Panspermia
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The origins of the universe and life itself are a mystery that humans are constantly contemplating and debating. Many explanations, including creationism and mere coincidence, have been offered to explain how or why the universe and life were created, but the idea that Earth was seeded from space seems a more probable mix of many probable theories. Panspermia, first mentioned in 5th century BCE by Greek philosopher Anaxagoras, and meaning “seeds everywhere” (Crick, 1982), is a theory that integrates the theories of the Big Bang, chemical evolution, and terrestrial as well as extraterrestrial evolution. Directed panspermia, is a theory by Francis Crick, stating that life was seeded here not accidentally, but purposefully by another race. The theories of panspermia are becoming even more probable with increasing scientific evidence of life having the possibility of originating in space.
In order to understand how life could have originated at all, one must first look at how the universe was formed. A very popular theory, and one that is the basis of panspermia, is the theory that the universe was created in a giant explosion, otherwise known as the Big Bang. The approximation of the age of the universe is anywhere from seven to fifteen billion years old, with about 10 billion years old being commonly accepted (Crick, 1982). At that time, the entire contents of the universe may have been contained in an extremely small area, making it extremely dense and hot. This “fireball” (Crick, 1982) was a mixture of quickly reacting matter and radiation under extreme conditions, causing it to expand very rapidly. At first, the extreme temperatures (about one hundred billion degrees) were too hot to allow atoms or their complex nuclei to exist, but as the universe expanded and cooled, atoms could be formed and for millions of years later the rapid expansion and cooling allowed the matter to condense to form stars and galaxies. Clouds of gas in the universe were the first forms of matter, eventually condensing to form stars and later planets (Hoyle and Wickramasinghe, 1978). Gravity began to gain a more important role as it clumped together more and more matter until the extremely hot and dense masses created nuclear reactions which formed the first stars. Planets are believed to have been formed by a further condensation of spinning material left over from the creation of a star (Crick, 1982), but this is not completely clear. With an idea of how the primitive planets came to exist, one could then move on to address how the first signs of life could have appeared.
Life on earth is said to have possibly originated four billion years ago and would most likely have originated in the state of simple single-celled organisms. Despite the vast variety, all life has in common the presence of genetic material, known as DNA and RNA. Crick (1982) proposes that all living things use a four-letter language (adenine, cytosine, guanine, thymine, and also uracil in RNA) to carry genetic information, as well as a twenty-letter language to make proteins, which shows a surprising uniformity that could perhaps be universal, in the entire sense of the word. The implication of a universal language for genetics is that life on other planets could be very similar to life on Earth, and that there is indeed a relation or common ancestry between life on and off of Earth. Although life on earth originated about four billion years ago with the creation of the solar system, science proposes that the universe could have been habitable about nine billion years ago. Chemical evolution on a distant planet at that time could have happened at an accelerated rate, compared to chemical evolution on earth, and the first life forms could have evolved from the organic molecules. Any extraterrestrial life started at that time (imagining that life evolved at an equal or even faster rate than on earth now) would be one billion years more advanced than the current human race, but at the time of earth’s creation. This considerably advanced life form could have possibly seeded earth. This directed panspermia requires that intelligent life forms had to have been present at least before earth was created with enough time to send the components for the beginnings of life. Panspermia alone states that the earth could have been accidentally seeded by a lowly evolved life form traveling to Earth on a meteorite. Both ideas are possible, although one must ask where life could have been created in the first place.
If life must have originated in outer space, there are a few possibilities of where it could have started. If life, or the catalyst for life, were to have entered Earth from outer space, meteorites are the most likely candidates. Nevertheless, new scientific research has found evidence that extremophiles like certain archaea, bacteria, and even lichen can survive in the vacuum of space in a dormant state (Young, 2005). A study by Indian scientists including Chandra Wickramasinghe found living bacteria in the earth’s upper atmosphere and performed tests indicating that the bacteria were falling from space. Wickramasinghe is a strong proponent for panspermia, claiming that life came to Earth in the form of germs or spores, and continues to rain down on the earth, which may be responsible for new epidemic outbreaks and diseases (Reaney, 2001). Meteorites found on earth have also been found to contain amino acids, and laboratory tests have produced amino acids spontaneously from reproductions of interstellar gas (ESA, 2002).
If directed panspermia is the case, than life must have first started elsewhere and evolved. An extraterrestrial race would most likely have developed on a planet in a system circling a star similar to the sun. About twenty percent of the two hundred billion stars, or four hundred million stars, in the Milky Way are likely candidates to have habitable planets, similar to Earth (Hoyle and Wickramasinghe, 1978). Panspermia is