system
Given the following post, respond as if you're commenting on Reddit:
human
[Harry Potter] Spinning a Time Turner sends the user back one hour. If Harry Potter had gotten his own turner, could he have enchanted it to spin ~100,000 times and traveled back in time to the 80s to try to save his parents?
gpt
You can't change time. If time is a river, and you get out of the river and to upstream and jump back in, the river's direction does not change.

Harry couldn't have saved his parents, because if he did, he wouldn't have been in a position in the future to go back in time to save them in the first place.