The 25 science fiction stories I most liked

Isaac Asimov

In the United States fiction is classified depending on the length of the work, with four subsequent stages:

1. Novel, any work that has more than 40,000 words.
2. Novella, a work between 17,500 and 40,000 words.
3. Novelette, between 7,500 and 17,500 words.
4. Short Story, less than 7,500 words.

Naturally, the limits are not strict, and in practice they depend on who classifies each book. In Spanish, however, we have fewer categories:

1. Novel.
2. Short novel, which applies to works of intermediate length.
3. Story, with few characters and a simple plot.

Wormholes

Science fiction novels make it clear that, even if we were able to reach relativistic speeds (close to the speed of light), our need to personally explore the universe wouldn’t be satisfied. We’d like to travel to other stars with the same ease with which we cross the Atlantic today. We’d like to measure in days, if not hours, the time of a trip to the center of the galaxy (which probably contains a large black hole). Is there any chance of this happening?

To do this, we should discover in the future some property of the universe, now unknown, that would help us break the speed limit of light, which seems firmly established, and which would make us spend thousands of years on trips to most stars, except the nearest.

To solve the problem, science fiction authors have used essentially two different procedures:

The age of the Nobel Prizes in science

Age of scientific Nobel Prizes, by decades

In my conference closing the 1997-98 term at the Universidad Autónoma of Madrid, entitled The myth of progress in the evolution of Science, I wrote this:

The Nobel prizes provide an interesting measurement of the evolution of scientific progress during the twentieth century. These prizes award the most important advances in the fields of Physics, Chemistry, Physiology and Medicine. Statistics show a few worrying trends, such as the progressively higher age of the scientists who have received the Nobel Prize: the average age has gone up from 47 in the first decade to 60 in the last. The number of Nobel prizes awarded to people below 40 has gone down from nine in the thirties and fifties to zero in the nineties. Not one person born after 1950 has yet received a Nobel prize.

The problem with hierarchical multiverses

Lee Smolin

In an earlier post in this blog I mentioned a list of theories about multiverses, independent and often mutually contradictory, prepared by George Ellis, the cosmologist. These multiverses can be divided into two large groups:

• Non-hierarchical multiverses: such as the chaotic inflationary multiverse, where each universe is supposed to be a bubble that has stopped its inflationary growth, amid a permanent and total inflationary environment.
• Hierarchical multiverses: like Smolin's (which Ellis does not mention) and the multiverse of universe simulations (in other words: that we live in a simulation). In this post I speak exclusively about this type of multiverses, which share a property that, in my opinion, makes them implausible, if not impossible.

The problem with the Hubble constant

Cosmic Microwave Background Radiation
NASA-WMAP

The Hubble constant, which measures the speed of expansion of space in the universe, has very curious properties. For instance, although we call it constant, it turns out that it is not a constant, as it varies over time. That is why its current value is represented by the symbol H₀, but since its value was different at other times, it can be represented by other symbols, such as H_CMBR, which refers to its value at the time when the cosmic microwave background radiation originated, about 13.7 billion years ago.

The Twilight Zone

It has been said that the series titled The Twilight Zone was the best TV series of all time. I cannot give my opinion, for I haven’t seen so many series, so I cannot compare them, but this is what I have read.

The series, which ran for five seasons between 1959 and 1964, was dedicated to fantasy, science fiction, psychological horror and the supernatural. It was created and presented by Rod Serling, who also wrote the script of 92 of its 156 episodes. Rod Serling is well known for the scripts of two famous films of the sixties: Seven days in May and Planet of the Apes. The spectacular surprise ending of the second film (which is not in the book on which it is based, Pierre Boulle’s novel of the same title) is at the same level as many episodes of The Twilight Zone.

Productivity measures for the increase in life expectancy

In my previous post in this blog I spoke about the article entitled Are ideas getting harder to find? which can be downloaded from the Stanford University website. In this paper, the authors also analyze the increase in life expectancy in the USA and the effort necessary to achieve it, and reach the following results:

Moore's law, a self-fulfilling prediction?

