METI’s First Message Is a Music Lesson for Aliens

Tromsø, Norway is usually a destination for northern lights lovers—tourists and scientists alike. But on October 16, the small city north of the Arctic Circle took on a new cosmic role. A radio telescope in the city, a hotspot for aurora investigators, became the origin point of a transmission aimed at the exoplanet GJ 273b, a potentially habitable world just over 12 light years from Earth. Or really, at any GJ 273b inhabitants who might be listening.

The meat of the transmission was carefully crafted by METI International—the alien hunters so serious about Messaging Extraterrestrial Intelligence that they splintered off from the SETI Institute to get more ambitious. It's the first information-rich message they've sent since forming in 2015. And with this bit of code, constructed in partnership with the Spanish Sónar music festival and the Institute of Space Studies of Cataloniar, they want to teach aliens about music—one radio wave pulse at a time.

Sending a message to ET isn't easy. On the terrestrial level, the team first had to get access to a radio telescope, which can be tricky: The instruments are in high demand, and time slots tend to go to projects that are likely to produce, well, results. So METI sent someone who had experience asking for time and resources no one really wanted to give them: their exoplanet hunter Ignasi Ribas. “Twenty years ago, when we didn't know if exoplanets were out there, exoplanet hunters were in the same position we are," says METI president Douglas Vakoch. Fortunately, the director of Tromsø's EISCAT 930 MHz transmitter was intrigued, and gave the group access to the facility for a three-day transmission.

Extraterrestially, the researchers had to choose one target from nearly limitless potential worlds. METI has two main criteria: the planet has to be (relatively) close to Earth, and it has to be a place that aliens could plausibly evolve and thrive. Which usually means it has to be in the Goldilocks Zone—not so cold that any water would be locked away in an glacier, and not too hot that it would just evaporate. “You want a star that has some staying power,” says Vakoch. “You need time for life to cook up.” Smaller stars have longer lives, and GJ 273b orbits a red dwarf named Luyten's Star.

But perhaps harder than all that was deciding what they wanted to say once they'd phoned ET. The METI team wanted to tackle altruism, but the radio telescope METI partnered with was interested in sending a message that would convey Earth culture. So METI joined forces with the Spanish Sónar music festival to create a music-based message, and it was up to METI to make sure any extraterrestrials on the receiving end understood what they were hearing—if they can hear, that is.

Music actually turns out to be a decent universal language. Aliens don’t have to see in order to perceive it. And even if extraterrestrials can't appreciate a good tune, Vakoch is hopeful that they might enjoy the mathematical relationships between the notes. They encoded their entire message in a binary system of two alternating frequencies (an industry standard among alien hunters), pulsing the frequencies 125 times per second. Interpreting those beeps and boops (which act a lot like ones and zeros for computers) is ultimately up to the aliens. "It's like creating a puzzle," says Mike Matessa, a cognitive scientist and friend of Vakoch's who helped develop METI's message. "We tried to make it as easy as possible, but it’s really challenging when you can’t refer to anything in your culture, only science."

So they started with math. The basic 1 + 1 = 2 kind that they assume is a constant across the galaxy. From there, they build up all the mathematics you need to understand music from the foundation: You need to understand the relationships between triangles to understand the sine function to understand sine waves to understand electromagnetic waves to understand sound waves to understand music. "We try to ground things in reality whenever we can," Matessa says. "You can’t hold up an apple and say, 'apple.' But you can send a tone and say that it had a certain frequency and duration."

One of the messages' novel features is a clock. "We introduce notions of time like a second by having a pulse and saying, 'This is one," says Vakoch. "Then we pulse for two seconds and say, 'This is two, and the pulses vary because the two is twice as long as the one.'" Then they expanded on those basics just as they did with the mathematical concepts underpinning musical theory. As the aliens work their way through the message, converting pulses to a numbering system, doing basic arithmetic, the clock will tell them how many seconds have passed, hopefully confirming that that initial pulse—the second—was a measurement of time. Which will also help them figure out that Earthlings will be listening for a response from them in 25 years. It's everything human scientists would want to receive in an alien transmission. "It's designed for the SETI scientists of other worlds," Vakoch says.

Their next message, scheduled for April 2018, will be more musically complex. Not only will they send musical samples from Sónar artist community, they'll actually be able to use the EISCAT 930 MHz transmitter to send simple melodies composed of a number of frequencies. They’ll transform a device meant to study the Northern Lights into an interstellar musical instrument.

And there's still so much more METI would like to tell the universe about us. "How can you talk about altruism or kindness or other human qualities, and how do you build that up from math?" Matessa says. "It's advanced storytelling using languages that any civilization can understand." METI wants to compose as many messages in as many different sensory modalities as possible, in the hopes that one of them could start a meaningful conversation between worlds.

Read more: https://www.wired.com/story/metis-first-message-is-a-music-lesson-for-aliens/

What kind of eclipse are you likely to see? Let our visualizations show you

The path of the eclipse is 70 miles wide meaning most of the US will see a partial eclipse. Mona Chalabis visualization will give you a sense of what you should prepare yourself for

A total solar eclipse will take place on Monday, the first in 38 years. As the moon passes in front of the sun, a shadow will be cast across all of North America. But the way that will look depends on where you are in the country.

