November 17, 2023: A behind-the-scenes tour of a facility making new nuclear weapons, a nanoscale bulldozer and neurological medical care for transgender people. —Robin Lloyd, Contributing Editor | | | The U.S. is modernizing its nuclear arsenal, making upgrades to old weapons and building new ones, Scientific American reports in an article that is part of " The New Nuclear Age," a special report on a $1.5-trillion effort to remake the American nuclear arsenal. The effort includes building 30 new plutonium pits a year at Los Alamos National Laboratory in New Mexico, the birthplace of the bomb. Pits are fire-resistant metal hollows, typically about the size of a bowling ball, containing a nuclear weapon's core—fissile material such as highly enriched uranium and plutonium. The details of how the pits are made and how they work are among America's most closely guarded secrets. Yet in June 2023 Los Alamos officials invited a group of journalists to tour the facility for the first time in years. Scientific American sent science journalist Sarah Scoles.
The tension: Not everyone believes this new weapons work is necessary. Pit production foments controversy because it's costly and potentially risky, and because the existing pits might still work for a while. The physics of plutonium is complex, and no one knows when the original pits will expire.
The takeaway: China is rapidly growing its nuclear arsenal, and Russia, at war with Ukraine, touts new missile tests and its own nuclear modernization. The U.S. is doing the same. The renewed focus on nuclear weapons threatens to create a 21st-century arms race and an increased reliance on the shaky peace that nuclear weapons may or may not help keep. | | | A mockup of a plutonium pit is shown at Los Alamos National Laboratory in the 1940s, where Manhattan Project scientists were developing the first nuclear weapons. Credit: Los Alamos National Laboratory | | | A team of researchers has discovered that a heart-shaped molecule will jump in straight lines when given an electric jolt. The hopping hearts are an entirely new kind of molecular nanomotor—a tiny machine that expends energy to move purposefully against the entropic tides that constantly pull the small-scale world into random, useless motion. When excited with an electrified microscope tip, the heart-shaped ditolyl-ATI molecules jump—but they don't hop around willy-nilly, chemist Grant Simpson inadvertently figured out earlier this year. "Somehow," he says, "I'd come to the realization, slowly, that they're only moving in one direction."
Why this matters: Some human-made nanomotors can spin in place, but few can reliably move from point A to point B. The mechanical magic of the new motor comes from the interaction between the molecule and the copper surface it moves along—as if a train engine had parts both in the car and embedded in the track below.
The upshot: The new nanomotor is a small but significant step toward the dream of a nanotechnology that can build things nature's way: bottom-up, atom by atom. Researchers developing miniature machines imagine using them to create novel materials, to supercharge industrial catalysis and to manipulate biological tissues with the agility of real enzymes. | | | Visuals from Noisy Text Image-generating AI that had once been offered only to specialists is now available to anyone with a web connection. The most popular of today's image generators use a technique called a diffusion model, which is relatively new on the AI scene. Read this graphic-filled story to learn about the model and how DALL-E 2, Midjourney and Stable Diffusion became so good all at once. | | | • Migraine, stroke and epilepsy disproportionately affect members of the transgender community, but neurologists are often unprepared to respond, writes Z Paige L'Erario, a board-certified neurologist and transgender activist. Scientific research in the past decade has demonstrated that being transgender can have a lot to do with the health of the brain and the rest of the nervous system. A complex interplay of factors is involved, including stress and discrimination as well as the nuanced effects of hormonal medications that many transgender people use as part of their medical transition process. Simply put, transgender people have both distinct risks and treatment needs that the neurological community needs to better understand, L'Erario concludes. | 5 min read | | | ICYMI (Our most-read stories of the week) | • Who would take the brunt of an attack on U.S. nuclear missile silos. | 8 min read | • A flawed way of diagnosing dyslexia leaves thousands of kids without help. | 15 min read | • Understanding consciousness is key to unlocking the secrets of the universe. | 3 min read | | | • As AI-generated content fills the Internet, it is corrupting the training data for models to come. What happens when AI eats itself? | 2 min listen/watch | | | Your dedicated chief newsletter editor Andrea Gawrylewski is set to return on Monday. Thanks for reading my awkward imitations in her absence. I leave you with this bit of mental provocation: So-called psychedelic drugs such as LSD and psilocybin (a chemical found in "magic mushrooms") show enough promise as a treatment for PTSD and depression that scientists are designing ones that are non-hallucinogenic, according to this story. The reason: some neuroscientists now suspect that the drugs' mental-health benefits don't come from tripping. If this topic intrigues you, check out science journalist Jane C. Hu's free newsletter "The Microdose." I heard Hu speak this week, along with health and fitness journalist Michael Easter, at an event at NYU. Easter's newsletter, "The 2%," is a fun journey through optimizing one's mindset, nutrition and especially exercise. He is particularly enthusiastic about rucking—walking for a distance while wearing a heavy backpack. Happy trails!
| —Robin Lloyd, Contributing Editor | | Subscribe to this and all of our newsletters . | | | | Scientific American
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