After extensively researching this subject throughout psychical research my conclusion is that it is in other realms of existence. So it ain't up above and hell is not down below instead heaven is in another realm of existence and the lower realms of existence that you may want to call hell. I am currently reading a book called the evidence for an afterlife by Dr. Jeffery Long an Nde researcher his view is that nde's the nine lines of evidence he presents in his book proves that an afterlife exists.
I would have to disagree in science their is no such thing as proof. So the best you can get is strong evidence that points to the high probability of an afterlife. But with just those nine lines of evidence in his book it still doesn't amount to strong evidence for an afterlife. It's until you look at all the evidence for an afterlife together then you can say their is very strong evidence for an afterlife.
The nine lines of evidence he mentions such as blind people from birth that are able to see during cardiac arrest and clinical death. He also mentions accurate veridical out of body perceptions that are collaborated by doctors and nurses and staff. I would say Near death experiences and out of body experiences evidence does provide a lot of good evidence for an afterlife. However, just from that phenomenon it would be hard to come to any preliminary conclusions on rather their is an afterlife or not.