The path of the total eclipse (when none of the sun is visible) is only 70 miles wide, so unless youre an eclipse chaser and willing to travel, youre more likely to see a partial eclipse.

(Note: these visualizations are inspired by the word mooning, which has been in use since about 1600 and means exposing to moonlight.)

The
The totality of the eclipse in various parts of the US Photograph: Mona Chalabi for the Guardian

If the image above looks ever so slightly imprecise, it should. Even Nasa concedes that perfectly calculating the mathematics of the eclipse is difficult because the universe is more subtle than that.

Nasa explains:The earth is neither smooth nor perfectly spherical, nor does it rotate at a perfectly constant, predictable speed. The moon isnt smooth, either, which means that the shadow it casts isnt a simple circle. And our knowledge of the size of the sun is uncertain by a factor of about 0.2%, enough to affect the duration of totality by several seconds.

In other words, theres still a lot we dont understand about our universe. Contemplate that as you enjoy Mondays moon miracle.

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Read more: https://www.theguardian.com/science/2017/aug/20/total-solar-eclipse-monday-data-visualization

Her Code Got Humans on the MoonAnd Invented Software Itself

Margaret Hamilton wasnt supposed to invent the modern concept of software and land men on the moon. It was 1960, not a time when women were encouraged to seek out high-powered technical work. Hamilton, a 24-year-old with an undergrad degree in mathematics, had gotten a job as a programmer at MIT, and the plan was for her to support her husband through his three-year stint at Harvard Law. After that, it would be her turnshe wanted a graduate degree in math.

But the Apollo space program came along. And Hamilton stayed in the lab to lead an epic feat of engineering that would help change the future of what was humanlyand digitallypossible.

As a working mother in the 1960s, Hamilton was unusual; but as a spaceship programmer, Hamilton was positively radical. Hamilton would bring her daughter Lauren by the lab on weekends and evenings. While 4-year-old Lauren slept on the floor of the office overlooking the Charles River, her mother programmed away, creating routines that would ultimately be added to the Apollos command module computer.

People used to say to me, How can you leave your daughter? How can you do this? Hamilton remembers. But she loved the arcane novelty of her job. She liked the camaraderiethe after-work drinks at the MIT faculty club; the geek jokes, like saying she was going to branch left minus around the hallway. Outsiders didnt have a clue. But at the lab, she says, I was one of the guys.

Then, as now, the guys dominated tech and engineering. Like female coders in todays diversity-challenged tech industry, Hamilton was an outlier. It might surprise todays software makers that one of the founding fathers of their boys club was, in fact, a motherand that should give them pause as they consider why the gender inequality of the Mad Men era persists to this day.

When I first got into it, nobody knew what it was that we were doing. It was like the Wild West.  Margaret Hamilton

As Hamiltons career got under way, the software world was on the verge of a giant leap, thanks to the Apollo program launched by John F. Kennedy in 1961. At the MIT Instrumentation Lab where Hamilton worked, she and her colleagues were inventing core ideas in computer programming as they wrote the code for the worlds first portable computer. She became an expert in systems programming and won important technical arguments. When I first got into it, nobody knew what it was that we were doing. It was like the Wild West. There was no course in it. They didnt teach it, Hamilton says.

This was a decade before Microsoft and nearly 50 years before Marc Andreessen would observe that software is, in fact, eating the world.The world didnt think much at all about software back in the early Apollo days. The original document laying out the engineering requirements of the Apollo mission didnt even mention the word software, MIT aeronautics professor David Mindell writes in his book Digital Apollo. Software was not included in the schedule, and it was not included in the budget. Not at first, anyhow.

But as the Apollo project unfolded, the centrality of software in accomplishing the mission started to become clear. In 1965, Hamilton became responsible for the onboard flight software on the Apollo computers. It was an exciting time, and the US was depending on the work that she was doing. But sometimes the pressure kept Hamilton up at night. Once, after a late-night party, she rushed back to the computer lab to correct a piece of code shed suddenly realized was flawed. I was always imagining headlines in the newspapers, and they would point back to how it happened, and it would point back to me.

By mid-1968, more than 400 people were working on Apollos software, because software was how the US was going to win the race to the moon. As it turned out, of course, software was going to help the world do so much more. As Hamilton and her colleagues were programming the Apollo spacecraft, they were also hatching what would become a $400 billion industry.

For Hamilton, programming meant punching holes in stacks of punch cards, which would be processed overnight in batches on a giant Honeywell mainframe computer that simulated the Apollo landers work. We had to simulate everything before it flew, Hamilton remembers. Once the code was solid, it would be shipped off to a nearby Raytheon facility where a group of women, expert seamstresses known to the Apollo program as the Little Old Ladies, threaded copper wires through magnetic rings (a wire going through a core was a 1; a wire going around the core was a 0). Forget about RAM or disk drives; on Apollo, memory was literally hardwired and very nearly indestructible.

Apollo flights carried two near-identical machines:one used in the lunar modulethe Eagle that landed on the moonand the other for the command module that carried the astronauts to and from Earth. These 70-pound Apollo computers were portable computers unlike any other. Conceived by MIT engineers such as Hal Laning and Hamiltons boss, Dick Batton, it was one of the first important computers to use integrated circuits rather than transistors. As Mindell tells the story, it was the first computerized onboard navigation system designed to be operated by humans but with fly-by-wire autopilot technologya precursor to the computerized navigation systems that are now standard on jetliners.

