Construction of the Dark Energy Spectroscopic Instrument (DESI) was approved this week by the U.S. Department of Energy, according to Engadget. It will observe millions of galaxies and create a 3D map that covers 10 billion light years. The instrument will measure redshift, and scientists will use it to determine the age of each astronomical body. Dark energy is a force that competed with gravity to form the universe.
The DESI will have a camera with 5,000 optical fibers and a database containing sound waves from the first 400,000 years of the universe. These sound waves are detectable as temperature patterns and variations. The project is run by the University of Michigan.
Dark matter on the other hand is part of space that isn’t visible, but scientists can make maps of dark matter to see this invisible space. Most of the observation is indirect and utilizes the lensing effect that dark matter has on stars and galaxies.
The Blanco telescope in Chile is the main tool scientists used to study dark matter. It has a 570 megapixel camera that features 62 CCD sensors. About 0.4% of the night sky has been studied so far in the Dark Energy Survey (DES) according to Engadget.
There is some confusion about the difference between dark energy and dark matter, and if they are the same thing. According to Cornell University, they are different entities. The universe is made of about 25% dark matter and 70% dark energy. Dark matter must exist to account for the gravity that holds galaxies together. Dark matter amplifies small fluctuations in the Cosmic Microwave Background during the formation of the universe. This led to the large scale structures observed today.
Dark energy is explained in terms of the expansion of the universe. It is also called the cosmological constant or quintessence. Since the universe is expanding at an accelerating rate, some thing must be causing it and that is assumed to be dark energy.
The DESI will be installed at the Mayall 4-meter telescope at Kitt Peak National Observatory starting in 2018.