To create a Fibonacci sequence, each number is formed by adding the two previous numbers. So, if we start with 1 and 1, the sequence goes 1, 1, 2, 3, 5, 8, 13 21 etc. There are interesting and well-known examples of Fibonacci numbers appearing in nature, and a related concept is the golden ratio. However, fewer people (including us until now) know about the silver ratio, explained in this Numberphile video.
An interesting example of silver and golden ratios is paper sizes. A2, A3, A4 etc paper are all ‘silver rectangles’ or ‘Japanese rectangles’ depending on your nomenclature. If you fold one in half you get the same shape (but smaller obviously). So folding A3 in half gives A4 etc. In contrast, the old foolscap shape was based on the golden ratio, in which removing the largest possible square gives you a smaller version of the same shape.
The Guardian gets our prize for the best article title this week, whether you have read Douglas Adams or not: “The answer to life, the universe and everything might be 73. Or 67.” This article discusses Hubble’s constant – the rate at which the universe is expanding (if you didn’t know it was expanding, you should definitely read this!). Even the unit of the Hubble constant is interesting – “kilometres per second per Megaparsec”. This is an interesting combination of ‘rates of change’ – see Topic 1 in our accompanying website.
On the space theme, but nearer to home (i.e. in our own solar system), plumes of water have been found emerging from Europa, one of the Galilean moons of Jupiter, as described here in the New York Times. This is interesting in its own right, as Europa has long been thought to be a decent place to look for life outside Earth. But what makes this especially fascinating is that the discovery has been made by looking at old data from previous space missions.
Sticking with Jupiter, Physics Reddit this week had this simulation of the Trojan asteroids. And an old favourite from YouTube is this video of asteroid discovery from 1980 – 2010. Please watch all 3 minutes – the way it builds up is hypnotic. What you are watching is the increase in humankind’s knowledge of asteroids over just a 30 year period. It’s quite hard to watch it and retain any confidence that we won’t be hit tomorrow! The fact we won’t just shows how much space the Solar System takes up.
And nothing to do with space at all, we couldn’t finish this week without linking to something on the whole Yanny and Laurel thing… Here is AsapScience explaining some relevant stuff about what is going on. If Yanny and Laurel wanted to buy a dress, they probably wouldn’t be able to choose between black/blue and white/gold. Remember that? Here’s the Guardian on that dress.