The system stored more than 12,000 words in its permanent memorythe copper ropes threaded by the Raytheon workersand had 1,024 words in its temporary, erasable memory. It was the first time that an important computer had been in a spacecraft and given a lot of responsibility for the mission, says Don Eyles, who worked on the lunar module code while at MITs IL. We showed that that could be done. We did it in what today seems an incredibly small amount of memory and very slow computation speed. Without it, Neil Armstrong wouldnt have made it to the moon. And without the software written by Hamilton, Eyles, and the team of MIT engineers, the computer would have been a dud.

This became clear on July 20, 1969, just minutes before Apollo 11 touched down on the Sea of Tranquility. Because of what Apollo software engineer Don Eyles has termed a documentation error, the Apollo computer started spitting out worrying error messages during this critical phase of the mission. But heres where the technical arguments won by Hamilton and others saved the day. The error messages were popping up because the computer was being overwhelmed, tasked with doing a series of unnecessary calculations when, in fact, it was most needed to land the module on the surface of the moon. Back in Houston, engineers knew that because of Apollos unique asynchronous processing, the computer would focus on the task at handlanding the Eagle on the Sea of Tranquility. When the software realized it didnt have enough room to do all the functions it was supposed to be doing, it went through its error detection process and focused on the highest priority job, Hamilton says.

That would never happen

One day, Lauren was playing with the MIT command module simulators display-and-keyboard unit, nicknamed the DSKY (dis-key). As she toyed with the keyboard, an error message popped up. Lauren had crashed the simulator by somehow launching a prelaunch program called P01 while the simulator was in midflight. There was no reason an astronaut would ever do this, but nonetheless, Hamilton wanted to add code to prevent the crash. That idea was overruled by NASA. We had been told many times that astronauts would not make any mistakes, she says. They were trained to be perfect. So instead, Hamilton created a program notean add-on to the programs documentation that would be available to NASA engineers and the astronauts: Do not select P01 during flight, it said. Hamilton wanted to add error-checking code to the Apollo system that would prevent this from messing up the systems. But that seemed excessive to her higher-ups. Everyone said, That would never happen, Hamilton remembers.

But it did. Right around Christmas 1968five days into the historic Apollo 8 flight, which brought astronauts to the moon for the first-ever manned orbitthe astronaut Jim Lovell inadvertently selected P01 during flight. Hamilton was in the second-floor conference room at the Instrumentation Laboratory when the call came in from Houston. Launching the P01 program had wiped out all the navigation data Lovell had been collecting. That was a problem. Without that data, the Apollo computer wouldnt be able to figure out how to get the astronauts home. Hamilton and the MIT coders needed to come up with a fix; and it needed to be perfect. After spending nine hours poring through the 8-inch-thick program listing on the table in front of them, they had a plan. Houston would upload new navigational data. Everything was going to be OK. Thanks to Hamiltonand Laurenthe Apollo astronauts came home.

Also thanks to Hamilton and the work she led, notions of what humanity could do, and be, changed not just beyond the stratosphere but also here on the ground. Software engineering, a concept Hamilton pioneered, has found its way from the moon landing to nearly every human endeavor. By the 1970s, Hamilton had moved on from NASA and the Apollo program. She went on to found and lead multiple software companies. Today her company, Hamilton Technologies, is just a few blocks away from MIT, where her career begana hub of the code revolution thats still looking toward the stars.

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Read more: https://www.wired.com/2015/10/margaret-hamilton-nasa-apollo/

Guardian of the galaxy: Nasa seeks new ‘planetary protection officer’

Role involves safeguarding Earth from extra-terrestrial infection, and stopping other planets being contaminated by robotic or human explorers

Nasa is looking for a planetary protection officer who will help safeguard Earth from alien bacteria.

No, it isnt the script of an elaborate science fiction film, but an actual job advertisement on the US governments website.

According to the site, the unusual role involves creating policies to ensure the avoidance of organic-constituent and biological contamination in human and robotic space exploration.

The job description says the three-year position involves frequent travel and comes with an annual handsome salary of up to $187,000 (141,000). The roles security clearance level is secret.

NASA People (@NASApeople)

Interested in @NASA‘s opportunity to become a Planetary Protection Officer?! Vacancy is open! Learn more on @USAJOBS https://t.co/qj10DH6s3M

August 2, 2017

The successful candidate, who must be a US citizen or national and hold a degree in physical science, engineering, or mathematics, will make sure that no microbial life travels from Earth to infect other planets, and vice versa.

The planetary protection officer will oversee all space flight missions that may intentionally or unintentionally carry Earth organisms and organic constituents to the planets or other solar system bodies, and any mission employing spacecraft, which are intended to return to Earth and its biosphere with samples from extraterrestrial targets of exploration, the ad says.

The ad was created on 13 July but this week started to gain more attention after it was posted on Twitter, prompting a slew of mildly amusing jokes and faux job applications.

