Let's say we have a time machine that teleports any object within its chamber to the past...this is a common subject of many science-fiction books...that people from past or future travel through time and end up on the surface of the planet instantly...but what they don't realize are a lot of parameters which make all their books and stories wrong:
1- the surface of the earth does not stay at the same height. it moves, it goes up or down. the city that is here now might go under dust, so even if any one teleports from past or future they might end up under the dust and suffocate, or appear on a space which used to be a road but now it's located meters below, so they might fall and die.
2- The whole planet is also moving, so is the solar system, so is the galaxy. what if even the whole universe is also moving with a speed that we can't even imagine. So if any one teleports from any time to the present time they might end up in the empty space some where in the galaxy between stars and freeze instantly.
3-anything within the chamber will also teleport
4- going to past is almost impossible, cause if even a single molecule of air is translocated, it'll cause a series of changes that will affect the future. In simpler words, nothing would look similar to what we see now.
5- going to past will cause 2 different worlds, one which is now, and other in the past , going to just be created
