If anyone is interested in the history and an accessible, but deep understanding of black holes I highly recommend Kip Thorne’s book “Black Holes and Time Warps” (1994). The first half of this article follows a summary of that book closely.
If anyone's keen to go deeper and catch up on the latest thought on such things it's not to late to slide into the Seventeenth Marcel Grossmann Meeting, Pescara, Italy (7-12 July 2024).
Sergiu Klainerman: The nonlinear stability of slowly rotating Kerr black holes
The full proof of the nonlinear stability of Kerr consists of five papers, three written in collaboration with Jeremie Szeftel, one in collaboration with Elena and Jeremie Szeftel and another supporting paper authored by Dawei Shen.
In my lecture I will describe the main architecture of the proof as well as some of the most important consequences.
You can set this up in accessibility->accessibility shortcut and select color filters. Then in accessibility->Display & Text Size->Color Filters select gray scale. Triple tapping the power button will now toggle gray scale. I use a red tint when in bed.
The phases of the moon and the shadow cast on the moon during a lunar eclipse are not related. The phases of the moon are caused by the position of the moon relative to the Earth and the Sun. Imagine two lines extending from Earth to the Sun and the Moon, if the angle at Earth is 90 degrees, the moon appears half full to the people on the side of the Earth that can see it. If that angle is 180 degrees, it’s full. Zero degrees is a new moon. The reason the phases last all night is because the moon rotates ~27 days, therefore changing its relative position to the sun only slightly in a night.
A lunar eclipse occurs during a full moon and the Earth, Moon and Sun are aligned. causing the Earth to cast a shadow on the Moon. This doesn’t happen every Moon rotation because the Moon’s orbit is slightly off.
You can fairly well demonstrate this to yourself with a dark room, a single lamp, and a soccer/basketball.
Put the light at one wall center, the ball in the middle, and walk around the ball. You can see the new, quarter, full, quarter ball lit up just as you can from Earth. (Naturally, the sun is too close in this example, so the shadow lines won’t be as crisp.)
I wanted an example of a simple genetic algorithm in swift, couldn't find it so I wrote it from something I found in python. 0% special, but thought i'd share. Take it or leave it, dude.
That's because Character is very, very different from ASCII in Swift (a character in Swift holds an extended grapheme cluster. See https://developer.apple.com/reference/swift/character). I also doubt the way they compute its ASCII value is optimal:
extension Character {
var asciiValue: UInt32? {
return String(self)
.unicodeScalars
.filter{$0.isASCII}
.first?
.value
}
}
Certainly if it is optimal, but probably also if it isn't, I would change the program to not do that conversion in inner loops.
Yep totally, going to take another pass to try and make it faster. This was just a make it work experiment. Had a few fun troubles with random, but at the moment it just crawls :(.
I have lost many hours here, and have shared with many
I’m not worthy.