Quantum mechanics or classical physics?

John Stewart Bell

The debate about which theory explains better the behavior of elementary particles, either quantum mechanics (with strange consequences such as state superposition and quantum collapse) or a still unknown classical physics-type theory that eliminates the need for such phenomena, has been going on since Bohr and Einstein started this debate almost one century ago.

The issue seemed to have been decided when John Steward Bell formulated in 1964 the famous Bell inequality, which I described in another post. However, as some physicists still raise the question, other means of distinguishing between the two types of theories are still being sought. One of them is the Leggett-Garg inequality (LGI), to which I will dedicate this post, based on a recent article in Physics World, dated August 12, 2024.

Time travel in science fiction

H.G. Wells

A few years ago, I published in this blog a series of posts about the scientific aspect of time travel, the paradoxes it could cause if it were possible (which almost certainly it is not) and proposed solutions to these paradoxes, such as the quantum multiverse, one of the most absurd theories physicists have ever concocted. In another post I talked about the scientific errors in Michael Crichton’s sci-fi novel Timeline, which tries to avoid the paradoxes in this way, but does it poorly.

Here I am going to speak about time travel from a literary point of view, as a subgenre of science fiction. In this context, it’s irrelevant that time travel may or may not be possible. We are interested in the question, because this is one of the most frequent topics in this type of literature.

The number of productions of this genre dealing with time travel is huge. I have tried to make a list of the novels and short stories about this issue that I have read (or written), and their number is overwhelming. Furthermore, I am sure I’m forgetting many titles, especially short stories, which are more difficult to remember, as they are distributed among collections and anthologies, sometimes by a single author, sometimes by several. Finally, we should add all the works I haven’t read yet, which are probably even more numerous.

The first problem we should solve is finding a clear definition of the works that belong to this subgenre. The list of works provided by Wikipedia, apart from being incomplete, mixes productions belonging to different genres, such as the following:

•         Legends of sleepers, such as the legend of the monk and the little bird, which appears in cantiga CIII of Cantigas de Santa María by Alfonso X the Wise and in many other sources. A monk falls in ecstasy while hearing a little bird sing, and when he wakes up he discovers that three centuries have passed. In the United States, Washington Irving’s Rip van Winkle is famous, whose protagonist falls asleep one night and wakes up 20 years later. This type of works does not belong to science fiction, because in them there is no science.

•         Magic fiction stories, such as The Goloshes of Fortune by Hans Christian Andersen or The Story of the Amulet by E. Nesbit. For a purist, the two Harry Potter novels where time travel takes place would also fall into this section, but I prefer to include them in science fiction, because magic, in these books, is an analogy of science.

It is also doubtful whether we should classify in this subgenre short stories and novels that do not deal with time travel in the strict sense, but with means of viewing the past. The device used to achieve this is usually called a chronovisor or a chronoscope. I will cite here The Dead Past by Isaac Asimov and my novel A Face in Time, although the latter also belongs to the subgenre of time travel. In Harry Potter and the Chamber of Secrets there is one of these visions through time, although it uses magic, rather than a chronovisor.

The first science fiction story that belongs to this subgenre, as it uses an instrument to travel through time, is the story The Clock That Went Backwards by Edward Page Mitchell (1881). I didn’t like it too much, because the author is influenced by the anti-Spanish black legend in the Netherlands version.

Ray Bradbury

A very special case is the story The Toynbee Convector by Ray Bradbury, which is usually classified in the time travel science fiction subgenre, but could belong to another subgenre. I’m not going to say which, for doing so could spoil the fun for those who haven’t read it yet. I recommend this story, because it’s quite innovative.

Another unique case is Cryptozoic by Brian Aldiss, which combines time travel with a strange theory about time: it asserts that we don’t go from the past towards the future through the present, but rather the other way around. Our existence begins with our death, we live life backwards, and end when the zygote divides into a sperm and an egg within the mother’s womb. This novel caused great controversy among its readers, who were divided between those who judged it to be pure nonsense, and those who considered it a great achievement by its author. In another post I wrote that perhaps Aldiss got the idea from the story The Blind Man's World by Edward Bellamy, where the Martians remember the future and don’t know about the past.

The following table shows the science fiction novels and stories about time travel I have liked best:

Date	Títle	Author	Type of work
1888, 1895	The Chronic Argonauts and The Time Machine	H.G. Wells	Short story and short novel
1950	Time’s Arrow	Arthur C. Clarke	Short story
1950	Forever and the Earth	Ray Bradbury	Short story
1952	A Sound of Thunder	Ray Bradbury	Short story
1954	A Thief in Time	Robert Sheckley	Novella
1955	The End of Eternity	Isaac Asimov	Novel
1955-60	Guardians of Time	Poul Anderson	4 short stories
1962	The Rescuer	Arthur Porges	Short story
1969	Brother Assassin	Fred Saberhagen	Novel
1999	Harry Potter and the Prisoner of Azkaban	J.K. Rowling	Novel

Finally, I will mention my own work, which includes two novels: A Face in Time, which I have mentioned above, and Beyond the Black Hole, where a young drug addict is sent to the past, in the land of the Dakotas.

The same post in Spanish

Thematic Thread on Literature and Cinema: Previous Next

Manuel Alfonseca

Correlation or causality

Francis Galton, Darwin’s cousin, best known for promoting eugenics, invented the mathematical concept of correlation. Since then, many mistakes have been made relating correlation and causality, which sometimes coincide, but can also be completely different.

Two variables are said to be correlated when increases in one resemble increases in the other, and decreases in one resemble decreases in the other. But not all correlations are the same: to distinguish them, Galton devised the correlation coefficient, a number between -1 and 1.