You could be excused, when you first hear Dane Rudy describe his company, for thinking that he wants to use raccoons to send satellites into space. Trash pandas, though, are not the future that Rudy is talking about.

He's talking about rockoons—rockets launched from high-altitude balloons. Rockoons trace their trajectory back to the military, like the 1950s Air Force program called Farside. (Check out the news anchor's vintage intonations in this archival video about the program's fifth—and first successful—launch attempt.)

Rockoons, Rudy believes, deserve a reboot. Through his company, Leo Aerospace, he wants to balloon small satellites into the stratosphere, then shoot them to orbit with rockets. When launched from the ground, rockets require lots of fuel to push through the dense air of those first miles. If another vehicle floats them way up before they have to fire, they can use their fuel for what really matters—getting to space—rather than wasting it on leaving the ground. Right now, small satellites usually have to carpool on serious rockets, with names like Falcon, which is inconvenient, inefficient, expensive, slow—all the things small satellites are supposed to not be.

Last Wednesday, Rudy was in the LA Grand Hotel, surrounded by soft-jazz piano and spiral-arm chandeliers, to try to figure out what rockoons could maybe do for the military. Back in April, the Defense Advanced Research Projects Agency—Darpa—announced that it would hold a "Launch Challenge": To win, competitors have to launch something small into space two times in a span of weeks.

It's going to be a bit of a fire drill: Less than a month before the first launch, sometime in the last quarter of 2019, Darpa will tell competitors where it will take place. Then, less than two weeks before go-time, the agency will give them details about orbit, payload, and pad. And then they must rinse-repeat within weeks, with new requirements that they'll only receive after the first launch. The agency will give $10 million to the first-place winner, plus $400,000 to all who qualify to enter at all, and $2 million to everyone who nails the first launch.

At the Grand Hotel, Rudy was attending Darpa's "Competitors’ Day," an opportunity for would-be launchers to come together and get a read on the situation. It's kind of a PowerPoint-heavy Opening Ceremonies, minus musical numbers, and the ballroom is full of launch vehicle makers, propulsion companies, component constructors, New Space upstarts, Old Space stalwarts, spaceport representatives, and also the guy who sent the first hot dog toward space.

Everyone's name badge has the same graphic, which looks like a flat plain, edged by mountains. Four rockets launch at once from the landscape, which resembles classic aerospace-innovation geography. It's Edwards Air Force Base, or White Sands Missile Range. It's Area 51, or the Academy in Colorado Springs. And toward the end of 2019, Darpa may ask these competitors to launch from federal places like these, or from the commercial spaceports popping up around the country.

At the beginning of the meeting, Todd Master, the Launch Challenge program manager, steps up to a podium. "For a really long time, we’ve enjoyed and benefited from space being a sanctuary," he says. The guy next to me, who has a Sputnik tattoo on one forearm and an infinity symbol inked on the other, writes something in his notebook.

"That environment has been changing," he continues. "We’re in an environment now where we view ourselves as threatened in space."

Here’s part of what this means: More entities than ever can get to orbit. If you can get to orbit, it's no huge technological leap to trespass onto someone else’s space—by, say, slamming into their satellite. This problem has been part of the space race from the beginning. After all, the reason we invented rockets was to shoot each other with missiles, not because of the romantic human urge to explore the cosmos. And hackers could even target the software and signals satellites send, without shooting anything physical into space in the first place.

One ultra-satellite is vulnerable to take-down, physically or cyber-ly. But if you take that satellite's skills and disperse them across a network of hundreds or thousands of small, replaceable sats? The flock functions fine even if a few get destroyed or corrupted. And if a big one becomes compromised, you can quickly reestablish its capabilities in miniature. So Darpa hopes the DoD will pivot to constellations of small space objects, sent up so often that the citizenry simply shrugs its collective shoulders at every successful rocket launch. It doesn't even have to be a rocket. “I don’t care if FedEx is three trucks and two boats and an airplane,” says Master. "Get it there and I’ll pay you.”

