Since the discovery of the first exoplanet in the 1990s, scientists have found more than 4,000 exoplanets, some like the giant gas planets of our solar system, and others like earth-like planets. Some exoplanets may have very harsh environments, perhaps as hot as venus or mercury, or as extremely cold as other planets. Of course there are also exoplanets that may have relatively suitable temperatures, may be located in the habitable zone of a star system, are a potentially habitable planet, and may even be a living planet.

The existence of reproductive isolation, so that these situations can not occur, even if there are some individuals of different species sometimes complete the mating, but they generally can not produce offspring, or produce offspring can not continue to reproduce

Although scientists did find that people still have consciousness at the time of death, but the consciousness does not stay for a long time, may not have time to react, the consciousness disappeared