Can the past actually be affected by events in the present? If the present can be affected by events in the past, it seems reasonable to think that the converse would be true as well. After all, from a time traveler’s perspective, the past is the future. Feedback?
That’s the whole idea of time travel. A time traveler starting in the present and going to the past becomes the cause that alters the past.
Right, I understand that. I guess my phrasing wasn’t clear. I’m not talking about a time traveler altering the past by interfering with it. I’m talking about events in the present having the same effect on the past as they do the future. We know that entropy increases with time, but is it actually direction-specific?
Entropy is direction-specific, but that doesn’t mean everything is. For example, some have noted that antimatter behaves in some ways like regular matter traveling backward in time since it interacts precisely opposite of how normal matter does. Not only that, a matter-antimatter reaction will produce photons and obliterate the matter - exactly what we’d expect if the 2 particles came to a dead stop at a certain moment in time while we continue toward the future. Of course, there are probably other things that can propagate backward in time, not the least of which is the cause of psychic abilities (yes, they’re real, just hard to find). 
Do you mean that the particles don’t have two collide?
Could you explain why entropy is direction-specific? I can’t see it. In fact, I see uncertanty increasing with time whether you consider the past or the future. Doesn’t increasing uncertainty imply increasing entropy?
Once you flatten time, there is no past present or future. Its just a pancake of space.
Don’t forget the syrup.