Henri Poincaré was the brilliant mind who gave us the beginnings of chaos theory and Poincaré conjecture. He was also the doggedly persistent nut who was the last member of resistance to a twenty-four hour day and a sixty-minute hour. Let's look at his doomed quest to decimate our day.
Decimal, or metric, time has earned itself quite a reputation. Although plenty of political and social movements espoused the ten-or-hundred-hour day, the hundred-minute hour, and the hundred-second minute, the most infamous was the French revolution. The decimal day was meant to be part of a decimal year. Its base-ten roundness was meant to foster good, solid, rationalist thinking. While no one could say that it ushered in The Terror, it certainly didn't prevent it.
The decimal day did not die with the revolution. Love for it remained in certain circles, particularly in a little group called the Bureau des Longitudes. While not wielding a great deal of power now, it was quite a big deal back when no one quite knew how to measure longitude, and when no two countries could agree on the same international longitude anyway. In 1884, the Bureau des Longitudes was one of the many bodies making a play to have the zero arc run through their nation. In an age full of empires, when all countries wanted an international reputation, this was quite a coup. As we now know, the French Bureau had to forgo the honor, but was thrown a bone. The little bee they had in their bonnet about metric time was once again allowed to fly free. Their country and the world challenged the Bureau to show them what they could produce.
What they got, eventually, was Henri Poincaré, a mathematical genius whose Poincaré conjecture was solved in 2002, and whose musings on the three-body problem - the complicated way three bodies affect each other in space - started the ball rolling on chaos theory. Poincaré believed in decimal time with all his heart, and when he joined the Bureau in 1893, he pushed decimalization of time hard.
Poincaré wanted a lot of things changed. For example, he wanted a circle to have 400 degrees, instead of 360. He found mixes of base-ten and base-six messy. Rising through the ranks of the Bureau, he went from secretary in 1893 to president in 1899, pushing the new and improved system all the way. It must have been disappointing when, in 1897, the Bureau debuted a compromised system. Each day would still have 24 hours. It was only the minutes and seconds that would get changed to hundredths of an hour and a minute respectively. Unsurprisingly, this did not sweeten the deal for anyone. At home, people complained that they'd have to change everything from their watches to the navigational equipment of ships. Other governments were openly incredulous. Although a successful mathematician, physicist, engineer, and philosopher, Poincaré was a failure as a standardizer.