i used to think of this all the same when i was younger... one of the things that came to my mind back then was there actually being an edge and thinking if there is NOTHING on the other side of this edge nothing can not have a clearly drawn line between existing and not existing... so my next thought was that the universe was actually growing (expanding) and getting bigger and bigger and bigger... and the bigger it gets the faster it spreads... and i thought well then this is interesting.. what is the speed of existence??