Semi to intelligent life exists on other planets.
Debate Rounds (4)
Life exists on other planets. Despite incredibly infinitesimally small chances, Earth, after billions of years and "perfect" placement in the galaxy, became flush with life. Organisms, both intelligent and not are everywhere. The Universe (which is ever expanding) is filled with trillions and trillions and trillions of galaxies. The number is so large that we can not really even comprehend it. Each of these galaxy's has planets and suns. Of these planets, there must be at least one that has beaten the odds (like earth) and now has life on their planet.
Good luck to the opposition!
Although there are lots of galaxies (at least 100 billion), that does not mean that there is a proportional number of habitable planets. In order for a planet to sustain life, it must meet a great number of criteria. Some assumptions on these criteria are that it has to be terrestrial, present water in liquid state, have an atmosphere, have geological activity, have low orbital eccentricity, short day/night periods, have an magnetic field, etc. Even with all this considered, not necessarily life will arise, and if it does, still there can be unicellular life in a planet that never evolves to higher forms of life.
Finally, to say that intelligent life exists on other planets, it must exist NOW. The Homo genus is estimated to be only about 2.3 million years old, we've only been around for about 0.05% of Earth's existence. Even if there are other planets bound to have intelligent life, it is extremely likely that it was already extinct or that it hasn't been born yet.
Many scientists and others believe that in order for life to be present, water is a central force. While this may or may not be true (we tend to base the success of life on Earth on things that WE thrive on. Aliens may or may not have to live under our ecosystem/environmental standards. (More on this soon.) Mars once had water on the planet (as shown on http://www.sciencedaily.com...). The fact that a planet right next door once had water already shows the possibilities of many more planets thriving with water. Again, this is all based on possibilities (however, my side of the debate can only be based on probability and luck etc.)
Another reason to believe that aliens do not have to thrive in an environment that mimics Earth's, is the different environments that the multitude of animals live in. Fish who live in the extreme depths of the ocean experience a much different sense of pressure as land-dwellers. Just because humans are unable to go down to these depths without equipment doesn't mean that animals do not live down there. To add to this, antarctica, a continent on earth experiences periods of time where days can last 24 hours or near and vice versa. This is not to say that life doesn't exist there (penguins, seabirds to name a couple. (http://library.thinkquest.org...).
In addition, you say that the Homo genus is estimated to be about 2.3 million years old, which is only 0.05% of earths existence. This is true. However, the homo genus is not the only semi to intelligent forms of life. Anything from a cockroach - which has existed for over 350 million years - to the dinosaurs etc. In addition to this, "The process of biological evolution was very slow at first. It took two and a half billion years, to evolve from the earliest cells to multi-cell animals, and another billion years to evolve through fish and reptiles, to mammals. But then evolution seemed to have speeded up. It only took about a hundred million years, to develop from the early mammals to us." (http://www.hawking.org.uk...).
Lastly, half a billion years of semi to intelligent life is recorded to have existed on earth. This is about 1/10th of earths existence (and it should continue to flourish for many many years to come). The chance that another planet has existed with a sustainable ecosystem (for an alien, not necessarily for a human - as many an ignorant person has falsely believed) exists and according to Stephen Hawkings, is not necessarily difficult "But, the fact that several pulsars are observed to have planets suggests that a reasonable fraction of the hundred billion stars in our galaxy may also have planets. The necessary planetary conditions for our form of life may therefore have existed from about four billion years after the Big Bang." (Stephen Hawking http://www.hawking.org.uk...) The chances of life occurring on another planet is difficult, however extremely possible. The chances of life existing concurrently is smaller still, however is still extremely possible.
First of all, let's reexamine the "water on mars" argument. PRO says that "he fact that a planet right next door once had water already shows the possibilities of many more planets thriving with water". Actually, it does not show that. Exactly because of the fact that Mars is "right next door" it is expected to share some similarities with Earth. More distant planets have, probably, less similarity with us.
When I mentioned "short day/night periods" I wasn't talking about exactly 12h. 24h days are still quite short. In order for life to succeed, days can not last years or decades, for that would create extremely hostile environments evolution-wise, with some generations living entirely during day time and others during night.
Finally, for life to develop in a star system, the star must be "fit" for having habitable planets, that is, must be a F, G or K star (yellow-white, yellow, orange) . That is because stars with masses bigger than 1.5 suns age to fast for life to develop, while on the other extreme, small stars are not good candidates because of the tidal lock effect . So the pulsars which presented planets, for example, probably won't present any life-bearing planets.