Townie Bagels (@TownieBagels)

.@NASA was this the idea for planetary protection officer you had in mind? pic.twitter.com/JPpBrt5yhA

August 2, 2017

Steve Rogers (@Supes252)

Dear .@nasa I hear you’re looking for ‘Planetary Protection Officer’ we’ll now submit our interest in the position pic.twitter.com/HTOnMgSiJ1

August 2, 2017

jillthrash (@jillthrash)

There’s one other name you may know me by . . . Planetary Protection Officer. #nasa #PlanetaryProtectionOfficer pic.twitter.com/5Lz9FctcRB

August 3, 2017

The job was created in 1967 in order to make the US compliant with the International Outer Space Treaty.

In 2014, Catherine Conley, the current previous planetary protection officer, told Scientific American that one of her concerns was that humans travelling to Mars could contaminate the planet if they died there.

She said it was important not to pollute other planets and repeat the mistakes humans have made on Earth.

If you wanted to drill into an aquifer on Mars, it would be in the interest of future colonists that you keep the drilling clean because organisms can grow in the aquifer and change the conditions so that it is no longer available. Weve seen that happen on Earth. That would be really unfortunate.

Read more: https://www.theguardian.com/science/2017/aug/03/guardian-of-the-galaxy-nasa-seeks-new-planetary-protection-officer

Space historian Amy Shira Teitel is changing the face of online educaiton

The Daily Dot is celebrating Woman Crush Wednesday, better known as #WCWonTwitterandInstagram, by highlighting female creators onYouTubewhose work we admire.

Like all great love stories, Amy Shira Teitels longtime affair with space history has been a winding and unpredictable road. She has turned this lifelong pursuit into a full-time business that has launched her as a writer and expert. Now the author, blogger, vlogger, and TV host is using her digital media presence to champion women in science, technology, engineering, and mathematics (S.T.E.M.)—making the often-academic topic of space accessible to anyone who is interested.

As a 7-year-old, Teitel presented a poster to her second-grade class on the many ways Venus was the opposite of Earth. But despite being obsessed with space and science throughout her education in Canada, Teitel soon realized that it was the history of science that intrigued her the most. After picking up a masters degree in science technology studies, a program that wasnt the right fit, Teitel moved to Phoenix. Not yet ready to pursue a Ph.D. but at a loss on how to pursue academia any other way, Teitel spent her days blogging on Vintage Spaceand nights working as a personal trainer. Four months into her blogging career, started in 2010, her Vintage Space articles began to gain traction across publications like Nerdist and the Guardian; Al Jazeera began asking her to write regular, original content.

With her niche blog gaining steam, Teitel decided to put a Ph.D. on the back burner to see what other unexpected opportunities might present themselves. In 2012, she first opened her YouTube channelas a space to make teasers for her blog posts, which were filing at a vast 2,500 words. The channel eventually transformed into a full-time education hub with videos covering everything about space exploration from the 1960s onward. Her videos quickly gained notice not only for their original content, but for the fact that she—a pink-haired cat lover with tattoos—was inspiring other women in the overly male dominated field of education on YouTube. It was her YouTube videos that sparked DNews to hire her as a regular host, and spurred her TV appearances on Science Channel, American Heroes Channel, SyFy, and the Travel Channel.

Like a skilled acrobat spinning plates without missing a step, Teitel added author to her business card in 2015 after publishing her debut book, Breaking the Chains of Gravity. After my deep research and years of watching her channel, I can confidently say that everything she puts her mind to will work out strongly.Her years of building a brand around her passion continue to show others that it is possible for them to do the same. So as young girls continue to push back against the boys’ club of S.T.E.M., Teitel stands as a heroine using her videos to shatter taboos around who and how someone can succeed in science.

Read more: https://www.dailydot.com/upstream/amy-shira-teitel-wcw-youtube/

Space historian Amy Shira Teitel is changing the face of online educaiton

The Daily Dot is celebrating Woman Crush Wednesday, better known as #WCWonTwitterandInstagram, by highlighting female creators onYouTubewhose work we admire.

Like all great love stories, Amy Shira Teitels longtime affair with space history has been a winding and unpredictable road. She has turned this lifelong pursuit into a full-time business that has launched her as a writer and expert. Now the author, blogger, vlogger, and TV host is using her digital media presence to champion women in science, technology, engineering, and mathematics (S.T.E.M.)—making the often-academic topic of space accessible to anyone who is interested.

As a 7-year-old, Teitel presented a poster to her second-grade class on the many ways Venus was the opposite of Earth. But despite being obsessed with space and science throughout her education in Canada, Teitel soon realized that it was the history of science that intrigued her the most. After picking up a masters degree in science technology studies, a program that wasnt the right fit, Teitel moved to Phoenix. Not yet ready to pursue a Ph.D. but at a loss on how to pursue academia any other way, Teitel spent her days blogging on Vintage Spaceand nights working as a personal trainer. Four months into her blogging career, started in 2010, her Vintage Space articles began to gain traction across publications like Nerdist and the Guardian; Al Jazeera began asking her to write regular, original content.

With her niche blog gaining steam, Teitel decided to put a Ph.D. on the back burner to see what other unexpected opportunities might present themselves. In 2012, she first opened her YouTube channelas a space to make teasers for her blog posts, which were filing at a vast 2,500 words. The channel eventually transformed into a full-time education hub with videos covering everything about space exploration from the 1960s onward. Her videos quickly gained notice not only for their original content, but for the fact that she—a pink-haired cat lover with tattoos—was inspiring other women in the overly male dominated field of education on YouTube. It was her YouTube videos that sparked DNews to hire her as a regular host, and spurred her TV appearances on Science Channel, American Heroes Channel, SyFy, and the Travel Channel.

