The arrow of time only goes forward as per our current understanding. It seems like it's impossible to travel to the past. I mean the absolute past, like thousands or millions of years ago—not the relative past from an observer’s perspective of light (as in general relativity). Is the past lost forever?
Even if we couldn't travel to the past, I think it's at least theoretically possible to see, hear, and feel the past if we could estimate it in detail.
Let's imagine that we gathered all the information of the present down to its atomic level and even smaller, from the perspective of Earth. We feed this data to a highly advanced AI that can process all this information and recreate the past by simulating each step back in time. Movements of atoms, electrons, etc., are all perfectly predicted based on the information of the previous snapshot.
With this, we have a simulated reality of every point in time of the past—except for any past event that left no information or evidence in the present. However, I think the missing data could at least be estimated based on its impact on other events.
Once the simulation goes as far back as we want, we can experience the past in a virtual reality that contains detailed information of any specific place and time on Earth. This is because we gathered information only from Earth, so we could simulate the past only from Earth’s perspective.
Is this the absolute reality of the past? No, it's only an estimate, but it could give a vivid and detailed experience of the past. This doesn't cause any paradoxes, as we are not actually traveling to the past.