Gordon Moore

In an article that can be downloaded from the Stanford University website, entitled Are ideas getting harder to find?, the authors raise the following situation:

In many models, economic growth arises from people creating ideas, and the long-run growth rate is the product of two terms: the effective number of researchers and their research productivity. We present a wide range of evidence... showing that research effort is rising substantially while research productivity is declining sharply. A good example is Moore’s Law. The number of researchers required today to achieve the famous doubling every two years of the density of computer chips is more than 18 times larger than the number required in the early 1970s... [W]e find that ideas — and the exponential growth they imply — are getting harder to find. Exponential growth results from large increases in research effort that offset its declining productivity.

Media manipulation: the Nobel Prizes and religion

James Peebles

The 2019 Nobel Prize in Physics has been assigned to cosmology and divided among three scientists: James Peebles, a Canadian, who receives half the prize for his theoretical work; and Michel Mayor and Didier Queloz, who have shared the other half for having discovered the first planet outside the solar system that revolves around a star in the main sequence.

The theory of the Big Bang was proposed in 1931 by George Lemaître, as a consequence of the extension to the past of the Hubble-Lemaître law. In 1948, Ralph Alpher and Robert Herman predicted that, if the Big Bang theory is correct, there must be a cosmic background radiation with a temperature close to 5 Kelvin. In 1965 Arno Penzias and Robert Wilson discovered the existence of such cosmic radiation, whose temperature turned out to be close to 3 Kelvin. That same year, Robert Dicke, James Peebles and other collaborators reasoned that the radiation discovered by Penzias and Wilson is precisely the signature of the Big Bang predicted by Alpher and Herman. During the 70s, Peebles was one of the leading theoretical cosmologists who studied the field of the formation of the great cosmic structures (galaxies and groups of galaxies). For these works he has now been awarded the Nobel Prize.

Harry Potter and the multiverse

In the previous post in this blog, I discussed the current absence of great men in many fields of human activity; in particular, in science. Shortly after writing that post, an interview with Sabine Hossenfelder in a major Spanish newspaper (La Vanguardia) made me see that I’m not alone in denouncing the crisis of science, at least in the field of theoretical physics, which includes theories about the multiverse, about which, a few weeks ago, I published another post.

Sabine Hossenfelder is a German theoretical physicist. She has lately become news by publishing a book: Lost in Maths: How Beauty Leads Physics Astray (2018), where she asserts that theoretical physics has progressed practically nothing in the last 60 years, and advocates dedicating public funds to research the fundamentals of quantum mechanics, rather than squandering them on colossal particle accelerators or in research on baseless lucubration, such as string theory and multiverses.

Why we have no great men today

G.K. Chesterton

First, a clarification: I won’t let myself be dragged by political correctness. I’m not going to change the title of this post to “great human beings.” For me, the word “man” (equivalent to the Latin homo) still has a main generic meaning, different from the meaning whose Latin antecedent is vir (male), opposed to woman or female.

The absence of great men is a common place today and affects almost all fields:

Updated UN data on the world population

In a post published in this blog in December 2015, Julio A. Gonzalo and I analyzed the data on the world population provided in 2012 by the UN, along with their future forecasts until the year 2100. A few months ago, the UN has updated those data and forecasts with the figures available in 2019. As seven years have elapsed, it is possible to compare the forecasts made in 2012 with the real situation just now.

The scientific mistake in Tökland

The mystery of Tökland Island is one of the best-known novels of the Spanish writer Joan Manuel Gisbert, which in 1980 won him the Lazarillo Award.

In the first part of the book, a millionaire is trying to find the right person, who in the second part should help him unveil a tremendous secret, and so he builds an underground labyrinth in the depths of the fictional Tökland Island, offering a grand prize to the person who will manage to solve all the problems posed by the successive rooms of the maze.

At first, all who try to solve the challenge posed by the maze fail ignominiously. At last, the protagonist of the novel decides to attempt the adventure, but as he does not trust himself to solve every problem alone, he prepares a team of collaborators, specialists in various fields, who will contact him from a ship that will remain close to the island, and while he goes through the labyrinth will help him solve the problems he finds there.

