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Big bang news

Author: Javier Sánchez Cañizares
Published in: Revista Palabra, pp. 58-61.
Date of publication: May 2014.

On 17 March, the unambiguous signal of gravitational waves from the Bicep2 telescope, located at the South Pole, was announced in style at finding . This is one of those findings that, as in the case of the Higgs boson, fundamental physics has been waiting for a long time, since the detection of such waves would give us access to the echo of the inflationary process that occurred moments after the big bang that gave rise to our universe.

The Bicep2 telescope (acronym for Background Imaging of Cosmic Extragalactic Polarization) has been making measurements at the South Pole since 2010. The existence of gravitational waves had already been predicted by Albert Einstein's general theory of relativity. Quantum mechanics considers these gravitational waves to be the wave version of gravitons, the particles responsible for the gravitational force. Their detection would place us in the moments immediately after (around 10-36 seconds, trillionths of trillionths of a second away) the initial burst with which the universe came into being. But let's take it one step at a time.

To be more precise, when we talk about the big bang we are referring, first and foremost, to a model or physical theory that tries to explain the evolution of the cosmos from its origins to what we know today. We contemplate a universe with galaxies, stars and planets, in which life and human beings could have appeared, but which has not always had these characteristics: the universe would come from a great initial explosion (hence the popular name of big bang) manager of the expansion of the same space in which the cosmic theatre takes place. Curiously, our theory cannot say anything about this big bang, because its equations then cease to work. We are faced with what physicists and mathematicians call a singularity, a status in which the relevant physical quantities become infinite or cease to be well defined.

Experimental support

Since the proposal of the big bang model in 1931, thanks in particular to the work of the physicist and priest Georges Lemaître, this hypothesis has received considerable experimental support.

First, the finding redshift of light emitted by distant stars. Just as the frequency of an ambulance siren becomes more severe as the vehicle moves away from us, light from distant galaxies reaches the earth at a lower frequency than it should. Moreover, this effect is directly proportional to the distance average between the source of light in question and our planet. This is known as Hubble's law (after the great American astronomer who first measured this effect), and is a first indication that the universe itself is expanding. Just as points on the surface of a balloon that is inflating move apart faster the further away they are from each other, so it is the same for the galaxies in our cosmos.

However, for various reasons, this finding was not then decisive for the adoption of the big bang model as the standard scientific theory of the origin of the universe. There were still other competing models (among others, the steady-state model of Fred Hoyle and Dennis Sciama). It was not until the measurement of the microwave background radiation (made unequivocally in 1965 by Penzias and Wilson) that the big bang received widespread recognition by the academic community. When we speak of background radiation we refer to electromagnetic waves of very leave high intensity (which is why it was so difficult to detect them), which permeate the entire cosmos and which would be like a fossil remnant of the big bang. This is the electromagnetic radiation that was released when the subject stopped absorbing and emitting it continuously, a few hundred thousand years after the big bang. Today, this background radiation is by far the most important empirical signal for physical cosmology. Telescopes measure it more and more precisely, and scientists analyse the multitude of data that are collected in order to contrast them - through various very serious statistical treatments - with the various cosmological hypotheses that seek to refine the model of the big bang.

Other measurements

This model has also been supported by other measurements, such as the relative proportion of light elements in the universe (about 74% hydrogen, 24% helium and the minimum remaining for the other elements) and the large isotropy of the background radiation, which is very uniform across the sky, but with slight deviations from point to point. These small deviations were necessary in the beginning as seeds from which the large concentrations of subject that populate the known universe could emerge.

Precisely this last empirical data allows us to go into one of the problems of the standard model and to assess the importance of the finding announced a few weeks ago. The background radiation is practically the same throughout the universe, which can only be explained by the fact that all the regions of the universe were together, in equilibrium, at the initial moments. However, the time since the origin of the universe is estimated to be about 13.7 billion years, while the radius of the universe as we know it today (there are of course more, but not yet enough time for their light to reach us) is about 46 billion light years... Something is wrong then: either the universe is larger than it should be, or not all its regions were at contact at the beginning. But the isotropy of the background radiation tells us that the latter must be true.

