Search for Extraterrestrial Life: The Existence of

Search for Extraterrestrial Life: The Existence of Non-Human Intelligent Beings in Our Galaxy The possibility of extraterrestrial life has always intrigued philosophers, scientists, theologians and even lay people for centuries. The fascinating question of whether there are other intelligent creatures in space, however, remains unsolved despite technological advancements in science particularly because thus far, there still lacks conclusive evidence.

Motivations for the search for non-human life range from scientific and philosophical levels, technical and practical levels, to even the need to eliminate the loneliness of the human race in time and space.

Scientists and astronomers remain committed to the search because the answer to this question has profound consequences: it will explain the nature and destiny of intelligent life on the universe, the culmination of evolution in different galaxies and provide more insight on the role of human beings on the universe, as well as what they are capable of accomplishing (Drake, 1988).

Lineweaver (2006) also explains that there is also the possibility that extraterrestrial life will provide the human race with important technological and scientific information that might take them numerous resources and hundreds of years to establish. Notable scientists such as Stephen Hawkins and Carl Sagan adopt the mediocrity principle that posits that intelligence life is likely to exist in other planets because the universe is too huge to only accommodate the human race.

The National Aeronautics and Space Administration, NASA (2015) also estimates that there are over 100 million worlds in the Milky Way galaxy that are bound to accommodate complex forms of alien life that are yet to be discovered. Nevertheless, some assert that the possibility that life might exist in other galaxy is not proof that it actually exists, and they conclude that the human race is the only form of intelligent life in the universe. This text seeks to explore the debate on extraterrestrial life further.

It starts by reviewing findings and scientific arguments that favor the possibility of other forms of life in the Milky Way galaxy. It goes on to evaluate how life might exist in non-earthlike conditions and the differences believed to exist between simple and intelligent forms of life. It then takes a look at the counterarguments from those who assert that extraterrestrial life is unlikely based on their own scientific hypotheses, and concludes with an answer to the question about the existence of extraterrestrial life in this galaxy.

Scientific arguments favoring the existence of extraterrestrial life Astrobiology, which is the study of extraterrestrial life, has been able to accomplish numerous milestones since the dawn of space exploration since the 1960s. In 1953, William Whemell, a British philosopher, published his book titled 'Of the Plurality of Worlds: An Essay', which raised issues similar to modern day arguments of life in other planets. He argued that there were other planets that orbited the stars (Aczel, 1998).

In 1974, Carl Sagan, an American astronomer and astrobiologist, estimated that more than a million civilizations might exist in the Milky Way galaxy alone and since there are billions of galaxies in the universe, this implied that the number of intelligent alien species was enormous (Ward and Brownlee, 2003). Sagan then assembled messages that could be sent to space to test this theory, through the Voyager Golden Record and the Pioneer Plaque, which were designed such that they could be understood by extraterrestrial beings that may have found them.

Dr, Frank Drake came up with an approach that would estimate the number of civilization that might be in existence in the universe. He came up with the Drake equation, which summarized the main concepts scientists had to consider when assessing the possibility of extraterrestrial life.

According to Drake (1988), the equation posits that the number of civilizations in the Milky Way galaxy with which radio communication was possible (N) was the product of; the average rate of star formation necessary for intelligent life (R*); the fraction of these stars that had planetary systems (fp), the number of planets in a particular solar system that could support life (ne); the fraction of planets on which life actually appears (fl); the fraction of planets that could support life when it appears (fi); the fraction of civilizations that were capable of developing technology that can release signs of their existence into space (fc); and the approximate length of time such civilizations could release the detectable signals into space (L).

The National Research Council has often emphasized the relevance of the Drake Equation in searching for manifestations of distant technology. Another notable scientist in astrobiology, Stephen Hawking, argued that life is based on chains of carbon atoms, and other atoms such as phosphorous and nitrogen. He then speculated that other chemical bases such as silicon could also support life using the strong anthropic principle that supposes there are many different universes, each having different values of atoms and physical constants that could support life (Hawking, n.d).

