“The color of the emitted light depends on the relative heights of the starting and ending energy levels. A crash between closely spaced levels (such as two and one) releases a pulse of low-energy reddish light, while a crash between more widely spaced levels (say, five and two) releases high-energy purple light.”

“Atoms consist of a positive nucleus and negative electrons flying around outside it. Electrons closest to the nucleus feel a strong negative-on-positive tug, and the bigger atoms get, the bigger the tug. In really big atoms, electrons whip around at speeds close to the speed of light.”

“Even fictional characters sometimes receive unwarranted medical opinions. Doctors have diagnosed Ebenezer Scrooge with OCD, Sherlock Holmes with autism, and Darth Vader with borderline personality disorder.”

“All we know for sure is that if some astronomer turned a telescope to a far-off star cluster tonight and found incontrovertible evidence of life, even microbial scavengers, it would be the most important discovery ever—proof that human beings are not so special after all. Except that we exist, too, and can understand and make such discoveries.”

“Unlike modern pills, these hard antimony pills didn’t dissolve in the intestines, and the pills were considered so valuable that people rooted through fecal matter to retrieve and reuse them. Some lucky families even passed down laxatives from father to son. Perhaps for this reason, antimony found heavy work as a medicine, although it’s actually toxic. Mozart probably died from taking too much to combat a severe fever.”

“Also unlike a planet, an electron—if excited by heat or light—can leap from its low-energy shell to an empty, high-energy shell. The electron cannot stay in the high-energy state for long, so it soon crashes back down. But this isn’t a simple back-and-forth motion, because as it crashes, the electron jettisons energy by emitting light.”

“When you do the math and examine how much energy is produced per atomic union, you find that fusing anything to iron’s twenty-six protons costs energy. That means post-ferric fusion* does an energy-hungry star no good. Iron is the final peal of a star’s natural life.”

“Today alpha equals 1/137.0359 or so. Regardless, its value makes the periodic table possible. It allows atoms to exist and also allows them to react with sufficient vigor to form compounds, since electrons neither roam too freely from their nuclei nor cling too closely. This just-right balance has led many scientists to conclude that the universe couldn’t have hit upon its fine structure constant by accident.”

“All the elements other than hydrogen and helium make up just 0.04 percent of the universe. Seen from this perspective, the periodic system appears to be rather insignificant. But the fact remains that we live on the earth… where the relative abundance of elements is quite different.”

“For his part, Mendeleev scanned Lecoq de Boisbaudran’s data on gallium and told the experimentalist, with no justification, that he must have measured something wrong, because the density and weight of gallium differed from Mendeleev’s predictions. This betrays a flabbergasting amount of gall, but as science philosopher-historian Eric Scerri put it, Mendeleev always “was willing to bend nature to fit his grand philosophical scheme.” The only difference between Mendeleev and crackpottery is that Mendeleev was right: Lecoq de Boisbaudran soon retracted his data and published results that corroborated Mendeleev’s predictions.”

“Germans at the time believed, a little oddly, that dyes killed germs by turning the germs’ vital organs the wrong color.”