The Great, Belching Black Hole — Eats Gas, Burps X-rays

Was Einstein smarter than a sixth-grader? When it came to black holes, maybe not. For much of the 20^th century, astronomers and physicists were unsure about whether black holes — which were predicted by Einstein’s General Relativity Theory — even existed.  That was a fair enough doubt, since the idea of a superdense star remnant with a gravity field so powerful not even light could escape it did defy credibility. Even Einstein himself thought they were just a mathematical curiosity that couldn’t possibly exist in the real universe.

Today, every schoolchild knows better. Astronomers have found giant black holes lurking at the cores of galaxies, the Milky Way among them, and more modest black holes all over the place, including up to 60 in our home galaxy. Now, that cosmic census has expanded dramatically: using the orbiting Chandra X-Ray Observatory, astronomers have spotted 26 of the more modest variety of black hole in the Andromeda galaxy, which is not only the Milky Way’s closest neighbor, but also its near twin.

Along with nine black holes detected previously, that brings Andromeda’s total to 35. If that many are detectable, says Harvard astronomer Robin Barnard, lead author of a report on the new objects in The Astrophysical Journal, “we know there must be lots we can’t detect — maybe tens of thousands, maybe more.”

The reason: a star-size black hole like the ones Barnard and his colleagues found can be detected only if it’s gulping down gas, and that’s relatively rare. It only happens, in fact, when the black hole orbits an ordinary star and dines on its outer atmosphere. As it does, the gas heats up to millions of degrees as it tries to cram its way down the black hole’s voracious gravitational throat, and in so doing emits bursts of X-rays—sort of giant, electromagnetic burps.

In the handful of cases in which that’s happening, Chandra can easily spot a star’s digestive blast. “If you look at the central region of Andromeda in visible light,” says Barnard, “you see a huge mass of stars — billions upon billions of them.” If you look with Chandra, though you see just a few hundred bright dots — the ones emitting x-rays.

Some of those emissions are actually not produced in Andromeda, but rather, come from the giant, gas-sucking black holes at the cores of other galaxies which just happen to lie in the background, but much, much farther away. “These background galaxies are incredibly bright,” says Barnard, but they’re easy to identify because their X-ray light varies up and down relatively slowly as their gas supply waxes and wanes, a pattern different from that produced by the smaller black holes in Andromeda itself.

Other dots of X-ray brightness come from stars in Andromeda that orbit neutron stars, the dense remnants of dead stars that aren’t quite massive enough to collapse into black holes. These pull gas from companion stars as well, and while the gas merely collides with their surfaces, that impact heats it up enough to produce X-rays too. The difference, says Barnard, is that the mix of X-ray “colors,” or wavelengths, is quite different from those generated by black holes.

Once you weed out the X-rays from background galaxies and from neutron stars, says Barnard, what’s left is black holes, ranging from five to ten times the mass of the Sun. Getting a perfectly clear picture might, in theory, require the astronomers to weed out emissions from the giant black hole at Andromeda’s core too. Unlike those in the background galaxies Chandra sees, however, Andromeda’s black hole, says, Barnard, is “wimpy. It’s ten to a hundred times fainter than the small black holes we can see, even though it’s a million times more massive.” That’s because there doesn’t happen to be a lot of gas available for swallowing these days — which is the case for the Milky Way and most nearby galaxies as well, although that could change before too long, thanks to an interstellar gas cloud spotted in 2011 that’s hurtling toward our galactic center and could arrive in September or October. (Astronomers expect some x-ray fireworks, but little more.)

There’s actually one more class of black holes that physicists have speculated about: teeny tiny ones, smaller than an atom, which might have formed in the intense turbulence of the first moments of the Big Bang. These probably would long since have vanished, although there was some speculation that new ones mightemerge from the Large Hadron Collider atom-smasher in Europe.

That would have been a triumph for science — but since it could in theory have destroyed the Earth, it’s just as well that it didn’t happen.

We Still Need Information Stored in Our Heads Not “in the Cloud”

Is technology making us stupid—or smarter than we’ve ever been? Author Nicholas Carr memorably made the case for the former in his 2010 book The Shallows: What The Internet Is Doing To Our Brains. This fall we’ll have a rejoinder of sorts from writer Clive Thompson, with his book Smarter Than You Think: How Technology Is Changing Our Minds For The Better.

My own take: technology can make us smarter or stupider, and we need to develop a set of principles to guide our everyday behavior and make sure that tech is improving and not impeding our mental processes. One of the big questions being debated today is, What kind of information do we need to have stored in our heads, and what kind can we leave “in the cloud,” to be accessed as necessary?

In 2005, researchers at the University of Connecticut asked a group of seventh graders to read a website full of information about the Pacific Northwest Tree Octopus, or Octopus paxarbolis. The Web page described the creature’s mating rituals, preferred diet, and leafy habitat in precise detail. Applying an analytical model they’d learned, the students evaluated the trustworthiness of the site and the information it offered.

