«The Big Bang theory, the 'grand explosion' that would have
given rise to our world, belongs to the general culture of our time; but few
know that it was first proposed by Georges Lemaître, physicist and Catholic
priest»[1]. Lemaître was able to arrive at this
cosmological model due to his commitment to a realistic philosophy and to the
fact that he knew how to combine theoretical reasoning with astronomical
observations.
Physics in Lemaître's times
The Big Bang
cosmological model was forged in the first half of the 20th century, which was
characterized by a crisis in all areas. In the field of the arts, for example,
classic molds were broken in order to bring about the consummation of
non-figurative painting, the theatre of the absurd and atonal music.
This crisis affected
science as well, because the confidence of the positivist man collapsed with
the arrival of the new physics. Quantum and relativistic theories presented a
different vision of reality: "the real elements were not the atoms of chemistry,
but the waves of electrons and protons, whose mutual interactions were governed
by the speed of light and the quantum of energy"[2]. Things were not that simple - as 'explainable' as they had appeared to
be in the previous century - although faith in the ability of human reason was
still absolute.
Art changed because
the mentality of the author and his concept of things had changed. Science,
however, was not moved not by fad or fashion, but because the nature of what
was observed turned out to be different than previously supposed: observed
reality was forcing it to change. Max Planck, the initiator of quantum theory,
expressed it thus in a conference which he pronounced in November, 1941:
"This relay becomes a bitter need wherever scientific research is faced in
nature with some new fact that the established way of representing the world is
not able to reason"[3].
Some scientists
renounced a rational understanding of the deeper realities when faced with this
disconcerting panorama. For others, the new physics represented a different way
of thinking: to accept that "the world of sensory perceptions was not the
only one that conceptually you could attribute existence, they also had another
world which [...] we could not access directly [...], but which inexorably
impelled the researcher to find its final form. And given that it was necessary
to assume the existence of that which is sought, it served to strengthen the
conviction that there truly was, in the absolute sense of the term, a real
world"[4].
Unraveling this real
world was not an easy task. The researcher could not settle for bringing to
light what was hidden in the apparent chaos. It should "admit successively
discovered universal truth, as an unknown land which was being explored and colonized"[5]. This was the attitude of certain researchers of the time, among them
Lemaître.
Lemaître's academic training
Georges Lemaître was
not alien to this context. However, the scepticism into which some fell did not
affect him. The strong religious training he received from his family and the
love of the classics taught in the Jesuit schools where he studied led him to
passionately seek the truth. As he himself said in an interview: "I was
interested in truth from the point of view of salvation as well as truth from
the point of view of scientific certainty. It seemed to me that there were two
roads leading to the truth, and I decided to follow one and the other"[6].
His childhood was
very normal. He was cheerful and communicative and did not show any special
inclination for anything. However, one teacher, Father Henri Bosmans influenced
his career choice by passing on his taste for the history of mathematics[7], encouraging him to read the original texts of the mathematicians of
ancient Greece, especially Euclid, as well as the more modern Euler and Laplace.
Arriving at the
University, he did not settle for technical engineering studies. His eagerness
to go beyond drove him to also enroll in the Philosophy School. Some of these
classes were taught by Désiré Mercier, future Cardinal of Mechelen, who founded
the priestly fraternity The Friends of Jesus, which Lemaître would later join.
As a child he dreamed
of becoming a priest, but his piety matured when he participated as a volunteer
in the First World War. During the war he had time to read and think. An author
who captured his attention was Léon Bloy. He was attracted by the religiosity
of this philosopher: reflexive, critical and full of love for the poor and
simple. This more intense spiritual life made him feel the need to find, from
time to time, moments exclusively dedicated to God. During these moments of
meditation he decided to change his engineering studies for physics and mathematics,
and later entered the Seminary of Mechelen.
While he was at the
Seminary, a book[8] on the theory of relativity by Albert Einstein fell into his hands,
written by Arthur Eddington, who became the main popularizer in the
English-speaking world of the works of the German physicist. He was so
captivated by the new theory that, as soon as he was ordained as a priest, he
went to the Cambridge Observatory to
study it under the tutelage of Eddington, with a scholarship that he had
obtained from the Belgian Government.
