Could extraterrestrial life exist? This question has been explored by humans for many years. When humans have not used telescopes or probes to explore the outer planets, many people may think that extraterrestrial life and alien civilizations are common, because we do not know much about those planets before. As a simple example, we humans once thought that mars, which is more than 55 million kilometers away from earth and 400 million kilometers away, might also have an ecosystem similar to that of earth, until july 1965, when the first successful mars probe, mariner 4, sent back the first pictures of the surface of mars, which shocked the scientific community. The first successful rover, mariner 4, returned the first picture of the surface of mars in july 1965, shocking the scientific community. In the images returned by the rover, mars was a dead world full of craters, without a trace of life, much less an intelligent civilization like earth.

Mars, another terrestrial planet in the solar system in addition to the earth in the habitable zone, has more similarities with the earth, has a lot of habitable conditions, and is considered a potentially living planet, but we humans have not found extraterrestrial life on mars until now. Could it be that life really exists only on earth in the universe, and that intelligent civilizations really exist only on earth?

This seems unreasonable, because deep in the vast universe, there are countless planets like earth, planets with more superior environment than mars, even if we have not found alien life and alien civilization on mars for the time being, it does not mean that there is no alien life and alien civilization in the universe. Just like we do not find frogs in the pond in front of our house, but we cannot directly conclude that there is no such animal as frogs on earth. Moreover, our human perception of life may still be rather one-sided, because at present we have only discovered the existence of life on earth, so when searching for habitable planets and alien life, we will refer to the situation on earth, such as whether there is liquid water, whether there is an atmosphere, etc. However, when scientists are exploring, there are some discoveries that may overturn our perception of life, because there are some organisms that are extremely resilient and may not need sunlight to survive.

"Alien world" Found in 5.5 million year old cave

Just a few kilometers away from the coast of the black sea, there is a mysterious cave known as the movel cave. This mysterious cave was previously undiscovered by humans until 1986, when scientists discovered it while searching for a site to build a nuclear power plant. After confirmation by scientists, it was learned that the cave was formed about 5.5 million years ago.

What are the secrets inside this cave, which has been isolated from the world for millions of years? In the absence of sunlight, is the interior as dead as mars? In order to uncover the truth about the interior of this cave, scientists went deep inside the cave and found something inside the cave that overturned our human perception of life.

Want to enter this mysterious cave is also not an easy thing, scientists need to first drill to the bottom of a roughly 20 meters deep, and then also need to go through a narrow passage before arriving at a larger cave, in which there will be a small lake. It is not surprising to find a lake inside a cave, because in the interior of many caves there will be a variety of caves, so that people are surprised that in this cave actually survived some very resilient creatures.

In this 5.5 million-year-old cave, not only is there no sunlight, the environment is also very harsh, the oxygen content in the air is only about half of that outside, and the carbon dioxide content is 100 times the atmospheric carbon dioxide content. In addition, the air is also filled with some highly toxic gases, such as phosphine. In such an environment, we humans obviously can not survive, not only we humans, many creatures may not be able to survive, but scientists found that the cave actually exists 48 species of organisms, and 33 species are unique to this place, that is, in other places is not.

This is strange, it is reasonable to refer to the earth's ecosystem, including us humans, countless species of living things are actually energy from solar energy, plants provide photosynthesis of the way to convert solar energy into oxygen and organic matter, and then these energy flows through the food chain to animals until the top of the food chain. There is no sunlight inside this cave, which means there is no external energy input, so where exactly do these creatures get their energy from?

Scientists believe that in some caves, although there is no sunlight exposure, nutrients will flow into the cave from outside through groundwater or other means, bringing nutrients to the creatures inside the cave. However, the surface of this mysterious mowell cave is completely impermeable to water, which means there is no more way for energy input.

Although there is no water inflow, scientists have found many bacteria in this cave that can convert sulfide into sulfuric acid and ammonia into nitrate, from which these bacteria obtain energy, and some bacteria will obtain energy directly from methane or other gases, which will then flow through the food chain to more advanced organisms, such as spiders, scorpions, leeches, etc. It is also due to the fact that there is no sunlight in the caves, so these creatures have lost their eyesight.

Could extraterrestrial life exist?

This is also too incredible, since these caves on earth without sunlight exposure can exist some unknown creatures, in those planets where the environment is similar to the earth's caves theoretically there will be similar creatures, such as europa, titan, etc., as we often say. Many people believe that there may be some fish-like creatures in the subglacial oceans of europa, while there may be some creatures that feed on methane on titan. If this is really the case, then alien life and alien civilizations may be common.

Because deep in the vast universe, there are too many planets like earth, similar to europa and titan. Moreover, the age of the universe is already up to more than 13 billion years old, there is perfectly enough time to develop alien life, alien civilization, and it may be very one-sided for us to search for alien life, alien civilization by only referring to the survival conditions of earth creatures.