On this day in science history: 2 August

From the days of ancient technology to modern science - find out what happened on this day in the history of science.

2nd August 2017
The line of GMT at the Greenwich Royal Observatory © Oli Scarff/Getty Images

The line of GMT at the Greenwich Royal Observatory © Oli Scarff/Getty Images

1880 - Greenwich Mean Time adopted by Parliament

The Definition of Time Act receives the Royal Assent, finally providing Britain with a unified standard time. The development of a national rail network and the electrical telegraph system that needed to be set to precise times encouraged this Parliamentary Act.

1932 - Positron discovered

First picture of a positron track, taken by Carl Anderson, 1932 © SSPL/Getty Images
First picture of a positron track, taken by Carl Anderson, 1932 © SSPL/Getty Images

American physicist Carl D. Anderson discovers the positron, the antiparticle to the electron. In 1928, Paul Dirac used Einstein’s Theory of Relativity to theorise that every particle corresponded to an antiparticle with the same mass but the opposite charge. Anderson’s discovery provided the first experimental evidence of this.
The breakthrough came when Anderson detected a particle that moved in the wrong direction in a magnetic field to be a negatively-charged electron, but was much too light to be the heavy, positively-charged proton.

1939 - Einstein and Szilárd write to Roosevelt, prompting Manhattan project

Albert Einstein and Leo Szilard reenacting the signing of their letter to President Roosevelt warning him that Germany may be building an atomic bomb. (Photo by March Of Time/March Of Time/The LIFE Picture Collection/Getty Images)
Albert Einstein and Leo Szilard reenacting the signing of their letter to President Roosevelt © March Of Time/The LIFE Picture Collection/Getty Images

Hungarian physicist Leó Szilárd convinces Albert Einstein to sign a letter to President Franklin D. Roosevelt, encouraging him to consider action concerning the possibility of Germany developing nuclear weapons.

The discovery of nuclear fission earlier that year by German chemists Otto Hahn and Fritz Strassmann and the potential for Germany to access uranium through Belgium’s mines in the Congo was of great concern to Szilárd. At their recommendation, Roosevelt initiated the Manhattan project, leading to the use of atomic bombs in 1945.

LISTEN: Radio 3's HG and the H-Bomb

1989 - Three of Neptune’s moons discovered

Computer graphics of Voyager 2 spacecraft's mission to Neptune: path of spacecraft as viewed from Earth. © Time Life Pictures/NASA/The LIFE Picture Collection/Getty Images
Computer graphics of Voyager 2 spacecraft's mission to Neptune: path of spacecraft as viewed from Earth. © Time Life Pictures/NASA/The LIFE Picture Collection/Getty Images

NASA confirms that the Voyager 2 space probe has discovered three more moons in orbit around Neptune, later named as Galatea, Despina and Larissa.

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