When someone slips and accidentally travels into a different dimension they physically do not exist here any more. All is left of them is the emotional memories left behind within their friends and families.
I returned from an inter dimensional worm hole that caused me to disappear not just today but over ten years ago as well.
My younger self was found walking a dirt road outside the city when my Dad drove by a nearby highway and saw me walking. He stopped immediately and drove me home. At home was my baby brother playing with a yard stick drawing circles in the dirt when he saw me and began crying.
He mentioned that I had disappeared for days that even our dog ran away to look for me. They found the dog but not me. Nobody knew what happened to me however I still had the memory of slipping dimensions ten years into my future. In other words, I remembered today.