Mirror of Reality

How deep can we go?  What are the faintest and most distant galaxies we can see with the Hubble Space Telescope ?   This is the challenge taken up by the Frontier Fields,  a new campaign to see deeper into the universe than ever before.  To achieve this goal,  astronomers are using a trick from Einstein's theory of general relativity.   The most massive objects in the Universe — very massive clusters of galaxies — warp space in such a way that light rays passing by are deflected, much in the way light passing through a glass lens is bent. This is called “gravitational lensing,” and these clusters act as nature’s telescopes, magnifying and stretching the light from those galaxies located behind the clusters. The distorted, magnified, and mirrored images of the distant galaxies reveal the underlying distribution of invisible dark matter within the lensing clusters.  The stunning images of the Frontier Fields combine the power of HST with these natural telescopes of massive clusters of galaxies to give us the intrinsically deepest observations ever obtained.