The limits of quantum computing

Alan Turing

In an interview in a major Spanish newspaper (La Vanguardia) published on July 27, 2019, David Pérez García, a researcher in quantum physics, says this: We are just in the beginning of some technologies that we still don’t know how far they will go. He is right, because the future is hardly predictable, but when it comes to quantum computing we tend to think that these computers, if they are viable, will let us solve problems quite different from those that can be addressed by the traditional computers to which we are used. In this context, however, mathematics can help us distinguish between what can be done, and what is completely impossible.

Although quantum computing is a fairly modern concept, its theoretical foundation was established by Alan Turing during the 1930s. Let us review a little of what he showed, for in this way we can correct a few optimistic ideas spread by the media, often driven by experts who approach the issue from very different points of view, compared to Turing.

The optimism of Teilhard de Chardin

Pierre Teilhard de Chardin

Teilhard de Chardin’s vision of the future is essentially optimistic, perhaps too much. In his book The Phenomenon of Man he outlines his vision of the future evolution of human beings, which he presents as a process of increasing convergence towards a unifying center with the appropriate name of Omega Point.

By studying the unifying process that should take us to the next stage (or the final point) of our evolution, Teilhard distinguishes three different areas:

Anniversaries of space exploration

Armstrong, Collins & Aldrin - Photo NASA

Fifty years after the arrival of man on the Moon, a couple of European sexagenarians remember the first landing:

“Do you know what day is today?”

“Saturday, why?”

“I mean the date.”

“July 20th 2019, what about it?”

“Exactly fifty years ago, man reached the Moon.”

“Oh yeah! But wait, there is something wrong here, didn’t they arrive on the twenty-first?”

"No, it was the twentieth, but it took them over six hours to get down from the capsule. By then, in Europe it was the twenty-first, but in the United States it was still the twentieth.”

“True! I remember it well. I saw it on TV. I was ten years old.”

“Me too.”

George Ellis and the multiverse

George Ellis

George Ellis is a South African cosmologist who rose to fame almost half a century ago when he wrote a book together with Stephen Hawking (The Large Scale Structure of Space-Time, 1973), today considered a classic.

In an earlier post in this blog, published in November 2014, I mentioned that there are six independent theories about the multiverse, almost all of them incompatible with each other. In a recent article titled Theory Confirmation and Multiverses published in the book Why Trust a Theory?, edited by Radin Dardashti, Richard David and Karim Thébault (Cambridge University Press, 2019), George Ellis updates the different multiverse theories. He does not mention six, as I did five years ago, but nine, although he has left out one of the six I mentioned in my post (Smolin’s), perhaps because this theory has been abandoned in the meantime. The nine theories are:

What are scientists researching about?

Plant research in space (NASA)

In previous posts I have mentioned some dangers faced by the future of science in the face of the growing obstacles suffered by basic research and the tendency of politicians to prioritize practical applications. The arguments I offered in those posts were qualitative. It is possible, however, to obtain real quantitative data, extracted from the journal Science News, which publishes a fairly complete summary of the results of research in all fields of science and technology. By analyzing 23,946 articles published during 30 years, I have obtained the following table, which shows the number of scientific news related to fourteen of the most researched topics in the fields of biology and medicine during that period of time. (More than half the research results belong to those two fields).

Daring to say “I don’t know”

I don’t know. It seems quite simple. Why so few people dare to say it?

Several years ago, when it became fashionable in popular newspapers to publish mini-surveys, answered by four or five people, about a current issue, I wondered at seeing that, whatever the question, not one of them ever answered I don’t know. Everyone was perfectly clear about what they should answer in every case.

Some of the questions had substance:

• How would you end the civil war in Yugoslavia?
• How would you solve the unemployment problem?
• How would you stop terrorism?

Five years in PopulScience

Albert Einstein

This week we celebrate a small anniversary: five years since this blog was created. In this time, 245 posts have been published. The Spanish version of the blog is a little older: it was created 30 weeks before, in January 2014, and has published 257 posts.

