19 January, 2015

Can there be life on other planets? Conditions for its existence

Panspermia, a theory for the origin of life
Is there life on other planets? Is it possible? What circumstances would have to be for life as we know it on our planet Earth, which develops exuberantly, it is of other planets? What are the chances that life on other planets, however distant they are?
And the most important question, whether there is any possibility, but the distance makes communication impossible, Could there intelligent life on those planets? 

Since man is set at the stars, these questions have arisen him , pounding his mind, as some of the big questions that should be answered in our modern times. In this informative article will try to find an answer. One day, a scientist tried to estimate the chances of life on other planets would simply calculating statistically your chances as variables sine-qua-non life exist on earth. And the result, he estimates and assumptions on the variables involved, indicated that 10 civilizations would be detectable. It was about the Drake equation , which took into account several variables to calculate this possibility, but that is not considered valid (even you can considered science) because it depends on a highly subjective statistical approaches, can give very different results, plus it did not take into account important elements for life not then know and we will see now. Maybe the variables taken into account were very ambiguous, based on mere conjecture; but if we go to the merits, we are on track, because how what conditions have to have a planet so that it can develop life ? That is the million dollar question ... scientists have different opinions, and although I am not one of them, if we follow the logic and my (few, I must say) knowledge of the origin of life and the influence of several factors that make the earth a perfect breeding ground for her culture, can draw some interesting conclusions.

The origin of life

To know what life needs to develop, first we look at the only example we have; evaluate under what circumstances it could arise in our beloved Earth  ( Abiogenesis ) to extrapolate to other situations . On Earth, as we shall see, there have been a series of coincidences which would be as barren and inhospitable as Mars . 
We do not know for sure how life came to Earth, some argue that it is of extraterrestrial origin (Panspermia or Transpermia ) but wherever it may be, Life had to start somewhere, and given the appropriate conditions on Earth, and often the simple answer is correct, it is logical to think thatlife originated on Earth itself .



One of the most highly regarded theoriesby the scientific community is that the high energy from volcanoes, lightning , and ultraviolet radiation could have helped trigger chemical reactions in a primitive giant ocean ( Panthalassa ) producing more complex moleculesfrom simple compounds such as methane and ammonia . 
Among these simple organic compounds would be the building blocks of life are built. As more this "organic soup", the different molecules react with each other. Sometimes more complex molecules were obtained. The presence of certain molecules may increase the reaction rate.

Evolution of Life ( NASA )

This went on for quite a while (billion years), more or less random reactions until a new molecule by chance was created: the "replicator" (it was created and undid many times until survived) . This had the bizarre property of promoting chemical reactions to get a copy of itself, which really started the trend . Other theories have been postulated replicator. In any case, DNA replicator has replaced. All known life (except some viruses and prions ) use DNA as their replicator , in an almost identical. ( Wikipedia ). Based on the original terms of the Earth where life began (water, temperature, etc) can surmise about the conditions required for the same so that it came to be started on any other planet , with varying success, reaching complex or staying in the early stages of our evolution beings.



Prerequisites: 

1) Star suitable
addition to a star of adequate size, it has to have a long enough life and the development of life takes millions of years,  a billion took on earth appeared the first replicator , and 4,500 million humans appeared.

Evolution of life on Earth ( Antonio Corts Piris )
If time the planet we compare with the time of one minute, we aparecer√≠amos at the last second . 
In addition, the evolution toward intelligent beings everything indicates that it is unlikely (at least in the first 5 billion years on a planet similar to added), which in our case a number of situations and adjustments due to changing environment that led to the collaboration and sociability and therefore intelligence (we checked watching our "brothers" bonobos, chimpanzees, gorillas, monkeys and other species despite sharing 98% of our DNA, have stalled evolutionarily), but this deserves another entry on the subject. 2) Situation in the Milky Way solar system habitable planet our assumption has to be away from the galactic center where supernova explosions that emit a lot of harmful radiation to living things and the atmosphere are much more frequent.