The hosts set the crowd loose with an explicit mandate to network. Some attendees have vehicles in the works, while some make only vehicle parts. Some are the taker-carers of logistics. Some are from the spaceports. Few attendees, in other words, have the standalone resources to complete the Launch Challenge. I end up in a gaggle with Rudy. Nearby, someone from Northrop Grumman talks to the founder of Ruckus Composites, a company that mostly does carbon fiber work for the bike industry. But the founder, Shawn Small, is a space geek—he’s the one with the Sputnik tattoo.

Small also makes rockets sometimes, telescopes other times. He sent that first hot dog 22 miles up. Also chicken, on a mission called “A Pollo 13.” He wonders to me, at the end of the day, exactly why Darpa wants this responsive technology. “What do they know?” he asks. As in, what do they know that we don't.

A lot, probably, about all the things that could realistically go wrong in space. The military mindset is a strange thing, tasking itself with thinking constantly about how we are threatened, or could be. And for Darpa, right now, the way to shrink risk is to shrink satellites.

As I get ready to leave, I ask Rudy if it’s strange, for him, to be thinking about doing defense work (Rudy says he isn't sure whether Leo will enter the challenge). On Leo's website, the company describes using little satellites to track crop health, illegal fishing, port traffic. But like all launch technology, rockoons are dual-use. Most space companies—from the big SpaceXs and Boeings to the smaller Planets and Rocket Labs—do defense or intelligence work.

Partly for that reason, Leo Aerospace just went through a national-security-focused accelerator, MD5, to gain experience in navigating the byzantine bureaucratic processes involved in defense contracting. "You learn a lot of things you wouldn't expect," Rudy says, when you get into the defense world, but what he has learned has convinced him the sector is "trying to make the world a better, safer place."

And a more watched one, in which the US doesn't lose whatever shadow space race is going on. Darpa, in fact, was founded partly because of the surprise Soviet launch of Sputnik—the world's first (small) satellite. The US, henceforth, would be the surpris-er. So no matter what the agency publicly says about quick-launch and smallsat infrastructure, it surely is anticipating some surprises to come, and planning a few of its own.

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Her name was Lola. No, not “L-O-L-A, Lola,” from the Kinks’ song, but a Mexican Redhead.

Well, actually, not that either, it turned out.

“We don’t really say that anymore,” the avian veterinarian said as he helped Lola out of her carrier. “She’s an Amazon. A green-cheeked Amazon, Amazona viridigenalis. That’s what the scientific name means. Though most people just call them red-crowned parrots.”

That was my introduction to a bird species, one of whom I adopted 10 years ago from a friend of a friend, as these things go among people who live with pet birds. But it was only after I moved to Los Angeles that I found out about her feral cousins, the large wild flocks of red-crowned parrots that live in the San Gabriel Valley, just northeast of Los Angeles.

Parrots, of course, are not uncommon around Los Angeles: More than a dozen different species have established wild populations in the area, descendants of pet birds that escaped at some point and managed to make a home for themselves in some part of the sprawling metropolis. But for the red-crowned parrots, Los Angeles is more than an additional habitat. The city is a sanctuary for this endangered species.

In the 1970s and ’80s, tens of thousands of chicks and adults were poached from the red-crowned parrots’ original habitat in northeastern Mexico, in the states of Tamaulipas and San Luis Potosí, and brought to the United States to be sold in the pet trade. Because of the poaching and habitat loss from deforestation, their population dwindled in Mexico, and red-crowned parrots are now listed as an endangered species in Mexico and by the International Union for the Conservation of Nature.

In the meantime, however, their pet cousins in the United States escaped or were let go by owners who realized too late that wild-caught parrots make terrible pets, and that even tamed ones are demanding and noisy. Red-crowned parrots established sizable wild populations in Florida and California. In the Los Angeles area, there are about 2,000 to 3,000 individuals, a number that could at this point rival or exceed that of the remaining wild population in Mexico. Feeding largely on non-native nut and fruit trees, red-crowned parrots started to breed and became a permanent feature of the greater Los Angeles landscape over the course of the 1980s and ’90s.

