#1 First, forget the question about what the hell or heaven is. We do not deal with that here. We deal with the question of where does hell or heaven can be? As of now, nobody knows. If anybody knows, they have not told yet. Or they are not here to say to us. So, it is up to us to find it.
The first that comes to my mind is the Earth itself. There are still unexplored places on Earth, especially ocean. But to spice up, we will leave our Earth. So, let us look at our solar system. It is essential to mention ours since there are numerous other solar systems. Keeping the focus on our solar system, we first look at the planets. We have fairly mapped the surfaces of Mercury, Venus, and Mars. Mercury is apt for the traditional definition of hell. Unfortunately, we have not been able to capture any live activity, at least on the surface. Venus and Mars are also reasonably checked and are not the candidates. Jupiter is an exciting option, a gaseous planet, we hardly know what is there in it, within and below the Earth-sized gigantic storms. Volumetrically, Jupiter is approximately 1300 times larger than Earth. So, we have space more than required to accommodate the billion dead on Earth. However, being gaseous with turbulent storms, we do not have a platform to host any events. Going beyond, we are looking at planets with a much cooler atmosphere. Thus, an ideal environment is still absent. Titan, one of Saturn’s satellites, has a liquid ocean below a thick icy surface, a potential location of interest to the scientific community. Neptune, Uranus, and Pluto also can be neglected.
A tenth planet (Or ninth, if Pluto is avoided) is being investigated. Some pieces of evidence of its existence are available though none is conclusive. Nevertheless, being extremely far from the sun, a habitable atmosphere may not exist. Thus, in a nutshell, we can rule out our solar system as a potential location for heaven or hell. Beyond the solar system, we only have the Viking probes to check for anything. The only other means for scientific exploration is by telescopes. In the last two decades, numerous exoplanets have been discovered. These are good locations for our interests. However, we are too early to conclude. A question also arises regarding the time required for the dead to travel there. They may have to travel at the speed of light. If not, the journey itself will be tiring. Till now, I evaded the question of requiring a physical body to enjoy the physical pain and pleasures of hell and heaven. I take the liberty of avoiding the question.
In summary, I can say that we do not have any idea of the locations of hell and heaven. Personally, these are mere creations of the human mind. For the hardcore believers, I have a satisfying answer. Yes, there exists hell, but not sure of heaven. If you are a follower of X, then you have a chance to go to X Hell or X Heaven. I do not know where you will qualify. However, the hells of Y and Z are ready and waiting for you. For others, I will give you a clear answer to this question after my death if I can.