Isotopes of helium a thousand times lower than helium-4 (2.17 K). This difference is explained by quantum statistics, since helium-3 atoms are fermions, while helium-4 atoms are bosons, which condense to a superfluid more easily. The most common isotope, , is produced on Earth by alpha decay of heavier radioactive elements; the alpha particles that emerge are fully ionized nuclei. is an unusually stable nucleus because its nucleons are arranged into complete shells. It was also formed in enormous quantities during Big Bang nucleosynthesis. Terrestrial helium consists almost exclusively (99.99986%) of this isotope. Its boiling point of 4.2 K is the lowest of
Boiling Springs, Pennsylvania The Boiling Springs Tavern, a restaurant in downtown Boiling Springs, is a popular dining destination. Parts of the tavern, which is located along an old stagecoach route, date to 1832. One of the newest eateries in town, Caffe 101, opened in 2010 in a historic building at 101 Front Street. Boiling Springs has an annual juried arts and crafts show, called Foundry Day, on the first Saturday in June. The booths and food vendors stretch down Front Street, next to Children's Lake. The annual Carlisle Summerfair Festival's "Anything Floats" event is held on the 4th of July. Teams create their