An old idea rejected by Einstein could hold the keys to solving one of the greatest scientific mysteries of the day: why the universe is expanding more and more speed, something happens despite the action of gravity, a force that tends to unite, not separate, objects can see in the sky. Now, Christian Marinoni and Adeline Buzzi, two physicists at the University of Provence in France, have concluded that the "cosmological constant" Einstein, a kind of repulsive force that opposes gravity, is the best way to explain dark energy, the main suspect in the acceleration of the universe. Marinoni and Buzzi, who have published their work in Nature, have come also to the conclusion that we live in a flat universe.
In 1917, Albert Einstein inserted into his general theory of relativity correction factor, which he called the cosmological constant, to force the equations to predict the universe stationary (ie, unchanging) in which he believed. The cosmological constant was a kind of repulsive force opposite to gravity, something necessary, Einstein believed, that the universe was stable and did not end collapsing in on itself due to the gravitational action of matter it contains.
However, just two years later, in 1919, astronomer Edwin Hubble showed that, far from collapse, the universe was indeed expanding, growing bigger and bigger. And the subject matter contained in it, instead of going along, she was separating. Einstein dismissed, therefore, his cosmological constant, which came even consider as the "biggest mistake" of his life. An "error", however, which now depend for scientists trying to explain the universe in which we live.
Dark energy
Indeed, many years after Hubble made his momentous discovery, it became clear another disheartening fact: the universe is not only expanding, but the pace of that expansion is accelerating. That is, the expansion rate is not constant, but increases with time. What is extraordinary force able to oppose gravity and achieve a similar effect? So far, science has been unable to answer this question.
What is known is that, so that gravity would slow the expansion, should be a lot more stuff than we can see. All ordinary matter, which form galaxies, stars and planets, barely aware of 4% of the total mass of the universe. Another 23% of this mass consists of dark matter, a mysterious type of matter that does not shine and therefore can not see. And 73% is constituted by something that, for want of a better, scientists have named "dark energy." A strange force that, somehow, would be responsible for the current acceleration of the universe.
To conduct their study, Buzzi Marinoni and have developed a simple method that allowed them to measure the "geometry" of the universe. A method based on observation of 500 pairs of distant galaxies and allowing them to measure what is the curvature of space.
"Curved or flat?
But what exactly is the geometry of the universe? Do we live in a kind of multi-dimensional area or is it rather a spacetime fabric that curves gently and without ever closing on itself? Or maybe even do not bend at all and actually dwell in a flat universe? The question, one of the biggest questions of cosmology, for us very concrete implications which go far beyond being mere theoretical issues. In fact, the geometry of the universe has a decisive in the objects we observe.
In a curved or spherical, the light coming from distant stars, galaxies or deforms during its long journey, so that the image you see does not correspond to reality but is distorted. It would, to some extent, like look at us on the surface of a metal ball and see your face completely deformed. In a flat space, however, the distortion disappears and allows us to examine celestial objects as they are.
But how know which of the possibilities is correct? Until now, scientists have sought the answer endlessly studying the properties and characteristics of the light coming from the stars, the only physical link that connects us to them.
studying in detail the light, examining photon to photon, has been able to learn, for example, if the object emits it toward or away from us, and how fast. Or even know the chemicals that contains the source emitting the light, allowing us to determine the composition of distant stars or planets, despite the vast distances that separate us. What we can not know is how far that light has been deformed during your trip and, therefore, to what extent is real or not, we are seeing.
We do know, for example, that the wavelength of a ray of light is unaffected by the movement towards the red part of the electromagnetic spectrum (red shift) or towards the blue, as if the subject issuer is receding or approaching. And we also know that light rays undergo alterations when passing near strong gravitational fields, such as galaxies or black holes.
Modern observation instruments are capable, however, to correct these distortions and introduce electronic light as if they never occurred. But calculate how the light affects the geometry of the universe itself is a completely different thing.
500 pairs of galaxies
"The most interesting aspect of our work," says Marinoni, is that there are no previous data that we use. " This means that their findings do not depend on others and that calculations could be wrong. The researchers therefore decided to try to explain the dark energy by studying the geometry of the universe. And is that the geometry of spacetime can distort, as we have seen, the images we receive from the structures found on him.
So the scientists decided to look for evidence of these 500 pairs observed distortions of distant galaxies in orbit around each other. Using the magnitudes of the observed distortions, Marinoni and Buzzi were plotting the way for the space-time fabric. One way, as have been determined, raises the possibility that we live in a flat universe. And if we live in a flat universe, the old idea of \u200b\u200bEinstein's cosmological constant gain strength again. Therefore, it could even be the key we're looking to understand dark energy. (ABC)
