Hope this idea helps.
Assume you do not have this idea before, this idea may helps you research in a direction that may allow time travelling machine inventor peeking the history, the images or observation of our earth in the past. Though it may be a kind of unclear proposal of research, but it theoretically work. It can be possible when you see most of our dreams come true in this age.
The fact: we all knew the universe we observed through telescopes happened at least few light years ago. That means it is a state in the past. Therefore, the light ray from our earth emitted to other planets in the universe is the same. Assume we can go faster than the light , we can catch the light emitted and view it . It is images in the past. The time difference is the time you go in the past.
This theory is impractical as we all know that light wave is the fastest and cannot be surpassed.
But the importance of my idea is that, with new development of technolgy we can view other slower waves that reflect too. Just like infrared, ultraviolets and other invisible rays.
That is to say, we have no need to travel faster than light ray, but achieving as fast as we can and trace the slower ray. View it with viewer that can see the invisible ray we can see the past.
With this idea, we just need to develop a view and go to somewhere in the universe we can see what happened to our earth in the past. It can be a foundation to invent time travelling machine and go to the past and seek information we want.
Going the future? I don't think this idea can do the reverse way!