Important day for SI nerds, the meeting to formally redefine the kilogram, the kelvin, the ampere and the mole is happening today! Watch a livestream of the vote here: bipm.org/en/the-si/ If the resolution is approved, the SI will be based on fundamental physical constants, instead of physical objects. Timetable and resolutions being decided today is available here: For the first time bipm.org/utils/en/pdf/C…

70 years ago today, at the end of a miracle month of breakthroughs, John Bardeen (L) & Walter Brattain (R) demonstrated the first transistor to colleagues at @belllabs. It's been described as one of the most important inventions of the 20th century (shown here with Schockley): They had spent the past month working on a point-contact transistor, a semiconductor device which can amplify electrical signals. It was developed to replace vacuum valves & tubes which were fragile, got hot and consumed lots of power.

(📷: Wikicommons)