There is alien life:
What are the odds that alien life exists elsewhere in the universe? In 1961, astronomer Frank Drake wrote an equation to quantify the probability of finding an advanced civilization elsewhere in our universe. The equation took into accountfactors such as the fraction of stars with planets around them and the fraction of those planets that were capable to hold life. The universe is astonishingly big. The Milky Way has more than 100 billion stars, and there are over a trillion galaxies in thevisible universe, the tiny fraction of the universe we can see. Even if habitable worlds are rare, their sheer number – there are as many planets as stars, maybe more – suggests lots of life is out there.
Water is a key ingredient for life as we know it. And water, surprisingly, is fairly common in our solar system. For example, evidence is building that liquid water may flow underneath the surface of Mars. Europa, a moon of Jupiter, appearsto also have a liquid ocean and so might its moons Callisto and Ganymede. Saturn's moons Titan and Enceladus also have evidence of water. This builds the evidence that aliens do exist. Planets with water are the only planets that can be inhabited (so we think)and even in our solar system some of our planets may hold life. Never mind the rest of our Universe which will also be likely to hold water, meaning they are habitable for extraterrestrials, more evidence aliens exist.
Alien life may occur outside of Earth and which may not of started on Earth. Since the mid-20th century, active ongoing research has taken place to look for signs of alien life. Depending on the category of search, methods range from the analysisof telescope and specimen data to radios used to detect and send communication signals.
The concept of alien life, and particularly alien intelligence, has had a major cultural impact, chiefly in works of science fiction. Over the years, science fiction has introduced a number of theoretical ideas, each having a wide range ofpossibilities. Many have piqued public interest in the possibilities of extraterrestrial life. One particular of attempting communication with alien intelligence. Some encourage aggressive methods to make contact with intelligent alien life. Others argue todo so may give away the location of Earth, making an invasion possible in the future.
There isn't alien life:
The universe is large, and old, with time and room for intelligence to evolve, but there’s no evidence of it. Could intelligence simply be unlikely to evolve? Unfortunately, we can’t study alien life to answer this question. But we can studysome 4.5 billion years of Earth’s history, looking at where evolution repeats itself, or doesn’t. We have been totally unable to discover proof of alien life. A British scientist has claimed that humanity could be alone in a universe that’s totally not possessingof alien life. Nick Longrich, a senior lecturer at the University of Bath, has said that the evolution of intelligent life on Earth (us) is so unlikely it may have happened just once. It comes down to whether intelligence is a probable outcome of natural selection.
There is such a small chance that there is alien life exists that we have come to stop believing that it does. There are not many other planets in the solar system that hold water meaning that alien life may not exist. But still we don’t know if they need water to survive. That may be our weakness.