A Radio Telescope on the Moon

One of the most interesting radio frequencies for radio telescopes is that emitted by hydrogen atoms when excited by an energy input. Upon returning to its ground state, the atom emits a photon with a frequency of 1.42 gigahertz. This frequency corresponds to the microwave region, which ranges from 300 MHz to 300 GHz. If we focus a radio telescope on a cloud of gas and dust in our galaxy, which is composed mostly of hydrogen, this frequency is easy to detect.

But what happens if we try to detect this frequency in very distant regions of the universe? The expansion of the universe affects these waves by lengthening them (that is, decreasing their frequency), in the same way as the frequency of the cosmic microwave background radiation, which was initially in the visible and infrared regions of the spectrum, is now in the microwave region, with its peak at a frequency of 160.2 GHz.

Mysterious Particles

Some physicists sometimes act as if the hypotheses they propose to explain the mysteries of the universe are always true. But a hypothesis is nothing more than a proposal to explain a natural phenomenon, and it cannot be considered a confirmed theory until it has provided one or more surprisingly accurate predictions. This last detail, which is essential, is usually omitted.

In 2020, I read two popular books on cosmology and particle physics (the two branches of physics are closely related):

Can density be infinite?

First photo
of a black hole

Einstein’s general theory of relativity allows for the existence of objects with infinite density (singularities). There are two types:

1.      Black holes, accumulations of matter in a null volume, either at the center of a galaxy, or as the result of a supernova explosion.

2.      The universe, at its initial moment (the Big Bang).

A star like the sun is in equilibrium because the gravitational attraction, which tends to make it contract, is equal to the expansion caused by the nuclear reactions taking place inside the star. When a star much larger than the sun exhausts its nuclear fuel (first hydrogen, then helium, then other elements), as there are no longer nuclear reactions to stop the contraction, the star implodes. When the implosion rebounds, the star throws large quantities of matter into space: a supernova explosion, which for some time makes the star brighter than a whole galaxy. But there is always a remainder of matter, which gives rise to a new type of object.

Is time infinite?

S.Augustin, by Louis Comfort Tiffany
Lightner Museum

Since ancient times, man has been interested in the enigma of time. Even though we all experience time, time is an enigma. As St. Augustine said in his Confessions (B.XI C.XIV): What is time? If no one asks me, I know; if I want to explain it to a questioner, I don’t know.

As I said in another post, the explanations devised to solve the enigma of time are of two types: those that consider it cyclical, with or without multiple repetitions, which would allow the passage of time to be represented geometrically by a circle, and those that consider it linear, which represent it by a straight line. In turn, this last case is divided into several: one can accept, or not, that time had a beginning; and one can accept, or not, that there will be a final moment of time. Combining these two alternatives, we have four different cases. So in total there are six possibilities, which we will analyze next in the light of modern cosmology:

Singularities

Hal 9000, from the film
2001, a space odyssey

A singularity is a mathematical concept applied to a function of a variable that reaches an infinite value for one or several finite values of its independent variable.

For example, the function y=1/x presents a singularity for x=0, since it is often said that 1 divided by zero is equal to infinity.

Three questions without scientific answers

Although I have spoken about some of these things in other posts, I’ll put together here three questions that, for now, don’t have a scientific answer, and perhaps never will.

• Did the universe begin to exist at the Big Bang, or was there something before? This controversy is much older than many think. Three quarters of a millennium ago, Thomas Aquinas wrote this in his Summa Theologiae (Part I, Question 46):

It cannot be proven by demonstration that the world has not always existed.

In other words, according to Aquinas, the question of creatio originans (that the world had a beginning) cannot be solved by human reason. It should be noted, however, that creatio ex nihilo (the fact that the world was created) would be within the reach of reason. In other words: reason would let us reach the conclusion that the universe was created, but we cannot prove that it had a beginning.

Roger Penrose versus William Craig

Roger Penrose

I thank Plácido Doménech Espí for drawing my attention to this debate held in 2019 between Roger Penrose and William Craig, entitled The Universe: How did it get here & why are we part of it?

Roger Penrose rose to fame as a cosmologist in 1970 when he proved, with Stephen Hawking, a theorem stating that the application of Einstein’s theory of General Relativity to the entire universe requires the existence of at least one singular point in the universe (a point where all the geodesics of the universe meet). In other words, the Big Bang.