Lemaître's
ability to get on well with people and extraordinary
talent inspired Eddington to invite him join in his scientific research. He
explained the mechanisms that cause the energy radiated by the stars and the
correspondence between mass and luminosity and, most importantly, taught him to
relate astrophysics to the theory of relativity.
In addition, the two
coincided in the love of truth. The contemplative spirit of Lemaître provoked a
passion to reach the great and universal truth of the cosmos. Eddington, as a
Quaker, was constantly driven to inquire: "In science and religion truth
illuminates the forehead as a lighthouse showing the way; we are not asking to
reach it; it is much better that we are allowed us to search for it"[9] 9. This was another reason why both got along so well.
The following year,
1924-25, he traveled to the United States to attain his doctorate from the Harvard College Observatory and the Massachusetts Institute of Technology
(MIT), after obtaining another research grant. There he acquired fluency in the
calculation of stellar distances, using the observation of stars of variable
brightness called Cepheid variables. He also visited the Mount Wilson Observatory to discuss with Edwin Hubble the redshifted
light that had been detected in the spectrum of light
coming from other galaxies.
The expanding universe
After ccompleting the academic year, he returned to Belgium where he began to
teach at the University of Leuven thanks to a letter of recommendation[10] which his Cambridge professor, Arthur Eddington, had sent them. In
those early years of teaching he completed his doctoral thesis and wrote an
article[11] in the Annales de la Société Scientifique in Brussels providing a solution to the
equations of the General Theory of Relativity, interpreting the redshifted
light as a manifestation of the expansion of the
universe.
Lemaître tried to
calculate the speed of separation of the galaxies, but the value obtained was
higher than the current value. This figure was so huge that it led him to
believe that the size of the universe must have been much lower in the very
recent past. If the pace of expansion had always been the same, the age
assigned to the universe would be lower than that obtained for the Earth[12]. Given that this made no sense, Lemaître preferred to consider a world
of exponential expansion with an infinite past, where its size was almost
constant at first, later to increase rapidly.
In 1922 the Russian
mathematician Alexander Friedmann had found several solutions[13] to Einstein's equations, some of which described expanding universes
and other which were contracting. But Friedmann died prematurely and did not
have the opportunity to compare his mathematical calculations with the
astronomical data of the moment.
The scientific
community did not like the idea of an expanding universe, because since ancient
times all the theories of celestial movement advocated the concept of a
globally stable, static and, therefore, immutable and eternal universe.
Einstein, who participated in this thinking influenced by Spinoza's pantheism,
was irritated to discover the works of Friedmann and Lemaître because he hoped
that the solution he proposed would constitute a unique description of the
universe.
Eddington was the
exception. He admitted not only the expansion of the universe, but he also
acknowledged having been surpassed by his disciple: "Working with
Professor McVittie, several months ago I carried out research in order to
clarify whether Einstein's spherical universe is stable. Before our analysis
was finished, we read the article by Father Lemaître, where several issues related
to the Einstein and De Sitter's cosmological constructs were perfectly and
completely resolved. My goal was to analyze the problem from the astronomical
point of view, and although my initial desire was to obtain a concrete, and in
principle, new result, I was surpassed by the brilliant solution of
Lemaître"[14]. From that moment on, Eddington became the great champion of Lemaître:
he sent his work to various scientists[15] and had a personal conversation with Einstein, trying to convince him.
After some time, the German physicist ended up giving in.
The history of the beginning
Lemaître had no
difficulty in hypothesizing a universe with an infinite past. His studies of
Thomistic philosophy[16] had shown him that this thesis did not contradict his belief in a God
as creator of the world, as a created universe does not need a beginning in
time. Nothing would prevent God from creating the universe forever. Although
time was infinite, in the past as well as in the future, it would still have a
cause. Temporality and eternity are moving at different levels: eternity is
given all at once, while time is the succession of the earlier and the later.
