Trying to think about the shape of the universe is like trying to think about what protons in an atom look like – just too extreme to visualize. But now someones made a map of it. It’s taken more than 1000 hours of observations from the Hubble telescope to construct a cosmic ‘scaffold’ of dark matter – the invisible stuff upon which stars and galaxies are put together.
There’s something great about the fact that the way they have mapped it is not by concentrating on what’s visible, but the unseen stuff in between. Apparently, only one sixth of what comprises the stuff of the universe is ‘ordinary matter’ (gas, stars, planets, galaxies to you and me) – the rest goes completely unseen. Astronomers have desribed the challenge of mapping the universe as ‘similar to mapping a city from night-time aerial snapshots showing only street lights’. Being able to map the dark matter is like being able to see the whole city (streets, people, houses, everything) in daylight for the first time.
How did they do it? Dark matter attracts "ordinary" matter through its gravitational pull and distorts the light passing through it so they could not only show that the distribution of galaxies follows the distribution of dark matter, but could show where the dark matter itself was. Hubble observations were combined with those of powerful ground based telescopes to give a 3D picture."For the first time, we can see what’s really out there" said Prof Carlos Frenk of the University of Durham
Its almost too big a thing to comprehend but I suppose it just goes to prove that the most important things are often those things that you can’t see. All they need now is a great big ‘You are Here’ arrow.