There is multiple timelines or dimensions as you call them. Many people have experienced them in what science calls "Astro Travel or Astro Projection" during your sleep. But of course there is skeptics like anything else. Unless you have experienced it yourself you don't know for sure. But I'm sure someone here will say no or because science hasn't proven it or anything. However the practice and known origins of it goes back thousands of years. Many things over the years science claimed it wasn't real or this wouldn't work and time & time again they have been proven wrong. As we advance in technology this stuff will be proven right highly doubtful in our time but in the future most likely. Same with time travel as well.
Also there is proof that you do get reborn albeit into either a different race or *** sometimes. Perfect example is a friend of my mom's. His son started to ramble on about stuff he shouldn't know at 2-2.5 years old about cars. He started to name cars going back from the 1970s to the 1920s in the UK. Then he claimed he was this driver that had died in a crash around this year. Mom heard him on the phone explain all of this and saw the video of him saying all of it. Mom did a ton of research and found out everything this 2-2.5 year old kid who had never talked about cars before until he passed this one spot in the road was true. Lot's of examples out there of this happening. This was many years ago as he is now well into his teens but over time those children who have done stuff like this don't remember saying that stuff or saying their name they had before or what they did or were interested in. In this case he had raced cars as a hobby.
Also as a former EMT I saw people brought back from the dead as they flatlined on the table in the hospital or in the ambulance. Many came back saying they experienced exactly what Buck described. Some didn't but many did. As we would ask them as it fascinated many of us on the dept.
When someone is getting chest compressions and is truly gone they have been known to sh!t themselves at that point you stop chest compressions as there is no more point in trying. That is taught in any EMT class. Yes you still transport to the hospital but they will announce the patient as DOA when you get there.
If it's not proved now, then how can you (or anyone) be so sure that it is real? Belief doesn't make something reality.
"As we advance in technology this stuff will be proven right highly doubtful in our time but in the future most likely."
Why do they teach you to give up just because you can't revive on-scene? If you are keeping blood and oxygen going to the brain, then if they can get the vital functions going, survival is possible.
