Chinese is hard.
"At the end of three years of learning Chinese, I hadn't yet read a single complete novel. I found it just too hard, impossibly slow, and unrewarding. Newspapers, too, were still too daunting. I couldn't read an article without looking up about every tenth character, and it was not uncommon for me to scan the front page of the People's Daily and not be able to completely decipher a single headline."Read David Moser's (University of Michigan Center for Chinese Studies) scintillating essay, "Why Chinese Is So Damn Hard" - even for the Chinese themselves.
Stairs. Such a long trudge forward to get any height .. but wait, Jess Riedel explains that 'alternating tread stairs allow for extremely steep stairs without making the tops of each step too short.'
Take a look at this diagram - the alternating tread stairs are in green - so what's going on?
Alternating tread stairs in green: get upstairs fast. But how does it work?
Also from Jess Riedel. Alex and I watched this all the way through. If you want to go to Mars you'd better have plenty of delta-v, so big engines. Designing those calls for state-of-the-art computational fluid dynamics.
Great videos of their combustion chamber simulations and re-entry vehicle flows:- from SpaceX.
As I write, Clare and Alex have just departed for Midnight Mass. Have a good Christmas.