30 April 1871

The Camp Grant massacre takes place in Arizona Territory.

The Camp Grant massacre, which occurred on April 30, 1871, is one of the darker episodes in the history of the American West, particularly in the Arizona Territory. It involved the brutal killing of 144 Aravaipa and Pinal Apache men, women, and children.

During the late 19th century, tensions between Native American tribes and settlers, as well as the U.S. military, were high. The Apache tribes, including the Aravaipa and Pinal groups, were often in conflict with American settlers and the military due to territorial disputes, resource competition, and retaliatory attacks.

The massacre took place near the site of Camp Grant, an army post located along the San Pedro River. The Aravaipa and Pinal Apaches had surrendered to U.S. Army authorities at Camp Grant and were placed on a reservation near the camp as part of a peace initiative led by Lieutenant Royal Whitman.

Despite their peaceful intentions, a group composed of about 100 Tohono O’odham (Papago) warriors, joined by some Anglo-American settlers and Mexican-Americans from Tucson, coordinated an attack on the Apache camp. The attackers killed approximately 144 Apache, mostly women and children, as most of the Apache men were away from the camp. Only eight Apache children were spared, as they were taken to be sold into slavery.

The massacre sparked outrage when it became public knowledge. Public opinion was divided, with many in the Tucson area justifying the attack as a necessary action against Apache raids, while others in different parts of the country condemned it as a horrific and unjust massacre.

The federal government held a trial in Tucson to address the massacre. Despite the evidence, the jury, composed primarily of settlers sympathetic to the attackers, acquitted all defendants involved in the incident.

30 April 1905

Albert Einstein completes his doctoral thesis at the University of Zurich.

Albert Einstein’s doctoral thesis, which he completed in 1905 at the age of 26, was titled “A New Determination of Molecular Dimensions.” The thesis was submitted to the University of Zurich and was later published as a paper in the Annalen der Physik (Annals of Physics) journal.

In his thesis, Einstein developed a new method for calculating the size of molecules in a liquid by analyzing how they scatter light. This method, known as “Einstein’s theory of Brownian motion,” provided a way to experimentally verify the existence of atoms and molecules, which had previously been debated among scientists.

The theory of Brownian motion played a crucial role in the development of modern physics and chemistry, and it remains an important topic of study to this day. Einstein’s thesis marked the beginning of his scientific career and laid the groundwork for his future groundbreaking work, including the development of the theory of relativity.

30 April 1939

The 1939-40 New York World’s Fair opens.

On April 30, 1939, a very hot Sunday, the fair had its grand opening, with 206,000 people in attendance. The April 30 date coincided with the 150th anniversary of George Washington’s inauguration, in Lower Manhattan, as the first President of the United States. Although many of the pavilions and other facilities were not quite ready for this opening, it was put on with pomp and great celebration.

David Sarnoff, then president of RCA and a strong advocate of television, chose to introduce television to the mass public at the RCA pavilion. As a reflection of the wide range of technological innovation on parade at the fair, Franklin D. Roosevelt’s speech was not only broadcast over the various radio networks but also was televised along with other parts of the opening ceremony and other events at the fair. On April 30, 1939, the opening ceremony and President Roosevelt’s speech were seen on black and white television sets with 5 to 12-inch tubes. NBC used the event to inaugurate regularly scheduled television broadcasts in New York City over their station W2XBS. An estimated 1,000 people viewed the Roosevelt telecast on about 200 television sets scattered throughout the New York metropolitan area.

In order to convince skeptical visitors that the television sets were not a trick, one set was made with a transparent case so that the internal components could be seen. As part of the exhibit at the RCA pavilion, visitors could see themselves on television. There were also television demonstrations at the General Electric and Westinghouse pavilions. During this formal introduction at the fair, television sets became available for public purchase at various stores in the New York City area.

After Albert Einstein gave a speech[citation needed] discussed cosmic rays, the fair’s lights were ceremonially lit. Dignitaries received a special Opening Day Program which contained their names written in Braille.

30 April 1905

Albert Einstein is awarded his doctoral thesis at the University of Zurich.

Einstein’s official 1921 portrait after receiving the Nobel Prize in Physics
In 1900, Einstein’s paper “Folgerungen aus den Capillaritätserscheinungen” was published in the journal Annalen der Physik. On 30 April 1905, Einstein completed his thesis, with Alfred Kleiner, Professor of Experimental Physics, serving as pro-forma advisor. As a result, Einstein was awarded a PhD by the University of Zürich, with his dissertation “A New Determination of Molecular Dimensions”.

In that same year, which has been called Einstein’s annus mirabilis, he published four groundbreaking papers, on the photoelectric effect, Brownian motion, special relativity, and the equivalence of mass and energy, which were to bring him to the notice of the academic world, at the age of 26.