Faced with this problem, known as the "horizon problem", physical cosmologists (originally Alan Guth) have proposed the solution of the "inflationary theory". This is an addition to the initial big bang theory which postulates that the universe underwent an enormous expansion (a tremendous swelling of several tens of orders of magnitude), shortly after its birth (the trillionths of trillionths of a second we were talking about earlier), in a gigantic exponentially accelerating process. The universe, as it cooled, underwent a kind of "phase transition": like a subcooled liquid below zero Degrees , it suddenly turned to freeze, radically changing its appearance and releasing a huge amount of energy.

The physical origin of this enormous growth is under discussion and may have to do with the process of separation of the fundamental forces of the universe (gravitational, strong nuclear, weak nuclear and electromagnetic). In the beginning there would have been only one single force, but as the cosmos became cooler, the differentiations that we know today began to occur. The first force to distinguish itself would be the gravitational force, before inflationary growth, and the second to do so would be the strong nuclear force. Perhaps the latter process triggered inflation, but we do not yet know enough physics to be able to say for sure.

model inflationary

Until now, the inflationary model explained many properties, but all of them were already known before its formulation. The point is that, if the inflationary process really took place, it would have to have left some remnants of its passage that have not yet been measured, i.e. that are true predictions of model. These remnants would be gravitational waves, small ripples of space itself that would reach us like waves. These remnants would be gravitational waves, small ripples in space itself that would reach us like the waves that wash up on the beach after a big storm in the middle of the ocean. But measuring these waves directly is not so simple. At present, we could only know about them indirectly, through the effects they would have left on the background radiation that travels along with them (the debris left by the waves on the sand). And this is what Dr. John M. Kovak and his team at the Harvard-Smithsonian Center for Astrophysics have been measuring for several years, until they were able to shout the current "eureka". Specifically, this team of scientists has measured spiral polarisation patterns in the light of the microwave background radiation, something that is considered an unquestionable indication of its relation to the gravitational waves that were amplified during the inflationary period.

Are we in the midst of a rambling disquisition? Yes and no. Although the results have to be validated by the academic community, great experts endorse each of the explanations that are linked in the same paradigm. Science can advance thanks to the communal effort of a large issue community of people over a long period of time, and it also has its mechanisms for purification and correction of errors.

The current finding is therefore an endorsement of the inflationary model of the big bang. As is often the case in such cases, as the path becomes clearer, new questions arise. It is very likely that astronomers will devote the next decades to studying gravitational waves in order to obtain some answers to scientific enigmas such as subject and dark energy. In particular, it remains to be determined which subject of model inflationary is compatible with data of Bicep2.

Compatible with the creation

Some, going a little further than what the data we have, have raised their voice saying that this finding is compatible with the model of "multiverses" predicted by some of the inflationary theories. The model of multiverses, today, is not established science, but "promised" science, purely speculative. It entails serious epistemological problems, since it is not clear how it would be possible to experimentally verify the existence of universes parallel to our own if we do not have access to them. However, if we could have experimental evidence for the existence of such parallel universes in the future, it would pose no more of a problem for the believing perspective than the existence of other worlds and solar systems in the universe we inhabit. If anything, it would highlight the exuberance of creation, making us increasingly aware of our humble yet grandiose position in it, as creatures in solidarity with nature who have been given the power to contemplate it in all its splendour.

The finding of gravitational waves is on the same level of importance as the recent finding of the Higgs boson. The certification of its finding will almost certainly mean the award of the award Nobel Prize for its discoverers. But it also carries with it a confirmation of the human capacity to truly know, in ever greater depth, the secrets of the cosmos. There is no doubt that science is a genuinely human activity, something we should all rejoice in, as it is a sharing in the light of the Creator's intelligence that can lead us to Him.

Certainly, the big bang model is scientifically strengthened by these results. But let's not forget that this model is not a scientific demonstration of creation. Science always deals with the how of material transformations, having among its presuppositions the existence of something. Creation describes the mystery of the existence of that which should not exist. However, it is not superfluous to add that between the model of the big bang and the mystery of creation there is quite a lot of compatibility B. And, ultimately, it is one step closer to the question of the ultimate why of being and not of nothingness. This great question can only be answered by "the Love that moves the Sun and the other stars" (Dante Alighieri, Divine Comedy: Paradise, Canto XXXIII).