Thursday, September 21, 2017

The Tunguska event

On June 30th, 1908, at dawn, a mysterious explosion took place in an almost uninhabited region of central Siberia. The explosion leveled 2000 km2 of taiga, uprooting about 80 million trees, which were left lying on the ground, away from the central point of the event, like the spokes of a wheel. The most probable theory considers the event as the impact of a meteorite or comet, although nobody could find the debris. Unlike other cases, as the Arizona Meteor Crater, no crater was found in the place of the event. As an explanation of these anomalies, it was concluded that the explosion of the celestial body took place at a high altitude (between 5 and 10 km). Taking into account the effects, it has been calculated that the energy released by the explosion would be in the span of 3 and 30 megatons. Recall that the most powerful nuclear weapon ever detonated (by the Soviet Union) was a 50 megatons hydrogen bomb, over 1000 times stronger than the Hiroshima bomb, which only released 20 kilotons. (One megaton equals 1000 kilotons). During the cold war, the Soviet Union boasted of possessing an even larger bomb (100 megatons) that they couldn’t use in Europe, as the effects of its explosion would reach their own territory.

Thursday, September 14, 2017

A few clarifications on the quantum revolution

First of all, let as clarify a few concepts, for recent news published in the media tends to encourage confusion.
·         Qubit: the quantum unit of information. While classical information is expressed in bits, which may take only the values 0 or 1, qubits are formed by superposition (or linear combination) of two quantum states, |0> and |1> (i.e. the horizontal or vertical polarization of a photon) and its value is: α|0>+β|1>, where α and β are two complex numbers called probability amplitudes.
·         Quantum Cryptography: It encrypts information through a protocol that takes advantage of the quantum properties of matter. The procedures devised so far can be deciphered by opponents using quantum procedures, but it is known (or believed) that they are impossible to decipher by classical means. The first quantum cryptography protocol, BB84, was proposed in 1984 by Charles Bennett and Gilles Brassard of IBM.

Thursday, September 7, 2017

Medical Dietetics, Science or Fashion?

Food containing magnesium
The advices given by medical dieticians about healthy food oscillate continuously as time goes by. They rather look like the alternatives of fashion, than the discoveries of science. Here are a few examples:
         In the fifties and sixties it was fashionable to disparage the consumption of olive oil and recommend the use of seed oils, supposed to be healthier. Heart patients were advised to consume various seed oils, while olive oil was not even mentioned. Sometimes it was asserted that the consumption of olive oil increases cholesterol in blood. This policy caused significant damage to Spain, one of the main olive oil exporters, as stated in a newspaper article published in 1968:
The economic problems of the olive grove are motivated, to a great extent, by the change in the taste of the consumers, who sometime ago were forced to use different seed oils, and now, when we are trying to bring them back to a higher consumption of olive oil, they don’t want to do it in the proportion advisable for this market of the Spanish fruit, as it is rather more expensive.

Thursday, August 31, 2017

The scientific ignorance of politicians

Robert N. Proctor
Let’s look at a few recent quotes in the press about the scientific ignorance of politicians, as a sample of a new discipline called agnotology by Robert Proctor:
- Ross Pomeroy, August 23, 2012. Headline: Politicians ignorant of science because we are. This article contains the assertion that the percentage of scientists (including medical fields) in the US House of Representatives is 6.9%, about the same as the proportion of scientists in the global population (6.4%).
- Nigel Morris, August 2, 2010, Independent (UK). Headline: Only scientist in Commons ‘alarmed’ at MPs ignorance. The text explains that Julian Huppert, a research biochemist who became the Liberal Democrat MP for Cambridge at the last election, said he was alarmed at the lack of scientific knowledge among colleagues.

Thursday, August 24, 2017

62 years later: scientific predictions by George Thomson

George Paget Thomson
In a previous post in this blog I expressed distrust about the predictions made by scientists and popular writers about the future of science and technology. Most of them never take place. Sometimes they are overly optimistic, sometimes overly pessimistic.
Sometimes, however,  they are true, if only in part. In 1955, George Paget Thomson (Nobel Prize in physics for the discovery of electron diffraction) published a book about technological predictions (The Foreseeable Future, Cambridge University Press). I will summarize here the conclusions of his first chapter about the future of energy:
Until the population increase can be stopped, which is not foreseeable until 2050, energy consumption will continue to increase. Among the various sources, hydraulics will quickly reach its practical limits; coal and oil will be depleted sooner or later; solar energy is too dispersed and its use too expensive; wind and tidal power will never be major sources. The only alternative is nuclear energy: for the time being, fission energy, until fusion becomes possible.
This paragraph written 62 years ago could have been written today. In this field, progress has been very slow. In contrast, Thomson’s predictions about the evolution of transportation have been less accurate and can be summarized as follows:
Increasing the maximum speed of cars does not make sense. The maximum speed in railroads (100 miles per hour) has hardly grown in the last century and  is not expected to improve much. The only option to increase the speed of shipping would be by building large submarines powered by atomic energy, capable of moving at 60 or 70 knots. Major advances can only be envisaged in commercial air navigation, which will soon reach 2.5 times the speed of sound: crossing the Atlantic will take one hour.
Thomson’s predictions for commercial air navigation have not been met. The only step in that direction, the Concorde, was a failure. The super-submarines have never come into existence. By contrast, railroads have more than doubled their top speed.
In biology, he correctly predicted the rise of biotechnology, genetics and the industrial use of microorganisms. In medicine, on the other hand, he expressed doubts about increasing the average duration of human life beyond 70 years (by 1955 it was 63) unless it were possible to eliminate death completely and maintain youth indefinitely. In his words:
This new state of affairs will profoundly alter man’s attitude toward death, perhaps not for his good. It will make him more cowardly, as he will have more to lose.
Thomson fails dramatically in his predictions about the future of computing. He believes that one can now say that computers do think (while they were in the first generation!), But the only future applications he envisages are the verification of scientific theories and performing economic and electoral predictions. As their publication can influence the result of what they predict, he assumes that these predictions and polls will be considered top secret by governments. In this way, according to Thomson, the use of computers will lead, in the long run, to less information dissemination. What has happened is exactly the opposite.
It is interesting to mention his predictions about the importance of scientific popularization, which compensates for the growing specialization in science and technology:
[Popularization] is not easy to do, and those who dedicate themselves to it deserve as high a place in scientific estimation as the researchers. Generally, those who are not specialists in a field are better able to explain to others.

