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