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Detecting the gravitational waves: the discovery of the century in the sciences of the universe?

It is obvious to everyone that man can not travel, he can not directly explore the distant structures of the universe. The distances to them are colossal. So we have to admit that we have a very narrow area of ​​space exploration, even if we include the areas touched by the farthest space probes. We can even say that the data in the whole history of astronomy has been attributed only to what we had here, on Earth, and in a small sphere surrounding the terrestrial space. And the progress made in the last decades is also decisive for the realization of more and more performing exploration devices, and for a more precise knowledge of the laws governing the cosmic structures. With their help - and not otherwise - we can extract good information about the visible universe.

Fortunately, the cosmos, as huge as it is, is still open to knowledge. True windows suitable for his reception and understanding are open right here in the vicinity of the Earth, allowing us to explore his depths with amazing precision.

An overwhelming miracle, available to anyone: the open sky with a glance

We have a beautiful, overhead sight above the top. It's enough that, on a serene evening, let's look up. Some estimates show that almost 10,000 visible stars are visible to the entire vault. Others think it would be 5,000 stars. This means that someone located in a concrete place in the northern hemisphere, say, could see during a serene night between 2,500 and 5,000 stars.

In any case, the brilliance of the stars gives us a first idea of ​​the extraordinary depths of the universe, of the remarkable chance of living on Earth where the stars are visible. They are there, and in their luminous signal the man-understanding-being-is accustomed to seeking a meaningful sign, a meaning. This is how we are lying for a moment on the starlit vault, we can see one of the irresistible invitations of life. We feel, suddenly with the eyes of the brilliant stars, an impetus to the quest for 
knowledge, to metaphysical core reflections, to poetry or spiritual depths. In the stars of the vast heavenly vault we find the first testimony of the vast distances in the Universe. And even if we only look at them, we are already witnesses of an overwhelming paradox: how great, how deep and old is the celestial vault, and just a moment's eye, she entered the whole of man's minds in his reflections - a faint creature , which lives for a few decades on a small Earth that seems insignificant ... And, as the whole history of thought can prove it, this paradoxical state raises hard questions, revealing the faces of a phenomenal human condition.

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Four centuries of astronomy: an electromagnetic reading of the universe

The exploration of the sky has not, however, remained within the limits of the resolution powers of the human vision. More than 400 years ago they began exploring the space through telescopes, devices that enhanced the image of the heavenly vault. These artificial eyes, set before our eyes, gave us the possibility of better observations, more accurate measurements and calculations about the movement of the ashtrays, and more fine details about the characteristics of the soil. There followed decades in which tools and heavenly observation devices were diversified and refined. The man was not content merely to observe the heavenly vault in the visible spectrum. This is how radio astronomy, infrared or ultraviolet, X-ray or gamma-ray astronomy, through specialized specialized "eyes", have become more and more sensitive to receiving radiation from a wider spectrum to capture as much as possible of the rain of heavenly radiation.

But all of this has something in common. All this time, the exploration of the cosmic space took place only through light, electromagnetic radiation of various wavelengths. And, exploring the universe in this way, it reveals itself as a sea of ​​lights, clothed in light, a light that "tells" through its every part a part of its history. The brightness of stars, rays reflected by planets, cosmic radiation, all travel to us, being received and recorded by telescopes. Further, the extraction of the universe data from the light coming from it is possible because the photons are faithful carriers of this precious information. The stars that gave it, the length of the journey and the characteristics of the space that has passed through us are all imprinted in a tiny shimmer of light. As the key to decoding the encoded messages in photons (spectrography) has become increasingly important, more and more discoveries have been made about the history of the universe and about the cosmic phenomena that have occurred in the remote and remote regions that would otherwise have been inaccessible to us.

Gravitonography, a new astronomy? Cosmic radiographs in gravitational waves

On September 14, 2015, three scientific premieres opened a new era in cosmic space research! The data on these events were released only a few days ago, after months of careful calculations and repeated checks.

We are very likely to witness one of the most astronomical discoveries of the last four centuries. First of all, it is about detecting gravitational waves. At the same time, the first collision was made between two black holes - spent more than a billion years ago. At the same time, these achievements were made with the help of a new, astronomical observation instrument, particularly powerful. Finally, all these can constitute the elements that inaugurate a new era in astronomy. Most likely, in the years to come, we will no longer look at the sky just by light. Because we can sense it through a completely different "radiation" through gravitational waves. It is about the new astronomy of gravitational waves, a radically different way of reading the cosmos, one that offers a radiography (a gravitonography) of the universe through a new observation register.

