DDO Olympics: Science

However, before I begin, I would like to note that Pro has already made this debate quite semantic. I will continue to. It is now necessary, for the purpose of this debate, that the word ‘many’ is defined. Oxford Dictionaries defines it as “a large number of. ” [1] However, the question comes up of “a large number” compared to what? Given that, the resolution relates intelligent life to the universe, the universe shall be the comparison from which ‘many’ is made. As that there are approximately 10^24 planets in the observable universe, my opponent is essentially claiming that there is there are ‘many’ forms of intelligent life, when in comparison to 10^24 planets. I will argue that it is not likely that many forms intelligent life is widespread throughout the universe. I will argue for the ‘Rare Earth’ hypothesis that was introduced by Peter Ward and Donald Brownlee in their book “Rare Earth: Why Intelligent Life is Uncommon in the Universe,” which states that the rise of intelligent life on Earth was due to an unlikely combination of factors. I will refer to Ward and Brownlee as W&B. W&B introduce 18 factors that must be right in order for the existence of intelligent life. [2] Of course, throughout the debate, I will not defend all 18 factors, but I will put forward some of the main factors. In order for a planet to be able to support intelligent life, it must be located in a specific position within a galaxy, for most zones of galaxies are unable to harbour planets supporting life (dead zones). The zones of a galaxy that is able to harbour planets supporting life is called the galactic habitable zone. According to Evolution Wiki, “this [habitable] zone is primarily a function of distance from the galactic centre. ” [3] A habitable planet cannot be located too close to the centre of the galaxy, for as W&B explain: “Any galactic centre is a mass of stars, some the lethal neutron stars, and it seems unlikely that any form of life as we know it can live nearby. They then explain: “Any star going supernova would probably sterilize life within a radius of 1 light year of the explosion and affect life on planets as far as 30 light-years away. The very number of stars in galactic centres increases the chances of a nearby supernova. ” [4] The outer reaches of galaxies are also not suitable for life. Antarcticaedu. com, writes, “[as that distance increases]…The metal content of stars decline, and metals are necessary for the formation of terrestrial planets. ” It even may be that the type of galaxy a planet is situated can affect whether intelligent life will arise. This is illuminated by W&B: “[Earth] may be fortunate in being in a spiral rather than an elliptical galaxy. Elliptical galaxies are regions with little dust which apparently exhibit little new star creation. The majority of stars in elliptical galaxies nearly as old as the universe. The abundance of heavy elements is low, and although asteroids and comets may concur, it is doubtful that there are full sized planets. [5] Due to this, a significant proportion of the galaxy has been ruled out for possibility of intelligent life. Innovative research from Gonzalez et. al suggests that, due this, as well as the fact most stars’ rotation do not synchronize with the turn of the spiral arms of the Milky Way, the habitable zone only consists of about 5% of the Milky Way. [6] A planet must also be orbiting at the right distance from a suitable star, in order to harbour intelligent life. This notion is rather simple; it is taught in primary school! It is obvious that a planet must be orbiting from the right distance from a suitable star. In the Solar System, for instance, neither Venus, nor Mars, our neighbouring planets, are capable of harbouring intelligent life, whilst Earth is far more suitable. It is also necessary that a planet is orbiting a suitable star. Cohen elucidates: “A too-massive star would emit too much ultra-violet energy, preventing the development of life. A star that is too small would require the planet to be closer to it (in order to maintain liquid water). But such a close distance would result in tidal locking (where one face of the planet constantly faces the star, and the other always remain dark—as with the moon in its orbit around Earth). In this case one side becomes too hot, the other too cold, and the planet’s atmosphere escapes. ” [7] Consequently, ‘massive stars,’ ‘small red dwarf stars,’ ‘red giants,’ and ‘white dwarfs’ have virtually been wiped out as potential candidates. [8] Plate tectonics is required for the development and subsistence of complex life. Ward and Brownlee argue this is the case by pointing to several reasons. First, plate tectonics is necessary in order to creating and maintaining biodiversity. W&B write: “Plate tectonics can augment diversity by increasing the number and degree of separation of habitats (which promotes speciation)… [it promotes environmental complexity—and thus increased biotic diversity—on a global scale. A world with mountainous continents, oceans, and myriad islands, such as those produced by plate tectonics is far more complex and offer more evolutionary challenges, than would either totally land-or ocean dominated planets without plate tectonics. ” [9] Second, plate tectonics is necessary for the maintenance of greenhouse gases, which indirectly allows liquid water to exist. According to Cohen, “Plate tectonics play an important role in a complex feedback that prevents too many greenhouse gases existing in the atmosphere. ” [10] This, according to Kasting, “kept Earth’s surface temperature within the range that supports liquid water. ” [11] Third, plate tectonics ensures that the Earth has a magnetic field, which is beneficial, for it keeps harmful cosmic rays from reaching the Earth’s surface. W&B write: “without some sort of protection, life on Earth’s surface would be extinguished within several generations by cosmic rays hitting our planet’s surface…without plate tectonics, there would not be enough temperature difference across the core region to produce the convective cells necessary to generate Earth’s magnetic field. ” [12] As far as we know, the only planetary body, or moon with tectonic plates is Earth, although it is certainly possible that either Mars or Europa has some sort of tectonic activity in the past, or right now. [13] The final argument that I am going to propose this round is an argument from evolutionary history. Andrew Watson identifies four evolutionary steps needed to produce intelligent life: the emergence of unicellular bacteria, complex cells, specialized cells, and finally, intelligent life with an established language. Watson calculates, via mathematical models, that the probability of the 4 steps occurring is less than 0.01%. [14] However, Watson’s four steps are rather limited in scope, for there are even more steps to be taken into consideration. The origin of life itself is one; one that ridiculously hard to figure out. Another would be the Cambrian Explosion, a geological event that occurred approximately 542 million years ago, resulting in the rapid emergence of a significant portion of animal phyla existing today, that also has not been satisfactorily figured out. Of course, it is not realistic to expect ‘exactly’ the same event happening in a planet located 250 light years away; the point is that similar events must happen, in order for complex life to emerge. Thank you. [1] . http://is.gd... [2] Rare Earth pg. xxxi [3] . http://evolutionwiki.org... [4], [5] Rare Earth pg. 26-29 [6] . http://www.astrobio.net... [7] . http://tal.forum2.org... [8] . http://is.gd... [9] Rare Earth pg. 194 [10] . http://tal.forum2.org... [11] . http://www.earth.northwestern.edu... [12] Rare Earth pg. 213 [13] . http://is.gd... [14] . http://www.sciencedaily.com...