In order to explore the dark energy, the Dark Energy Spectroscopic Instrument (DESI) at Berkeley Lab has created largest and most detailed ever 3D map of the Σύμπαν by obtaining optical spectra from millions of galaxies and quasars. The idea is to measure the effect of dark energy on the expansion of the Σύμπαν by accurately measuring the expansion history over the past 11 billion years, through measurement of the position and receding velocity of about 40 million galaxies.
Until late nineties, it was thought that expansion of the Σύμπαν following Big Bang about 13.8 billion years ago, should slow down due to gravitational attraction between galaxies, stars and other matter in the cosmos. However, on 8 January 1998, astronomers of Σουπερνόβα Cosmology Project announced the discovery that Universe’s expansion is actually speeding up (instead of slowing down). This finding was soon confirmed independently by the High-Z Supernova Search Team.
For about a century, the Σύμπαν was thought to be expanding as a result of Big Bang. The discovery that the expansion of the Σύμπαν is actually accelerating means something else must overcome gravitational attraction and drive the acceleration of Universe’s επέκταση.
‘Dark’ energy is thought to drive the acceleration of Universe’s expansion. ‘Dark’ means lack of knowledge. Very little is known about the dark energy, however, it is known that the mysterious dark energy constitutes about 68.3% of the mass energy content of the Σύμπαν (the rest 26.8% is made up of dark matter, which clusters gravitationally but does not interact with light and the remaining 4.9% constitutes the entire observable Σύμπαν including all the ordinary regular matter that we all are made up of).
This is one aspect about the Σύμπαν that remains largely unknown to science today.
Το Φασματοσκοπικό Όργανο Σκοτεινής Ενέργειας (DESI) στο εργαστήριο Berkeley έχει σχεδιαστεί και ανατεθεί για την εξερεύνηση της σκοτεινής ενέργειας. Ο κύριος στόχος του DESI είναι να μελετήσει τη φύση της σκοτεινής ενέργειας. Πώς εξελίσσεται η ενεργειακή του πυκνότητα στο χρόνο και πώς επηρεάζει τη συγκέντρωση της ύλης; Για να το κάνει αυτό, το DESI χρησιμοποιεί τους χάρτες του για να μετρήσει δύο κοσμολογικά φαινόμενα: τις ακουστικές ταλαντώσεις του βαρυονίου και τις παραμορφώσεις του διαστήματος στο ερυθρό.
In the last seven months of operation, DESI has prepared the largest and most detailed 3D map of the Σύμπαν to date. The map shows locations of about 7.5 million galaxies up to a distance of 10 billion light-years. In the next five years, DESI will log 35 million galaxies covering almost one third of the observable Σύμπαν.
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πηγή:
Εθνικό Εργαστήριο Lawrence Berkeley. Δελτίο ειδήσεων – Το Φασματοσκοπικό Όργανο Σκοτεινής Ενέργειας (DESI) δημιουργεί τον μεγαλύτερο τρισδιάστατο χάρτη του Κόσμου. Δημοσιεύτηκε στις 3 Ιανουαρίου 13. Διαθέσιμο στο https://newscenter.lbl.gov/2022/01/13/dark-energy-spectroscopic-instrument-desi-creates-largest-3d-map-of-the-cosmos/
