Flu season is gearing up in the northern hemisphere, and this year’s strains appear more virulent than usual. In the United States, the Centers for Disease Control declared an epidemic on January 11; the CDC estimates that between 3,000 and 49,000 people die from influenza or its complications every year. By comparison, the infamous flu of 1918 may have killed 500,000 Americans. Although the very young, elderly, and diseased bear the highest risk of death, healthy adults still bear the responsibility of minimizing overall transmission of the virus. In other words, everyone should get vaccinated. On ERV, Abbie Smith writes that the influenza virus is highly mutable, and we must devise a fresh vaccine every year in anticipation of its new forms. This year’s vaccine has an efficacy of 62%, better than average. Meanwhile, on We Beasties, Kevin Bonham explains what happens when you are infected by more than one pathogen at a time.
Reports that researchers elicited a temperature “lower than absolute zero” might make one question the meaning of the word absolute. On Built on Facts, Matt Springer writes “temperature is a relationship between energy and entropy, and you can do some weird things to entropy and energy and get the formal definition of temperature to come out negative.” Usually collisions between atoms ensure that less than 50% of atoms in a sample are excited, no matter how much heat you add. But Springer analogizes “What if I start with a huge pile of ground-state atoms, and one by one I whack them with a hammer to get them excited and then throw my collection of excited atoms into a jar?” In this case, as more than 50% of the atoms are excited, physical equations yield a negative temperature. Chad Orzel explains that the smallest negative temperature (i.e. -.01 K) reflects the highest concentration of excited atoms, while larger negative temperatures (i.e. -100K) actually approach lukewarm. In his latest post, Chad Orzel breaks down the highly technical details of the researchers’ accomplishment.
On Starts With a Bang, Ethan Siegel makes headway on his tour of “110 spectacular deep-sky objects” first cataloged by Charles Messier in 1758. Before powerful telescopes were developed, the heavens consisted of the sun, moon, stars, a few bright planets, and the rare passing comet. Comets were actively sought by men like Messier, who one night saw a bright smudge—too ill-defined to be a star—that “neither brightened nor changed position nor altered in appearance over the subsequent nights.” He had spotted the beautiful Crab Nebula, an expanding lacework of stardust blown out by a supernova within our own galaxy. Unknown to Messier, some of his nebulae were entirely different galaxies, millions of light years distant, a structure scarcely conceived of in the 18th century (and not proven, on the basis of redshift, until 1912). Other Messier objects turn out to be spectacular star clusters, such as M13, which contains about 300,000 stars “from Sun-like ones down to red dwarfs and white dwarfs, a few blue stragglers (common to globulars), and a few red giant stars” within a diameter of 145 light years. But all these wonders of the universe looked about the same to Messier: things not to confuse with comets, ice orbiting the sun.