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Lightning can start nuclear reactions in the sky

Lightning. Photo: 4FR / iStock

Lightning can create fusion reactions in the air around it, according to research published today in the journal Nature. Nuclear reactions were thought to occur in some thunderstorms but the study provides the first conclusive evidence they are happening.

Why it matters: It's unclear how thunderstorms and lightning work. "How lightning initiates inside thunderstorms is a complete mystery, and how lightning initially moves inside the storms is not at all clear," lightning expert Joseph Dwyer from the University of New Hampshire tells Axios in an email. He says figuring out how some thunderstorms emit huge gamma-ray flashes thought to trigger the reactions "might tell us something interesting about what's going on inside the storms."

The question: It seems theoretically impossible for lightning to produce nuclear fusion reactions because the fuel for the reactions — a form of hydrogen called deuterium — isn't available in large enough amounts in the atmosphere. The 50,000°F temperature of lightning is also a lot cooler than the 30,000,000°F near the center of the Sun where nuclear fusion occurs. Yet scientists have observed by-products of these reactions being produced from lightning.

How it works: Lightning can emit high-energy bursts known as gamma-ray flashes. (How and when they occur — they are associated with a small fraction of lightning seen around the world each day — is a mystery itself.) The flashes are energetic enough to knock neutrons out of the nuclei of nitrogen and oxygen in the air, creating radioactive versions of them for a short time.

Researchers have seen signatures of neutrons being formed just after a lightning flash before. The new paper reports a second such observation on February 6, 2017 Japan along with detection of the radioactive nitrogen and oxygen produced when neutrons are removed from their nuclei.

"It leaves no possible doubt as to what's going on, and it's a beautiful and thorough analysis," says David Smith, a physicist at the University of California Santa Cruz who studies gamma-rays produced by lightning and wasn't involved in the research.

What's next: The gamma-ray flashes themselves were too bright for the researchers' instruments to record. Dwyer says having better instrumentation in places where there are lots of thunderstorms and on aircraft flying near storms would be a very important next step to confirm the bursts start the reactions.

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The worst flu season in eight years

Note: Activity levels are based on outpatient visits in a state compared to the average number of visits that occur during weeks with little or no flu virus circulation; Data: Centers for Disease Control and Prevention; Chart: Chris Canipe/Axios

This year's flu season caught many experts off guard with both its sustained prevalence and its virulence. At its peak, there was a higher level of flu-like illnesses reported than any other year during the past eight years. Watch in the visual as it hits its peak around Week 18.

Why it matters: Public health officials try to capture this data when developing the next year's vaccines. And, of course, they want to find better ways to prevent severe flu seasons. There's a "Strategic Plan" to develop a universal vaccine to protect against a wider range of influenza viruses, Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, tells Axios.

Steve LeVine 18 hours ago
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The stakes for who wins the AI race

A sentient computer saying 'Hello World' in English, Chinese and Russian.
Illustration: Lazaro Gamio/Axios

One of the most urgent themes in technology is the global rivalry for dominance of the evolving sector of artificial intelligence — geopolitical and economic supremacy is said to be at stake. Experts view the U.S. and China as the top contenders, but other nations, including Russia, are working on AI, too.

What it means: In its latest edition, the Economist draws a sharp line as to the extraordinary ramifications of the race. "The global spread of a technosystem conceived in, and to an unknown extent controlled by, an undemocratic, authoritarian regime could have unprecedented historical significance," the magazine wrote.