To mark the date by some kind of celebration, I have decided to compute the list of people most mentioned in the blog in these five years. The following table shows the names of the ten people most quoted and the number of times their name has been quoted:

Name	Times quoted in PopulScience
Albert Einstein	42
Isaac Newton	33
Stephen Hawking	20
C.S. Lewis	20
Aristotle	17
Charles Darwin	14
Isaac Asimov	14
Richard Dawkins	12
Plato	10
Ptolemy	9

Zero probability

In a previous post I mentioned that an event can happen once or several times, although the probability of its happening is zero. The probability of an event is defined as the ratio of the number of favorable cases to that of possible cases. Therefore, if the number of possible cases is infinite, while that of favorable cases is finite, the probability turns out to be zero.

At first glance it seems incredible that an event with zero probability can actually happen. I think the matter will be clearer with a simple example. Two friends, A and B, are talking, and what they say is this:

A: If I ask you to choose a number between 1 and 100, what is the probability that you choose a specific number, such as 25?

B: 1/100, obviously.

A: If I ask you to choose a number between 1 and 1000, what is the probability that you choose 25?

B: 1/1000.

A: If I ask you to choose a number between 1 and 10,000, what is the probability that you choose 25?

B: 1/10,000.

A: If I ask you to choose a positive integer number, what is the probability that you choose 25?

B: Zero, for the set of integers has infinite elements, and one divided by infinity is equal to zero.

A: Choose any number among all the positive integers and tell me which number you have chosen.

B: I choose 2²⁵⁰⁰-1.

A: You have just made an event with zero  probability.

Thinking a little you’ll see that the probability of choosing, among all the integers, any finite set, however large, is also zero. For instance:

A: If I ask you to choose ten different numbers between one and one hundred, what is the probability that you choose precisely the numbers between 11 and 20? (their order does not matter)

B: 1 / 17,310,309,456,440

A: And if I ask you to choose ten different numbers among all the positive integers, what is the probability that you choose precisely the numbers between 11 and 20?

B: Zero.

I leave to the curious reader to compute why the probability of choosing numbers 11 to 20 among those from one to one hundred is precisely what B has stated.

To finish this post, I’ll propose a few more exercises for the reader. Whoever solves them has the opportunity to write a comment explaining how they arrived to the solution.

1.      What is the last digit of 6²⁵⁰⁰?

2.      What is the penultimate digit of 6²⁵⁰⁰?

3.      What is the penultimate digit of 6^1,000,000?

4.      What is the probability that the last digit of 6ⁿ is odd?

5.      What is the probability that the penultimate digit of 6ⁿ is odd?

By Vincent Pantaloni, CC BY-SA 4.0, Wikimedia Commons

The same post in Spanish
Thematic Thread on Statistics: Previous Next

Manuel Alfonseca

Happy summer holidays. See you by mid-August

Mathematical theology

Ernst Zermelo

Ernst Zermelo (1871-1953) was a famous mathematician of the early twentieth century. Among his achievements, the following can be mentioned:

• In 1899 he discovered Russell’s paradox, two years before Russell. Although he did not publish it, he did comment it with his colleagues at the University of Göttingen, such as David Hilbert. Russell’s paradox proved that Cantor’s set theory is inconsistent, since it makes it possible to build the set of all sets that don’t belong to themselves. There are sets that don’t belong to themselves, such as the set of even numbers, which is not an even number. Others do belong to themselves, such as the set of infinite sets, which is an infinite set. Now we can ask ourselves: Does the set of all the sets that don’t belong to themselves belong to itself? This question leads us to a paradox: if it does belong, it must belong; and if it doesn’t belong, it mustn’t belong.
• In 1904 he proved the well-ordering theorem as the first step towards proving the continuum hypothesis, the first of Hilbert’s 23 unsolved problems. The well-ordering theorem states that every set can be well-ordered, which means that any non-empty ordered subset must have a minimum element. To prove it, he proposed the axiom of choice, which we will discuss later.
• In 1905 he began to work on an axiomatic set theory. His system, improved in 1922 by Adolf Fraenkel, is a set of 8 axioms, which today is called the Zermelo-Fraenkel (ZF) system. Adding the axiom of choice to this system, we obtain the ZFC system, which is most used today in set theory.

