This is an edition of The Atlantic Daily, a newsletter that guides you through the biggest stories of the day, helps you discover new ideas, and recommends the best in culture. Sign up for it here.Both Donald Trump and Ron DeSantis have signaled their willingness to sell out Ukraine to the Kremlin, and the Russians have gleefully taken notice. How could this be happening in the party of Ronald Reagan?But first, here are three new stories from The Atlantic.

Updated at 1:40 a.m. ET on March 17, 2023For three years now, the debate over the origins of the coronavirus pandemic has ping-ponged between two big ideas: that SARS-CoV-2 spilled into human populations directly from a wild-animal source, and that the pathogen leaked from a lab.

GPT-4 is here, and you’ve probably heard a good bit about it already. It’s a smarter, faster, more powerful engine for AI programs such as ChatGPT. It can turn a hand-sketched design into a functional website and help with your taxes. It got a 5 on the AP Art History test. There were already fears about AI coming for white-collar work, disrupting education, and so much else, and there was some healthy skepticism about those fears.

On a warm, windy fall night in Los Angeles, I stood in a conference room at the Warner Bros. Discovery television-production offices, straightened my spine, and stared down my showrunner, preparing to defend my idea for a minor character in our near-future science-fiction series.“This character needs a backstory, and switching jobs because she wants to work in renewable energy and not for an oil company fits perfectly,” I told the unsmiling head honcho.

This is an edition of The Atlantic Daily, a newsletter that guides you through the biggest stories of the day, helps you discover new ideas, and recommends the best in culture. Sign up for it here.Yesterday, not four months after unveiling the text-generating AI ChatGPT, OpenAI launched its latest marvel of machine learning: GPT-4. The new large-language model (LLM) aces select standardized tests, works across languages, and can even detect the contents of images.

This is an edition of Up for Debate, a newsletter by Conor Friedersdorf. On Wednesdays, he rounds up timely conversations and solicits reader responses to one thought-provoking question. Later, he publishes some thoughtful replies. Sign up for the newsletter here.Question of the WeekI was overwhelmed by your responses to last week’s question on cars! So for now, I’m going to hold off on a new question and promise to send out your excellent thoughts in the next newsletter.

Bad things happen to a human body in zero gravity. Just look at what happens to astronauts who spend time in orbit: Bones disintegrate. Muscles weaken. So does immunity. “When you go up into space,” says Saïd Mekari, who studies exercise physiology at the University of Sherbrooke, in Canada, “it’s an accelerated model of aging.” Earthbound experiments mimicking weightlessness have revealed similar effects.

This article was featured in One Story to Read Today, a newsletter in which our editors recommend a single must-read from The Atlantic, Monday through Friday. Sign up for it here.      Growing up in a strict household, I was taught to honor etiquette; I still call my elders “sir” and “ma’am,” and I always say thank you. But I almost never use the word please.

In the 40 years since Heartburn was published, there have been two distinct ways to read it. Nora Ephron’s 1983 novel is narrated by a food writer, Rachel Samstat, who discovers that her esteemed journalist husband is having an affair with Thelma Rice, “a fairly tall person with a neck as long as an arm and a nose as long as a thumb and you should see her legs, never mind her feet, which are sort of splayed.