1687 – Isaac Newton publishes Philosophiæ Naturalis Principia Mathematica.
Philosophiæ Naturalis Principia Mathematica (Latin for Mathematical Principles of Natural Philosophy), often referred to as simply the Principia, is a work in three books by Isaac Newton, in Latin, first published 5 July 1687. After annotating and correcting his personal copy of the first edition, Newton also published two further editions, in 1713 and 1726. The Principia states Newton’s laws of motion, forming the foundation of classical mechanics, also Newton’s law of universal gravitation, and a derivation of Kepler’s laws of planetary motion (which Kepler first obtained empirically). The Principia is “justly regarded as one of the most important works in the history of science”.
The French mathematical physicist Alexis Clairaut assessed it in 1747: “The famous book of mathematical Principles of natural Philosophy marked the epoch of a great revolution in physics. The method followed by its illustrious author Sir Newton … spread the light of mathematics on a science which up to then had remained in the darkness of conjectures and hypotheses.” A more recent assessment has been that while acceptance of Newton’s theories was not immediate, by the end of a century after publication in 1687, “no one could deny that” (out of the Principia) “a science had emerged that, at least in certain respects, so far exceeded anything that had ever gone before that it stood alone as the ultimate exemplar of science generally.”
In formulating his physical theories, Newton developed and used mathematical methods now included in the field of calculus. But the language of calculus as we know it was largely absent from the Principia; Newton gave many of his proofs in a geometric form of infinitesimal calculus, based on limits of ratios of vanishing small geometric quantities. In a revised conclusion to the Principia (see General Scholium), Newton used his expression that became famous, Hypotheses non fingo (“I contrive no hypotheses”).
1888 – Louise Freeland Jenkins is born.
Louise Freeland Jenkins was an American astronomer who compiled a valuable catalogue of stars within 10 parsecs of the sun, as well as editing the 3rd edition of the Yale Bright Star Catalogue.
She was born in Fitchburg, Massachusetts. In 1911 she graduated from Mount Holyoke College, then she received a Master’s degree in astronomy in 1917 from the same institution. From 1913 to 1915 she worked at the Allegheny Observatory in Pittsburgh. Afterwards, she was an instructor at Mount Holyoke from 1915 to 1920.
About 1921 she moved to Japan, becoming a teacher at the Women’s Christian College, a missionary school. She returned to the United States in 1925 after her father died. A year later she returned to teach at a school in Himeji. (Hinomoto Gakuen girl’s high school.)
In 1932 she returned to the US and became a staff member at Yale University Observatory. She was co-editor of the Astronomical Journal starting in 1942, and continued in this post until 1958. She would return to visit Japan later in her life.
She was noted for her research into the trigonometric parallax of nearby stars. She also studied variable stars.
1904 – Ernst Mayr, German-American biologist and ornithologist is born.
Ernst Walter Mayr was one of the 20th century’s leading evolutionary biologists. He was also a renowned taxonomist, tropical explorer, ornithologist, philosopher of biology, and historian of science. His work contributed to the conceptual revolution that led to the modern evolutionary synthesis of Mendelian genetics, systematics, and Darwinian evolution, and to the development of the biological species concept.
Although Charles Darwin and others posited that multiple species could evolve from a single common ancestor, the mechanism by which this occurred was not understood, creating the species problem. Ernst Mayr approached the problem with a new definition for species. In his book Systematics and the Origin of Species (1942) he wrote that a species is not just a group of morphologically similar individuals, but a group that can breed only among themselves, excluding all others. When populations within a species become isolated by geography, feeding strategy, mate choice, or other means, they may start to differ from other populations through genetic drift and natural selection, and over time may evolve into new species. The most significant and rapid genetic reorganization occurs in extremely small populations that have been isolated (as on islands).
His theory of peripatric speciation (a more precise form of allopatric speciation which he advanced), based on his work on birds, is still considered a leading mode of speciation, and was the theoretical underpinning for the theory of punctuated equilibrium, proposed by Niles Eldredge and Stephen Jay Gould. Mayr is sometimes credited with inventing modern philosophy of biology, particularly the part related to evolutionary biology, which he distinguished from physics due to its introduction of (natural) history into science.