In 2001, the California Bird Records Committee added them to the list of California state birds, where they joined species such as house sparrows, rock pigeons (the ones that perch on every urban power line), and starlings: species that are not native to the state, but have become integrated into California ecosystems over the last century.

I feel a small sense of wonder every time it strikes me that two of the birds who live with me are members of an endangered species whose members have become “naturalized citizens” of California. And I’ve been overcome with awe every time I’ve gone to see hundreds of red-crowned parrots come in to land in one of their night roosts in Pasadena.

But the implications of these parrots’ presence in the city goes beyond emotion and aesthetics. It makes me wonder, could Los Angeles become a sanctuary for other endangered species—even those who are not native to Southern California?

Some ecologists think so. Brad Shaffer, a biology professor at the University of California, Los Angeles, notes that cities not only destroy habitat, but also create new living spaces for animals and plants. Some of these spaces work well for native species, while others don’t. Some of these modified landscapes could offer refuge to species that are struggling to survive in their original habitats elsewhere.

In the past, some of the new ecological niches that have been created in cities have been occupied by non-native species through sheer serendipity, by plants or animals like the red-crowned parrots that happened to land in town and know how to take advantage of the niches they found.

But what if we deliberately offered sanctuary to endangered species in our cities—those that are native, of course, but also those that are not?

Shaffer suggests that spotted turtles, for instance, which are endangered on the East Coast of the United States, might thrive in Los Angeles. Endangered geckos might find an ecological niche on and around parts of our buildings that are currently unoccupied by any native lizards.

Of course, any experiment along these lines would have to be carefully planned and closely monitored—both to protect the introduced plants or animals from being exposed to new risks, and to prevent them from becoming invasive and causing harm to native species we want to conserve. So a great deal of scientific, legal, and educational work would need to be done to make cities function as something like “urban arks” in our current era of a possible sixth mass extinction caused by humans.

This idea might seem counterintuitive. After all, aren’t introduced species, moved around by humans, one of the root causes of ecological crises? From eucalyptus trees to ring-necked pheasants and zebra mussels, introduced species often compete with native flora and fauna for habitat and food. In some cases, they outcompete native species and become “invasive”—a label we give to species that spread and cause harm to native ecosystems.

Examples leap readily to mind: Feral cats have eaten their way through much of Australia’s native fauna. The brown tree snake has driven at least half a dozen bird species to extinction on the island of Guam. Kudzu—an East Asian arrowroot originally introduced for erosion control—turned into “the plant that ate the South” in the United States.

These striking examples of environmental harm tend to make one forget that the majority of introduced species either disappear quickly, or integrate into existing ecosystems without triggering ecological disaster. And imagining an “urban ark” would not be the same as introducing new species into wild areas that retain intact native ecosystems, but instead into environments that are already fundamentally transformed from their earlier states. Cities are in effect largely novel ecosystems that offer quite different ecological opportunities—as well as risks—than the ecosystems they replaced. An “urban ark” would seek to take advantage of these opportunities rather than letting them occur by accident, as they usually do.

The fact that urban landscapes, like many agricultural landscapes, are such new ecosystems—complex patchworks of native and introduced species, some desirable, some not, some invasive, some not—has led to something of a split among ecologists today.

Restoration ecology, the effort to reconstruct ecosystems that existed in a place at a particular time in the past, and to get rid of species that did not form part of the landscape in the past, remains an important project, especially in areas that are not primarily designed to sustain human populations.

But other ecologists have suggested that where a species comes from matters less than how it functions in its contemporary environment, especially in human-designed habitats such as cities.