Like a skilled acrobat spinning plates without missing a step, Teitel added author to her business card in 2015 after publishing her debut book, Breaking the Chains of Gravity. After my deep research and years of watching her channel, I can confidently say that everything she puts her mind to will work out strongly.Her years of building a brand around her passion continue to show others that it is possible for them to do the same. So as young girls continue to push back against the boys’ club of S.T.E.M., Teitel stands as a heroine using her videos to shatter taboos around who and how someone can succeed in science.

Read more: https://www.dailydot.com/upstream/amy-shira-teitel-wcw-youtube/

The hidden history of Nasas black female scientists

The diversity of Nasas workforce in 1940s Virginia is uncovered in a new book by Margot Lee Shetterly. She recalls how a visit to her home town led to a revelation

Mrs Land worked as a computer out at Langley, my father said, taking a right turn out of the parking lot of the First Baptist church in Hampton, Virginia. My husband and I visited my parents just after Christmas in 2010, enjoying a few days away from our full-time life and work in Mexico.

They squired us around town in their 20-year-old green minivan, my father driving, my mother in the front passenger seat, Aran and I buckled in behind like siblings. My father, gregarious as always, offered a stream of commentary that shifted fluidly from updates on the friends and neighbours wed bumped into around town to the weather forecast to elaborate discourses on the physics underlying his latest research as a 66-year-old doctoral student at Hampton University.

He enjoyed touring my Maine-born-and-raised husband through our neck of the woods and refreshing my connection with local life and history in the process.

As a callow 18-year-old leaving for college, Id seen my home town as a mere launching pad for a life in worldlier locales, a place to be from rather than a place to be. But years and miles away from home could never attenuate the citys hold on my identity and the more I explored places and people far from Hampton, the more my status as one of its daughters came to mean to me. That day after church, we spent a long while catching up with the formidable Mrs Land, who had been one of my favourite Sunday school teachers. Kathaleen Land, a retired Nasa mathematician, still lived on her own well into her 90s and never missed a Sunday at church.

Read more: https://www.theguardian.com/books/2017/feb/05/hidden-figures-black-female-scientists-african-americans-margot-lee-shetterly-space-race

The Man Whos Trying to Kill Dark Matter

For 80 years, scientists have puzzled over the way galaxies and other cosmic structures appear to gravitate toward something they cannot see. This hypothetical dark matter seems to outweigh all visible matter by a startling ratio of five to one, suggesting that we barely know our own universe. Thousands of physicists are doggedly searching for these invisible particles.

Quanta Magazine


About

Original storyreprinted with permission from Quanta Magazine, an editorially independent division of theSimons Foundation whose mission is to enhance public understanding of science by covering research developments and trends in mathematics and the physical and life sciences


But the dark matter hypothesis assumes scientists know how matter in the sky ought to move in the first place. At the end of 2016, a series of developments has revived a long-disfavored argument that dark matter doesnt exist after all. In this view, no missing matter is needed to explain the errant motions of the heavenly bodies; rather, on cosmic scales, gravity itself works in a different way than either Isaac Newton or Albert Einstein predicted.

The latest attempt to explain away dark matter is a much-discussed proposal by Erik Verlinde, a theoretical physicist at the University of Amsterdam who is known for bold and prescient, if sometimes imperfect, ideas. In a dense 51-page paper posted online on Nov. 7, Verlinde casts gravity as a byproduct of quantum interactions and suggests that the extra gravity attributed to dark matter is an effect of dark energythe background energy woven into the space-time fabric of the universe.

Instead of hordes of invisible particles, dark matter is an interplay between ordinary matter and dark energy, Verlinde said.

To make his case, Verlinde has adopted a radical perspective on the origin of gravity that is currently in vogue among leading theoretical physicists. Einstein defined gravity as the effect of curves in space-time created by the presence of matter. According to the new approach, gravity is an emergent phenomenon. Space-time and the matter within it are treated as a hologram that arises from an underlying network of quantum bits (called qubits), much as the three-dimensional environment of a computer game is encoded in classical bits on a silicon chip. Working within this framework, Verlinde traces dark energy to a property of these underlying qubits that supposedly encode the universe. On large scales in the hologram, he argues, dark energy interacts with matter in just the right way to create the illusion of dark matter.

In his calculations, Verlinde rediscovered the equations of modified Newtonian dynamics, or MOND. This 30-year-old theory makes an ad hoc tweak to the famous inverse-square law of gravity in Newtons and Einsteins theories in order to explain some of the phenomena attributed to dark matter. That this ugly fix works at all has long puzzled physicists. I have a way of understanding the MOND success from a more fundamental perspective, Verlinde said.

Many experts have called Verlindes paper compelling but hard to follow. While it remains to be seen whether his arguments will hold up to scrutiny, the timing is fortuitous. In a new analysis of galaxies published on Nov. 9 in Physical Review Letters, three astrophysicists led by Stacy McGaugh of Case Western Reserve University in Cleveland, Ohio, have strengthened MONDs case against dark matter.