But one can not be too far from the center of the Galaxy, as heavy metals, necessary for the formation of the core (and magnetic dynamo) are not found in abundance in the area.
If this condition we add the fact that the Milky Way has had a fairly quiet life , unlike many galaxies as they are not joined to another spiral galaxy, which could be lethal for the stability of solar systems affected .
This and the following conditions will realize how life can be rare in the known universe.

2) Water in abundance
for that life can arise and maintained, water is essential for their special characteristics , andmust be present on the planet, and stably liquid as solvent or base where life originates .With probably life originated in the ocean (without going further we have a 3% salt in the blood, essential to our life), allowing maintain stable temperatures within limits where carbon-based life as we know it can develop in addition to protecting the slow process of lethal solar UV . First a unicellular being (bacteria) was developed to then by evolution (favored by external radiation and adaptation), appeared the first multicellular, with more like seawater than blood. circulatory system with a liquid addition, the highest proportion of mass of living things is water , which organisms are used for various purposes such as transporting food, temperature control, etc



Moreover the large amount of water on Earth contributes to the temperature stability and softness climates (on the planet, and the first sea, cooling and heating the tropics the poles); absorbing the rays and heat of the sun, and up to 80% of the excess heat the greenhouse effect, like a giant battery heat and releasing it gradually through evaporation, so that the range of water temperatures allow development last end of life. If the Earth did not have enough water, its temperature probably range from inadequate for life values ​​(Life can only be given between about 0 and 50). Fortunately water is one of the most common molecules in the universe . While water has been detected in the known universe (even in the outer layers of cool stars), has never been found liquid water elsewhere in the universe . ( Water: Wikipedia ) So scientists at NASA exalt increasingly likely that detect water on some planet; if there is water, there may be life ( there life on Mars ?) .
For life pass from sea to land, first had naturally formed layer of ozone that protects life out of water from harmful ultraviolet rays.
3) Amount of solar radiation received
Depending on the distance to the star of the planet and the size of the star, the amount of energy received by the planet varies; If this distance is only changed by 5% on Earth, that would be very difficult for the water had on the same planet the three states of known water, making it very difficult development and existence of life. 
This is what scientists call "Zona Habitable "; a narrow strip in which the energy received from the sun is the right for life to originate and develop .

Redefining the habitable zone
Moreover, the ellipse of translation of the earth around the sun should be enough to move the temperature differences between seasons are not excessive . Because the Earth is slightly elliptical, we seasons, changing the pitch angle of incidence of the sun on earth. 
But if that ellipse out more exaggerated, excessive temperature change on the planet could make it very difficult life. 

4) Gravity 
The planet must be sufficiently large to prevent gases from the atmosphere to disperse, but not too large because the pressure would cause the water was solid state, despite temperatures.

Furthermore the planet's mass intervenes directly on the rate it is cooled, too small planet soon would be geologically dead (as discussed in the next section, the importance of a molten core with a certain amount of nuclear reactions is crucial). 
It is considered that a planet with a mass less than 0.3 times the mass of Earth could not harbor life.

5) Magnetic core
is shown that without magnetic core , high-energy radiation (known as solar winds)would sweep the atmosphere , dragging it off the ground, as they had created. Without themagnetic shield of the Earth  (magnetosphere) , life in it would not be possible , and our planet would have become another similar to Mars (planet in the past had plenty of water on its surface ), which has a very weak magnetic core.