From this perspective, the most important question for thinking about urban biodiversity in a city such as Los Angeles is not “What species used to be here?” Instead we should ask, “What animals and plants should form part of our environment in the future?”

That question can’t be answered without taking into account the city’s social and cultural as well as biological diversity. Along with solid scientific research, we need forums for discussing what I like to call “multispecies justice”: the relationship between what it’s right to do by other people, and what it’s right to do by other species.

Multispecies justice aims to create better urban habitats for both humans and nonhumans—sanctuaries that encourage both biological and cultural diversity.

Some discussions are already underway on how we might translate such a vision into reality. We could reintroduce native oaks and sages, for example, while providing space for community gardens, full of plants brought to Los Angeles from around the world. Respect for the lives of feral cats ought to be reconciled with the protection of urban birds. The need for more affordable housing should be balanced with the desire for more green spaces in urban areas that don’t have enough of either.

Turning the city into a multispecies sanctuary should be part of these discussions, not only because the city is already functioning in this way for species like the red-crowned parrots, but also because humans and nonhumans might need our “urban ark” in the future.

This essay is presented in partnership with KCET and the Laboratory for Environmental Strategies (LENS) at the University of California, Los Angeles.

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Call it the California Marijuanapocalypse of 2018. As of January 1, recreation cannabis has been legal in the state. A black market still runs underneath it all (Northern California alone supplies perhaps 75 percent of all marijuana across the United States), but cultivators and distributors are going legit, bringing themselves up to the rigorous testing and packaging standards mandated by the state.

This weekend, though, was a weekend of reckoning. For the first six months of the year, the state has allowed dispensaries to sell product that isn’t yet up to new code so manufacturers can adjust to the changes. Any of these noncompliant concentrates or edibles or simple flowers left on store shelves as of July 1 have to be destroyed. By one estimate, that could total $350 million in lost product.

So how exactly do you obliterate potentially tens of thousands of pounds of cannabis across the state? Not unlike how you get rid of yard trimmings.

The responsibility for destroying noncompliant cannabis products rests on the dispensaries, not the state—the government won’t be dispatching special trucks to pick up weed. So for a dispensary like the Apothecarium in San Francisco, it’s got to pull noncompliant marijuana immediately.

Which means an interesting trash day. “Noncompliant flower and prerolls will be composted,” says Eliot Dobris, spokesperson for Apothecarium. That is, rendered “unusable” by putting it in filthy, locked bins the public doesn’t have access to. Oils for vape pens go through an extra step. “Noncompliant cartridges will be rendered unusable with a hammer and then will be put in the landfill bin,” he says.

“And we have to do all of this on video,” Dobris adds, “so if there's ever a question, the state can have access to that video.”

The headaches are making their way upstream as well. The legal recreational cannabis supply chain, which packages and distributes product, is just coming into being. Flow Kana, for instance, is a cannabis brand that takes in marijuana from Northern California farmers and processes and tests it in accordance with the new laws.

Flow Kana workers saw the deadline coming and prepared as best they could. “We have product that has not made its way through our processing system that is still OK," says Cate Powers of Flow Kana. It’ll run the safety gauntlet on its way to market. "So the majority of our inventory is fine. It's only the stuff that was packaged and processed under the previous standards that is at risk."

Dispensaries statewide rushed to offload product with massive sales in the weeks leading up to July 1. But you can only offload so much weed. “Sacramento is seeing possibly up to 8,000 pounds of product that will need to be destroyed,” says Josh Drayton, spokesperson for the California Cannabis Industry Association. In the Los Angeles area—which houses the largest marijuana consumer base in the world—the number could run into the tens of thousands of pounds.

Really, it’s hard to tell for sure just how much cannabis is going to waste. Not all dispensaries have finished the licensing process. It’s not that dispensaries think they can hide off the grid—the transition to legal recreational cannabis is still unfolding. Accordingly, data is hard to come by. That’ll change as the supply chain matures and marijuana is more strictly tracked from seed to sale.