The researchers analyzed a diverse set of 153 galaxies, and for each one they compared the rotation speed of visible matter at any given distance from the galaxys center with the amount of visible matter contained within that galactic radius. Remarkably, these two variables were tightly linked in all the galaxies by a universal law, dubbed the radial acceleration relation. This makes perfect sense in the MOND paradigm, since visible matter is the exclusive source of the gravity driving the galaxys rotation (even if that gravity does not take the form prescribed by Newton or Einstein). With such a tight relationship between gravity felt by visible matter and gravity given by visible matter, there would seem to be no room, or need, for dark matter.

Even as dark matter proponents rise to its defense, a third challenge has materialized. In new research that has been presented at seminars and is under review by the Monthly Notices of the Royal Astronomical Society, a team of Dutch astronomers have conducted what they call the first test of Verlindes theory: In comparing his formulas to data from more than 30,000 galaxies, Margot Brouwer of Leiden University in the Netherlands and her colleagues found that Verlinde correctly predicts the gravitational distortion or lensing of light from the galaxiesanother phenomenon that is normally attributed to dark matter. This is somewhat to be expected, as MONDs original developer, the Israeli astrophysicist Mordehai Milgrom, showed years ago that MOND accounts for gravitational lensing data. Verlindes theory will need to succeed at reproducing dark matter phenomena in cases where the old MOND failed.

Kathryn Zurek, a dark matter theorist at Lawrence Berkeley National Laboratory, said Verlindes proposal at least demonstrates how something like MOND might be right after all. One of the challenges with modified gravity is that there was no sensible theory that gives rise to this behavior, she said. If [Verlindes] paper ends up giving that framework, then that by itself could be enough to breathe more life into looking at [MOND] more seriously.

The New MOND

In Newtons and Einsteins theories, the gravitational attraction of a massive object drops in proportion to the square of the distance away from it. This means stars orbiting around a galaxy should feel less gravitational pulland orbit more slowlythe farther they are from the galactic center. Stars velocities do drop as predicted by the inverse-square law in the inner galaxy, but instead of continuing to drop as they get farther away, their velocities level off beyond a certain point. The flattening of galaxy rotation speeds, discovered by the astronomer Vera Rubin in the 1970s, is widely considered to be Exhibit A in the case for dark matterexplained, in that paradigm, by dark matter clouds or halos that surround galaxies and give an extra gravitational acceleration to their outlying stars.

Lucy Reading-Ikkanda/Quanta Magazine

Searches for dark matter particles have proliferatedwith hypothetical weakly interacting massive particles (WIMPs) and lighter-weight axions serving as prime candidatesbut so far, experiments have found nothing.

Meanwhile, in the 1970s and 1980s, some researchers, including Milgrom, took a different tack. Many early attempts at tweaking gravity were easy to rule out, but Milgrom found a winning formula: When the gravitational acceleration felt by a star drops below a certain levelprecisely 0.00000000012 meters per second per second, or 100 billion times weaker than we feel on the surface of the Earthhe postulated that gravity somehow switches from an inverse-square law to something close to an inverse-distance law. Theres this magic scale, McGaugh said. Above this scale, everything is normal and Newtonian. Below this scale is where things get strange. But the theory does not really specify how you get from one regime to the other.

Physicists do not like magic; when other cosmological observations seemed far easier to explain with dark matter than with MOND, they left the approach for dead. Verlindes theory revitalizes MOND by attempting to reveal the method behind the magic.

Verlinde, ruddy and fluffy-haired at 54 and lauded for highly technical string theory calculations, first jotted down a back-of-the-envelope version of his idea in 2010. It built on a famous paper he had written months earlier, in which he boldly declared that gravity does not really exist. By weaving together numerous concepts and conjectures at the vanguard of physics, he had concluded that gravity is an emergent thermodynamic effect, related to increasing entropy (or disorder). Then, as now, experts were uncertain what to make of the paper, though it inspired fruitful discussions.

The particular brand of emergent gravity in Verlindes paper turned out not to be quite right, but he was tapping into the same intuition that led other theorists to develop the modern holographic description of emergent gravity and space-timean approach that Verlinde has now absorbed into his new work.

In this framework, bendy, curvy space-time and everything in it is a geometric representation of pure quantum informationthat is, data stored in qubits. Unlike classical bits, qubits can exist simultaneously in two states (0 and 1) with varying degrees of probability, and they become entangled with each other, such that the state of one qubit determines the state of the other, and vice versa, no matter how far apart they are. Physicists have begun to work out the rules by which the entanglement structure of qubits mathematically translates into an associated space-time geometry. An array of qubits entangled with their nearest neighbors might encode flat space, for instance, while more complicated patterns of entanglement give rise to matter particles such as quarks and electrons, whose mass causes the space-time to be curved, producing gravity. The best way we understand quantum gravity currently is this holographic approach, said Mark Van Raamsdonk, a physicist at the University of British Columbia in Vancouver who has done influential work on the subject.

The mathematical translations are rapidly being worked out for holographic universes with an Escher-esque space-time geometry known as anti-de Sitter (AdS) space, but universes like ours, which have de Sitter geometries, have proved far more difficult. In his new paper, Verlinde speculates that its exactly the de Sitter property of our native space-time that leads to the dark matter illusion.