In 1989, Penrose became one of the most famous scientific popularizers with The emperor’s new mind, a book with deep philosophical implications. Among other things, he proposed the following question, inspired by Gödel’s theorem: how is it possible that we can prove that a theorem is true, if it cannot be proved mathematically from a reasonable set of axioms? According to Penrose, this would indicate that human intelligence is qualitatively different from computing machines.

In 2004 he published a book of extremely hard popularization, The Road to Reality, which is full of equations, where he proposes a unification of Einstein’s general relativity with quantum mechanics (a theory of quantum gravity). Then came his own cosmological theory, Conformal cyclical cosmology (CCC), according to which the universe did not begin with the Big Bang, which would only be the beginning of the current aeon, but there would be an infinite succession of previous eons, each beginning with a Big Bang and evolving to global heat death, when all that would remain in the entire universe would be photons. At that moment, (no one knows how) the entropy would suddenly drop to a minimum value again, to start a new cycle.

William Craig has proposed the kalam cosmological argument, which can be summarized thus:

1. Whatever begins to exist, has a cause of its existence.
2. The universe began to exist.
3. Therefore, the universe has a cause.

William Lane Craig

Craig argues that the Big Bang was the beginning of the existence of the universe, so there must be a cause for that existence: an uncaused Creator, existing without beginning, changeless, immaterial, timeless, spaceless, enormously powerful, and omniscient, to be the author of the abstract world. In other word: God.

In the debate, Penrose began by arguing that there are three components of reality: an abstract or Platonic world (mathematics); a physical world (the material world); and a mental world (the world of consciousness). In addition, he points out the existence of three mysteries, which refer to the relationships between these three worlds:

1. The unreasonable effectiveness of mathematics (Eugene Paul Wigner): Why does the abstract world describe so well the workings of the physical world?
2. The origin of consciousness: How can consciousness arise from the physical world?
3. The mind’s ability to understand the abstract world: Why can we understand mathematics and apply it to describe counterintuitive phenomena?

Craig agreed with Penrose’s analysis, and added this consideration:

The abstract world cannot be the cause of the other two worlds, the physical and the mental, because it has no causal power and cannot make decisions. It is not clear that the physical world is the cause of the mental world: Penrose himself admits that this is a mystery. Can the mental world be the cause of the physical and the abstract worlds? It appears it can: we have the experience that our minds can produce physical changes through human intentionality. Could there not be an omniscient mind who is the author of the physical and the abstract worlds? That would solve the problem of the origin of the three worlds.

To this, Penrose could only reply that he does not like this idea (he declares himself an atheist) and would rather think that the abstract world is primordial, although he does not know how the other two worlds could proceed from the abstract world.

The second part of the discussion dealt with the fine-tuning problem. Craig indicated that there are three solutions to the problem:

1. Universal constants must have the value they have.
2. Our existence in such a fine-tuned universe may be due to chance in a multiverse.
3. Our universe has been designed by a Creator.

Penrose began by denying that fine-tuning is a fact, although he ultimately declared himself agnostic about this question. He proposed his CCC theory as an explanation of the origin of our universe. Craig pointed out that this theory is just another multiverse theory, in time rather than in space, (most multiverses are supposed to exist in space). Penrose, for whom this idea seemed to be new, embraced it happily and asserted that his theory has been experimentally confirmed, an assertion most current cosmologists would not accept.

My conclusion from this debate: Penrose was mostly on the defensive, and he was unable to offer one convincing argument in favor of his atheism.

The same post in Spanish

Thematic Thread on Science, Faith and Atheism: Previous Next

Manuel Alfonseca

Science or imagination?

A large part of the "scientific" research currently being developed, rather than being science, is just an exercise of the imagination of "scientists." It seems that we must consider as scientists all those who do mathematical speculations that have little or nothing to do with reality. And naturally, everything a scientist does is “science”. At least, scientific journals and high-profile media consider it as such.

Matter and antimatter. Why are we here?