Let's take them one at a time.
Several major scientific challenges about quasi (un) known gravity

Although it may be said that gravity is everyday within the reach of direct experience, a precise description of it has come very late in history. Isaac Newton (1643-1727), as well known, formulated a description of the behavior of gravity in 1687, without specifying, as he himself says, "its nature" [1]. Later, in 1915, Einstein (1879-1955) gave a new description of gravitational interaction, a geometric one, linking it to the deformation of space-time in the vicinity of dense bodies.

In general, as is well known, physics explains quite well almost the entire world of phenomena and objects observable through four fundamental interactions. It is the electromagnetic force and the strong nuclear force, which contributes, among other things, to the formation of atoms and molecules, and to the weak nuclear power, which is present in the phenomenon of radioactivity. On the other hand, on the natural scale and the cosmic structures, physics describes gravity, the fourth fundamental interaction, which contributes to the formation of galaxies, of the stars, to the movement of bodies in the Universe. Finally, the data so far has shown that each of these interactions corresponds to a particular corpusculus that carries it, but also a wave through which it propagates at a distance. The most handy example is light. The photon is the corpuscle of light and the electromagnetic wave is the one that transmits, makes remote electromagnetic interaction felt. Well, if for each of the three interactions (electromagnetic, hard and weak nuclear) the waves and the corresponding corpuscles are known, these elements of identification are deprived of gravity. Graviton has not been identified so far, missing a quantum description of gravity. Also, gravitational waves were not detected directly.

The recent discovery, which we refer to in the following, may be an important step forward in this approach.

Several cosmic events and their gravitational prints

First, it must be said that according to Einstein's theory of gravity, any sudden change in mass density in a space in space causes sudden changes in the manifestation of gravity. If a star explodes, if another strand collapses or two stars collide, changing the mass density of these events manifests as disturbances of the gravitational field. Gravity energy "waves" propagate at the speed of light in space.

Being extremely dense, the black holes exert a great deformation of space-time in their neighborhood. Observational data of the last decade have even shown that black holes in rotation cause special deformations in the form of twists in the space-time texture [2].

Secondly, also on the basis of Einstein's General Relativity, it was known of the existence of binary black hole systems in which each black hole rotates around the other. The theory provides that in such situations there is the possibility that the two black holes collide. Once, for billions of years, they have rotated one around the other, consuming energy through gravitational wave emission, they may be getting closer and closer. Fascinating each other, they could accelerate to each other, spinning and approaching faster, until they hit half the speed of light at impact!

However, although the collision of two black holes was predicted by theory, it was never observed. On the other hand, in accordance with the manifestations of dense bodies, if such a collision occurs, a significant disturbance of the gravitational field, a gravitational wave that spreads into the cosmos, should certainly occur.

Two premieres in astronomy: gravitational waves and fusion of black holes

The Laser Interferometer Gravitational-Wave Observatory (LIGO) detector, designed to detect gravitational waves, has detected such a signal that seems to come from the collapse of two black holes!

LIGO consists of two perpendicular tunnels, arranged in L-shaped, each with a length of 4 km. The LIGO interferometer detector (the interferometer being a device that uses light or laser to perform accurate measurements) uses the laser for observations. It is a beam divided into two beams that move back and forth along the two arms of the tunnel (in fact, tubes with a diameter of about 1 meter, having almost perfect vacuum space). Tubes are provided with mirrors to monitor the distance between the ends of their arms.

If a collision of two black holes occurs, then the waves (disturbances) of the gravitational field could be highlighted when they pass through the LIGO detector. This is because, as I mentioned, the gravitational wave distorts space-time. In other words, it compresses and expands space-time, thereby affecting the distance that the laser beam crosses across the two tunnel arms. When the gravity wave passes through the detector, the distance traveled by the laser beam is no longer the same as that measured before and after the wave passes.

That's how it happened, it seems. After it was inaugurated in 2001, for a while the detector operation was interrupted (for better technical endowment), LIGO was restarted. Shortly thereafter, in working order, with the new high-tech technology installed, researchers could detect a significant signal, a disturbance in the space-time sheet. So with a great chance! Based on the frequency of this signal and using the equations of general relativity, one could deduce that it is about the clash of two black holes!

