The first artificial satellite, Sputnik 1, was sent into space on Oct.4, 1957, and the exploration of the space started (A Brief History). One product of space exploration, the most distant human-made object Voyage 1, has escaped the sun by 13.8 billion miles, but it still has not escaped the influence of the sun (Davis). However, such a huge solar system is just a common one in the Milky Way, and the Milky Way is just one of the billions of galaxies in the universe.
After decades of exploration, the earth is still the only planet with lives live on so far. Despite this, most scientists and astronomers still believe in the existence of alien life. It is highly likely that there are other life forms in the universe, according to the origin of life, the properties of the universe, and the evidence collected.
Several moons of Jupiter and Saturn, including Europa, Titan, and Enceladus, are thought to be possible sources of extraterrestrial life (Purdom).
Liquid water resources have been found on those planets and moons through technologies human invents so far, but current technology can only explore planets in the solar system that may have lives. Most scientists believe there are lives exist on other planets. Space agencies are continuing to find extraterrestrials and sending messages to outer space. For instance, the National Aeronautics and Space Administration (NASA) is planning out a mission to Europa, which may launch as early as 2022(Wall).
First of all, the possibility of life on other planets is based on studies of the origin of life.
One theory about the origin of life is the spontaneous generation, and the other one is that life is produced from other life. Whereas the first theory was ended by an experiment by Louis Pasteur, then Darwin’s theory of evolution came to be known(Damineli A and Damineli D, 264). According to the current research results, the earliest evolution of life took place in the Archean age. Life formed after the water formed on the earth. In addition to the liquid water that formed with the birth of the earth born, some of it came from ice brought by comets (Williams).
If the beginning of life on the earth is water, then life was probably brought from another planet by comets. Moreover, the earth itself is made of matter that exists in the universe, and the same matter may exist on other planets to create conditions for life. Furthermore, Sir Francis Crick showed his view in life Itself there is no possibility of synthesizing a great majority of sequences at any time(Thompson). From this point of view, there is no actual source of the birth of life. The lives on earth could only have come from elsewhere in the universe and evolved due to the condition of the earth. Therefore, according to the studies of life formation, other planets are likely to have lives live on.
On the other hand, the properties of the universe decide the possibility of the existence of life on other planets. From the points made by Dr. Sagon, there are around 1022 stars in the universe. There will a start similar to the sun per million stars, and each one million those starts will have a planetary system that similar to the solar system. Similarly, there is one earth-like planet per million (Thompson). Life doesn’t happen by accident. It indicates that with a similar environment, lives perhaps evolve in a similar or even the same way. These data suggest that there are at least 10,000 earth-like planets in the universe, so it is quite possible to breed intelligent creatures. NASA has come up with a similar theory that “10 to 20 percent of stars around us have Earth-size planets in the habitable zone”(Dunbar). Moreover, life could form after a few billion years after Big Bang.
One of the foundations of life is chains of carbon atoms, but around 15 billion years ago, when the universe began in Big Bang, there was no carbon exist. The elements that make up the basis of life appeared after the matter in the universe had accumulated to form early stars (Hawking). The evolution of life is a long process, and if the basic matters for life were available billions of years after the birth of the universe, the earliest forms of life, such as bacteria or individual cells, might also have existed. Therefore, the size and age of the universe make it possible for life to emerge on other planets.
In the end, evidence from space stations suggests that life is likely to exist on other planets. In 1984, six Soviet cosmonauts claimed they had seen winged giants on Salyok-7 (Seaburn and Swancer). These six cosmonauts were highly trained. According to the description, they saw it twice. It is rare for more than one person to experience the same hallucination at the same time, and all of them performed well on a psychological assessment after coming back, so what they saw could be real. In 2014, the International Space Station (ISS) claimed the traces of life were found on the surface of the station (Rao). It’s against the laws of physics if tiny creatures rise from the earth to the height of the space station in the vacuum of space. The life found outside the space station probably comes from outer space. Therefore, the evidence that has been found in the solar system gives life on other planets a high probability.
In conclusion, the evolution of life, the vastness of the universe, and evidence of space station improve the strong possibility of the existence of lives on other planets. Although the extraterrestrials haven’t been found yet, human’s curiosity about creatures from outer space has never diminished. As technology advances enough to explore planets beyond the solar system, the possibility of discovering other forms of life may be higher. The universe is so vast, the possibilities are endless.