There's a theory about possible 'other dimensions'. Imagine if our timeline isn't the only possible timeline. Imagine if multiple timelines exist all at the same time and each timeline is different from each other because of the multiple choices you make everyday.
Say this morning you took route 1 to work - that's one timeline.
In another timeline you took route 2 to work - another timeline.
So perhaps the busy street was a possibility or dimension that could have 'been' if someone had made the decision to turn the condo area into a market?
I watched a lot of 'Fringe' and 3rd dimension stuff.
"Other dimensions" isn't so much a theory but more of a hypothesis or interpretation (yet to be proven true) that there could be multiple universes or multiple worlds, where each event is a junction or branch to other universes. This multi-world hypothesis was suggested to explain quantum mechanics (behaviour of sub-atomic particles), as well as to overcome the impossibility of travelling back into time.
One of the problems associated with travelling back into time is the so-called time paradox. For instance, if you travel back into time and prevented your parents from marrying, you wouldn't be borned. But if you weren't born, so how could you exist to travel back into time? This contradiction is called time paradox. So to overcome this time paradox, this mutli-worlds was suggested because there would be no contradiction. Your time travelling and actions only affect or create different universes. Your universe from which you got into your time machine and travel back into time is unaltered.
I sometimes cheekily tell people that ghosts can travel in four dimensions, and that's why we cannot see them all the time. They are there one moment, then *poof* -- they are gone.
For instance, let's say we live in a 2D world. This means we can only go in 2 directions: left-right and forward-backward. We cannot also jump up-down because that movement would be an extra (third) dimension.
Since we are 2D creatures, people can trap us simply by putting us in a ring (like a hoola hoop). We cannot escape the ring because the ring blocks our left-right and forward-backward direction. But if we are really 3D creatures, we can escape the ring simply by moving in the third dimension; that is, by jumping over the hoop or crouching under the ring.
So, how to trap a 3D creature? People would need to block all our 3D exits: left-right, forward-backward, and up-down. In other words, people can trap us by putting us inside a sealed box/cage. The four walls block our left-right and forward-backward movements, and the floor and ceiling block our up-down movement.
But if we are actually 4D creatures (like ghosts), we can escape easily this box/cage simply by moving in the 4-th dimension (in the same way a 3D creature escapes a 2D ring by moving in the third dimension by jumping over or crouching down under the ring). So to the people who trap us 4D creatures, we would be inside the cage/box one moment, and then *poof" we disappear (because we have moved in the fourth dimension to escape the trap). We might appear again outside the box, much to the surprise and horror of our 3D captors.