Academic career
By 1908, he was recognized as a leading scientist and was appointed lecturer at the University of Bern. The following year, after giving a lecture on electrodynamics and the relativity principle at the University of Zürich, Alfred Kleiner recommended him to the faculty for a newly created professorship in theoretical physics. Einstein was appointed associate professor in 1909.

Einstein became a full professor at the German Charles-Ferdinand University in Prague in April 1911, accepting Austrian citizenship in the Austro-Hungarian Empire to do so. During his Prague stay, he wrote 11 scientific works, five of them on radiation mathematics and on the quantum theory of solids. In July 1912, he returned to his alma mater in Zürich. From 1912 until 1914, he was professor of theoretical physics at the ETH Zurich, where he taught analytical mechanics and thermodynamics. He also studied continuum mechanics, the molecular theory of heat, and the problem of gravitation, on which he worked with mathematician and friend Marcel Grossmann.

On 3 July 1913, he was voted for membership in the Prussian Academy of Sciences in Berlin. Max Planck and Walther Nernst visited him the next week in Zurich to persuade him to join the academy, additionally offering him the post of director at the Kaiser Wilhelm Institute for Physics, which was soon to be established. Membership in the academy included paid salary and professorship without teaching duties at the Humboldt University of Berlin. He was officially elected to the academy on 24 July, and he accepted to move to the German Empire the next year. His decision to move to Berlin was also influenced by the prospect of living near his cousin Elsa, with whom he had developed a romantic affair. He joined the academy and thus the Berlin University on 1 April 1914. As World War I broke out that year, the plan for Kaiser Wilhelm Institute for Physics was aborted. The institute was established on 1 October 1917, with Einstein as its director. In 1916, Einstein was elected president of the German Physical Society 1916–1918.

Based on calculations Einstein made in 1911, about his new theory of general relativity, light from another star should be bent by the Sun’s gravity. In 1919, that prediction was confirmed by Sir Arthur Eddington during the solar eclipse of 29 May 1919. Those observations were published in the international media, making Einstein world famous. On 7 November 1919, the leading British newspaper The Times printed a banner headline that read: “Revolution in Science – New Theory of the Universe – Newtonian Ideas Overthrown”.

In 1920, he became a Foreign Member of the Royal Netherlands Academy of Arts and Sciences. In 1922, he was awarded the 1921 Nobel Prize in Physics “for his services to Theoretical Physics, and especially for his discovery of the law of the photoelectric effect”. While the general theory of relativity was still considered somewhat controversial, the citation also does not treat the cited work as an explanation but merely as a discovery of the law, as the idea of photons was considered outlandish and did not receive universal acceptance until the 1924 derivation of the Planck spectrum by S. N. Bose. Einstein was elected a Foreign Member of the Royal Society in 1921. He also received the Copley Medal from the Royal Society in 1925.

30 April 1980

 photo 47769940_2663510_zpst2zrgtoq.jpg

The Iranian Embassy siege starts in London.

On the 30th April 1980, six armed men entered the Iranian embassy in London. Its inhabitants were taken hostage – staff and guests who included the ambassador, British journalists and PC Trevor Lock, the policeman guarding the embassy. The terrorists were members of the Democratic Revolutionary Front for the Liberation of Arabistan, a group fighting for independence from Iran for their home region. They demanded the release of prisoners held by the Iranian government. Tense and protracted negotiations followed. These were complicated by Britain’s poor relationship with Iran, covert Iraqi support for the terrorists and international treaties around terrorists and the rights of embassies.

From the start, the British authorities decided that they would storm the embassy if any hostages were killed. It was also clear that they could not let the terrorists go. And so, while negotiations continued, preparations were made for that attack. The SAS were tasked with storming the embassy. Some of Britain’s best troops, the SAS was first founded in World War Two as a highly trained unit whose members relied on their own initiative rather than rigid command structures. Since the terrorist massacre at the 1972 Munich games, they had developed a group specially trained to deal with terrorist incidents – the Counter-Revolutionary Warfare wing, or Special Projects Team. These men were experts in difficult close quarters fighting and hostage rescues. At the start of the embassy siege, the SAS had a relatively low public profile. That was about to change.

The assault teams would burst into the embassy by as many different routes as they could, using stun grenades and tear gas to disorient the terrorists.They would move quickly and decisively to prevent the terrorists regrouping or killing their hostages. Still, high casualties were likely in an assault – it was estimated that 40% of the hostages would die, and the SAS would also lose men.

Understanding the situation was vital. The SAS had advised on security for the embassy when it was run by the previous Iranian regime, so they had knowledge of the building’s layout and potentially out-dated security information. Tiny microphones and video cameras were inserted through holes drilled in the walls, to give insight into the developing situation. The soldiers who would carry out the assault had reconnoitred entry points on the roof. The release of three hostages had given them further information.