Carl Sagan, nuclear winter, and the “climate wars”

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When Carl Sagan Warned the World About Nuclear Winter

Before the official report came out, the popular scientist took to the presses to paint a dire picture of what nuclear war might look like

For Smithsonian Magazine:

If you were one of the more than 10 million Americans receiving Parade magazine on October 30, 1983, you would have been confronted with a harrowing scenario. The Sunday news supplement’s front cover featured an image of the world half-covered in gray shadows, dotted with white snow. Alongside this scene of devastation were the words: “Would nuclear war be the end of the world?”

This article marked the public’s introduction to a concept that would drastically change the debate over nuclear war: “nuclear winter.” The story detailed the previously unexpected consequences of nuclear war: prolonged dust and smoke, a precipitous drop in Earth’s temperatures and widespread failure of crops, leading to deadly famine. “In a nuclear ‘exchange,’ more than a billion people would instantly be killed,” read the cover. “But the long-term consequences could be much worse…”

According to the article, it wouldn’t take both major nuclear powers firing all their weapons to create a nuclear winter. Even a smaller-scale war could destroy humanity as we know it. “We have placed our civilization and our species in jeopardy,” the author concluded. “Fortunately, it is not yet too late. We can safeguard the planetary civilization and the human family if we so choose. There is no more important or more urgent issue.”

The article was frightening enough. But it was the author who brought authority and seriousness to the doomsday scenario: Carl Sagan.

Read the rest at Smithsonian.com…

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Why the death of black holes is a big problem for physics

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Part 4 of my 4-part series on black holes for Medium members is up; part 1 is herepart 2 is here, and part 3 is here. If enough of you read, they may keep me around to write more, so please read and share! And yes, the title is a John Donne reference, because I was an English minor and am required to make literary references as often as I can get away with.

Gravity Be Not Proud

The discovery that black holes emit particles and might eventually evaporate threw theoretical physics into chaos. Here’s why.

For Medium:

Hawking ended up being one of the very rare ALS patients to survive the condition, at the eventual cost of being confined to a wheelchair and communicating primarily through a computer. And his work on black holes — along with the work of a small handful of other physicists — opened up a new field of research in quantum gravity.

The most shocking discovery to come out of Hawking’s work: Black holes can emit radiation and can eventually evaporate.

Unfortunately for physicists, the radiation from a real black hole is too faint to be seen, and even a smaller black hole, like the ones seen by LIGO, would take a mind-blowingly long time to evaporate. However, the prediction of this Hawking radiation and death of black holes exposed a major problem in theoretical physics, one that is still unsolved today.

Read the rest at Medium…

Doing astronomy using gravity

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Astronomy without light

Gravitational waves let us see the invisible universe in new ways

For Astronomy Magazine:

Humans have always practiced some form of astronomy. For thousands of years, that meant observing only the light our eyes could see — either unaided or with a variety of instruments, such as astrolabes or telescopes. The 20th century brought new types of telescopes, which detect light we can’t see: infrared, X-ray, and so on.

Today, we’re witnessing the genesis of a whole new type of astronomy, and this one doesn’t use light at all. It uses gravitational waves.

Read the rest at Astronomy Magazine

Guardians of the Galaxy…er, black holes vol. 3

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Part 3 of my 4-part series on black holes for Medium members is up; part 1 is here and part 2 is here. If enough of you read, they may keep me around to write more, so please read and share!

Seeing the Invisible

Black holes are invisible, but astronomers have developed a lot of ways to see them through the matter that surrounds them

No Rocket Raccoon, but my latest does have a guy named Grote. [Credit: National Radio Astronomy Observatory/moi]

For Medium:

In 1937, a deeply weird engineer named Grote Reber built a telescope in the lot next to his mother’s house in Wheaton, Illinois. Home observatories aren’t unusual, but Reber’s project was the first telescope designed to look for radio waves from space, and he was only the second person in history to find them. Karl Jansky, the first radio astronomer, had accidentally discovered astronomical radio waves while working on shortwave radio communications.

But Reber set out deliberately to study the cosmos in radio light. He found that the center of the Milky Way emitted a lot of radio waves and discovered an intense radio source in the constellation Cygnus. By the 1950s, astronomers found many other radio galaxies (as they were creatively named) that emitted very powerful radio waves from small regions at the centers of those galaxies.

