Stars and galaxies make up much of the universe’s ordinary, observable matter. But for decades, scientists have wrestled with a cosmic conflict: There should be much more.

Physicists have good estimates of how much matter was present in the early universe. Shortly after the Big Bang, roughly 83% of all matter in the universe was composed of invisible dark matter, with ordinary matter making up the rest...

The immune system, the body’s defense network against infections and injuries, can sometimes become too active. In these cases, it can produce too many immune mediators, fragments of genetic material or proteins that regulate immune responses.

An excess of these molecules in the bloodstream can cause severe inflammation, sometimes leading to life-threatening medical conditions such as sepsis and acute lung injury. Sepsis is an extreme and life-threatening response to a bacterial, viral or fungal infection...

Large language models (LLMs), the computational algorithms underpinning ChatGPT, Gemini and other artificial intelligence (AI)-powered conversational platforms, are now widely used worldwide. These models can rapidly answer questions, source information online, assist users with specific tasks and produce text tailored for specific purposes.

Over the past few years, computer scientists have introduced a wide range of LLMs, some of which can also complete tasks autonomously and take actions on a user’s behalf, for instance, answering messages, scheduling online appointments or updating programming code...

Scientists have developed a new way to predict the strength of the sun’s next activity cycle up to seven years before it reaches its peak.

The new method uses the number of sunspots at a newly identified “switchoff” point in the solar cycle, when the sun’s most extreme space weather suddenly comes to an end. Using this approach, researchers have made an early prediction for the strength of Solar Cycle 26.

A very early prediction shows a moderate Cycle 26 with a sunspot number of around 100–120, s...