Travelling to the past?

S.Agustín, por Louis Comfort Tiffany
Lightner Museum

In his Confessions (Book XI, chapter 14), St. Augustine wrote these words, still valid today:

What then is time? If no one asks me, I know what it is. If I wish to explain it to him who asks, I do not know.

In the current situation of our scientific and philosophical knowledge, we still don’t know what time is.

·         For classical philosophy and Newton’s science, time is a property of the universe. Therefore, time would be absolute.

·         For Kant, time is an a priori form of human sensibility (i.e. a kind of mental container to which our sensory experiences adapt).

·         For Einstein, time is relative to the state of repose or movement of each physical object. There is, therefore, no absolute time.

·         For the standard cosmological theory, there is the possibility to define an absolute cosmic time for every physical object, measuring the time distance since the Big Bang to the present.

·         For the A theory of time (using J. McTaggart’s terminology) the flow of time is part of reality. The past no longer exists. The future does not yet exist. There is only the present. If the A theory is correct, travel to the past is impossible, because you cannot travel to what does not exist.

·         For the B theory of time, the flow of time is an illusion. Past, present and future exist simultaneously, but for each of us the past is no longer directly accessible, and the future is not yet accessible. Einstein adopted the B philosophy of time. In a condolence letter written to someone who had lost a beloved person, he wrote the following:

The distinction between past, present and future is only a stubbornly persistent illusion.

The symbol of death

Azrael, the angel of death
Evelyn De Morgan (1855-1919)

For an educated classical Greek, the number 8 represented death. Why? Let’s see what this funeral assignment was based on.

1. Multiply by 8 the first 8 natural numbers.
2. Add the digits for each result.
3. If the total obtained has more than one digit, we add those digits again.

Multiply	Add digits	2nd addition
1×8=8	8	8
2×8=16	1+6=7	7
3×8=24	2+4=6	6
4×8=32	3+2=5	5
5×8=40	4+0=4	4
6×8=48	4+8=12	1+2=3
7×8=56	5+6=11	1+1=2
8×8=64	6+4=10	1+0=1

Observe that we obtain the sequence 8,7,6,5,4,3,2,1. For the Greeks, this succession starts at 8 and descends to die at 1. That is why number 8 represented death.

Algorithmic censorship and diversity in scientific research

Manuel Cebrian

Manuel Cebrian started working in USA at MIT, and after a long journey that took him to the West Coast of the United States and then Australia, he returned to MIT and is now in Berlin. He became famous thanks to having won two important competitions organized by the government of the United States, related to the use of social networks to solve more or less complex problems:

• DARPA Network Challenge (2009), which offered $40,000 reward to the first team that managed to discover, in less than 8 hours, the location of fifteen red balloons distributed in different locations in the United States by Pentagon personnel, using a social network of their own creation, built for one month before the competition date. Although they received many news about false sightings (fake news) Cebrian’s team managed to win the competition, against over 9000 participating teams.
• DoS Tag Challenge (2012), which offered $5,000 reward to the team that managed to locate five actors, identified by their photograph, who acted as though they were five criminal suspects that would remain visible for 12 hours in five European and American cities: New York, Washington, London, Bratislava and Stockholm. Although they just managed to locate three of the five suspects, Cebrian's team won the competition again, despite the unethical behavior of other participating teams, one of which copied their website to deceive possible informants, so they’d send their information to the web of a different group.

During his stay in Australia, Cebrian worked on forecasting the negative effects of natural catastrophes by analyzing data provided by social networks (essentially Facebook and Twitter). The bad news is that, increasingly in recent years, algorithms that estimate general interest of news and messages in social networks are influencing whether and how those news and messages are propagated over the networks. These algorithms decide whether the messages and news will be more or less seen, and whether the users will stay more or less time on the platform.