As we learned in Part 2 of this series, the sources of the radio waves in the Milky Way and beyond turned out to be supermassive black holes: powerful gravitational dynamos millions or billions of times the mass of our sun. As with Reber’s discoveries, the study of black holes has been driven by invention and creativity. In fact, every new advance in astronomy has led to new discoveries about black holes, and new technologies are being invented for the purpose of studying these weird objects.

Read the rest at Medium…

The Care and Feeding of Black Holes

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Part 2 of my 4-part series on black holes for Medium members is up; you can read part 1 here. If enough of you read, they may keep me around to write more, so please read and share!

The Care and Feeding of Black Holes

How intrinsically invisible objects become the brightest things in the universe

For Medium:

In the late 1950s, astronomers began spotting a number of bright sources of radio waves and visible light. These sources were pinpoints resembling blue stars, but further investigation showed they had to be something very different. For one thing, these quasi-stellar objects, as they were known then, were extraordinarily distant, much farther than any single star would be visible.

The spectra of these new quasi-stellar objects, or quasars, as physicist Hong-Yee Chiu abbreviated their name in 1964, showed they were emitting light through a completely different mechanism than starlight. The quantity of light quasars emitted to be visible across the universe meant they had to be driven by gravity.

Based on the data, astronomers concluded that each quasar was powered by a black hole millions or billions of times the mass of our sun. These supermassive black holes pull huge amounts of matter onto themselves, accelerating it until it glows very brightly. Additionally, the black hole jets a lot of matter away from itself rather than eating it, and those jets also glow intensely. These processes turn the ordinarily invisible black hole into something bright enough to see from billions of light-years away, outshining whole galaxies.

[read the read at Medium…]

My new series on black holes!

[ This blog is dedicated to tracking my most recent publications. Subscribe to the feed to keep up with all the science stories I write! ]

I’ve just started a new series on black holes for Medium members. The first part is available now, with three more parts to come. And if enough of you read, they may keep me around to write more, so please read and share!

Exploring Black Holes: Frozen Stars and Gravitational Dynamos

Black holes are gravitational superheroes. Here is their origin story, including World War I, magnificent mustaches, and Albert Einstein

For Medium:

February 11, 2016, was a landmark day. After many decades of searching, scientists announced they had detected gravitational waves for the first time: disturbances in the structure of space-time that travel at light speed. But there was a second triumph of physics hiding inside that one. The waves gave us the best evidence so far for the existence of some of the most fascinating objects in our universe: black holes.
Few scientists these days doubt that black holes exist. But in a way, all our evidence for them is circumstantial. Black holes, by their very nature, are difficult to observe. All light falling on them is absorbed, rendering them nearly invisible.
On the other hand, black holes are the strongest gravitational powerhouses possible. When they strip matter off stars or out of interstellar gas clouds, that material heats up and shines brightly. It’s a seeming paradox: invisible objects that end up being some of the brightest things in the universe. The black holes known as quasars can be seen billions of light-years away. [read the rest at Medium…]

City ant, country ant, and climate change

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Acorn ants as seen through a microscope. [Credit: moi]

I know, I know: it’s been a long time since I last had something published. This is largely because I took a little time off to finish my novel. With the first draft done, I needed to catch up. As a result, I have six or seven (depending on how you count) articles that are finished, but which won’t be published immediately. Anyway, here’s the first of those, published today:

What City Ants Can Teach Us About Species Evolution And Climate Change

Is the rapid evolution of a certain ant species to urban environments a preview of life on a warming planet? Some researchers are trying to find out.

For Undark Magazine:

Acorn ants are tiny. They’re not the ants you’d notice marching across your kitchen or swarming around sidewalk cracks, but the species is common across eastern North America. In particular, acorn ants live anywhere you find oak or hickory trees: both in forests and in the hearts of cities.

That’s why they’re so interesting to Sarah Diamond, a biology professor at Case Western Reserve University in Cleveland. “We’re comparing this little forest island within a city to traditional forest habitats,” she says. Specifically, she and her colleagues are looking at how well city ants can tolerate higher temperatures compared to their rural cousins. The experiment is made possible by what’s known as the urban heat island effect, which describes the tendency of the built-up infrastructure of cities — think heat-absorbing concrete and asphalt, for example — to create a hotter environment than less developed areas. [read the rest at Undark Magazine]