1935 – The National Labor Relations Act, which governs labor relations in the United States, is signed into law by President Franklin D. Roosevelt.
The National Labor Relations Act of 1935 (49 Stat. 449) 29 U.S.C. § 151–169 (also known as the Wagner Act after New York Senator Robert F. Wagner) is a foundational statute of United States labor law which guarantees basic rights of private sector employees to organize into trade unions, engage in collective bargaining for better terms and conditions at work, and take collective action including strike if necessary. The act also created the National Labor Relations Board, which conducts elections that can require employers to engage in collective bargaining with labor unions (also known as trade unions). The Act does not apply to workers who are covered by the Railway Labor Act, agricultural employees, domestic employees, supervisors, federal, state or local government workers, independent contractors and some close relatives of individual employers.
1968 – Susan Wojcicki, CEO of YouTube, is born.
In September 1998, the same month that Google was incorporated, its founders Larry Page and Sergey Brin set up office in Wojcicki’s garage in Menlo Park. Before becoming Google’s first marketing manager in 1999, Wojcicki worked in marketing at Intel in Santa Clara, California and was a management consultant at Bain & Company and R.B. Webber & Company. At Google, she worked on the initial viral marketing programs as well as the first Google doodles. Wojcicki also took part in the development of successful contributions to Google such as Google Images and Google Books.
Wojcicki grew within Google to become senior vice president of Advertising & Commerce and lead the advertising and analytic products including AdWords, AdSense, DoubleClick, and Google Analytics. She developed AdSense, which became Google’s second largest source of revenue. She oversaw Google Video, and proposed to Google’s board that the company should purchase YouTube, then a small start-up that was competing with Google. She handled two of Google’s largest acquisitions: the $1.65 billion purchase of YouTube in 2006 and the $3.1 billion purchase of DoubleClick in 2007. In February 2014 she became the CEO of YouTube.
Wojcicki, called “the most important person in advertising” was named to Time Magazine’s 100 most influential people in 2015 and described in a later issue of Time as “the most powerful woman on the internet”.
1971 – Right to vote: The Twenty-sixth Amendment to the United States Constitution, lowering the voting age from 21 to 18 years, is formally certified by President Richard Nixon.
The Twenty-sixth Amendment (Amendment XXVI) to the United States Constitution prohibits the states and the federal government from using age as a reason for denying the right to vote to citizens of the United States who are at least eighteen years old. The drive to lower the voting age from 21 to 18 grew across the country during the 1960s, driven in large part by the broader student activism movement protesting the Vietnam War. The impetus for drafting an amendment to lower the voting age arose following the Supreme Court’s decision in Oregon v. Mitchell, 400 U.S. 112 (1970), which held that Congress may establish a voting age for federal elections, but not for state or local elections.
On March 23, 1971, a proposal to extend the right to vote to citizens eighteen years of age and older was adopted by both houses of Congress and sent to the states for ratification. The amendment became part of the Constitution on July 1, 1971, three months and eight days after the amendment was submitted to the states for ratification, making this amendment the quickest to be ratified.
1996 – Dolly the sheep becomes the first mammal cloned from an adult cell.
Dolly was a female domestic sheep, and the first mammal cloned from an adult somatic cell, using the process of nuclear transfer. She was cloned by Sir Ian Wilmut, Keith Campbell and colleagues at the Roslin Institute, part of the University of Edinburgh, Scotland, and the biotechnology company PPL Therapeutics, based near Edinburgh. The funding for Dolly’s cloning was provided by PPL Therapeutics and the Ministry of Agriculture. She was born on 5 July 1996 and died from a progressive lung disease 5 months before her seventh birthday. She has been called “the world’s most famous sheep” by sources including BBC News and Scientific American.
The cell used as the donor for the cloning of Dolly was taken from a mammary gland, and the production of a healthy clone therefore proved that a cell taken from a specific part of the body could recreate a whole individual. On Dolly’s name, Wilmut stated “Dolly is derived from a mammary gland cell and we couldn’t think of a more impressive pair of glands than Dolly Parton’s”.