 Distant giant galaxy clusters, around 4 billion light-years away, have been able to lens galaxies twice that far away. Without gravitational lensing, we would never have detected these more distant galaxies. At these distances, we need to take into account the expansion of the universe in order to determine how far away they are. For that, we use the Friedman metric. With this and a stated set of coefficients for the flat-lamb to cold-dark matter model, we get the galaxy's distance from us when the light we see started its journey. The distance the light traveled to get here, and the distance from us the object is now. Here are a few examples. Astronomer Timothy Hamilton, using the Hubble Space Telescope, discovered these unusual objects now named after him. The objects are the stretched images of a gravitationally-lensed distant galaxy located more than 7 billion light-years away. One appears to be a mirror image. In this case, a precise alignment between the background galaxy and a foreground galaxy cluster 7 billion light-years away produced twin magnified copies of the same image of the remote galaxy. This rare phenomenon occurs because the background galaxy straddles a ripple of dark matter in the foreground galaxy. As the far away galaxy light passes through the cluster along this ripple, two mirror images are produced. Along with a third image, they can be seen off to the side. This Hubble image shows a massive galaxy cluster about 4.6 billion light-years away. Along its border, four bright arcs are visible. These are copies of the same distant galaxy, nicknamed the Sunburst Arc. It's almost 11 billion light-years away. Its light is being lensed into multiple images by strong gravitational lensing. The Sunburst Arc is among the brightest lensed galaxies known, and its image is visible at least 12 times within the four arcs. Here's a closer look at three of them. The lens makes various images from 10 to 30 times brighter. This allows Hubble to view structures as small as 520 light-years across. A rare detailed observation for an object that far away. This is a close-up look at the brightest distant magnified galaxy in the universe known to date. It is one of the most striking examples of gravitational lensing. In this image, the light from a distant galaxy, nearly 10 billion light-years away, has been warped into a nearly 90-degree arc of light in the galaxy cluster. The galaxy cluster that is bending the light buys 5 billion light-years away. Here's another one. The light from this galaxy travel 4.48 billion light-years to get here. These foreground galaxy clusters are magnifying the light from the faint galaxies that lie far behind it. The faint light from these lensed galaxies traveled up to 12.8 billion light-years. It's the gravitational lensing that allows us to see that far back in time. Without the magnification, these galaxies would be invisible for us. This is able 1689. It's one of the most massive galaxy clusters known. The gravity of its trillion stars plus dark matter acts like a 2 million light-year wide lens in space. Here's gravitationally lensed galaxy A1689-ZD1. It is one of the most distant spectroscopically confirmed sources with a redshift of 7.5. We are seeing what ZD1 look like when the universe was only 700 million years old. It is the earliest known galaxy where dust was detected in its interstellar medium. And surprisingly, it has the same ratio of dust to total mass as very mature galaxies such as our own Milky Way.