The core of the Earth is a curious geomagnetic dynamo , is believed composed mainly of iron and nickel and other heavier metals, comprising an outer liquid layer, and a solid core rotates slightly faster than Earth. This is induced by the movements having liquid conductive materials.
Fact: The core is cooling slowly and progressively (it's a big atomic boiler that keeps its heat due to the radioactive decay of elements , especially those isotopesradioactive than uranium (U), thorium (Th) and potassium (K )), and it is possible that when cool, magnetism set aside, the protection afforded us disappear, leaving the Earth exposed to external radiation, aboc√°ndola to a slow death without remedy.
Do not forget that for the generation of heat inside the earth are very important radioactive elements such as uranium 235, 238, 232 thorium and potassium 40, which should be present on the planet studied, so that the heat core is maintained sufficient for the development of the life time. Radioactive elements are the most unstable of the periodic table and the disintegration produce heat.
In addition, the star of the planet solar system must have a  heliosphere ; a magnetic field strong enough to protect the planet from the intense radiation from the rest of the galaxy; it is not known for sure if all the stars have (from a certain temperature (Curie temperature ) could not have heliosphere at all), although presumably occurs in the coldest section of every star. This heliosphere stretches and compresses as the solar system is orbiting the galaxy. 
6) Volcanic and tectonic activity 
A planet without volcanic activity would not renew the earth's crust and generate sufficient gas necessary for thermoregulation of surface temperature and CO2 (see condition 11; greenhouse). This condition is a consequence of the above condition 5. Moreover, as indicated by some scientists, it is possible that the origin of life took place at vents (or submerged volcanoes), to  play an important role in the mix of different elements constituents of life in the water submerged volcanoes many of the young Earth ( such as El Hierro ), and radiation and electricity from thunderstorms could ultimately unite the necessary parts (amino acids) to create the first " replicator "; one archaic be (ancient DNA) capable of reproducing itself, would have started the evolution and natural selection from that time would do the rest .

The volcano of El Hierro
Around these sources proliferate abundant life and a chemosynthetic bacteria derive their energy from sulfur compounds and water, thus replacing photosynthetic organisms at these depths. It is also possible that the greatness of evolution 's adapted to live in such conditions.
Since the UV radiation from the sun destroys any microorganism, and as the ozone layer could not develop until vegetables began to produce oxygen by photosynthesis in the sea, life could only have originated from some depth in the sea.

7) Composition of the planet 
's chemical composition of the surface is decisive. Life can not develop in extreme environments , such as excessively saline, alkaline or acidic (humans fail this to preserve food ) as well as all the above conditions, if the surface of the earth, besides water, contains some element excessively, that could make life unviable in its creation and development (such as corrosive chemical processes with sulfuric acid or other acids, etc).
It is also possible that initially the ocean had any excess compound, but by some natural process of feedback, it is filtered out and leveling your PH to be neutral.
For the formation of a planet like Earth would also be needed iron, silicon and magnesium, plus sulfur, calcium, etc. Therefore the atmosphere and the surface must meet certain conditions for life to lead, it is necessary that the surface of the ground is rocky (which occurs frequently);a gaseous planet usually extreme environments so a priori discarded; however although perhaps certain conditions are not suitable for the survival of complex beings like us, which could not even get to develop multicellular beings, there are circumstances in which bacteria and unicellular organisms find their breeding ground despite inhospitable atmosphere of the planet in question; so that scientists do not rule out life until thoroughly analyzed microscopically any indication. 8) Atmosphere of the planet that is too thick or too thin atmosphere could prevent the development of life. Besides its composition would be decisive; This is closely related to geological activity, the mass of the Earth, and materials that helped form the Earth in its origin.
Aim: The atmosphere of a planet often analyzed as an indication of biotic activity; if they have large amounts of oxygen, this is an indicator of the possible presence of life because oxygen is highly reactive and without the action of the plants would not remain in the atmosphere for a long time.
9) Materials needed for life
are fairly common, but are not expendable. I speak of compounds necessary for the "creation" of life as we know it ; on earth extant life is based on 26 elements, of which life is mainly six: hydrogen, oxygen, nitrogen, sulfur and phosphorus ., and the other only in small quantities it is quite possible that the first forms life requiring only carbon, oxygen, nitrogen and hydrogen , and that with the evolution of living beings have assimilated many as improving their biochemical functioning, lengthening their existence probabilities. The astrobiologistas, moreover, takes into account the Life does not have to be based on carbon ; chance can create beings composed of similar materials in a different solvent that does not have to be water, but the properties of this ideal, randomness in physics and chemistry of the universe can create totally different but susceptible molecules and form elements living beings.10) Rotation of the earth on itself Turning on itself at a certain speed to the sun, keeping temperatures in the range where life can exist, to dampen temperature differences in periods of 24 hours. All the planets revolve about themselves faster or slower, due to the kinetic energies of the cluster of galactic dust and asteroids in the construction of the planet (by gravity), and it would not be defined, depending on the other variables such as distance to the sun, including what speeds could turn to Life could develop, but what is clear is that the days have to have an average duration so that the temperatures reached on the sunny side are kept in a habitable range .

