Thursday, October 19, 2017

Virtual particles

Werner Heisenberg
Heisenberg's uncertainty principle, one of the consequences of quantum mechanics, makes possible the birth of virtual particles in the void, apparently transgressing the principle of energy conservation, the most holy in physics. The reason is that Heisenberg’s principle can be expressed in several ways, one of which relates the uncertainty about the energy to the uncertainty about time:
This expression can be interpreted in the sense that a pair of objects, each with energy E, can appear spontaneously in the vacuum, provided that they lasts at most a time Dt<ħ/(2E). These pairs of objects are called virtual particles. One of these particles is always matter, the other antimatter, and their duration, according to this principle, is ridiculously small. A virtual electron, for instance, would last 1.3×10-21 seconds (just above one sextillionth of a second). The higher the mass (energy) of the virtual particle, the less time it will last. After that time, the two particles will annihilate each other and disappear. Due to their short duration, the existence of virtual particles has not been experimentally verified.
Is it possible for these virtual particles to become real under certain circumstances? Yes it is, and it is believed that there are at least two situations (somewhat drastic, it is true) where this could happen.

Thursday, October 12, 2017

Is physics losing touch with reality?

In his famous posthumous book The Discarded Image, published in 1964, a few months after his death, C.S. Lewis shows he is ahead of his time by predicting a situation that today, when it has become usual in physics, gives a rather bad forecast for the future of this science. Let’s look at a relevant quote:
The mathematics are now the nearest to the reality we can get. Anything imaginable, even anything that can be manipulated by ordinary (that is, non-mathematical) conceptions, far from being a further truth to which mathematics were the avenue, is a mere analogy, a concession to our weakness. Without a parable, modern physics speaks not to the multitudes. Even among themselves, when they attempt to verbalise their findings, the scientists begin to speak of this as ‘making models’... Sometimes [the models] illustrate this or that aspect of [reality] by an analogy. Sometimes, they do not illustrate but merely suggest, like the sayings of the mystics... By accepting [an expression such as] the ‘curvature of space’ we are not ‘knowing’ or enjoying ‘truth’ in the fashion that was once thought to be possible.

Thursday, October 5, 2017

Scientific mistakes in Planet of the Apes

In 1963, the French writer Pierre Boulle published a famous science-fiction novel titled Planet of the Apes, which was adapted to the cinema for the first time in 1968, with Charlton Heston as the protagonist and script by Michael Wilson and Rod Serling, the latter famous for the TV series The Twilight Zone. A decade earlier, Boulle had published another bestseller, also successfully adapted to the movies: The Bridge over the River Kwai.
Boulle’s novel tells the story of three astronauts embarking on a two-year journey (measured in relativistic time) to a planet revolving around Betelgeuse (alpha of the Orion constellation) and find there an extraterrestrial civilization at a level similar to ours in the mid-twentieth century, where intelligent beings are three species of apes (identical to the terrestrial gorillas, chimpanzees and orangutans) while human beings (also identical to us) are devoid of reason. Of course, the only surviving terrestrial astronaut finds it very difficult to convince the apes that he is an intelligent being.

Thursday, September 28, 2017

Plato's Timaeus, the philosophical basis of the medieval cosmological model

Plato, according to Raphael Sanzio
Among Plato’s dialogues, Timaeus has always captured the attention of scholars, for it represents the first description in Greek philosophy of a coherent cosmological model, which reached great resonance by becoming part of the medieval model through the partial translation into Latin of this dialogue by the mysterious Roman philosopher Calcidius.
Very little is known about Calcidius. Although he lived in the fourth century, we do not know his date of birth or death, nor the place where he lived. It is not even known whether he was a Christian or a pagan (a Neo-Platonist). His book is dedicated to a certain Hosius, who may or may not be the bishop of Cordoba who participated in the Council of Nicaea.
It is often said that medieval philosophy in Western Europe was based initially on Plato, and from the twelfth century on Aristotle. This happened because, in the realm of the Western Roman Empire, the knowledge of the Greek language had been lost, therefore the Greek classics could no longer be read in their original language. There were no Latin translations, for the illustrated Romans of the imperial period could read the Greek language perfectly, so did not need them. What is not usually mentioned is that Plato’s works had also become inaccessible, with the sole exception of the Timaeus, which in the partial translation by Calcidius knew an unexpected boom during the Middle Ages, even stronger than Calcidius’s work during his life.

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.