How does the Hubble Telescope see back in time?

It has to do with how quickly light travels from those stars and other sources. Since those sources are very far from the telescope, the light that is emitted from them must travel from there to the telescope, which can take many years, during which time the properties of the source can change significantly. Consequently, when you look up at the sky the next time, you are looking into the past, and the majority of the stars that you see are no longer there. The same is true for the telescope.

Since light has a finite speed, objects far away from us appear to us as they did when they were first observed. The Hubble Space Telescope can see objects billions of light-years away, allowing us to observe the universe billions of years ago. This is possible because light from far-off objects takes billions of years to reach us, so we see them as they were when they were first emitted.