A mathematical model for time travel

Welcome for time travellers

On May 2 2017, Newsweek published an article with this title:

Time travel is mathematically possible with mind-boggling model

You may well imagine that, with that title, the article will rather fall into the category of sensationalist papers on seemingly scientific issues. Indeed, in a quick reading of this article I have detected the following inaccuracies:

1. The title does not make clear the difference between a theoretical possibility of traveling in time and building a time machine. That is, the different between theory and practice. What Ben Tippett has developed is a purely theoretical mathematical model.
2. It presents the idea as something new which puts an end to a string of failures and disappointing calculations. Space-time loops, however, are known to be compatible with the general theory of relativity since quite a long time ago. In 1992, for instance, Stephen Hawking came to the conclusion that it would not be possible to use them without negative energy, something that is not known to exist. In 2005, the Israeli Amos Ori proposed a procedure that would not require it, consisting of spinning around an empty toroid region surrounded by a sphere containing enormous amounts of matter (e.g. a black hole). This is not so different from what is being proposed now.

Is the increase in life expectancy accelerating?

Nick Bostrom

Some philosophers, such as Nick Bostrom and the transhumanists, have concocted an updated version of Nietzsche’s superman. Their forecasts are based on two scientific advances presented as imminent since several decades ago: immortality, which will be attained when the advances in medicine increase life expectancy beyond one year per year; and artificial intelligence, the design of super-intelligent machines. Both advances could be combined to attain immortality through artificial intelligence, by downloading our conscience (something we cannot even define scientifically) into a super-intelligent machine, so that it would go on existing inside the machine.

Unfortunately for transhumanists, the UN data do not confirm their expectations. Let us look first at the data about the evolution of the maximum life expectancy in the world from 1950 to 2015 (see table 1). These and the following data have been taken from https://esa.un.org/unpd/wpp/Download/Standard/Mortality/.

Four ideas by Alvin Plantinga about God and materialism

Alvin Plantinga

Taking advantage of the awarding of the Templeton Prize to the American philosopher Alvin Plantinga, this post will try to review a few of his thoughts in the debate between theism and materialism. As it is impossible to review all his work in detail, I will mention just four of his ideas:

1. The Mozart argument for the existence of God. Why are we able to appreciate beauty? According to the materialistic hypothesis, there is no explanation why evolution has led us to this, as it is difficult to see how this trait could be useful for our survival. Instead of good music, we should appreciate cacophony, which is more abundant in nature. If we assume that God exists, however, this fact is easy to explain, because God appreciates beauty (in fact, God is beauty). This argument, along with many others, is in this web address.

Is there a universe?

The Spanish Wikipedia defines the universe thus:

The universe is the totality of space and time, all forms of matter, energy and momentum, plus the laws and physical constants that govern them. However, this term is also used in slightly different contextual senses and refers to concepts such as cosmos, world or nature. Its study, at the highest scales, is the object of cosmology, a discipline based on astronomy and physics, which describes all the aspects of this universe, together with its phenomena.

Before applying to the universe, the Greek word cosmos meant order and beauty. Notice that this sense is maintained in one of its derivatives, the word cosmetic. The Latin word mundus also has the two meanings: as a noun, it means the world, the totality. As an adjective, clean, neat, elegant. Presumably the first sense was copied from Greece, and to translate the world cosmos they adopted the same word that represented in Latin its other meaning. Finally the word nature (physis in Greek) has phenomenal connotations (rather than to the universe, it refers to what happens in it). From this word come physics (the study of nature) and metaphysics (beyond physics).

Truth and New-Age syncretism

“What is truth?” asked Pilate. We are still asking. There are now philosophical currents that deny the existence of the truth, or the possibility of knowing it. Science, however, aims at the discovery of truth, and the fact that technology works, seems to indicate that the scientific discoveries of the last centuries, which have made our technological advances possible, must represent, at least in part, the truth about the world around us.

There are several different types of truth:

• Scientific truth: It is an incontrovertible fact that there is a cosmic background radiation. But the theories we use to explain its existence may not be true, or may be incomplete. Scientific theories are validated in terms of the facts they predict or explain. Thus, Einstein’s General Relativity is considered closer to truth (or to reality) than Newton’s theory of Gravitation, because the former explains the same facts as the latter plus a few more.
• Philosophical truth: Aristotle’s hylomorphism may be debatable, but assertions such as something exists, nothingness does not exist, are indisputable. Philosophical theories are validated on the basis of the evidence of their axioms or starting points (as cogito ergo sum) and the validity of their reasoning.

Another failed prediction

As you know, I love to point out the mistakes made by those who make future predictions. Since I was little more than a teenager, I have been saving clippings from the press and scientific journals that make more or less reasonable forecasts about the evolution of science and technology. In an earlier article I have pointed out that such predictions are seldom met, even when made by people who are both scientists and visionary, famous science fiction authors such as Arthur C. Clarke or Isaac Asimov.

I just unearthed an article published by Alexander Kusko in the IEEE Spectrum magazine in April 1968, with the following title:

A prediction of power system development, 1968 to 2030

And the following subtitle:

By predicting the trend of future power system design some 60 years hence, we should be better equipped to solve some of the technical and sociological problems that the industry faces today.

The assumptions on which Kusko's predictions were based were the following:

1. The population will triple. What did actually happen? The world’s population in 1968, according to UN data, was about 3.5 billion people. The world population in 2015 was 7.35 billion. According to UN estimates, the world population in 2030 will amount to between 8.2 and 8.8 billion people. Far from the 10.5 billion estimated by Kusko.

Turgenev and unhappy love

Alfred L. Kroeber

Together with Spengler, Toynbee and Sorokin, the American anthropologist Alfred Louis Kroeber was one of the four great philosophers of history in the twentieth-century. Father of the famous science fiction writer, Ursula Kroeber Le Guin, A.L. Kroeber hypothesized that cultural configurations begin with a precursor genius, continue with a stage of maximum bloom, and then enter a period of decay, more or less extended in time.

The history of Russia during the nineteenth and twentieth centuries provides two perfect examples for Kroeber’s analysis, two astonishingly parallel and simultaneous configurations in two different fields of culture: literature and music.

• In Russian literature we can point to a clear precursor (Pushkin), a time of maximum bloom (Gogol, Lermontov, Dostoyevsky, Turgenev, Tolstoy and Chekhov), and a period of slow decline (the Russian authors of the twentieth century).
• In Russian music there was also a precursor (Glinka), a period of maximum flowering (Borodin, Mussorgsky, Tchaikovsky, Rimsky-Korsakov) and another of slow decay (Rachmaninoff, Stravinsky, Prokofiev, Shostakovich).