If you went up in an elevator to the top of a 50m building then came back down, determine these quantities: Distance at the top:
Displacement at the top:
Distance when down:
Displacement when down:

If you walked into the building with your cup of coffee at 8:00 in the morning, took a ride up and down on the elevator for fun, and then went home, then ...

When you got to the top:

...  Your distance covered  =  50 meters

...  Your displacement since you started  =  50 meters up

When you returned to the bottom:

...  Your total distance covered  =  100 meters

...  Your displacement since you started  =  zero

If you walked into the building with your cup of coffee at 8:00 in the morning, took a ride up and down on the elevator for fun, and then went home, then ...

When you got to the top:

...  Your distance covered  =  50 meters

...  Your displacement since you started  =  50 meters up

When you returned to the bottom:

...  Your total distance covered  =  100 meters

...  Your displacement since you started  =  zero

Explanation:

3. dark matter

empty space could also be a simple vacuum