Not trying to step on anyone's toes here, since this is a discussion I want to discuss, not have people rant or rave at me, this is just my opinion and I want to contribute to the conversation:
I think it would only happen if God let it happen, think Chronicles of Narnia.
Also, there are these universal laws in place that literally stop unclean things from being in the presence of God, so it would be impossible for people to reach heaven without having been cleansed first, thus the Atonement of Christ.
HOWEVER, lets not forget about the spirit world (the waiting period before judgment). What if they somehow found a way to enter the spirit world, no? And came back with data and whatnot. THAT would be cool!
I think that finding a physical "Heaven" out there in the many dimensions of the cosmos, the vast majority of society would become religious even more then it is today because there would be physical proof it existed.
However, upon finding it, then I think Humanity would realize finding our Creator would also be physically possible.
You're assuming heaven is a physical place that can be reached by technology. In this case, I would have to refer you to C.S.Lewis' "The Magician's Nephew" for my response.
If this were the case, even if they made it to "heaven", from what I gather, they wouldn't be able to get in, seeing as how it is a walled city. Angels I don't think would mind, considering God called us His children. And considering God has been taking people there for visits quite regularly, at least in my crowd of Christians, I don't think it would bother Him that much either.
Thus, my conclusion: only a Christian scientist would be able to complete such a feat. Say what you want about how paradoxical that is. They do exist.
That was the New Jerusalem as it descended from God onto the new Earth. It's part of the new creation that's not supposed to come into being until after the Second Coming. Heaven itself isn't described in any detail that I recall, and I don't think there's any mention of gates.
My first reaction would be "Really?" with a slightly higher pitch in my voice than usual as a look at whomever proved it with my head leaning slightly to the right. Then I would say "What do you know, I was wrong, there it is."
Then some religious people would start their campains and I would have to explain over and over to some folk I know that I was still in the right to not believe it existed before this happened, because there were no evidence for it. And I'd probably use the situation to flip it on them and say that at least I didn't take it on faith.
If heaven was real.. Well, that's a good question. I think that if heaven was real then more and more people would believe in Christ and would be Christians in no time. But the thing is, if heaven wasn't real then how will people react? I can just answer the question by just saying that "The Heaven is where you find your balance"
I know someone who use to be a hardcore atheist, he then had a fatal problem (I cannot remember what was wrong with him.) and he was officially classed as dead, his death certificate was signed. But then he somehow woke up and said that he had seen Heaven, he said that there where in fact golden gates and clouds and a golden shining light which he thought was the God surrounded by his angles. But now he is a believer.
I've heard of people who 'died' and saw Buddha. He probably came from a western culture. If you were to ask we to conceptualize heaven, I would conceptualize it in the western cultural way in which I have been conditioned to envision it as.
Also you know what, I don't recall anywhere in the Bible that says there are fucking clouds in heaven, and I want him to describe these angels. Did he see angels as they are described in the Bible and Torah (with lion heads, multiple arms, and wings of eagles) or did he see it as they are described by lineages of Romanesque based artists in Europe (chubby, wearing togas, and flowing hair).
Because if there is a Christianic heaven, I expect to see freaky lion headed, goat hooved, chimeras with flaming swords, not fucking Renaissance paintings on clouds.
It's hard to disprove, and hard to prove but amazing what the brain can conccoct when it's deprived of oxygen.... Then it also also depends on how long they were actually dead. Clinically dead or just gone for a minute or two?