The matter making the solar system, the Earth, all living beings and ourselves, is made up almost entirely of atoms which, in turn, are based on three elementary particles: protons, neutrons and electrons. For each of these particles, as well as for many others, not usually part of atoms, there is an antiparticle. Therefore, there could be antimatter antiatoms, made of antiprotons, antineutrons, and antielectrons (positrons).

An interesting property of matter and antimatter is that they cannot be together. As soon as they come into contact, they completely disintegrate, transforming into energy. Everything suggests that our galaxy (the Milky Way) is made up almost exclusively of matter. There is also some antimatter, in the form of antiparticle clouds, outside the galaxy, close to it and attracted by its gravity, but in such a small quantity, compared to the mass of the galaxy, that for practical purposes it can be ignored. It has also been said that there could be some (but very few) anti-stars.

The hijacking of the Big Bang

The Big Bang theory was invented in 1931 by the Belgian priest Georges Lemaître, through the backward application in time of the Hubble-Lemaître law, discovered by Lemaître in 1927 and independently by Hubble in 1929. Indeed, if most galaxies are moving away from one another, because of the expansion of the space separating them, billions of years ago they must have been much closer, and at the limit all the visible universe would have shrunk to a point. We believe today that this happened about 13.8 billion years ago.

In 1948, George Gamow, Ralph Alpher and Robert Herman made two predictions that should be fulfilled if the Big Bang theory were true: the mass of the universe should consist of about 75% hydrogen and 25% helium; and there should exist a cosmic background radiation with a temperature of about 5º Kelvin. Other cosmologists, however, took this theory as a joke, and to make fun of it they gave it the name Big Bang, which although not quite appropriate, has remained fixed, perhaps forever.

My 10 Favorite Scientific Discoveries of the 20th Century

In a post published two weeks ago, I commented on an article in Science News that tried to answer this question: which were the ten most important scientific discoveries of the last century? Some of my readers asked what is my personal opinion. This is my answer.

To begin with, I will point out that scientific research can advance in four different ways:

1. Theoretical science, which tries to discover fundamental laws in the universe.
2. Experimental science, which confirms or falsifies theories by carrying out experiments.
3. Observational science, which instead of experimenting, observes. Astronomy, for instance, uses these methods, as experimentation is almost never possible.
4. Technology, the practical application of science, whose goal is to build devices that work.

More scientific misrepresentations from the media

On my first day every year, lecturing in the degree on Telecommunications Engineering, I used to say this to my students:

Don't believe any scientific news published in the press or in generalist media. Most of them are false or have been misunderstood.

In previous posts I have mentioned several cases of scientific misrepresentation by the media, although sometimes the fault lies not with the journalist, but with the scientist, who tries to sneak in philosophical ideas based on reductionist materialism as if they were science. In this post I'm going to comment on three relatively recent news stories, published in the Spanish press, and try to explain what is really behind them.

A Singular Universe

Javier Sánchez Cañizares is one of the contributors to the book Preguntas sobre Ciencia y Fe, published in 2014 and republished this year. In 2020, Javier has published a book in Spanish with the same title as this post, which can be considered as a book on philosophy of science at a high level of popularization. The goal of the book is to show that materialistic reductionism has no chance of providing a correct complete explanation, as our universe is singular because of several different reasons:

Scientific models: adjustment or validation?

Leonard Nimoy
as Mr. Spock

One of the ways in which science advances is by building models, which are often made up of more or less complex sets of mathematical equations, and trying to verify whether or not these models adapt to the functioning of the real world, as described by our senses and our instruments.

When building and using a model we must consider two distinct phases:

• Model adjustment: it consists of assigning values ​​to the parameters of the model to ensure that it fits the data we already have about the real world. A model not adjusted to such prior knowledge would be totally useless.
• Model validation: it consists of using the model to make surprising predictions that nobody could have foreseen without the help of the model. If these predictions are confirmed, they become surprising accurate predictions, validating the model. However, the validation is never final, for a new surprising inaccurate prediction could invalidate it in the future.

Let's look at a few examples:

Is there energy in the cosmos?