De Sitter space-times like ours stretch as you look far into the distance. For this to happen, space-time must be infused with a tiny amount of background energyoften called dark energywhich drives space-time apart from itself. Verlinde models dark energy as a thermal energy, as if our universe has been heated to an excited state. (AdS space, by contrast, is like a system in its ground state.) Verlinde associates this thermal energy with long-range entanglement between the underlying qubits, as if they have been shaken up, driving entangled pairs far apart. He argues that this long-range entanglement is disrupted by the presence of matter, which essentially removes dark energy from the region of space-time that it occupied. The dark energy then tries to move back into this space, exerting a kind of elastic response on the matter that is equivalent to a gravitational attraction.

Because of the long-range nature of the entanglement, the elastic response becomes increasingly important in larger volumes of space-time. Verlinde calculates that it will cause galaxy rotation curves to start deviating from Newtons inverse-square law at exactly the magic acceleration scale pinpointed by Milgrom in his original MOND theory.

Van Raamsdonk calls Verlindes idea definitely an important direction. But he says its too soon to tell whether everything in the paperwhich draws from quantum information theory, thermodynamics, condensed matter physics, holography and astrophysicshangs together. Either way, Van Raamsdonk said, I do find the premise interesting, and feel like the effort to understand whether something like that could be right could be enlightening.

One problem, said Brian Swingle of Harvard and Brandeis universities, who also works in holography, is that Verlinde lacks a concrete model universe like the ones researchers can construct in AdS space, giving him more wiggle room for making unproven speculations. To be fair, weve gotten further by working in a more limited context, one which is less relevant for our own gravitational universe, Swingle said, referring to work in AdS space. We do need to address universes more like our own, so I hold out some hope that his new paper will provide some additional clues or ideas going forward.

The Case for Dark Matter

Verlinde could be capturing the zeitgeist the way his 2010 entropic-gravity paper did. Or he could be flat-out wrong. The question is whether his new and improved MOND can reproduce phenomena that foiled the old MOND and bolstered belief in dark matter.

One such phenomenon is the Bullet cluster, a galaxy cluster in the process of colliding with another. The visible matter in the two clusters crashes together, but gravitational lensing suggests that a large amount of dark matter, which does not interact with visible matter, has passed right through the crash site. Some physicists consider this indisputable proof of dark matter. However, Verlinde thinks his theory will be able to handle the Bullet cluster observations just fine. He says dark energys gravitational effect is embedded in space-time and is less deformable than matter itself, which would have allowed the two to separate during the cluster collision.

But the crowning achievement for Verlindes theory would be to account for the suspected imprints of dark matter in the cosmic microwave background (CMB), ancient light that offers a snapshot of the infant universe. The snapshot reveals the way matter at the time repeatedly contracted due to its gravitational attraction and then expanded due to self-collisions, producing a series of peaks and troughs in the CMB data. Because dark matter does not interact, it would only have contracted without ever expanding, and this would modulate the amplitudes of the CMB peaks in exactly the way that scientists observe. One of the biggest strikes against the old MOND was its failure to predict this modulation and match the peaks amplitudes. Verlinde expects that his version will workonce again, because matter and the gravitational effect of dark energy can separate from each other and exhibit different behaviors. Having said this, he said, I have not calculated this all through.

While Verlinde confronts these and a handful of other challenges, proponents of the dark matter hypothesis have some explaining of their own to do when it comes to McGaugh and his colleagues recent findings about the universal relationship between galaxy rotation speeds and their visible matter content.

In October, responding to a preprint of the paper by McGaugh and his colleagues, two teams of astrophysicists independently argued that the dark matter hypothesis can account for the observations. They say the amount of dark matter in a galaxys halo would have precisely determined the amount of visible matter the galaxy ended up with when it formed. In that case, galaxies rotation speeds, even though theyre set by dark matter and visible matter combined, will exactly correlate with either their dark matter content or their visible matter content (since the two are not independent). However, computer simulations of galaxy formation do not currently indicate that galaxies dark and visible matter contents will always track each other. Experts are busy tweaking the simulations, but Arthur Kosowsky of the University of Pittsburgh, one of the researchers working on them, says its too early to tell if the simulations will be able to match all 153 examples of the universal law in McGaugh and his colleagues galaxy data set. If not, then the standard dark matter paradigm is in big trouble. Obviously this is something that the community needs to look at more carefully, Zurek said.

Even if the simulations can be made to match the data, McGaugh, for one, considers it an implausible coincidence that dark matter and visible matter would conspire to exactly mimic the predictions of MOND at every location in every galaxy. If somebody were to come to you and say, The solar system doesnt work on an inverse-square law, really its an inverse-cube law, but theres dark matter thats arranged just so that it always looks inverse-square, you would say that person is insane, he said. But thats basically what were asking to be the case with dark matter here.

Given the considerable indirect evidence and near consensus among physicists that dark matter exists, it still probably does, Zurek said. That said, you should always check that youre not on a bandwagon, she added. Even though this paradigm explains everything, you should always check that there isnt something else going on.

Original story reprinted with permission from Quanta Magazine, an editorially independent publication of the Simons Foundation whose mission is to enhance public understanding of science by covering research developments and trends in mathematics and the physical and life sciences.

