How Helium Was Discovered

In 1913, Danish physicist Niels Bohr proposed that electrons orbit atoms in fixed energy levels, where any jump between levels emits or absorbs a photon of light with an energy exactly equal to Planck's constant times its frequency. It was a revolution because it solved two problems. Under the previous model, orbiting electrons would quickly spiral into the nucleus, and also, spectral lines could now be accounted for (at least in light elements). But the model had its limits, and a French aristocrat would ultimately formulate a relation that would both show why Bohr's formula works intuitively, but also would ultimately usher in a new era of physics that would render the Bohr model obsolete.

By the 1750s, we had a pretty decent understanding of electricity. However, the theory was incomplete. This was demonstrated most precisely when Benjamin Franklin put a cork inside a charged metal can expecting it to be influenced by the can. However, the cork didn't move whatsoever. This confusion sparked a chain reaction of events that ultimately led to Coulomb's law, published in 1785.

Man, this video took me a while to make. It just may be my most ambitious project yet. Hopefully I didn't miss anything too important. If I did or made a mistake, feel free to let me know!

Johannes Kepler had the relative sizes of the orbits of our planets in the solar system mapped by the 1630s. The shape of the solar system had been known relatively well, but it was a shape without scale. Determining the size of the solar system was a much more challenging problem, mainly because there was no known way to make such a measurement. However, that all changed with the development of parallax and taking advantage of an even more fascinating phenomenon: the transit of Venus.

In 1875, French chemist Paul-Émile Lecoq de Boisbaudran discovered the element 'Gallium' after isolating it from a zinc blende ore. However, shortly after his publication, he received word from a Russian chemist with the name of "Mendeleeff" that claimed he had predicted such an element to exist 6 years earlier. This is the story of how that Russian chemist - and a fellow German chemist - turned rival - uncovered the periodic law of the elements and formulated them all into one cohesive unit, transforming chemistry forever.

Before the modern days of organic and inorganic chemistry, there was an old theory called "Vitalism" that had made its way into chemistry. Pioneered into the field by the one and only Jöns Jacob Berzelius, this theory postulated that only living things can create organic compounds through acts of the 'Vital Force.' But cracks in this theory started to form when his pupil, Friedrich Wöhler, synthesized a compound that is found in the most unexpected of places: human urine.

You might think DNA was always the frontrunner by biologists to be the master blueprint of life. However, that couldn't be further from the truth. This video documents how DNA went from experimental backmarker to the frontrunner of a heated scientific race that used betrayal and abuse of power to reveal a winner... and rewrite history.

Helium is a very common element in our universe. However, due to its characteristics, it's very rarely found on Earth. This video shows how scientists in the 19th century overcame this obstacle, over the course of decades, and isolated and discovered the rare gas. Hosted by Simplecast, an AdsWizz company. See https://pcm.adswizz.comfor information about our collection and use of personal data foradvertising.

For over two centuries, Newton’s law of gravity accurately predicted the motions of all the planets in the solar system. But that all changed in 1859, when French astronomer Urbain Le Verrier discovered a strange anomaly regarding mercury’s orbit. This led to a problem in Newton's reality that didn't have an answer until Albert Einstein proposed General Relativity in 1915. Einstein accurately modeled Mercury's orbit with GR, but it wasn't enough for his theory to be accepted as fact. He needed to predict a testable anomaly that had been previously unobserved, and one of his predictions was light bending around the Sun. In 1919, that prediction was put to the test, and what was found would make Einstein a worldwide celebrity practically overnight.

The gravitational constant, or at least what it represents, is a fundamental part of our universe. It represents the strength of gravity and, to our knowledge, remains unchanged throughout space and time. But how did our knowledge of this come about? It all started with the Principia, but Newton did not introduce the constant G. This video takes you through the historical process of discovering G and integrating it into the science landscape.