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The age of the Solar System, including Earth, was determined, and it turned out to be much older than believed earlier: more than 4 billion years, rather than the 20 million years suggested by Lord Kelvin in 1862. [2] The planets of the Solar System and their moons were closely observed via numerous space probes.
4.2.3 1920s. 4.2.4 1930s. 4.2.5 1940-1944. 5 ... historic inventions is a chronological list of particularly ... the son of Zacharias Janssen making a claim 47 years ...
The year 1920 in science and technology involved some significant events, listed below. ... the first successful human trial of insulin will occur 15 months later. ...
The 24-year-old from Brooklyn was the first to use a new technology called digitalization to capture images. Four decades later, we carry his invention in our pockets on our phones.
The invention of the collapsible periscope for use in submarine warfare is credited to Simon Lake in 1902, who called his device the omniscope or skalomniscope. Later, it was made to be raised and turned by hand. [89] 1902 Mercury arc valve. A mercury arc valve is a type of electrical rectifier which converts alternating current into direct ...
Pages in category "20th-century inventions" The following 127 pages are in this category, out of 127 total. This list may not reflect recent changes. A.
2000 BC: Pythagorean triples are first discussed in Babylon and Egypt, and appear on later manuscripts such as the Berlin Papyrus 6619. [6] 2000 BC: Multiplication tables in a base-60, rather than base-10 (decimal), system from Babylon. [7] 2000 BC: Primitive positional notation for numerals is seen in the Babylonian cuneiform numerals. [8]
The following articles cover the timeline of United States inventions: Timeline of United States inventions (before 1890), before the turn of the century; Timeline of United States inventions (1890–1945), before World War II; Timeline of United States inventions (1946–1991), during the Cold War