In light of this, Cebrian and his colleagues transferred their research on social networks to the way in which Artificial Intelligence (AI) affects human communication and cooperation. The theoretical analysis of computational models inspired by the changes made in the large platforms made it possible to conjecture that the functioning of social networks can be affected by algorithms capable of enhancing or weakening information. As a result of their use, messages and news originated by certain users reach a smaller number of followers, which could be considered a form of algorithmic censorship.

Concerned about the growing trend towards control of the Internet by large companies, Cebrian and his team have made a thorough analysis of the publications in the field of Artificial Intelligence, and of the cross-references between this and other fields of science and the humanities, between 1950 and 2017. It has been found that, although the number of publications on AI has increased progressively, the mutual impact with other sciences seems to be decreasing. Just four fields (Computer Science, Mathematics, Geography and Engineering) maintain a trend higher than a randomized cross-data distribution, and just one (Computing) is increasing, although at a level below that reached during the seventies and eighties.

Another result obtained by the analysis described in the just mentioned article is that research on AI is increasingly dominated by a few research institutions, and the most cited publications appear in a small number of journals and conferences. This decrease in diversity, which has reached 30% since 1980, affects authors, articles and citations, and suggests that cross-citing research hubs may exist, with well-defined preferences. On the other hand, the preponderance of large companies in these hubs (Google, Microsoft, Facebook) could lead to the goal of research changing, from finding solutions to important technological problems for human beings, to a new situation where the objective is collecting customer data and selling them to advertisers, thus controlling the purchase impulses of society.

Let us look at one of the most important and worrisome conclusions of the article:

The gap between social science and AI research means that researchers and policymakers may be ignorant of the social, ethical and societal implications of new AI systems.

Martín López Corredoira

This decrease in diversity, combined with censorship of what does not fit the orthodox model, also affects other fields of science. Consider, for instance, the field of cosmological physics (cosmology). The publication with the highest impact is now arXiv, to the point that it is currently very difficult to publish there, unless you belong to an important institution, and totally impossible if the article differs in any way from the ΛCDM model, the current standard for cosmology, as denounced in this book:

Nobody should have a monopoly of the truth in this universe. The censorship and suppression of challenging ideas against the tide of mainstream research, the blacklisting of scientists, for instance, is neither the best way to do and filter science, nor to promote progress in the human knowledge. The removal of good and novel ideas from the scientific stage is very detrimental to the pursuit of the truth. There are instances in which a mere unqualified belief can occasionally be converted into a generally accepted scientific theory through the screening action of refereed literature and meetings planned by the scientific organizing committees and through the distribution of funds controlled by "club opinions". It leads to unitary paradigms and unitary thinking not necessarily associated to the unique truth. 

The same post in Spanish
Thematic thread on Natural and Artificial Intelligence: Preceding Next
Thematic Thread on Science in General: Previous Next

Manuel Alfonseca

Will we live 500 years?

James H. Schmitz

A few years ago, especially in 2015 and 2016, news began to appear in the mass media announcing the imminence that our life expectancy is going to rise in an accelerated way, so we’ll soon achieve immortality. At that time I wrote in this blog three posts (this, this and this) where I declared myself skeptical about these forecasts. In another post, also published in 2016, I distinguished between two very different concepts:

• Life expectancy: the average duration of human life. Although it depends on the age of the person, the value usually given corresponds to the moment of birth. Life expectancy has been growing progressively in recent centuries, mainly due to advances in medicine, although recent data from the UN seem to indicate that this increase is decreasing.
• Longevity: the maximum duration of human life. Its value seems to be around 120 years, and no significant increase is noted in recent decades. In fact, there are only two people who were thought to have exceeded that longevity, the Japanese Shigeziyo Izumi and the French Jeanne Calment, but both cases are currently in doubt. The first lost his title of the longest-lived man in the world when it was discovered that his date of birth could actually correspond to a brother of the same name, older than him, who died quite young. In the case of the French woman, there is a controversial Russian study that asserts that her daughter could have exchanged her identity for her mother’s when the latter died, supposedly in 1934.