And the waste wasn’t for lack of trying on the cannabis industry’s part. “They've been having to multitask on many different levels,” says Drayton, “to build out business plans in municipalities that are allowing cannabis activities, they've needed to learn new compliance with staffing, with payroll.”

In the end, Californians want legal weed, which is why they voted for Prop 64. What they may not have realized is that the transition from illicit to legal comes with challenges that include the California Marijuanapocalypse of 2018. “We have to remember that, yes, that is going to be a growing pain we are going to have to deal with,” Drayton says. “But ultimately Prop 64 passed through wanting to prioritize public safety and public health.” The alternative is illegal, dirty cannabis that threatens not just people, but wildlife too.

California will get through this. Dispensary inventories might be low in the coming weeks as newly compliant products make their way onto shelves, but the market will even out as the industry adjusts to change. And on top of it all, the state is about to get a healthy helping of extra compost. How very California.

On Christmas Eve 2016, Andrew Seymour, an astronomer at the Arecibo Observatory in Puerto Rico, kissed his 4-year-old daughter, Cora Lee, goodnight, telling her he was off to track Santa. He walked to the well-worn telescope, occasionally passing revelers riding horses through the empty streets—a common sight in Arecibo during the holidays. Sometimes a lonely firework would light up in the distance. Close to midnight, he nodded to a guard and entered the nearly empty complex.

Quanta Magazine

About

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.

The radio dish was on a break from its regular schedule, so Seymour decided to test out new hardware that he and his colleagues had been working on. Soon after he began recording his observations, an extremely powerful radio source, 3 billion light-years away, decided to say hello. Seymour didn’t find Santa that Christmas, but rather an unexpected twist in the tale of one of the most mysterious objects in the cosmos.

The object that Seymour caught that night was the only known repeating fast radio burst (FRB), an ultra-brief flash of energy that flickers on and off at uneven intervals. Astronomers had been debating what might be causing mysterious repeater, officially called FRB 121102 and unofficially the “Spitler burst,” after the astronomer who discovered it.

In the weeks following that Christmas detection, Arecibo registered 15 more bursts from this one source. These flashes were the highest frequency FRBs ever captured at the time, a measurement made possible by the hardware Seymour and his team had just installed. Based on the new information, the scientists have concluded in a study released this week in the journal Nature that whatever object is creating the bursts, it must be in a very odd and extreme cosmic neighborhood, something akin to the environment surrounding a black hole with a mass of more than 10,000 suns.

The new work helps to strengthen the theory that at least some FRBs might be produced by magnetars—highly magnetized, rotating neutron stars, which are the extremely dense remains of massive stars that have gone supernova, said Shami Chatterjee, an astrophysicist at Cornell University. In the case of the repeater, it could be a neutron star “that lives in the environment of a massive black hole,” he said. Or it might also be like nothing we’ve seen before—a different kind of magnetar ensconced in a very intense, magnetically dense birth nebula, unlike any known to exist in our galaxy—“quite extraordinary circumstances,” he said.

Too Extreme to Find

It wasn’t obvious at first that the repeating burst had to live in such an extreme environment. In October, 10 months after Seymour detected that initial burst at Arecibo, Jason Hessels, an astronomer at the University of Amsterdam, and his student Daniele Michilli were staring at the data on Michilli’s laptop screen. They had been trying to determine whether a magnetic field near the source might have twisted its radio waves, an effect known as Faraday rotation. There appeared to be nothing to see.

But then Hessels had an idea: “I wondered whether maybe we had missed this effect simply because it was very extreme.” They had been looking for just a little bit of a twist. What if they were to search for something exceptional? He asked Michilli to crank up the search parameters, “to try crazy numbers,” as Michilli put it. The student expanded the search by a factor of five—a rather “naive thing to do,” Chatterjee said, because such a high value would be completely unprecedented.

