1. Kessler syndrome and space junk. Nature news has an article on the accumulation of space junk (dead satellites, rocket shards, etc) in low Earth orbit. The chart below is a nice visual. Of the 20,000 tracked objects, half come from two events: 1) Chinese government blew up a satellite in a missile test in 2007, and 2) Iridium–Cosmos satellite collision in 2009. Half of the debris coming from two events illustrates what’s known as Kessler syndrome, the risk of one collision causing more collisions in a growing cascade. You can think of space debris as a pollution externality, where on the margin nobody wants to pay the extra price to control debris (see the Nature piece on how that can be done), so it just keeps getting worse. Robin Hanson’s guess is that the Kessler scenario will eventually happen, with a runaway cascade creating millions of debris pieces in orbit. That led me to read this paper. One one hand, after doing some reading, I agree with Hanson the political will is lacking to stop the debris problem. So some sort of future cascade will eventually happen. But there’s a wide range of scenarios, and tracking and avoidance are in an arms race against debris. Plus you can always launch into orbits at additional cost to avoid debris. Bottom line: enjoyed learning about this, believe it will happen, believe everyone will get super angry when it does because it’s been predicted since 1978(!), but only moderately worried compared to all the other world’s problems. Your mileage may vary.
2. Kids should have more unstructured play time. Jonathan Haidt and Greg Lukianoff have a new book out The Coddling of the American Mind. Taken from their new book, they argue in a New York Times opinion piece this week that kids need far more unsupervised play to self-learn social skills than they get today. Here’s one bit:
But during the 1980s and 1990s, children became ever more supervised, and lost opportunities to learn to deal with risk and with one another. You can see the transformation by walking through almost any residential neighborhood. Gone is the “intricate sidewalk ballet” that the urbanist Jane Jacobs described in 1961 as she navigated around children playing in her Greenwich Village neighborhood. One of us lives in that same neighborhood today. His son, at the age of 9, was reluctant to go across the street to the supermarket on his own. “People look at me funny,” he said. “There are no other kids out there without a parent.”
A study by sociologists at the University of Michigan documented this change by comparing detailed records of how kids spent several days in 1981 and 1997. The researchers found that time spent in any kind of play decreased 16 percent, and much of the play had shifted indoors, often involving a computer and no other children.
3. White flight from Asians. This piece came out a couple of years ago but I just came across it. It documents how white flight from Asians happens, in a manner somewhat different than Hispanics or Blacks. For example Asian kids are seen as too competitive at school. And of course Asians have had higher incomes than whites for many decades. They use Johns Creek, a suburb outside Atlanta, and Cupertino, in the San Francisco Bay Area, as examples. As a white person who looked at schools while house shopping about 10 years ago in the bay area, the Cupertino example rang sadly true. I should note that Cupertino is quite wealthy, and votes solidly Democratic. That’s both before whites left, and after. I have an (Asian) friend on facebook who shared a picture of her daughter at a high school sport event this week, and having just read this article, it made me notice her daughter’s team was all Asian except for one white. And so it goes. link
4. Male variability paper gets unpublished. [Update Sep 17, 2018: turns out I was mistaken on what happened. Andrew Gelman dug into this, and turns out this is not a case of unpublishing due to political correctness. Rather just unpbulishing because editors decided too. My err in jumping to conclusions. I’ll leave the original note below just for the record.] From wikipedia the Greater Male Variability Hypothesis is that “males display greater variability in traits than females do.” It “has often been discussed in relation to cognitive ability, where it has been observed that human males are more likely than females to have very high or very low intelligence.” One of the leading hypothesis is with only one X chromosome, and a solitary Y chromosome, variability should be higher in males because they don’t have back up duplicate genes on their sex chromosomes. Which females have with two X’s. At one level unpublishing a paper on a fraught topic like this is no big deal. Yawn. Same old for decades. But in the internet age anyone can publish, so you can learn details on how these things go down. Which was new to me. So perhaps that’s the real story. Anyway. If you’re curious on how studies sometimes go down the memory hole, here’s the link.
5. Saved you a click. I’ll finish with links to stories that you can get nearly the full point in just a sentence. But click through for details if you want.
- Working age population in China peaked in 2011, falling to 23% of population by 2050.
- Fraction of mismanged plastic waste in East Asia is 60%, and less than 1% in North America.
- For the first time, researchers will release genetically engineered mosquitoes in Africa. That’s to (eventually if they keep going) control malaria using gene drive.
- At Dulles airpot, instead of pulling out their passports and handing over a boarding pass, travelers will instead have their faces scanned
And that’s all for this week! Thank you for reading.
Praxtime by Nathan Taylor 
I think unsupervised play is very important. It is OK to play by yourself.