When last I mentioned Newton, I noted that Sir Isaac’s genius wasn’t simply due to his laws of motion and gravity, which weren’t all that original, but rather his application and interpretation of those rules.
Father and Son
William Herschel was an astronomer of the 1700s and early 1800s. He is most famous for his discovery of the planet Uranus. But Herschel made several other important discoveries, including work on double stars, showing that some of them (what we now call binary stars) orbited each other under gravitational attraction. He also discovered infrared light, by passing sunlight through a prism, holding a thermometer just beyond the red light of the spectrum, and demonstrating that the thermometer was heated by in invisible light we now call infrared. He was the father of one son, John.
Tradition
Growing up, my father was a loving but strict parent. To this day I address my elders as Sir or Ma’am as easy as breathing. My father encouraged me to learn about crop rotation and animal husbandry, but those didn’t hold much interest for me. I worked the farm as required, but didn’t look forward to it with fondness. I’d much rather stand in the field outside our house at night and look at the stars.
Seeing Red
Ever since Henrietta Leavitt discovered the period-luminosity relation for Cepheid variable stars, and Edwin Hubble used her work to demonstrate the relation between the redshifts of galaxies and their distances, we’ve had a pretty good idea that the universe was expanding. Since then we’ve gathered much more evidence on the connection between redshift and cosmic expansion, including redshift observations of distant supernovae that show the universe is undergoing cosmic inflation due to dark energy. While cosmic expansion is now well established, there have been some interesting mysteries along the way. One of these involves some seemingly strange behavior of quasars.
Legacy
Marie Skłodowska-Curie was a pioneer in the study of radioactivity. She in fact coined the term. She developed a method for isolating radioisotopes, and discovered two elements (radium and polonium). She worked on radiation therapy of tumors, and developed established military radiological centers during World War I. She is the only person ever to have won a nobel prize in two scientific fields (Physics in 1903, and Chemistry in 1911). She also happened to be the mother of two daughters.
Star Light, Star Bright
The Sun is a star like many others. It is special to us because it provides Earth with light and heat, but on a cosmic scale our Sun is an average, rather smallish star. How we came to understand this fact is a story with origins in the ancient past.
Making Waves
George Thomson had some big shoes to fill. His father J. J. Thomson had won the Nobel prize for the discovery of the subatomic particle now known as the electron, and George had become a physicist as well. Fortunately George Thomson did quite well for himself, and was also awarded a Nobel prize. In a way, George won his Nobel prize for proving his father wrong.
Current Events
In the late 1800s there was an interesting physics demonstration that became rather popular. Take a partially evacuated glass tube with wires embedded on either end and run a high voltage across it. When you did this, the tube would glow, somewhat like a neon light. It was clear that an electric current ran from one wire (the cathode) to the other (anode) through the tube, but it was not clear what was causing the glow. By evacuating more air out of the glass tube, it soon became clear that the light was emitting from the cathode, and so they were called cathode rays.
The Four Elements
Over the past two centuries, we have gained a much better understanding of the atomic elements and how they have formed. One of the things we have learned is that we—and every other living thing on Earth—are made up mostly of four elements. These four atomic elements are oxygen, carbon, hydrogen, and nitrogen. Together they make up about 96% of our bodies.