurate.
By conducting a large-scale analysis on global genetic and linguistic data, the researchers found that languages sometimes behave in ways very unlike genetics. For instance, isolated languages have more, not less, diversity, and languages don't retain the echo of a migration out of Africa—unlike our genomes.
In 2011, researchers announced that they had reprogrammed the genome of the bacteria E. coli, changing it so that one of DNA's methods of encoding information went unused. While a technological tour-de-force, the scientists didn't actually do anything with the newly available bit of genetic code. Now a few years later, two different groups have used it to accomplish the same end: creating genetically modified organisms that may never be able to escape into the wild.
All forms of life we're aware of use what's called a triplet code: it takes three bases in a row in order to encode for one of the amino acids that make up a protein. A series of triplets, stretched out along the DNA, can be read to determine the precise order of amino acids. At the end of the list of amino acid codes, you'll find what's called a stop codon. The three stop codons (TAA, TAG, and TGA in their DNA form) don't code for any amino acids, which the cell interprets as an indication to terminate translation of codes into amino acids.
Since there are three stop codons that mean essentially the same thing, the earlier work involved replacing all instances of one of them (TAG) with a different one (TAA). The editing process preceded in stages but, by the time it was done, all 314 cases where TAG was used as a stop codon had been replaced. This, in effect, freed up TAG to encode something else, such as an artificial amino acid.
Update: SpaceX confirmed that it had received $1 billion in funding from Google and Fidelity Investments. The two companies will together own slightly less than 10 percent of the company. "This funding will be used to support continued innovation in the areas of space transport, reusability, and satellite manufacturing," SpaceX said in a short statement on its website.
Speaking to Ars, a Google spokesperson added, “Space-based applications, like imaging satellites, can help people more easily access important information, so we’re excited to support SpaceX’s growth as it develops new launch technologies.”
Ars has contacted Fidelity for a statement and will update if we receive a response.
It was an interesting week for ideas about the future of the Internet. On Wednesday, satellite industry notable Greg Wyler announced that his company OneWeb, which wants to build a micro-satellite network to bring Internet to all corners of the globe, secured investments from Richard Branson's Virgin Group and Qualcomm. Then in a separate announcement on Friday, Elon Musk said that he would also be devoting his new Seattle office to creating "advanced micro-satellites" to deliver Internet.
OneWeb, formerly WorldVu Satellites Ltd, aims to target rural markets, emerging markets, and in-flight Internet services on airlines, the Wall Street Journal reported. Both Branson and Qualcomm Executive Chairman Paul Jacobs will sit on the company's board, but Wyler did not say how much Virgin and Qualcomm invested in his company.
Wyler said that his company's goal is to create a network of 648 small satellites that would weigh in at around 285 pounds each. The satellites would be put in orbit 750 miles above the Earth and ideally cost about $350,000 each to build using an assembly line approach. Wyler also said that Virgin, which has its own space segment, would be launching the satellites into orbit. “As an airline and mobile operator, Virgin might also be a candidate to resell OneWeb’s service,” the Journal noted. Wyler has said that he projects it to take $1.5 billion to $2 billion to launch the service, and he plans to launch in 2018.
Today, under the heading of "Close, but no cigar," SpaceX released video of its Falcon 9 booster's failed landing following last weekend's successful launch. This was the company's first attempt at retrieving one of its boosters for reuse, and it publicly stated that it wasn't expecting success on the first try. But the video will clearly provide some information on what went wrong with the landing.
It shows the booster drifting above the barge that was its intended landing site; the lighting makes it a bit difficult to tell whether the rocket was oriented vertically at that point. Then, as it was clearly off target and headed past the far end of the barge, the booster tilted heavily in order to re-center itself on the landing site. Unfortunately, it was quite low by that point, and it ended up striking the barge while leaning heavily to one side. That set off the explosion of its remaining fuel, scattering rocket parts out into the ocean.
The majority of stars in our galaxy, and most likely the Universe as a whole, are small, (relatively) dim, low mass bodies. Because they emit much less light, the habitable zone for these stars is close in, where planets would take weeks to complete a full orbit. That's also close enough where the star's gravity can create tidal interactions with the planet's interior, slowing its spin until the planet perpetually shows a single face to the star (much like our Moon does to Earth).
Needless to say, leaving one side of the planet perpetually in the dark could have some rather interesting effects on the environment, including the idea of an "eyeball Earth." That's where the area facing the host star is melted while the rest of the planet remains a frozen wasteland. But now some researchers have suggested eyeball Earths may be a rarity: an atmosphere like Earth's is enough to keep a body from becoming tidally locked.
The tidal forces we recognize most easily are (duh) the tides on Earth, which are pulled around by the Moon's orbit. But tidal forces also operate on a moon or planet's flexible interior, creating a friction that gradually slows the body's rotation. That's why many of the moons in our Solar System are tidally locked, even though there aren't any oceans to be seen. (Although the internal friction may melt enough of the interior to create internal oceans.)
When galaxies collide, they tend to intermingle, ultimately forming a new, merged galaxy. And the supermassive black holes from the original galaxies’ cores should generally end up at the core of the new galaxy, according to current models. Some models predict that the two supermassive black holes could orbit each other, forming a black hole binary system. However, until recently, this has proved difficult to actually observe. Current instruments can’t resolve the difference between two supermassive black holes like these, which could be significantly less than a parsec apart.
But by using alternative methods, recent searches have found some promising candidates that could be supermassive black hole binary systems. In a new study, a team of researchers has reported a strong, clear signal from an extremely bright quasar that appears to be an example of a black hole binary. While this identification is still uncertain, the researchers conclude it’s the most plausible explanation of the behavior of that quasar.
Quasars are simply extremely bright supermassive black holes, with the intense light originating from their jets and accretion disks. The jets, which emerge at each pole, are probably caused by their magnetic fields interacting with their spin and mass. The black hole also often has a disk of material falling in, called an accretion disk, that can produce a lot of light, since the infalling material is hot from friction.