11) Greenhouse
That the atmosphere contains enough greenhouse gases contribute to creating greenhouse effect that prevents the energy the earth receives not miss too fast , ensuring mild temperatures of the planet.
Venus, Earth and Mars have this effect on our Solar System.



Without greenhouse temperatures vary sharply, making it impossible for life as we know it.

12) A large satellite
The relationship between  the Moon  and  Earth , by the size of the satellite, is very close, but I think the most important quality of our satellite , is that it helps keep the  magnetic field  (item 5) in the intensity required to deflect much Solar radiation harmful to living beings.
This is because the moon, going slowing slightly to Earth by tidal coupling induces the solid inner core of the Earth to rotate slightly faster (to maintain higher speed and higher density outer core act as incandescent fluid in which slides), which together with the convection currents (the hotter material tends to rise to the cooler areas near the mantle) and the  Coriolis produce the so-called geomagnetic dynamo  fed back (found in many objects).
Aim: The moon, according to the most accepted hypothesis was formed by large impact theory , in which two proto-planets formed in the same orbit, at a sufficient distance from each other so that gravity does not join, but over time the small ended up joining the biggest shock of adequate precision to give the result we see the moon being a result of the meeting of the materials result of that great shock dispersed.
Another reason to require a large satellite l is that scientists will indicate that due to the Moon  the Earth keeps turning in the same axis  (to have more mass in its central part and tidal coupling), which  is ensures that the temperature remains constant from Ecuador to the poles,  also if the planet had an erratic rotation axis ( precession ), climatic variations could be too steep, so the water temperature is not maintained in an appropriate range . for the emergence of life and would have been much more difficult their appearance and maintenance
But  I have my doubts that this condition is absolutely necessary , because the influence of gravity from the sun can be enough to keep rotating in the same axis; therefore it can be in most cases naturally.
Also,  the Earth has lengthened its day from 6 hours when it formed to the current 24 hours  (for the same friction coupling tide previously discussed), and however this does not seem to have affected the possibility of life on Earth. The following conditions have any doubts that are not essential for life in all cases, so classify them as less important.


