DESI will map millions of galaxies and reveal dark energy’s history – Astronomy Magazine
DESI uses a system of 5,000 fiber optic cables that can point at individual galaxies.
University of California/Lawrence Berkeley National Laboratory
Is dark energy constant?
What does this map of galaxies have to do with dark energy? Dark energy is the mysterious force that makes the universe’s expansion accelerate.
So by measuring how fast galaxies are moving thanks to the universe’s expansion, astronomers can estimate how much dark energy there is. And thanks to DESI ability to measure millions of distant galaxies, astronomers can measure how much dark energy there was at a given point of time in the universe’s history, up to 11 billion years ago.
That’s the main goal behind making such an expansive map of galaxies deep into space. DESI should be able to help determine whether the amount of dark energy in the universe stayed the same over time, as today’s standard ideas of cosmology predict. Or, alternatively, if the amount of dark energy somehow changed over the universe’s history.
“I’m very excited to see the maps that this facility will be able to make, and to see how our theories of cosmological structure information can get challenged and extended by this enormously large dataset,” said Daniel Eisenstein, a Harvard University astronomer and a member of the DESI team.