When it is said that God is eternal, it says something other than an indefinite
simple duration. The divine eternity is the possession of Being, without
changes, without a before or after, in a totally self-sufficient way. And this
can never occur in a limited being such as the universe, as it requires a
cause.
Notwithstanding, this
cosmological model proposed by the Belgian astrophysicist in 1927 would not be
definitive. In 1931, Eddington gave a lecture[17] in London on the end of the world from the point of view of
mathematical physics. Based on the thermodynamic concept of entropy, he
concluded that the cosmos in the future would arrive at a state of complete
dispersion, the complete decomposition of matter. Going back into the past, on
the other hand, order would tend to be total, inviting us to think about a
beginning for the world, something that Eddington rejected categorically.
This negation by the
Cambridge professor awoke in Lemaître a keen interest in the question of the
origin of the cosmos[18]. The possibility of understanding the infinite had been raised for
years. As he perceived the difficulty that the human mind has to completely
comprehend infinite space and time, and had a deep faith in the rationality of
the world and in the capacity of the human intelligence to discover truth, he
wondered whether physics was compatible with the fact that the universe had a
beginning. As he couldn't find any contradiction, he began to reformulate his
cosmological model from the viewpoint of quantum mechanics.
To adjust his new
theory, he added an initial stage to the two proposals in the previous model in
order to give the universe a finite age. Everything began at one point, where
the laws of physics made no sense, in which the universe was expanding and
space was 'filled' with the products of decay of the primitive atom[19] 19 similar to the radioactive substances that gave rise to matter,
space and time as we know them today. Gravitational attraction was gradually
slowing this expansion until reaching a stage virtually in equilibrium. Then
the galaxies and their clusters arose from local accumulations of matter. When
the formation of these structures finished, the expansion resumed hastily.
Philosophy and science in the big bang
theory
As a theoretical physicist, Albert Einstein was not concerned with
verifying any of his claims experimentally, although he said he would be
"willing to consider his theory untenable if it did not withstand certain
tests"[20]. He had read "A Treatise of
Human Nature" by David Hume and had identified with its skepticism,
and later became attracted to the thinking of Ernest Mach, an Austrian
philosopher and physicist, who furthered the empiricism of Hume[21]: with such influences, Einstein remained in conflict with the inherited
positivism of these philosophers and the theoretical approach of his discovery.
Proof of this was his resistance to accepting the expansion of the universe and
the introduction of the cosmological constant in his equations in order to
create a world in keeping with his thought: an immutable and eternal universe.
Later he recognized that this was the greatest mistake of his life.
With the demise of
these prejudices, the empiricism of Einstein was softening, finally settling
for a belief in an objective reality[22]. He affirmed that physical theories try to give "an image of
reality and to establish their relationship with the vast world of sensory
impressions"[23], and that our mental structures would be acceptable to the degree in
which they ensure that relationship. However, Einstein never admitted that
cosmos would have been able to have a beginning; his pantheistic idea of the
world prevented him from admitting as much. Moreover, he believed that Lemaître
wanted to introduce into science a divine creation.
On the other hand,
historians disagree when they talk about the philosophy of Arthur Eddington,
since his metaphysics is very ambiguous. Some label him as an idealist, others
as mystical, while others classify him as a neutral monist close to Bertrand
Russell[24]. Although Eddington combined theory and practice, his eclecticism
prevented him from seeing beyond the theory of relativity and astronomical
observations; he believed that the problem of causality in the world is saved
by proposing a less abrupt beginning. For this reason, he preferred to consider
a very small and compact universe, not very different from the primitive atom
of Lemaître, which gradually expanded until reaching the current situation[25].
As to Lemaître, he
was not attempting to exploit science for the benefit of religion; he was
firmly convinced that both are different paths to get to the truth. The
autonomy of science with regard to faith was proven when he declared that,
"from a physical point of view, everything happened as if theoretical zero
were really a beginning; in order to find out whether it was truly a beginning
or rather a creation, something that starts from scratch, would be a
philosophical question which could not be settled by physical or astronomical
considerations"[26].
