It's basic science that light can be bent. Eyeglasses bend light so that images can be clearer to those don't have 20/20 vision. The tiny rainbows that twinkle off of a crystal chandelier are another way light is bent. When it's hot out, waves appear to rise from the ground, rippling the air. Light is bent in all sorts of ways, but in space, how light travels and bends is more complex
Space telescopes bend the light that comes from stars forming and dying and that is how many of the images we have of our universe came about. When galaxies come up against each other, the collision of huge amounts of matter results in light being bent. Researchers can use these patterns of light to identify dark matter, which cannot be seen on it's own, but can only be found by tracking how light bends through the universe. Check out the video to learn more about how light bends in space.
