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

Star Trek, quantum mechanics, and the meaning of being human (kinda)

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The trouble with teleportation

A panel from “The trouble with teleportation”, featuring me as a science officer. [Credit: Maki Naro (art), moi (words)]

Quantum teleportation is a really fascinating area of research, but it’s hampered by the name, which evokes Star Trek. The reality is trickier, and why a Star Trek-style transporter may never be possible is an interesting question in and of itself. Comics genius Maki Naro and I created a comics explainer going into what teleportation is and isn’t, with plenty of Star Trek to keep us all going.

Why physicists hate time

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Wait a second: What came before the big bang?

Not everyone thinks the universe had a beginning.

This story originally appeared in the print edition of the September issue of Popular Science. This week, it appeared online with enhanced graphics. The text is by PopSci editor Rachel Feltman and me; the art is by Matei Apostolescu.

Cosmologists used to think the universe was totally timeless: no beginning, no end. That might sound mind-melting, but it’s easier on the scientific brain than figuring out what a set starting point would mean, let alone when it would be. So some physicists have cooked up alternative cosmological theories that make time’s role seem a little less important. The concepts are as trippy as those black-light posters you had in college.

[read the rest at Popular Science]

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

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

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…

How physics and biology work together to understand cell organization

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Cells get organized

How researchers probe the physics of motion, communication and organization in cell networks, and how understanding these systems could help us tackle serious issues in medicine and biology

self-organized bacterial community

A colony of bacteria organize with each other under certain conditions to maximize nutrient intake. [Credit: Eshel Ben-Jacob]

From Physics World:

Consider this scenario: in your haste to grab the latest issue of Physics World, you scrape your hand on your postbox. It’s nothing severe, just a little scratch, but if your immune system is functioning as it should, your body will perform an amazing feat of microscopic organization. Your body assesses the level of damage and threat from infection, sending security cells to the site to hoover up intrusive bacteria and seal the wound. Within a few days you’d hardly know the scrape was ever there: your skin and blood vessels repair themselves.

Except of course there’s no mind behind this repair. Your brain isn’t required to heal a wound: there’s no local oversight from any intelligent agent, and the cells involved don’t think. Instead, cells interact with their neighbours, and a larger pattern emerges from those small-scale interactions. That’s the key to “self-organization”, whether it occurs in the human immune system, swarms of locusts, water molecules in a snowflake or electrons in a magnetic material.

For that reason, researchers studying biological self-organization draw heavily on physics. Some directly investigate the physical interactions between cells and their environments; others use theoretical models drawn or adapted from physics to understand emergent behaviours in biological systems. It’s an interdisciplinary field, involving physicists, computer scientists, biologists, mathematicians and medical doctors.

The rest of this story is in the print edition of Physics World, which you can subscribe to through membership in the Institute of Physics, which costs £15, €20, or $25 per year. You can join by clicking here. You can also get a nice mobile- and tablet-formatted version of the story using the Physics World app, available in the Google Play and iTunes stores. However, if you just want to read the rest of this article, Physics World has kindly allowed me to offer it to you as a PDF download, which looks exactly like the printed version!