Thursday, October 26, 2017

Some clarifications on the cosmic background radiation

In 1948, Ralph Alpher and Robert Herman (both in George Gamow’s team) came to the conclusion that if the universe had come out of a Big Bang and had expanded since that point in time, there should exist a cosmic background radiation in the frequency of microwaves (or what means the same, at a temperature of about 5K, 5 degrees above absolute zero). Alpher and Gamow had published that same year another prediction about the average composition of the cosmos, starting from the Big Bang theory.
In 1964, Arno Penzias and Robert Wilson were working with a newly built very powerful radio telescope and detected a background noise that could not be eliminated. First they thought that it would be of terrestrial origin, but once all the possible sources of noise had been taken into account, the effect persisted. Then they came to the conclusion that such noise could not come from the solar system or from our galaxy (for in that case it would be more intense in one direction than in another), and that its origin had to be cosmic. The temperature of that radiation (that is, its frequency, considering the Wien equation) turned out to be about 3K. Robert Burke of MIT suggested to Penzias that such noise could be the cosmic background radiation predicted by Alpher and Herman. This was in fact confirmed. For their discovery, Penzias and Wilson received the Nobel Prize in 1978.
Along with the argument based on the average composition of the universe, the cosmic background radiation gave the accolade to the Big Bang theory, which became the standard cosmological theory (although see an earlier article on this blog).

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.