Read more: https://www.wired.com/2017/01/case-dark-matter/

With Hidden Figures, the World Finally Hears an Untold NASA Saga

On February 20, 1962, as millions watched, John Glenn became the first American to orbit the Earth. As with every NASA mission before or since, his solo voyage was the result of a massivecoordinatedeffort; however, that effortwent far beyond the Mission Control Center in Houston. Behind the Mercury spacecraft’s flightwas a team of engineers, physicists, and human “computers” whose work largely went unnoticedand now, in the movieHidden Figures, they’re finally getting the big-screen credit they deserve.

For many boys and girls watching Glenns landing, the national heroes at NASA didnt look like them. Women and people of colorlike the trio thatHidden Figures chronicles, Katherine Johnson (played by Taraji P. Henson), Dorothy Vaughan (Octavia Spencer), and Mary Jackson (Janelle Mone)might have played significant roles in space flight, but in the 1960s their stories simply werent told. “NASA history was largely about the astronauts, doing battle with the Soviet Union in space,” says NASA chief historian Bill Barry, who still vividly recalls watching Glenn’s flight on a black-and-white TV on his living room floor. But in the early 1990s, scholars began to show more interest in the history ofNASA’s workforce, and the institution’s archivists began to unearththose untold stories, in part by interviewing former female computers at the agency’s Langley Research Center in Virginia. Later, writer Margot Lee Shetterly spoke with them as well while researching her bookHidden Figures: The American Dream and the Untold Story ofthe Black Women Mathematicians Who Helped Win the Space Race, which was optioned for a film before it was even published.

Hidden Figuresfocuses on the story of Katherine Johnson, who painstakingly re-confirmed thousands of calculations made bythen-brand-new IBM computersmany of them to eight significant digitsin order to correctly predict Glenns landing. But Barry, ever the historian, sees the true hero as Vaughan, a onetime high school math teacherwho recognized the potential of working in mathematics at the rapidly growing NASA, where she stood upfor women computers of all races. And when IBM machines threatened to make the job of human computer obsolete, Vaughan recognized the changing landscape and, with the foresight of a successful start-up founder, taught her computers to become programmers, eventually becoming the leader of computer programming. “Now, were in a time when technology is shifting jobs in a similar way as it did in the 60s,” says Barry. Dorothy saw what was coming, and reinvented herself again and again.”

Usually, filmmakers working on projects about space travel just ask to use the NASA insignia, like in The Martian, or to shoot scenes on NASA property, like at the NASA Jet Propulsion Lab in Transformers. But Ted Melfi, the co-writer and director of Hidden Figures, which opens wide this weekend, spent hours going through the script with Barry, at a level of detail the historian hadnt seen since Tom Hanks’ 1998 docuseriesFrom the Earth to the Moon. Barry ensured that the Hidden Figures team got the details right, from the models of cars at the Langley parking lot in 1962 to how long it would take news of a Russian rocket launch to reach the White House. “There were lots of weird, quirky historical things,” says Barry. “You wouldnt notice them, unless youre a geek like me.”

Barry even got to assist on a couple of Easter eggs. In a scene showingJohn Glenn (played by Glen Powell) sitting in the rocket before launch, look for a woman in a white scarf, painting on the side of the capsule. Thats Cece Bibby, the artist who designed the insignia for the craft known as Friendship 7. In the 1960s, the names of rockets were usually stenciled on by men, but Glenn wanted a special design—and when he found out the artist behind the insignia was a woman, he insisted she hand-paint it onto the spacecraft, despite the protestations of her male superiors.

But Bibby’s isn’t the only story that’s known by surprisingly few people. Astronaut Stephanie Wilson, who has flown to the International Space Station twice, hadnt heard of the women of Hidden Figures before the book and movie. In fact, Wilson built her career at NASA without female engineers as role models. “When I entered the aerospace workplace in the late 80s, there were 85 engineers, and five were women,” she says. She heard about space travel by watching male astronauts go into space, and talking to a male astronomer in her hometownbut mostly, because of the promise of space travel. “To be adventurous, to be on the forefront of explorationto be an astronaut really appealed to me,” she says. And with the movie’s reviews helping it clock in at over 90% on Rotten Tomatoes,now young women who share that sense of galactic curiosity today can look back to the women who made history in spacebefore looking up to the stars themselves.

Read more: https://www.wired.com/2017/01/nasa-history-hidden-figures/

Picture of the Day: The Room Where Satellites Get Tested

Seen here is the ESA’s incredible satellite testing room in Noordwijk, the Netherlands; officially known as the Compact Payload Test Range in the ESA’s ESTEC technical centre area. In an informative blog post, the ESA adds:

In this zone of silence, satellite antennas are tested ahead of launch. Metal walls form a ‘Faraday cage’ to block all external signals, isolating the facility from TV and radio broadcasts, aircraft and ship radars, and even mobile calls. Spiky foam cladding absorbs radio signals internally to create conditions simulating the infinite void of space.
 
The white surfaces in front of the ‘anechoic’ blue background are reflectors that pass signals from an illuminating antenna to the antenna under test… To increase its capabilities, the Compact Payload Test Range (CPTR) was recently equipped with a state-of-the-art Near-Field Scanner (NFS) to measure the electromagnetic fields closely surrounding a test antenna. Via mathematics, the equivalent radiation at large distances is calculated.
 
This new set-up and test technique allow the measurement of larger antennas (up to 8 m in diameter) over a larger frequency range (0.4–50 GHz). [source]

Read more: http://twistedsifter.com/2016/05/the-room-where-esa-satellites-get-tested/