A Roman emperor who was also a philosopher. The last of what historians call the Five Good Emperors, a string of competent rulers. He wrote a diary full of self-exhortations, confessions, and reminders to act like a good person, which can be an interesting read from such a privileged autocrat. My highlights: Book: Meditations.

Birthday: 15 February

Famous story of dropping things off the tower of Pisa, probably apocryphal; didn't do it in reality, only talked about it as a thought experiment. 350 years later, astronauts replicated Galileo's experiment on the Moon (they brought two balls to drop them on the lunar ground), you can see it on YouTube.

Rolled balls of varying mass down inclined planes. Noted that the distance travelled grows with time squared (acceleration). These experiments took him many years for some reason.

There were no stopwatches in that time, so how did Galileo time it? With his lute as an incline, he put bells as gates for the ball to break through. Then spacing the bells increasingly distant so that the chiming sounds became equidistant.

Measuring the acceleration: differences in length increased according to some constant.

The constant varied, it wasn't always 10 as you see above. Galileo couldn't understand it, but we know it was measuring error.

Aristotelian idea: All objects have a natural state that they want to reach. Heavy objects want to go down, heavier objects even more so.

Galileo thought experiment: basket containing ten stones, and a single stone separate. Which of these two objects falls faster? The basket, if heavier, supposedly falls faster. What happens if you tie the eleventh stone to the basket? He arrived to the conclusion that all objects must fall at the same speed.

Birthday: 10 December

The first programmer. Long before there was anything like a computer, only Charles Babbage's theory which she translated to French (with extra notes), she got it – how it would work. This is hard to do when you don't grow up around computers, the idea of computation which surrounds us today and seems obvious had not occurred to anyone. Even Babbage wasn't able to envision it. That's why we say she was the first programmer.

After Babbage refused her offer to work with him, she spent ten years abusing opiates and alcohol (given by her mother who thought she should less cerebral and more ladylike), then died.

The "father of vaccines" – cool story. Jenner figured out that getting people sick with cowpox (a mild disease) made them much less likely to be killed by smallpox (a serious disease). There was already a practice called variolation which was just straight-up infecting people with smallpox. And here is the origin of the name vaccine. Cowpox is translated into Latin as variolae vaccinae ("cow's smallpox"). So giving people cowpox is called "vaccination".

Now vaccination is the general practice of infecting people with a mild variant of a deadly disease. Often a mild variant doesn't exist, so we craft one in the lab.