Third novelty: extraordinary precision

The calculations show that the wave generated by the collision of two black holes could change the distance traveled by the light with a slight value. More specifically, in the 4 km (as long as each of the two tunnels) is a distortion of ten tenths of the diameter of a proton (10-19 m)! Or perhaps by a more suggestive comparison, it is about sensing a spatial distortion that is equivalent to measuring the distance from the Sun to the nearest star (Proxima Centauri), ie at 4 light-years, with less precision than the thickness of a hair! [3] Even so LIGO proved good for such a resolution. By detecting gravitational waves, LIGO proves that we are dealing with one of the most accurate, refined astronomical observation devices.

Fusion of black holes: a colossal collision and echoes after a billion years

But not only gravity wave sensing is a premiere, but also a collision of black holes. We recall, in this respect, a relevant aspect. In the elementary particle physics the mass defect has long been known. It is a significant difference between the mass of two particles taken separately and, comparatively, in a bound state. The mass of two protons, for example, bound by the strong interaction inside a core (mass of bound state), is not identical to the sum of the masses of the two protons taken separately. In fact, nuclear fusion is done with the loss of a mass percentage (mass defect), this being the energy released at the merger. In the case of the formation of helium nuclei from hydrogen nucleus fusion, for example, the mass defect is 0.7%. It may seem a little, but in real terms the amount of energy is enormous if we take into account that a process of this kind is the main source in the energy emitted by the sun and the stars.

Well, as I said, the LIGO detector did not show the gravitational waves. Moreover, it has been proven that they contain very valuable information for the research of the universe. First, the frequency of the received signal and the calculations show that the recorded wave originates from the collision of two black holes that have 29 and 36 solar masses, respectively. The calculations of Einstein's equations indicate that the black holes collided at a speed comparable to the speed of light! It could also be deduced that this collision was now 1.3 billion years old!

In particular, calculations show that the merger of the two gave rise to a new black hole, but only 62 solar masses! As with the mass defect in particle physics, the mass of the new black holes is less than the sum of its contributors to the collision. The merger of black holes is therefore accompanied by a mass defect, but in this case of colossal value. In accordance with Einstein's famous formula (E = mc2), the collision is so violent that fusion converts, in a fraction of a second, 3 solar masses (!) Into gravitational energy, reaching a peak power of about 50 times higher than the entire visible universe! This energy, released in the form of gravitational waves, propagated throughout the universe at the speed of light, and its disturbance came to us after 1.3 billion years.

Researchers wanted to be sure of the outcome. That's why they were confronted with the records at the Livingston detector with those obtained in another similar detector located in Hanford. By doing so, they tried to eliminate the situation that the disturbing signal was caused by a local event. Indeed, the recordings made on September 14 showed that at 7 milliseconds from the LIGO recording in Livingston, the other LIGO detector located in Hanford recorded the same signal. [4] Moreover, descriptions provided by general relativity equations provide a signal identical to that recorded for a collision of two black holes, as shown by the two charts.

Fourth novelty: Exploring the dark universe by detecting gravitational waves

All this shows us that through this method we can decipher the gravitational waves and from them we can extract precious data about the cosmic phenomena that can not be seen through the light radiation! It is seen that, as with light, gravitational events also have gravitational "signatures" as well as those printed in the light that have led astronomical electromagnetic waves so far.

Until now, the universe has been explored by light. But beyond all that we have revealed in stars and galaxies, we have also discovered that physical light has limits in its power of revelation. Light can not easily and without major loss of information pass through an interstellar or dense intergalactic dust cloud. (A part of our galaxy, for example, is not visible, as a cosmic dust region stops the light radiance emanating from cosmic bodies located beyond the dusty area.) On the other hand, there are bodies that do not emit light and do not reflect light , such as black holes. They are very difficult to detect through light. Rather than the absence of light than the outline of their contours and their surface, electromagnetic radiation suggests the presence of black holes.

