This year is the 600th birthday of the University of Franche-Comté, the 10th university created in France in 1423. For @IDLofficial I gave a talk on optics history here since the science faculty was created in 1845. First batch of tweets follow; text in English, slides in French. The story begins with our project with @SSAC_Univfc to save the lab archives that date back over 100 years. We found many old cans of photographic negatives from the 1970s and one was especially intriguing – who were these "ancestors"?

Something different! Delighted to announce that a paper I wrote 22 years ago (!) on a supposed portrait of English scientist Thomas Harriot (c1560-1621) is finally online: TL;DR: Sorry but there's no real evidence that the portrait is Harriot ... 🧵 hal.archives-ouvertes.fr/hal-03839673
Harriot was a polymath. He produced the first telescopic drawing of the moon before Galileo, he discovered the law of refraction before Snell or Descartes, and he explored Virginia, learning Algonquian to translate. It would be nice to know what he looked like.

To kick off the week, here is an updated (and long!) thread on the history of nonlinear optics. First a real surprise! The explicit use of the terminology “nonlinear optics” can be traced back to Erwin Schrödinger in 1942. Yes you read that right. Schrödinger himself! Although this paper isn’t really what we would describe today as non-linear optics. Rather it describes “vacuum light-light scattering” or nonlinear QED. But the wording Schrödinger used definitely sounds familiar! It builds on earlier work by Born, Infeld, Euler.

I was honored to speak at Moscow State University last week for the 60th anniversary of laser nonlinear optics. But in fact, the first nonlinear effects in optics were observed in the pre-laser era by Vavilov in Moscow in 1926! Here are some slides from my talk (thread). Sergey Ivanovich Vavilov (Серге́й Ива́нович Вави́лов) was a giant of physics. He invented the term "nonlinear optics" in his 1950 book & was co-discoverer of Cerenkov radiation. Regrettably he died before the Nobel Prize for Cerenkov radiation was awarded in 1958.

An important anniversary next week! 20 years since I left @UoA_Physics in beautiful Aotearoa to live in beautiful Besançon. In the best academic tradition, must be time for a 20 year Activity Report! Thread follows: @fc_univ @FemtoSt @INSIS_CNRS @CNRS_Centre_Est Important caveat. Don’t believe for a second that everything ran smoothly! Many failures - rejected papers & funding, most ideas went nowhere, many mistakes. But you keep at it and with LOTS of help you somehow get somewhere in the end.

As promised a thread (17 tweets) with a selection of photos from the Live Science lecture last night. 200 students, 25+ demos & a team of 7 to setup. Thanks to @CocoLapre for the photos & a full list of thanks to everyone is at the end. First up dispersion & rainbows. After breaking up white light, we put it back together. Great chance to talk about how flat screen displays work at this point.

Lecture demonstrations for a Saturday morning. First - a rainbow. Very simple with a projector, card and a flask. Methyl Cinnimate is better than water for doing this as it has a higher refractive index. And complementing a rainbow is the classic dispersion of white light in a prism demo - colors seem to have saturated on the card but not on the reflection on the table.