Georges Lemaître

During the 1950s two cosmological theories entered in competition: the Big Bang, proposed by Georges Lemaître, and the steady state, proposed by Hermann Bondi and Thomas Gold. Although the second had to renounce the principle of the conservation of energy, the most sacred of physics, atheist cosmologists preferred it to the Big Bang, as it seemed to them that this theory required to accept God's creation. In the words of the English astronomer Raymond Littleton, in his popularization book The Modern Universe (1956):

A theory such as this [the Big Bang] that puts back creation to a singular instant in the remote past... to some minds it is an objection that it would imply the removal of the question of the origin of the material of the universe from the realm of science... This consideration does not of course mean that the explosion theory is necessarily wrong, but it puts the act of creation, as we might name it, beyond the reach of science.

In other words: Raymond Littleton objects to the Big Bang theory because it could force us to recognize the existence of a creative God. It cannot be said more clearly.

4 clarifications about the history of the universe

James Peebles

Certain statements by James Peebles, recent Nobel Prize in physics, have aroused controversy, although what he said is not something new, as theoretical physicists have long been saying precisely the same thing.

The Big Bang theory was proposed in 1931 by Georges Lemaître, by extending to the past the Hubble-Lemaître law. In 1948, Ralph Alpher and Robert Herman predicted that, if the Big Bang theory is correct, there must be a cosmic background radiation with a temperature close to 5 Kelvin. In 1965 Arno Penzias and Robert Wilson discovered the existence of such cosmic radiation, whose temperature proved to be 2.72548 Kelvin. The temperature is exactly the same in all directions, except for two effects that cause small differences, but never affecting more than the third decimal place.

Mistakes in popular science in the media: Stephen Hawking didn’t discover everything

Stephen Hawking

Stephen Hawking has been in the last decades a scientific icon for the media. His painful personal situation turned him into a celebrity who inevitably attracts attention. Therefore, the media have a tendency to exaggerate his scientific work, attributing to him achievements that weren’t his, which he would be the first to repudiate, if he were still among us.

For example, on the occasion of his death, the following headlines appeared in several media:

•         AlDiaNews.com: Stephen Hawking, author of the Big Bang theory dies at 76

•         ElTiempoHoy: Creador de la teoría del Big Bang y los agujeros negros: fallece Stephen Hawking a los 76 años. (Creator of Big Bang’s theory and black hole theory: Stephen Hawking dies at 76).

•         Gizmodo Univisión: Del Big Bang a la Teoría del Todo: el increíble legado científico de Stephen Hawking (From the Big Bang to the Theory of Everything: Stephen Hawking’s incredible legacy).

The standard cosmological model

Map of the Cosmic Background Radiation

In 1927, the Belgian priest and astronomer Georges Lemaître discovered Hubble’s law.

Yeah that’s right. Hubble did not discover the law until 1929. What happened was that Lemaître published it in French in a low-impact journal (Annales de la Société Scientifique de Bruxelles), while Hubble published it two years later in English in the Proceedings of The National Academy of Sciences, received much more publicity and his name got associated with the discovery.

Combined with Einstein’s cosmological equation, Lemaître-Hubble’s law implies that the universe is expanding. In an article published in 1931 in Nature, Lemaître drew the consequence by proposing the Big Bang theory, so called in derision by its opponent Fred Hoyle in 1950. The name caught on.

In 1948, Ralph Alpher, George Gamow and Robert Herman made two surprising predictions, based on the Big Bang theory: the average composition of the mass of the cosmos (three quarters hydrogen and one quarter helium), and the existence of the cosmic background radiation. Both were confirmed during the sixties. From that point, the Big Bang theory became the standard cosmological theory.

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).

Pending problems in the standard cosmological model

The standard cosmological model, prevailing since 1998, is called LCDM and is based on the following statements:

• The universe began with a Big Bang, after which there was a phase of accelerated expansion (inflation), which then declined to levels close to the current ones. Ordinary matter appeared later, formed essentially by hydrogen and helium.
• The average curvature of the cosmos is close to zero (flat universe): three-dimensional space is approximately Euclidean.
• The average density of matter in the cosmos is equivalent to about 30% of the critical density (which separates an open, unlimited expanding cosmos from a closed cosmos that would contract again). Since the ordinary density of matter detected so far represents less than 5% of critical density, the remainder (over 25%) must be an unknown form (dark matter). In fact, it would be what is called cold dark matter, which explains the initials CDM in the name of the model. I talked about dark matter in an earlier post.