Typically, an essay’s introduction should include its thesis statement. This rule of thumb should serve well when writing class essays.
Johnson’s thoughts led her to question whether our current approach of searching for aliens through searching for DNA, RNA, and nucleic acids was truly appropriate. Perhaps we need to think differently. Here’s one suggestion.
Origin
The question of extraterrestrial life remains unresolved, although some scientists speculate that its origin may lie elsewhere than Earth. They assume that similar forces that cause life on Earth could facilitate its presence elsewhere – however there is no scientific proof supporting such claims.
Others argue that complex life is unlikely anywhere in the Universe, citing what’s known as the Rare Earth Hypothesis as proof. This theory stems from the requirement for liquid water, carbon-based chemistry, and energy sources for life to exist on other planets such as Mars; without these resources it would be hard for living organisms to form on these worlds.
Even in the absence of verifiable evidence, many continue to search for signs of extraterrestrial life. Some scientists are even exploring terraforming – the process of altering planets or moons to make them more habitable; although this practice has its critics. This topic remains highly contentious due to speculation rather than actual research conducted into it.
Astrobiologists are studying extraterrestrial life as part of astrobiology. Scientists are searching for signs of life on other Solar System bodies, including Mars. Radio telescopes are also being used to search for any intelligent life signals emanating from other worlds.
Meaning
Extraterrestrial is the scientific term for life not native to Earth, ranging from prokaryotes to intelligent beings – even civilizations more advanced than our own! Though no direct evidence has yet been discovered of extraterrestrial life beyond Earth itself, many scientists remain hopeful it could exist on other planets.
Astrobiology, or the study of extraterrestrial life, encompasses numerous areas of scientific study. This field involves radio astronomy which attempts to detect possible alien transmissions, telescopes that seek habitable extrasolar planets and even chemistry which investigates basic building blocks of life as they interact throughout space based on the belief that chemical reactions occur naturally throughout our galaxy.
Scientists investigate meteorites as evidence of past extraterrestrial life, for instance carbon-rich meteorites often contain active sites of hydrogenases – enzymes which provide energy to bacteria and archaea by breaking down hydrogen gas – while other types contain chemicals resembling organic molecules.
Though no physical evidence has yet been discovered of extraterrestrial life, speculations of otherworldly visitations has inspired works of science fiction. If extraterrestrial life were discovered it could have far-reaching implications for our understanding of the Universe as well as alter many fundamental theories we currently hold dear.
Types
Before recently, most scientists held that extraterrestrial life existed somewhere in the Universe, an assumption supported by both astronomy and biology principles combined with careful scientific postulations. Astrobiology is a major field of science dedicated to searching for signs of extraterrestrial life.
Although no direct evidence for intelligent alien life has yet been discovered on other planets, belief in intelligent extraterrestrial life has grown increasingly widespread. With discoveries like liquid water on Mars and organic material found in SNC and carbonaceous meteorites as well as our knowledge that life exists under many diverse environmental conditions (temperature, pH levels, salinity levels, pressure and radiation) on Earth; many believe there could be similar life forms elsewhere in space.
Some individuals (contactees) have reported being in regular contact with aliens, with many reporting receiving messages from them; whether these have any scientific significance is up for debate.
Some researchers have attempted to detect extraterrestrial life by searching electromagnetic transmissions from distant worlds – a process known as SETI or the Search for Extraterrestrial Intelligence. Others have attempted to trace evidence of biological life by investigating terrestrial molecular biosignatures (e.g. chemical and morphological) under different environmental conditions with an eye towards expanding these investigations to other worlds.
Examples
Before recently, most scientists believed it highly unlikely that life existed on other planets. With billions of stars in our galaxy and trillions of similar galaxies across space and time, it seemed unlikely that events necessary for abiogenesis (the origin of life) to take place elsewhere would occur.
Space probe data and careful astronomical observations have significantly increased the probability that life exists beyond our solar system and Milky Way Galaxy, giving new hope to exobiology or “astrobiology”, the study of extraterrestrial life.
Science uses several criteria to asses the likelihood of finding extraterrestrial life on other planets, such as high cosmic abundances of the key elements required for cell life and an environment enabling molecular interactions (typically liquid or gas). Furthermore, this environment must not be too stable – otherwise organisms would collapse quickly – nor too volatile – lest any of their molecules escape too rapidly.
Researchers believe that, if life exists on another planet, its primary form would likely be photosynthesis, which relies on solar radiation for fuel. To take advantage of it, its environment must be near enough Earth so as to be heated by sunlight without becoming so hot as to destroy an organism’s cells or cause them to undergo burning from sunlight’s radiation.