Evidence that there was still life on earth billions of years ago also suggests that there is a good chance there was spontaneous generation of life in other planets. DNA might have replaced earlier forms of cell organizations such as RNA, which had the potential of reproducing themselves in other form in different locales of the universe.

Although Hawking (n.d) states that there exists many other life forms in the galaxy, he asserts that the possibility of this life developing intelligence is low particularly because it took two and a half billion years for human single cells to develop to multi-cells, a necessary precursor to intelligence. Scientists have often argued that the extinction of dinosaurs was caused by a collision of the earth with a small body, more than 60 million years ago.

Hawking posits that the existence of intelligence on earth can be attributed to the absence of such a collision in the last 70 million years. Findings that support the existence of life in the Milky Way galaxy NASA has been able to inspect planets and moons at close range to investigate the possibility of life. In 1976 NASAs Viking Landers detected chemical signatures in Mars that indicated life may exist in the planet (NASA, 2015).

An experiment was conducted where radioactive carbon nutrients were mixed with soil to test for the production of radioactive methane gas. The result was positive, which implied that there was something in the soil that metabolized the nutrients in order to produce the methane gas. However, the test was later declared a false positive because other similar tests that were conducted failed to provide evidence of life.

In 1977, a strange pulse of radiation was detected by the Ohio State University Telescope near the constellation Sagittarius, suspected to have been a result of an unexplained astronomical event or a message with powerful transmitters. The signal still baffles scientists and philosophers to date. In 1996, NASA (2015) claims that scientists discovered rocks in Mars that contained mineral magnetite and organic molecules found on a variety of Earth bacteria. Numerous discoveries in the 21st century continue to fascinate philosophers, theologists and scientists.

For instance, in 2001, the infrared signal given off by Europa, Jupiter's moon, was explained by frozen pieces of bacteria, which are a sign of life. In 2002, the University of Texas also established that microbes may be living in Venus, which would explain the limited presence quantities of sulphur dioxide, hydrogen sulphide and carbon monoxide (Kelly, 2012). The University posited that microbes living in the Venusian atmosphere could also explain the carbonyl sulphide they had been found.

Traces of sulphur on Europa were also interpreted as a sign of waste products of bacteria colonies by Italian scientists in 2003. NASA (2015) explains that in 2004, astronomers received another suspicious signal from a section between the constellations Aries and Pisces. Although it was probably a natural phenomenon, some astronomers still insist that it was a frequency that transmitted by aliens wishing to be noticed. Of particular excitement were the discoveries of the Kepler 22b, 20f and 20e, Earth sized planets, by NASA's Kepler Space Telescope in 2011 (Kelly, 2012).

Approaches used in the search of live in the Milky Way galaxy To understand the approaches used in the search of live in the Milky Way galaxy, it is imperative to first establish what scientists, astrobiologists and astronomers look for in their search for life in the Milky Way galaxy. Rosenthal (2011) explains that life on Earth is organic and hence needs water, oxygen and minerals for sustenance.

In looking for life on other planets, therefore, scientists look for other chemical elements that sustain human life, or cell fragments that function in a way that would support other forms of life. They examine dust and particulate matter from space hoping to find biological entities made up of oxygen and carbon, the building blocks of life. Other basic elements they search for include hydrogen and nitrogen, which attach themselves to form large molecules that are the building blocks of proteins that make DNA and life.

Aczel (1998) also states that scientists try to identify habitable localities in the galaxy by looking for water, particularly because they believe it is essential for any form of life while it is in liquid form. The basic assumption applied is that any planets that have liquid water on them must harbor life. Scientists believe that Mars once had water although it is no longer present because its small size could only accommodate water for a billion years.

There has also been evidence that Europa also contains an ocean of liquid water. Scientists consider a planets proximity to the sun when determining whether a planet can support life. Ward and Brownlee (2003) explain that planets that are too close to the sun may not allow liquid water to exist on the surface. Due to technological advancements in the 21st century, the search for extraterrestrial life seemed to have focused more on identifying and sending signals to intelligent creatures that are believed to exist.