Lemaître, due to his
strongly humanistic education, his commitment to a realistic philosophy based
on Aristotle and Thomas Aquinas[27] and uniting quantum and relativity theories with experimental data, was
able to formulate the theory of the big
bang, a cosmological model that would be tempered later by George Gamow[28] 28 and so many others, but which maintains his principal idea: an immensely
large universe that is accessed by the knowledge of the extremely small, which
brings us to overcome the paradox of the existence of an initial physical
instant, breaking with the static vision of the cosmos that had been held up
until that moment.
Eduardo
Riaza
[1]
ARTIGAS, Mariano, «The origen of the universe.
Georges Lemaître: the father of the big bang»,
in ACEPRENSA, 79/95, 7 junio 1995.
[2]
PLANCK, Max, Scientific Autobiography,
Madrid, Nivola, 2000, p. 86.
[3] Ibid. p. 87.
[4]
Ibid. p. 90.
[5]
YEPES, Ricardo, Understanding today’s
world, Madrid, Rialp, 1993, p. 63
[6] AIKMAN, Duncan, New York Times Magazine, February 19, 1933, p. 3.
[7] Cfr. LAMBERT, Dominique, Un atome d’univers. La vie et
l’oeuvre de Georges Lemaître, Bruselas, Lessius, 2000, p. 28.
[8] EDDINGTON, Arthur, Space, Time and
Gravitation: An Outline of the General Relativity Theory, Cambridge University Press, 1920.
[9]
EDDINGTON, Arthur, Science and the Unseen
World, Nueva York, The Macmillan Company, 1929, p. 23.
[10] Cfr. LAMBERT, Dominique, Un atome d’univers. La vie et
l’oeuvre de Georges Lemaître, Bruselas,
Lessius, 2000, p. 70.
[11]
LEMAÎTRE, Georges, «Un univers homogène de masse constante et de rayon
croissant, rendant compte de la vitesse radiale des las nébuleuses
extra-galactiques», en Annales de la
Société Scientifique, Bruselas, 1927.
[12] The estimated age of the Earth at that time was 2
billion years. Currently we calculate it at approximately 4.5 billion years.
[13]
Cfr. FRIEDMANN, Alexander, The universe
as space and time, Sevilla, URSS, 2003.
[14]
Cfr. HELLER, Michal y DAVÍDOVICH,
Artur, Friedman y Lemaître, Sevilla,
URSS, 1991, p. 63.
[15] Willem de Sitter (Netherlands) y Harlow Shapley (USA).
[16]
Cfr. AQUINO, Tomás de, On the eternity of
the world, Madrid, Encuentro, 2002.
[17] EDDINGTON, Arthur, «The end of the World from the standpoint of Mathematical Physics»,
in Nature, March 1931 Nº 3203, pp.
447-453.
[18] Cfr. LAMBERT, Dominique, Un atome d’univers. La vie et
l’oeuvre de Georges Lemaître, Bruselas, Lessius, 2000, p. 111.
[19]
Lemaître thought that initially there was a “primitive atom” from which sprang
all matter and energy of the universe.
[20]
ARTIGAS, Mariano, Karl Popper:neverending
search, Madrid, Magisterio Español, 1979, pp. 16-17.
[21]
Cfr. ISAACSON, Walter, Einstein.
His life and his universe, Barcelona, Debate, 2008, pp.
110-111.
[22]
Cfr. Ibid. pp. 500-501.
[23] EINSTEIN, Albert y INFIELD, Leopold, The evolution of physics, Barcelona, Salvat, 1995, p. 236.
[24]
Cfr. MARTÍN, Karim Gherab. “Philosophy of science and neutral monism in Arthur
S. Eddington”, in THÉMATA, Philosophy
review, Nº 36, 2006. pp. 101-127.
[25] Cfr. SINGH, Simon, Big Bang, Barcelona, Biblioteca Budirán, 2008, p. 250.
[26] LAMBERT, Dominique, Un atome d’univers. La vie et
l’oeuvre de Georges Lemaître, Bruselas, Ed. Lessius, 2000, p. 278.
[27]
Cfr. Ibid. p. 52.
[28] Cfr. GAMOW, George, The
creation of the universe, Madrid, Espasa-Calpe, 1963.