Summing up, we're looking for a star, of a specific category, at least 4 billion years old, with terrestrial planets located in a small "habitable zone" around it. This alone excludes most of the universe from our filters. After that, the planet must meet the criteria I mentioned before: present water in liquid state, have an atmosphere, have geological activity, have low orbital eccentricity, short day/night periods, have an magnetic field, etc. This excludes most planets. Even after that, the planet still have to present chemicals that can create unicellular life. This life must than evolve, undisturbed, for billions of years, during which the climate and atmosphere must evolve accordingly to sustain the new lifeforms that are walking towards intelligence. All of that before some interplanetary event destroys or set back that planet's life. And also, endure these and other hardships long enough to survive to this day (I must remember PRO says life EXISTS now, and not that THERE WAS life in other planets). And PRO believes the compound odds of all of that happening are at least 50%. I am sorry for my disbelief, but I think it is mathematically impossible for this odds to reach such high level.
http://space.about.com..., "the initial results from the Kepler mission revealed 1,235 planet candidates, while 54 of them were orbiting their host star in the so-called "habitable zone"." The Keplar did not survey the entire galaxy (because the number of planets is much too vast), however the number of planet candidates would increase by a lot. In the test, the percentage of planets in the habitable zone is about 4%. In 1964 Stephen H. Dole estimated the number of habitable planets in our galaxy to be about 600 million. Although the percentage of planets in the Universe would not be as high as 4% (since not all galaxies are the same) even if the number was much much smaller, say 0.00000001%, the number of habitable planets would be 50,000,000,000,000,000. If we were to further eliminate 99% of these (As an estimate for the number of planets greater than 4Billion years, even though it does not necessarily take this many years... This number is specific only to Earth), the numbers would still be phenomenally large. By sheer numbers, the odds of life on another planet are incredibly great.
I realize that playing the odds still does not confirm life on another planet, however if you have a number of stars (MINIMUM remind you) of a septillion, without even including the number of planets, the odds are clearly in life's favor.
In addition to the mathematical odds being in life's favor, so far we are only taking in to consideration an ET that lives and has evolved similarly to the humans and the species on Earth. To be as narrow minded to believe that all evolution and planetary ecosystem must mimic Earth's exactly is an unfair argument. Animals evolve differently, and on Earth are able to adapt to situations that may seem extreme compared to another planet.
Relative to this, CON also did not rebut the claim I made about the different environments that animals live in today (Fish living at the bottom of the ocean experiencing "extreme" pressures etc.) I rebutted and responded to all of CON's claim's (the short length of time with which the homo genus has existed, the proportional numbers, etc.) whereas CON picked and chose which to respond to and what to ignore. Also, CON's statement in the first round "Although there are lots of galaxies (at least 100 billion)" vastly underestimates the ACTUAL number of galaxies, which as stated on (http://imagine.gsfc.nasa.gov...), is 5-fold from his stated (500 billion... AT LEAST).
As I have shown, mathematical odds are not in life's favor at all, it is by a fortunate accident that there is life even in Earth. Contrasting the great number of habitable planets, the odds of life existing in each one of this planets are extremely low. Dr. Morowitz estimates that probability of a protein molecule being formed by chance is 1/10236, or about the same as throwing 4 billion pennies into the air and having them all land heads-up. That is for just one molecule. For this to become life, it is another unlikely step. For that protein to evolve to become intelligent life, there are at least another 4 steps, not as unlikely as the first, but still very unlikely. If we assume the odds of each step occurring in due time to be about 0.1% (which is pretty optimistic), the final odds of intelligent life evolving is around 1 in 10,236,000,000,000,000 (1 in 10^16). I said "in due time" because, as we know, planets are only habitable for a certain time. Life on Earth will likely cease in about one billion years or so, as the Sun becomes hotter. Most planets life sustaining periods shall also be around a few billion years, so it makes no sense to believe that, left alone, life will inevitably evolve to intelligence at some point.
Concerning the claim that animals can live in different environments, that does not change much. Life can come in many different ways from the ones we are used to, maybe there can even be non carbon based life somewhere. But whatever kind of life there is, it will still require a quite specific set of unlikely conditions.
Thus, I have shown that the probability of life arising in a given planet is very tiny, almost zero. So, even though there may be an enormous amount of habitable planets, the combined odds of one of them presenting life still is not significant.
dashy654 forfeited this round.
In the first round it was agreed that it cannot be said that "Semi to intelligent life exists on other planets", what, from my point of view, was a victory for my side. But for the rest of the debate, we focused on the question of whether it was possible to say that it is at least even odds of life existing or not in other planets.
Although Pro has given solid numbers stating that there are an enormous number of planets in the universe, when you compare this numbers to the equally astonishing small odds of life succeeding in each of this planets, those previous numbers don't look so impressive.
I do like to believe that we are not alone on the universe. But I realize this belief is based mostly on faith, because as I demonstrated, the odds of that being true are negligible, and the odds of another civilization making contact with us are much smaller.
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