But light can not reveal to us either the distant past of the universe. It is known that through the light we travel in the past, visualizing cosmic events once. Through the light that comes from far, we can see old vestiges, protogallaxes and protoss as they were long ago. In this way we were able to identify very ancient cosmic formations, located very distant in space, so located very close to the beginning of the universe. The farthest such cosmic structures (in time and space) detected so far were those located only 300,000 years away from the Big Bang moment. In this regard, the research of cosmic space can not go as far as possible in the past. Not if it is led by light only. Because light traces stop at this wall, about 300,000 years from the Big Bang. The Big Bang combo model indicates that after the primordial explosion followed a Dark Ages, a period in which photons could not circulate freely in space, which is why there is no evidence in light of this form of light, electromagnetic radiation residues to reveal something.

By sensing the gravitational waves, astrophysics enters a new era in which it can reveal the dark side of the Universe, which until now has been invisible to telescopes that use sensors suitable for electromagnetic radiation of different wavelengths. This is an extraordinary chance if we take into account that the Dark Universe contains dark matter and dark energy, covering nearly 96% of the entire Universe! With gravitational waves, we will be able to look into this dark universe and, guided by traces other than light, we will be able to discover new flames from the inaccessible cosmos map so far.

This discovery announces that many of what were invisible, undetectable (by electromagnetic radiation) could be seen through gravitational waves. It is thus announced radically new technical possibilities to look deeper into the Universe, and so on in the past. Moreover, as some optimistic researchers say, this new technology might be the one that offers a chance to get closer to the Big Bang moment.

Finally, the study of gravitational waves could eventually help solve one of the greatest problems of physics, unifying forces, namely clarifying a bridge linking the quantum theory to gravity theory.

As expected, for the discovery of such a large scale, the first challengers appeared. These are the names of the universe, the people who assert that we are dealing with only a few numerical matches, data that do not yet prove the existence of gravitational waves through unavoidable physical records [5]. But science has no better way to validate a discovery than to go through a series of appeals, giving again and again better evidence. In the coming months, more and more measurements and data will be collected to see if this crucial discovery is supported, along with everything that has been said here. However, no matter how things will happen, a considerable step has been taken to detect gravitational waves.

A possible reflection on the phenomenal intelligibility of the universe

As happens when our gaze meets a territory where we can not see its edges, which we can not see in our eyes, we are now pushed to an essential reflection of the world and the life we ​​live in. A different reflection of the hasty judgments of the day. And yes, it is wonderful that we do not have a full-blown year to hide the sky, which always covers the brightness of the shades. Because in every clear sky, the celestial vault fulfills its purpose, luring us with a rare metaphysical disposition, pushing us to a reflection of what is beyond the sensitive world around us.
By raising his gaze, thought can be exalted, rising more easily from the horizon of life to the heights of existential reflections. In this way, thoughts come to grind the fringe of the extraordinary condition of man, seeing the wonderful gift of our life - beings endowed with multiple sensory paths and analyzers capable of perceiving the world, and the invaluable possibility of knowing and knowing this universe open to us - beings willing to know and capable of understanding the world.
It is wonderful that we can ask questions, that we can seek answers, that we can imagine procedures to verify the truth of what has been discovered, that we can convey the discoveries and the close data from the efforts of knowledge to the coming generations, their advancement in the mysteries of the universe and life to continue. In this way, the discovery of gravitational waves and their use in the understanding and understanding of the universe reveals a new facet to the rationality of the world. The universe is not told just by light, but by all manifestations of its interactions. The rationality of the world is evident in all its manifestations, and in each of them human meaning can be found. Not just the crumbles of light carry in them precious information about the world we live in, illuminating the universe, making it intelligible for the light of the human mind. And the gravitational waves reveal it, in a new, complementary form, encouraging the advancement of human explorations into its abyss. And, secretly, light is present here, in the form of the fiery laser beam that records the deformations of the space, the discreet passage of the gravitational waves. The most discrete remote actions in the entire known universe leave traces in space-time, and the light can bring them to light!
We could see here, in the footsteps of patristic reflection, a universe that "speaks" without words, encouraging us to seek answers about its rationality and our ability to understand it. A universe that we can see, looking up to the celestial vault, on a serene evening, and which invites us to exalt our spirit to more and more comprehensive searches and understandings, capable of giving us a sense of life. And from the endeavor of philosophers, great scholars, and spiritual biographies, we learn that this lifting of our gaze to the beauty of the world continues with the rise of conscience to the most comprehensive questions of life, and is accomplished only by exalting the person himself into an ever more open life to the neighbors, able to give themselves to them, as thanksgiving for all these miraculous gifts He has received from Above!

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