Let's Read: A Problem

In this post, we read through Borges's story A Problem, which is about Don Quixote, a story written by Cervantes:

The story follows the adventures of a nobleman named Alonso Quixano who reads so many knightly stories that he goes insane and decides to become a knight-errant, reviving chivalry and serving his country, under the name Don Quixote de la Mancha. He recruits a simple farmer, Sancho Panza, as his squire. 

His name means "Don Quixote, of la Mancha". La Mancha is a region in central Spain, where Don Quixote lived in.

A Problem

Jorge Luis Borges

An Off-by-one Error in the Tet Offensive (1968)

North Vietnam used UTC+07:00 since 1968-01-01.

South Vietnam used UTC+08:00 since 1960-01-01.

The relevant new moon was on 1968-01-29, 16:31 UTC,
in North Vietnam time, 1968-01-29, 23:31.
In South Vietnam time, 1968-01-30, 00:31.

In Chinese and Vietnamese calendars, months begin on the day of the new moon. Years begin on the second or third new moon after the winter solstice.

Tet was on 1968-01-29 in North Vietnam.
Tet was on 1968-01-30 in South Vietnam.

Causality is not fundamental in the world

Today we tear down the illusion of causality, with quantum mechanics.

This started when I was reading The Order of Time (2018) by the rather poetic physicist Carlo Rovelli, and read that he said that causality is not certain, and two events can have a superposition of causality: a superposition of two possibilities: A causes B, and B causes A.

Quantum corelations with no causal order

The paper that started this seems to be a highly cited (over 200 currently) Quantum correlations with no causal order (2012), Ognyan Oreshkov, Fabio Costa, Časlav Brukner.

The abstract starts with a question: is causality fundamental?