When Michilli’s laptop displayed the new data plot, Hessels immediately realized that the radio waves had gone through a hugely powerful magnetic field. “I was shocked to see how extreme the Faraday rotation effect is in this case,” he said. It was like nothing else ever seen in pulsars and magnetars. “I’m also embarrassed because we were sitting on the critical data for months” before attempting such an analysis, he added.

The discovery sent ripples across the community. “I was shocked by the email announcing the result,” said Vicky Kaspi, an astrophysicist at McGill University. “I had to read it multiple times.”

Final confirmation came from a team searching for aliens. The Breakthrough Listen initiative ordinarily uses radio telescopes such as the Green Bank Telescope in West Virginia to scan the skies for signs of extraterrestrial life. Yet “since it’s not obvious in which direction they should point the telescope to search for E.T., they decided to spend some time looking at the repeating FRB, which clearly paid off,” said the astronomer Laura Spitler, namesake of the Spitler burst.

The Green Bank Telescope not only confirmed the Arecibo findings, it also observed several additional bursts from the repeater at even higher frequencies. These bursts also showed the same mad, highly twisted Faraday rotation.

What Powers Them

The extreme Faraday rotation is a signal that “the repeating FRB is in a very special, extreme environment,” Kaspi said. It takes a lot of energy to produce and maintain such highly magnetized conditions. In one hypothesis outlined by the researchers, the energy comes from a nebula around the neutron star itself. In another, it comes from a massive black hole.

In the nebula hypothesis, flares from a newly born neutron star create a nebula of hot electrons and strong magnetic fields. These magnetic fields twist the radio waves coming out of the neutron star. In the black hole model, a neutron star has its radio waves twisted by the enormous magnetic field generated by a nearby massive black hole.

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Researchers haven’t come to an agreement about what’s going on here. Kaspi leans toward the black hole model, but Brian Metzger, an astrophysicist at Columbia University, feels that it’s somewhat contrived. “In our galaxy, only one out of dozens of magnetars resides so close to the central black hole. What makes such black hole-hugging magnetars so special that they would preferentially produce fast radio bursts? Did we just get really lucky with the first well-localized FRB?”

And the debate may get muddier before it gets cleared up. Chatterjee said theorists are certain to soon jump on the paper and start producing a multitude of new models and possibilities.

Burst Machines

The Spitler repeater is still the only FRB source that has been nailed down to a particular galaxy. No one knows quite where the other bursts are coming from. To say with any certainty that some—or all—of these energetic radio flashes come from highly magnetized environments, researchers need more data. And data are coming in. The Australian Square Kilometer Array Pathfinder (ASKAP), which is not yet officially complete, has already netted more FRBs than any other telescope in the world. With a tally of about 10 FRBs last year alone, it has proven to be “a remarkable FRB-finding machine,” said Matthew Bailes, an astrophysicist at Swinburne University of Technology—although none of them repeat.

Soon another telescope with a highly unusual design, called CHIME, will come online in Canada, and should spot many more FRBs—maybe 10 times more than ASKAP. Other next-generation telescopes, like the Square Kilometer Array (SKA), with dishes in South Africa and Australia, will surely contribute as well. As we register more of these flashes, chances are that some of them will repeat. Once scientists can sift through such data, the Faraday rotation effect may help them understand whether all FRBs are powered by a similar mechanism—or not.

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.

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Heredity is a powerful concept. It’s the thing that ties families together—that gives shape to their shared history of stories, of homes, of personalities. And more and more, it’s the way we understand families’ shared genetic inheritance. But that more modern biological notion of heredity comes with some new, technical baggage: It’s easier to talk about the high blood pressure that runs in your family than it is to discern the alleles that define it, all the meiotic divisions that had to occur before that trait was passed down to you. And misunderstanding the role DNA does or doesn’t play in determining one’s fate can have dangerous consequences.

