3D+1T space has at times been used as an analogy to try to help people to understand 4D space.
An example is that a tesseract would exist as a cube that exists a finite time with a start time and finish time.
One of the things I just realised is the effect of 'turning' into time from our spatial dimensions.
We generally turn left or right sideways.
Generally we can consider that you would turn one direction into the time dimension.
You could spiral turn into time but that's fine for another story.
The interesting thing about turning into 'time' is that it mimics the effect of the tesseract existing through a time period. The difference is that initially we exist in the moment or in the current 3D space.
To turn into time - just as we turn into the 4th dimension - you would do so around a plane or cross section of ourselves. Now, how do you turn into time when there is nowhere to go except the 3D space that exists?
The answer is interesting in that you turn into the past and future. Everything on one side of the plane, that you are turning around, turns into the future and everything on the other side of the plane turns into the past.
Now if you don't actually move anywhere but stand in place and just turn into the time dimension a problem arises...
The part of you that turns into the past is trying to occupy space already occupied by your former self when you were standing unturned. There exists a problem of multiple things trying to exist simultaneously in the same location.
That was quite interesting to come to understand as a problem with using the 3D+1T space to model 4D space.
But it does show up something interesting. If you were angled into time and existed for but a single moment then to us you would appear as a cat scan going from one side to the other. Cool.
If you existed for more than a single moment and you started walking somewhere it would appear as if part of you started moving before the rest of you did. In a stretch-catch up kind of way. Cool too.