Universe or multiverse?

In the posts in this blog I have often said that theories about the multiverse (there are many) are not science, but speculations, because it is impossible to design an experiment that demonstrates the existence or non-existence of these multiverses.

In an article published in May 2023 in the journal Springer Nature, entitled Is Everyone Probably Elsewhere?, the authors claim that it would at least be possible to distinguish between the following two hypotheses:

1. Our universe is unique, it does not belong to any multiverse.
2. Our universe belongs to some multiverse. Of course, we would have no idea what type of multiverse it would belong to.

The lost worlds of 2001

Arthur C. Clarke

2001: A Space Odyssey (1968) is one of the most representative science-fiction films in the world of cinema. Its script, which took several years to develop, was elaborated jointly by Arthur C. Clarke, a renowned science-fiction writer during the golden age of this genre, and Stanley Kubrick, a famous film director. While he was working on the script, Clarke wrote a book with the same title as the film, which was published after the film’s release.

In 1972 Arthur C. Clarke published a book entitled The Lost Worlds of 2001, where he mixes reminiscences about the elaboration of the script with discarded chapters from the book. By reading this book, we can follow the process of the construction of the film by Clarke and Kubrick and the successive stages of the plot. I agree with them that the final script was much better than the intermediate versions. Reading this book has led me to the following two comments:

The aliens are coming!

Before the 20th century, some philosophers considered the possibility of the existence of intelligent aliens, from outside the Earth. We can cite Lucretius (De Rerum Natura, book II, 1st century BC), Nicholas of Cusa (15th century), and Giordano Bruno (16th century). The idea was happily adopted by science fiction writers, such as Lucian of Samosata (Vera Historia, 2nd century) and Cyrano de Bergerac (Comic History of the States and Empires of the Moon, 1656), of whom I spoke in another post.

During the 19th century, public attention focused on possible intelligent inhabitants of other bodies in the solar system, especially the moon and Mars. In 1835, The Sun newspaper published in New York six false reports declaring that flying men had been discovered on the moon. It is said that nine out of ten Americans believed it. In fact, The Sun had published a science fiction novel as though if it were real news, making reference to existing people, such as the astronomer Sir John Herschel. Near the end of the century, The War of the Worlds by H.G. Wells (1898) raised the possible existence of Martians, at the time of the scientific controversy over the canals of Mars, which was not finally solved until 1965.

Chariots of the gods

During the 1970s, a Cinerama film with the same title as this post was exhibited and advertised with the following words: Can we say that the existence of extraterrestrial intelligent beings has been proved?

Although watching the film was worthwhile, because it shows many wonderful landscapes and artistic works, I was not convinced by the point it was trying to make. Eric von Däniken, author of the book of the same title, in which the film is based, seems to have very little faith in man’s creative capacity. As soon as a human production seems difficult, he always attributes it to the intervention of aliens. He does so with the pyramids of Egypt, the Mayan astronomical observatories, the mortar of the Incas, and many other things.

Jules Verne’s scientific predictions for 2889

Jules Verne

In a science fiction story published in English in the United States in 1889, entitled In the Twenty-Ninth Century and subtitled One Day of an American Journalist in 2889, Jules Verne made several scientific predictions that, according to him, would take almost a millennium to be put into practice. Let us look at a few of the most interesting:

•         The average lifetime of the human population will have increased from 37 in 1889, to 68 in 2889. According to the UN, the average longevity in the world exceeded 68 years in the five-year period from 2005 to 2010, almost nine centuries before Verne’s forecast. Here, as elsewhere, he underestimated.

•         The land and sea voyages of the nineteenth century will have been replaced in the XXIX by air travel, or intercontinental underwater pneumatic tubes. At present, little more than a century after Verne’s story, although air travel has achieved great primacy, land and sea travel continue to exist, and for distances less than a thousand kilometers make a successful competition to air travel. Intercontinental pneumatic tubes, on the other hand, are still science fiction, although there some recent steps in this direction.

The mystery of the Great Pyramid

The Great Pyramid of Giza, also called Pyramid of Cheops or Pyramid of Jufu, was built to be the tomb of the pharaoh Jufu (called by the Greeks Cheops), of the fourth dynasty, the high point of the Ancient Egyptian Empire. The reign of Jufu is usually dated in the 26th century before Christ, over 4500 years ago.

