Strictly speaking, when telescopes look at the light from distant galaxies, they are not literally looking back in time. The past no longer exists, so no one can directly look at it. Instead, the telescopes are looking at the present-time pattern of a beam of light.

Do telescopes see back in time?

Large telescopes can look so deep into the Universe that they can also look back billions of years in time.

Why do telescopes look back in time?

Because light takes time to travel from one place to another, we see objects not as they are now but as they were at the time when they released the light that has traveled across the universe to us. Astronomers can therefore look farther back through time by studying progressively more-distant objects.