DESI is the Dark Energy Spectroscopic Instrument which has been recentelly placed and switched on on the telescope Mayall, to the Kitt Peak National Observatory in Arizona. The supertelescope was really waited, it will observe five thousands of galaxies at once, until to study 30 millions of them, drawing so a new map of the universe. The new map of the sky will be in three dimensions and it will help even to further study the role of the dark matter in the formation and the expansion of the universe.
What will do DESI
Like we said DESI will draw a new map of the sky in three dimensions, starting from the closest universe until to push itself up to 10 billion of light years away from us. The galaxies and the quasars that will be examinated are about 30 millions and the precision of the new supertelescope has no precedent.
Specifically the duty of the super telescope is the one to measure the redshift of the galaxies, which is the movement of the light toward bigger wavelenghts compared to the ones of the moment of the emission. Basically the redshift determinates the movement speed of a planetary body.
All of it will be useful to collect informations and clues about how the cosmic contrast evolved in the time, which is the contrast between the gravity and the dark energy. The first one is that force that makes the objects closer. The second one, we assume, does the opposite thing, which means that it pushes away the objects, and it is, so, considered the engine of the expansion of the universe.
Observe and study the galaxies’ groups
The telescope has 5.000 fiber optic to observe the sky, each one of them has the same functions of a mini telescope. DESI will, so, use the optical spectroscopy, collecting 5.000 spectres at once (as well as the number of galaxies that it is able to examinate simultaneously), having a visual field of 8 square degrees.
To collect the informations of every “little piece” of sky DESI will spend 20 minutes. This means that every twenty minutes it will be able to pass to a new group of five thousand galaxies. While it observes them it will be able to understand how much the universe expanded while the light of these galaxies travelled toward the Earth. Like we said DESI will start from the closest galaxies and it will push itself up to 10 billion of light years from us. Farther away it will look further back in the time it will travel.
The remotest galaxies that it will be able to observe will be, so, a picture in the past of 10 billion of years ago.
DESI isn’t the first telescope to attempt it, but no one never covered a so large space of universe and no one never was so detailed to do it.
The studies of DESI and the dark matter
The job of DESI, that like we said will be useful to create a new map of the universe, will be useful even to finish some studies, which could revolutionize the current conception of the universe.
One thinks that is possible, by having a new such extremely detailed map of the universe, having even a much more precise view of the gravity and of the role that it plays. This could drastically change our current models about the creations and the expansion of the universe. We might be able to understand some mechanisms of the universe without need further informations about the energy and the dark matter.
And, about the dark matter, it is in reality right about it that they want to focus once obtained the new map. They think, infact, that it is letting expanding the universe, through a force called vacuum pressure. This is caused by the floating of the textures of the space-time. They think that the vacuum pressure, back in the time of the primordial universe, was much bigger and it slowly decrease until the current level.
Finally, another thing that DESI will be able to do is to test the theory of the space-time gravity, by thoroughly looking how the gravity was able to connect the particles, by creating planets, stars and galaxies.
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