With the lowest melting and boiling points of any known substance, helium—alone among the elements—will not solidify even as its temperature approaches absolute zero. Instead, it takes on extremely unusual physical properties, as physicists discovered in 1937. It becomes a superfluid. With zero entropy, zero viscosity, and extremely high thermal conductivity, superfluid helium can overcome friction to climb out of an open jar. What does superfluid helium do if placed in a rotating container?
Back in the day
Located near the demilitarized zone that marked the border between North and South Vietnam, Khe Sanh was the site of a protracted battle during the Vietnam War. It involved months of near-constant artillery attacks on the local US Marine base, matched by a bombing barrage of surrounding areas by US planes. The US forces retained the base but gained no advantage, and both sides suffered heavy casualties. Why do some historians believe the North Vietnamese never intended to capture the base?
Born on a day like today
In 1858, Jex-Blake enrolled in college against the wishes of her parents. She struggled to find a medical school that would accept women, and though she persuaded the University of Edinburgh to admit her, she could not graduate. She took her fight to Parliament, which passed a law enabling women to receive medical degrees. Jex-Blake founded two medical schools for women, and, after obtaining her degree in 1877, became the third female doctor in the UK. What became of her Edinburgh home?