In fact, Drake (1988) believed that the reason contact with alien creatures had not been made was because the Earth's detection technology was not advanced enough. Since the 1940s astronomers continue to listen intently to radio telescopes to discern signals that may be coming from out of space. Rosenthal (2011) also states that scientists try to identify unidentified flying objects (UFOs) and unidentified submerged objects (USOs) because they believe that they provide proof of life from other planets.

How might life exist in non-Earthlike conditions? Stephen Hawking sought to explain how life might exist in other planets. He first defined life as an ordered system with the ability to sustain itself amidst disorder and the ability to reproduce itself (Hawking, n.d). For life to exist in non-earth like conditions, therefore, any form of living being must have two elements: instructions that help it reproduce and to sustain itself, as well as the mechanisms needed to carry out this instructions.

Sufficient quantities of carbon, oxygen, hydrogen, sulphur, phosphorus and nitrogen may also facilitate the formation of living organisms on planets with temperatures and chemical make ups like those of the Earth. Extra terrestrial life could be explained by self replicating chemical reactions made possible by the presence of oxygen, carbon and water in different locales in the universe.

On the other hand, Aczel (1998) believed that life in other planets could be explained by the Darwinian Dynamic, a fundamental principle that explains evolution of order in both living and non-living physical systems. He opined that life, regardless of where it exists in the universe evolves according to set principles, and if it present on Earth, then it must also be present in other planets.

The differences between life and intelligent life Over the years the focus of the search for extraterrestrial life has shifted from looking for any form of life to looking and communicating with intelligent life believed to exist in the solar system. Evidence of cell fragments and bacteria- like organisms in other planets are proof that simple life is may be present.

Recent findings by NASA, such as species of microbes on Mars and frozen bacteria on Europa also point to the existence of simple life formed as a result of biochemical reactions among a variety of elements (NASA, 2015). On the other hand, the possibility of intelligent life continues to intrigue scientists and astronomers. In contrast to simple life, intelligent life is characterized by understanding, communication, a capacity for logic, self-awareness, emotional knowledge and creativity.

In fact, Drake (1988) claims he focused on the possibility of intelligent life and alien civilizations when coming up with the Drake formula. While simple life is based purely on chemistry and biology, expectations for intelligent life in the universe is based on the laws of physics, the arrangement of the universe and a bit of biology.

The fact that technological development occurred independently in Central America, China and the Middle East could imply that other forms of life in the galaxy also advanced their intelligence due to population pressure and the need for survival. While simple life can be used to provide more insight on the nature of atmospheres of other planets, intelligent life is motivated by the search technological knowledge that may exist in alien civilizations.

For example, numerous efforts have been made to communicate with intelligent life that is believed to exist in other planets, including a radio message from Arecibo, two messages on Voyage I and II, and two other messages on Pioneer X and XI, all spacecrafts used in space exploration (Drake, 1988). In an attempt to convey messages without the use of a language, pictures are sent into space with information about life on planet earth and the various cultures that are accommodated.

Radio telescopes are also used by astronomers signal to alien civilization. Modern day astronomers and scientist believe more than ever that intelligent life exists and that non-human races are always trying to communicate with Earth, which explains the need for better detection technology and more funds for further exploration of the Milky Way galaxy. Arguments that dispute the possibility extraterrestrial life Attacks on the possibility of existence of extraterrestrial life began as early as 350 B.C.

when Aristotle, one if the most influential Greek philosophers, elaborated on the uniqueness of the earth in majority of his writings (Aczel, 1998). Aristotle's philosophy, which formed the basis of teaching in Europe at the time, asserted that the Earth was at the center of the earth and that the moon and stars rotated around it, with the Sun as a bright circle in the sky. This philosophy prevented the idea of extraterrestrial life from earlier on in History.

The inability to identify other planets orbiting the stars at the time also led to conclusions that life could not exist anywhere else. Enrico Fermi, a nuclear physicist, discouraged the search for life in the Milky Way with his famous quote "Where is everyone?"(Aczel, 1998) His question, which.