Interesting presentation with a good introduction. By Dr Geoff Emberling of the International Kurru Archaelogical project.

Via https://ikap.us/2019/01/02/memories-of-the-kings-and-queens-of-kush

Mathematician Terence Tao on how we measure the cosmos. Two videos by 3Blue1Brown:

• https://www.youtube.com/watch?v=YdOXS_9_P4U - part 1
• https://www.youtube.com/watch?v=hFMaT9oRbs4 - part 2

Very nice explanation!

• 00:00 Most people don't understand rainbows
• 01:08 Light refraction explained
• 08:20 How does a rainbow form?
• 13:10 Circular rainbows
• 15:14 Why are rainbows curved?
• 17:30 Why can’t you see a rainbow with sunglasses?
• 18:43 Why is it brighter underneath a rainbow?
• 20:44 Different types of rainbow
• 23:46 Invention of the cloud chamber

Our world is built up of roads and cars to get us to our destination! But what about cycling and even walking? Have we been brainwashed to think that the car is always king?

Via Krister Isaksson's blog, also see masto thread (both in Swedish).

Another good video on the subject by Shifter.