Lady Laura 
When people speak of traveling to the past, they worry about radically changing the present by doing something small, but barely anyone in the present thinks they can radically change the future by doing something small.
Barbara R. Nelson
Daniel de Kay@cmconseils It’s not that simple.
From today, any action could result in a gazillion different futures. So whatever we do creates any of these futures.
If you travel back in time, you want only one of these futures preserved, and as such any small thing might break that ONE future.
Of course if you have an intention to create a specific future, your actions matter differently.