Luckily, acclaimed science writer Carl Zimmer is here to unravel the tangled history of the science and pseudoscience surrounding heredity, in all its many forms. In his expansive, engrossing, and often enlightening new book, She Has Her Mother’s Laugh, Zimmer takes readers on a tale through time and technology, from the inbred Holy Roman Empire to the birthplace of American eugenics to the Japanese lab where scientists are reprogramming skin cells into eggs and sperm. But Zimmer says it’s not a book about genetics. It’s a book about the question genetics was invented to answer. Namely, how did the past become the present, and how will the present shape the future?

Big questions, Zimmer. Now here are a few for you.

WIRED: You argue in this book that it’s time to redefine heredity, to get away from a DNA-centric notion of inheritance, right at a time when people are only just beginning to tap into their own genomes. What gives?

Zimmer: People have been trying to use genetics as a form of identification for a very long time. Of course they didn’t always call it that. DNA is just a modern substitute for the old idea of blood. But in many ways it hasn’t evolved much from the time we thought of ancestry as a pure substance. We still say “I’ve got some Irish blood in me,” but it’s not like you can take out just the Irish blood and fill a cup with it. It’s the same with the bits of DNA in your genome that came from people that once lived in that part of the world. We’re all an amalgam of fragments that have all traveled different paths and each only influences us in very subtle ways.

What we really want from heredity is an explanation of why we are the way we are, and genes alone can’t give us that. There are other things we inherit that matter just as much—like the chemical modifications to our DNA that turn genes on and off or the microbes that abound in our bodies or the human-made environments we’re born into. We literally pass down the whole world to our children, and right now our children are inheriting climate change.

So maybe people should spend less on spit kits and more on carbon offsets…

Look, the reason there’s demand for consumer genetics right now isn’t just because the costs are crashing. It’s also because humans have all these long standing traditions about heredity. On the one hand it’s important to find a connection with our pasts. Especially for people whose families have been severed by things like slavery and genocide. Because, we have to remember that for centuries heredity has been used as a weapon to dehumanize and erase some groups of people. For those people genetic testing can be one the most profound experience of their lives. But consumer genetics can only give you really rough estimates right now. It’s going to get a lot more powerful very quickly, it’s just not there yet.

You got your full genome sequenced a few years ago and uploaded it to a public genealogical database for scientific research. Given the privacy concerns that have emerged since then, particularly around the case of the Golden State Killer, do you ever wonder what kind of consequences it might have for your family?

Well when I first got sequenced I made the decision with my family that I wasn’t going to write about it until after we looked at the results with our genetic counselor. But since there wasn’t much in there to worry about in the end I did wind up posting the genome online along with the analysis, as a teaching tool for researchers. And yes, 50 percent of that DNA is also in my kids but nobody knows which 50 percent. I mean, these are hard questions, I don’t think there’s any one correct answer. I understand people who don’t want to share their DNA at all, and ultimately I think people should have autonomy over their own data. At some point people might be able to do some unpleasant stuff with my genome, but right now it’s mostly astrology. There’s a huge leap to go from sequenced DNA to certainty about what that DNA means. And another huge leap to changing DNA to get an outcome we want. We hardly understand any of it.

Changing DNA? Like with Crispr?

Yes, and other gene-editing tools.

Crispr gets a lot of coverage (including here at WIRED). But as you chronicle in the book, it’s certainly not the first technology that promised to alter the genetic inheritance of future generations of humans. Do you think this time will be different?

No, honestly it doesn’t feel that different. Not to diminish the importance of Crispr; it’s certainly going to be a mainstay for developing medicines and crops going forward, at least until the next better tool comes along. Working on this book I talked to a guy who was able to turn a wild plant into a domestic crop in one shot, a single generation with gene editing. So we are going to start taking control of heredity in really awesome, powerful ways. That being said, we shouldn’t indulge every fantasy and nightmare we might have about fundamentally changing human nature. We just have to look at human history to see how wrongheaded and dangerous that can be.

Consider the following physics problem.

