Dark energy is one kind of force which is making the whole universe larger. Galaxies that are close to milky way appear to be moving away at a faster speed than expected. And this universe is getting bigger and bigger since the big bang. For this dark expansion, energy is responsible. Albert Einstein was the first scientist who developed the concept of dark energy. Scientist Einstein developed the cosmological constant the symbol Λ (capital lambda). So the dark energy is the biggest mystery in the universe. If scientist solves this mystery, we can get solutions to many problems.
Astronomers were trying to find “first light.” After years of preparation, the construction of new hardware astronomers collects light particles from a space object. The DESI (Dark Energy Spectroscopic Instrument) in Arizona, on October 22, captured the first light. Because of this, we can now map our universe again. We can measure the exact distance between galaxies. And we can solve the most mysterious question in physics: what is dark energy that builds 70 percent of the universe. The number of galaxies lives together in groups. There is also a cluster of a hundred to thousand galaxies. The first map of the universe looks like a stickman. The striking images were the first glimpse of the large scale universe. CFA (Redshift) survey was constructed one galaxy at a time. This involved measurement of the galaxy spectrum, splitting of light by its wavelength or colour. And finding out the presence of different chemical element like (hydrogen, nitrogen, and oxygen).
Chemical signatures shift towards longer redder wavelength and this called a redshift. Redshift tells us that the galaxies which are at a larger distance move faster than closer galaxies. Hence by measuring the redshifts, we can measure the distance between galaxies. But this will not give a more accurate answer. New instruments like DESI will help to measure 12 million of galaxy redshifts. It will give a detailed map of the universe, and with this map, we can get answers to many solutions.