The same post in Spanish
Manuel Alfonseca

Thursday, August 17, 2017

Is time an illusion?

Albert Einstein
Physicists sometimes deny the reality of irreversible time and consider it an illusion, a psychological phenomenon. In a letter of condolence written in 1955, Einstein said this: ...the distinction between past, present and future is only an illusion, although persistent. A curious way to comfort those who have lost a beloved one. His reasons for saying this were the following:
·         In Newton equations of universal gravitation, if the sign of the variable representing time is changed, the equations don’t change. If we look at the film of a gravitational process, the theory predicts that we won’t be able to detect if the projection was made in the right sense or in reverse.
·         The same is true of Maxwell equations, which describe the behavior of electromagnetic waves.
·         The same is true of Einstein equations of General Relativity, which replace Newton equations to describe gravity.
·         The same happens with the Schrödinger equation, the basis of quantum mechanics.
But there is a problem: the equations mentioned do not make all of physics. The second principle of thermodynamics implies the existence of an arrow of time. In 1928, in a book titled The nature of the physical world, the inventor of this term (Arthur Eddington), said the following: if your theory [opposes] the second law of thermodynamics... [it will] collapse in deepest humiliation.
Every physical theory is a simplified abstraction where some parts of reality have been eliminated. If the irreversibility of time is one of those simplifications, it is not surprising that the final result is always reversible. In real events, however, there is no abstraction or simplification. All the physical theories, including the second law of thermodynamics, must be applied together. If this is done, the alleged temporal symmetry goes away.
Newton and his apple
One of the first applications of Newton’s theory describes the fall of an apple. If a film being projected shows several pieces of an apple on the ground, which suddenly set in motion and gather in a single fruit, which then rises upwards until it gets attached to a tree, would we doubt that it has been projected in reverse? The fact that we don’t is a consequence of the second law of thermodynamics.
·         This also applies to the movements of celestial bodies. Imagine a recording of Mercury moving in its orbit, with the sun visible. By studying the solar sunspots we could deduce whether the film is projected correctly or in reverse. Sunspots are a consequence of thermodynamic phenomena.
·         Radioactive decay is another example of a theoretically reversible process that in practice is irreversible. In fact, the proportion of uranium-238 and lead-206 in a rock provides a reliable method to calculate its age. The chain of disintegrations from uranium to lead is far more likely than the reverse chain, although physical theories affirm that both things could happen in theory.
·         Whatever Schrödinger equation says, the Copenhagen interpretation of quantum mechanics requires an irreversible time. If a photon hits an electron with some energy, the electron is left in two overlapping spin states. If the spin is measured, the quantum superposition collapses into a positive or a negative value. This process involves a direction of time: first comes the impact of the photon, then the electron in two superimposed states, finally a measurement and a quantum collapse. The reverse process cannot happen.
In these examples, when all of physics is taken into account without excluding thermodynamics, the supposed reversibility of time disappears. Apparently physicists put their theories above reality, doing the opposite of what the scientific method demands. Not even great men like Einstein were exempt.

El mismo artículo en español
Manuel Alfonseca

Thursday, July 13, 2017

The destruction of language

C.S. Lewis
Languages change continually. Over time, some words disappear, others are created to be applied to new concepts that did not exist before, and others change slightly in meaning. The process can continue until a word comes to mean something totally different from its original sense, or even opposed. Sometimes, various meanings of the same word coexist simultaneously.
In a book entitled Studies in Words, published in 1960, C.S. Lewis coined the word verbicide to refer to the murder of a word, making it lose its meaning with a use different than its previous one, which is subsequently lost. An equivalent symmetrical case is coining new words that are in fact totally unnecessary, since there were already other words perfectly applicable for that meaning.
The media have a great responsibility in these processes, since they frequently adopt, launch or indiscriminately copy vogue words, without regard to the consequences. Most of them are unnecessary or lead to the verbicide of some useful word. Let’s look at some of the ways this process can take place, as C.S. Lewis points out in the introduction to his book: