Telescope Tracks 35 Million Galaxies in Hunt for Dark Energy

A super telescope has begun the most detailed survey of the Universe ever undertaken
29 October 2019
Dark Energy permeates the Universe and pushes galaxies apart
Dark Energy permeates the Universe and pushes galaxies apart. Credit: NASA/ESA

Astronomers have calculated that dark energy makes up most of the Universe and the atoms that build planets, stars, and galaxies probably account for just 5%.

"It is just embarrassing to live in a Universe where you only know 5% of it," said Ofer Lahav, Perren Chair of Astronomy at University College London, in a recent interview with BBC News.

"The nature of dark energy, and what it is, may well lead to a revolution in physics — the whole of physics!"

Just what is dark energy?

The Big Bang theory of the creation of the Universe originally predicted that its expansion would slow down, and that it would possibly begin to contract as a result of the pull of gravity.

However, in 1998, astronomers were shocked to discover that not only was the Universe continuing to expand, but that this expansion was also accelerating.

The most widely held view is that something is counteracting the pull of gravity — and that something has been termed dark energy — the mysterious force thought to drive an accelerated expansion of the Universe.

In the hunt for dark energy, an international team of researchers will use a device called the Dark Energy Spectroscopic Instrument (DESI). It has been retrofitted on to the 4m Mayall telescope at the Kitt Peak observatory in Arizona.

Inside DESI are 5,000 optical fibers, each acting as a mini-telescope that can image a galaxy every 20 minutes. The instrument will capture light from 5,000 different galaxies simultaneously, precisely map their distance from Earth, and gauge how much the Universe expanded as this light traveled to Earth.

The program is set to last five years — in just one year scientists will have surveyed more galaxies than all the other telescopes in the world combined.

Read more about DESI and the search for dark energy on BBC News.

Related SPIE content:

Robotic fiber positioners for dark energy instrument

Gravity waves and dark energy in focus at SPIE astro meeting

Hitoshi Murayama plenary: Studying the Birth and the Fate of the Universe Using Multi-Object Spectroscopy

Dark energy survey operations: years 4 and 5

Dark energy spectroscopic instrument (DESI) fiber positioner production

Dark Energy Spectroscopic Instrument (DESI) fiber positioner thermal and wind disturbance test

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