The current height of the Great Pyramid is 138.8 meters, but the pyramid is truncated, having lost its top. It is easy to calculate that its original height was about 8 meters higher: 146.7 meters, or 280 Egyptian cubits. The base of the pyramid is a square with a side of 230.34 meters, or 440 Egyptian cubits.

Observe a curious point: the semi-perimeter of the pyramid (twice the side of the base) is equal to 880 cubits. If we divide it by the height of the pyramid, we get the following:

(880/220) = (22/7) = 3.142857...

The eerie silence

A little over half a century ago, saw the beginning of project Ozma (named for the princess ruling the fictional country of Oz), which continued with the SETI program (Search for ExtraTerrestrial Intelligence). Assuming that there must be many cases of extraterrestrial intelligence, most of which will undoubtedly have reached a technology capable of communicating by means of electromagnetic waves, surely some of them are sending messages that perhaps we can detect and answer. Initially it was thought that we could take the initiative, sending messages to stars that might harbor planets with life similar to ours, but this was soon considered too expensive, so all efforts were allotted to intercept messages, not necessarily addressed to us. After half a century of efforts, nothing has been achieved. There have been a few false alarms, but none that has been confirmed.

In a previous article I mentioned the Fermi paradox, which holds that we must be alone in the galaxy, because otherwise any extraterrestrial intelligence with several million years advantage would by now be here, because it would not take long to colonize the whole galaxy, even at the interstellar speeds we will reach in the next few centuries.

Are we alone in the galaxy?

Enrico Fermi

In their famous book of hard scientific popularization, The Anthropic Cosmological Principle, published in 1986, the cosmologists John Barrow and Frank Tipler offer a proof that we are alone in the galaxy by means of a variant of the Fermi paradox (if there are any extraterrestrial intelligences in the Galaxy, why aren’t they here?) which can be summarized as follows:

1.      In 100 years we will have succeeded in creating life in the laboratory. Not just life, we will also be able to build a complete human being from its chemical components and information about the human genome, which can be stored in a digital memory.

2.      In 100 years we will have managed to build artificial intelligences as intelligent as human beings, able to replace us in any place and circumstance.

3.      Our current space technology allows us to reach a speed of 0.0003 c (where c is the speed of light). At that speed, a spaceship would take about 50,000 years to reach the nearest stars.

Anthropic and supranthropic properties

In a previous post I wrote about the fine tuning problem, based on the verification that many of the properties of the universe seem designed to make our existence possible. In other words: those properties verify the anthropic principle, another way of saying that the universe must fulfill all the conditions needed for our existence, since we are here. On the other hand, the mediocrity principle states that the anthropic conditions of the universe should be the necessary minimum to make our existence possible.

Robin James Spivey has lately published a book titled Aqueous solution, where he asserts that certain properties of the cosmos are supranthropic (they go beyond the anthropic principle) because they are not required for our existence, but their presence guarantees our long-range survival. According to Spivey, those properties are an inkling of design stronger than the anthropic properties, as the mediocrity principle opposes their presence.

The probability of existence of extra-terrestrial intelligence

Normal statistical distribution.
The text makes reference to a uniform statistical distribution.

Probability is a well-known mathematical concept that was initially defined to quantify random data in mathematically known environments and has been extended to other situations.

For instance, the probability that the next car passing near me has a license plate with four identical figures is computed by dividing the number of favorable cases between the number of possible cases. The first number is ten: 0000, 1111, 2222, ... , 9999. The second is ten thousand: 0000, 0001, 0002, ... , 9998, 9999, in a uniform distribution. Therefore the indicated probability can be computed as one thousandth. Here we haven’t considered that vehicles can be removed from circulation, an independent random process that would not change significantly the result of the computation.

The problem is, sometimes we are interested in computing data in mathematically unknown environments. This can happen, for instance, when we ignore the number of favorable cases, or the number of possible cases, or both. In such situations, we can estimate the unknown data with more or less uncertainty. We speak then of a priori probability.