Let's solve this simple problem two different ways. For the first method, I will use Newton's Second Law. In one dimension, I can write this as:

Using this equation, I can get the acceleration of the object (in the x-direction). I'll skip the details, but it should be fairly easy to see that it would have an acceleration of 1 m/s². Next, I need the definition of acceleration (in the x-direction). Oh, and just to be clear—I'm trying to be careful about these equations since they are inherently vector equations.

With a starting velocity of 1 m/s and an acceleration of 1 m/s² for 1 second, the final velocity (in the x-direction) would be 2 m/s. Great, right?

Now for the second method—using the momentum principle. This says that a net force changes the momentum of an object. The one dimensional momentum is the product of the object's mass and velocity (at least for speeds much slower than the speed of light).

The momentum principle can then be written as the following equation.

The initial momentum of the object is 1 kilogram-meter/second and with a force of 1 N for 1 sec, the final momentum is 2 kg*m/s. Dividing this momentum by the mass gives a final x-velocity of 2 m/s. The same as before.

OK, now you have a basic feeling for the momentum principle and Newton's 2^nd Law. Which method is better? Great question. Let me go over some of the key things to consider.

The Momentum Principle Works at High Speeds

I mean really high speeds. Not fast like a bullet, but fast like a cosmic particle that comes crashing into our atmosphere fast. If you want to model the forces on a particle moving near the speed of light (3 x 10⁸ m/s), then the plain version of Newton's 2^nd Law doesn't work. However, the momentum principle still works if you use a better definition of momentum. Instead of just the product of mass and velocity, momentum can be defined as:

In this expression, the c represents the speed of light. The cool thing is that this definition of momentum also works for super slow objects (like a rocket). If the velocity of the object is much smaller than the speed of light, all that stuff on the bottom in the expression is approximately equal to 1 and you get the previous definition of momentum.

Momentum Is a Conserved Quantity

In physics, we like to calculate things that are conserved. A conserved quantity is something that stays the same in a system if there are no external interactions. Yes, momentum is one of these quantities. If you have a system consisting of multiple particles that only interact with other particles in the system then the total vector momentum of this system is constant. Yes, it's a big deal.

In the introductory physics course, there are two other conserved quantities that we look at—the angular momentum and energy. So, by focusing on the momentum principle instead of Newton's 2^nd Law it emphasizes conserved quantities. I think that's a good thing.

Newton's Laws Are About Aristotle

Yes, Aristotle—you know, that Greek philosopher. If you like, you can think about Newton's Laws of motion as a response to the other common idea of motion—Aristotle's Laws of motion. Aristotle basically said that forces and motion worked like this:

• The natural state of an object is to remain at rest.
• If you push on an object with a constant force, it moves at a constant speed.
• If you stop pushing on an object, it will stop moving.

Newton's 1^st law says that the natural state of an object is to be at a constant velocity and the second law states that there is a relationship between the net force and the acceleration of an object. So, in a sense these are a response to Aristotle. With that being said, perhaps it's better to just skip the whole Aristotle thing. Oh, sure—many people still have the same ideas about force and motion that Aristotle had, but I like just starting over from scratch and using the momentum principle instead.

What's Wrong with the Momentum Principle

There is a problem with the momentum principle—it's not all unicorn dust and rainbows. The first problem is that of communication. A colleague recently pointed out that when someone uses the momentum principle, it's clear that person has used the textbook Matter and Interactions (Chabay and Sherwood published by Wiley). I've previously explained why I like this textbook so much, but one of the big differences is the use of the momentum principle.

By using the momentum principle for cases that could also be modeled with Newton's 2^nd law, we add a new set of vocabulary and terminology. If you aren't used to talking about physics in this way, it can sort of make other feel like it's a different language. Of course, it's not really that different—but initial impressions can make a big difference. This is especially true for people just learning about forces and motion. So, in a way you could say that using the momentum principle is like taking a step backwards when you are trying to explain some cool idea.

But still, in the end these two methods are essentially the same thing.