Their judgment? The tree octopus was legit. All but one of the pupils rated the website as “very credible.” The headline of the university’s press release read, “Researchers Find Kids Need Better Online Academic Skills,” and it quoted Don Leu, professor of education at UConn and co-director of its New Literacies Research Lab, lamenting that classroom instruction in online reading is “woefully lacking.”

There’s something wrong with this picture, and it’s not just that the arboreal octopus is, of course, a fiction, presented by Leu and his colleagues to probe their subjects’ Internet savvy. The other fable here is the notion that the main thing these kids need—what all our kids really need—is to learn online skills in school. It would seem clear that what Leu’s seventh graders really require is knowledge: some basic familiarity with the biology of sea-dwelling creatures that would have tipped them off that the website was a whopper (say, when it explained that the tree octopus’s natural predator is the sasquatch).

But that’s not how an increasingly powerful faction within education sees the matter. They are the champions of “new literacies”—or “21st century skills” or “digital literacy” or a number of other faddish-sounding concepts. In their view, skills trump knowledge, developing “literacies” is more important than learning mere content, and all facts are now Google-able and therefore unworthy of committing to memory. But even the most sophisticated digital literacy skills won’t help students and workers navigate the world if they don’t have a broad base of knowledge about how the world actually operates. “When we fill our classrooms with technology and emphasize these new ‘literacies,’ we feel like we’re reinventing schools to be more relevant,” says Robert Pondiscio, executive director of the nonprofit organization CitizenshipFirst (and a former fifth-grade teacher.) “But if you focus on the delivery mechanism and not the content, you’re doing kids a disservice.”

Indeed, evidence from cognitive science challenges the notion that skills can exist independent of factual knowledge. Dan Willingham, a professor of psychology at the University of Virginia, is a leading expert on how students learn. “Data from the last thirty years leads to a conclusion that is not scientifically challengeable: thinking well requires knowing facts, and that’s true not only because you need something to think about,” Willingham has written. “The very processes that teachers care about most—critical thinking processes such as reasoning and problem solving—are intimately intertwined with factual knowledge that is stored in long-term memory (not just found in the environment).”

In other words, just because you can Google the date of Black Tuesday doesn’t mean you understand why the Great Depression happened or how it compares to our recent economic slump. There is no doubt that the students of today, and the workers of tomorrow, will need to innovate, collaborate and evaluate, to name three of the “21st century skills” so dear to digital literacy enthusiasts. But such skills can’t be separated from the knowledge that gives rise to them. To innovate, you have to know what came before. To collaborate, you have to contribute knowledge to the joint venture. And to evaluate, you have to compare new information against knowledge you’ve already mastered.

So here’s a principle for thinking in a digital world, in two parts: First, acquire a base of fact knowledge in any domain in which you want to perform well. This base supplies the essential foundation for building skills, and it can’t be outsourced to a search engine.

Second: Take advantage of computers’ invariant memory, but also the brain’s elaborative memory. Computers are great when you want to store information that shouldn’t change—say, the date and time of that appointment next week. A computer (unlike your brain, or mine) won’t misremember the time of the appointment as 3 PM instead of 2 PM. But brains are the superior choice when you want information to change, in interesting and useful ways: to connect up with other facts and ideas, to acquire successive layers of meaning, to steep for a while in your accumulated knowledge and experience and so produce a richer mental brew.

The Space Sorority: Fifty Years of Women in Orbit

The first man on the moon was a character in popular culture decades—even centuries, perhaps—before Neil Armstrong actually filled the role. The assumption was that humanity would reach the moon someday, and it was simply  a given that the first historic step would indeed be taken by a man. “This country should commit itself, before this decade is out,” President Kennedy declared in 1961, “to landing a man on the moon and returning him safely to the Earth.” There was no need for the gender-neutral “landing a person on the moon,” no clumsy “and returning him or her safely to the Earth.” Astronauts were supposed to be men and they jolly well would be.

But only until they weren’t. The boys-only rule ended fast, just two years later, when the Soviet Union sent Valentina Tereshkova into orbit for a flight that lasted just minutes shy of three full days. The 50th anniversary of that journey is June 16th, and in the half century since Tereshkova’s flight, 57 other women have strapped in and blasted off, representing nine different countries—most recently China. The U.S. did not join the space sorority until 1983, when Sally Ride flew, but America made up for that dallying, sending a total of 45 women into space since then. They have faced the same challenges as the men, experienced the same thrills as the men and, on occasion, paid the same price as the men. Four women—Christa McAulliffe, Judith Resnik, Laurel Clark, and Kalpana Chawla—died in the Challenger and Columbia disasters.

The U.S. space program is now in a state of drift, with no American vehicle currently capable of carrying human beings to space, and NASA thus dependent on the Russians to ferry our crews up to the International Space Station—at a cost of $70 million per seat. But China—as in so many other things—is a rising power in space and on June 11, sent its second female astronaut, Wang Yaping, into orbit on what is just the country’s fifth crewed mission. She was preceded last year by Liu Yang.

There was less global hoopla when Yang flew than when Rice did, and much less than when Tereshkova did. The fact that human beings travel in space continues to be—and should be—something that delights and even surprises us. The fact that women are among those explorers is, at last, becoming routine.