Muscles move because of four things working together: electricity, calcium, proteins and energy. Each muscle is a bundle of long fibers, and inside every fiber millions of myosin proteins act like tiny hands that grab actin protein ropes and pull, shortening the fiber. Myosin can only pull, never push, which is why joints need pairs of muscles such as the biceps and triceps to move in both directions. A signal from the brain travels along nerves to the fiber and releases calcium, which unblocks the actin so myosin can latch on. ATP, made from the food you eat, supplies the energy for each pull, and millions of these pulls happening at once shorten the whole muscle.

Indonesian Vice President Gibran Rakabuming Raka handed his resignation to parliament after questions were raised about his eligibility for office and his academic credentials. Gibran is the son of former president Joko Widodo, and his resignation came as Widodo publicly backed the president, Prabowo Subianto. Gibran had been elected vice president in 2024 as Prabowo's running mate. His candidacy was made possible by a 2023 Constitutional Court ruling on the minimum age for candidates, which was itself controversial. Parliament will now consider the resignation.

Angkor, near Siem Reap in northern Cambodia, was the capital of the Khmer Empire, which ruled much of mainland Southeast Asia between roughly the 9th and 15th centuries. At its height the city spread across about 3,000 square kilometres, making it the largest pre-industrial city on Earth by area. Its growth depended on water: huge reservoirs called barays, along with canals and embankments, stored monsoon rain and carried it to rice fields. That system let farmers harvest more than once a year and fed a very large population through the dry season. The temple complex of Angkor Wat, built in the early 12th century, is the best-known monument and still stands at the heart of the park.