13) A suitable rotational inclination
Thanks to the inclination of the earth stations have .  The characteristics and behavior of the planet axis of rotation must also be considered. If the inclination provided to the perpendicular considered to ecliptic, is practically nil, Ecuador planet always receives the maximum radiation reaching much higher than the rest of the planet temperature .On the other hand, if the rotation axis is tilted too much, the difference in weather conditions between different seasons would be too extreme, which would have the same effect as an orbit too eccentric. But not only the inclination of the planet in a given time is important, but also the evolution of this over time. For example, the axis of rotation of the Earth is between 21.5 ° and 24.5 ° with a period of 41,000 years. Again we find that if this variation is too high planetary conditions will not be sufficiently stable to that complex organisms can thrive. (Source:  hadrons and leptons .) This condition can also occur naturally ; Mars p. ie. has a similar inclination to Earth with respect to the sun, but its orbit is much more elliptical than Earth and its satellites are much smaller than the earth. 14) Great neighboring planets is advisable that planets exist neighbors of sufficient mass to help protect the planet of large meteorites that could destroy early ( as does Jupiter in our case ), or directly sterilize all forms of life that might have developed; yet the Earth has received large meteorite impacts in the past that have not yet slowed the development and evolution of the tenacious life, so that  might not be a sine-qua-non condition the origin of life may occur . Conclusion You see the variables that have influenced and influence the existence of life on earth are quite limiting, looks like a cluster of coincidences ( Rare Earth hypothesis ) ; need a planet with an iron composition, rocks, water and other suitable radioactive compounds that ensure sufficient molten core million years, tempered by a sun and adequate distance from the center of the galaxy where the radiation is relatively low among other factors ... regrettably, I think it would not be surprising that of all the Big-Bang / Big Crunch that may have had in the life of the universe only on a few occasions have been given the necessary conditions for the development of life, and it is likely that life has not had time to evolve into intelligent beings in most cases.
Therefore, Life requires some stability and conditions for its emergence and development; Today more than ever, we must take care of our planet, because it is not ours, but we have been given by our ancestors.
There are many conditions such as air, water and elements that can be summarized in one, call itatmosphere "Vital" with components and circumstances similar to Earth's early atmosphere, special atmosphere in which life could have originated .
Even if we ask ? What is life and we analyze in depth we can conclude that life is random, is chemically and physically interacting with their environment according to natural laws, managing the energy available; Life is nothing but an artistic representation of nature, accident produced in an environment and suitable conditions; organic machines created by randomly whose ultimate goal is survival and reproduction , competing with other living beings by the available energy.
Therefore intelligent life is just a coincidence of increased product complexity of living organisms and their relationships in a constant evolution by adaptation to a harsh environment of competition for energy; intelligent life is expected to finish developed around Earth-like system. Possibly with the advancement of computer can be simulated correctly in a super computer the conditions in the laboratory for the development of life and even define the beings that could evolve of these conditions and process variables.
Some scientists argue that if the dinosaurs had not been extinguished, it is possible that over time a dinosaur, for casual evolution, to become intelligent, taking our place. To what extent the mass extinctions that have occurred on Earth have accelerated or slowed the process is unknown to what can only theorize.
I look forward and excitement all the advances that field occur in the next few years if a war for resources not destroy us before. However, while our species managed to not adapt to a human apocalypse, life always finds its way limits bordering on the impossible, with extremophile organisms living in extreme conditions in many parts of the world ; fully evolved and adapted to their environment beings evolution has made ​​life make its way to colonize almost every corner of the planet.

Neofronteras
Possibility of extraterrestrial contact
Human beings, in their infinite curiosity and quest for truth, scanning the skies for signs of remote galaxies and planets similar to ours that might harbor life.
Well-eyed giant tellers as telescopes tech able to see places light years, as space telescopes like the Hubble  or observatories capable of scrutinizing all radio signals or other received in search ofany traces of life of a planet  that had launched into space its waves as we do now, or signs (high oxygen and water for example) in the presence of life .


Furthermore, although the chances of another planet with life are not so small, and have given the conditions that exist, the chances of intelligent life are even smaller . In our case, it is very possible that if there had been a mass extinction 65 million years ago, suitable for the development of intelligent life circumstances do not occur ; the complexity of living beings have increased, but stagnating in specialized niches of organisms living in established ecosystem (such as shark, millions of years ago has not significantly changed). The evolution of humans was caused by a series of coincidences and situations that led him to adapt quickly (or extinct) occurring leaps in evolution in a geologically very short term, and led him away, by inertia, to increase their intelligence: Our specialization , unlike most animals (except maybe ants, bees, etc with limited social level), is based in society; collaboration and family ; almost five billion years were necessary for it to appear on Earth a being who had self-awareness and the surrounding environment; at that time they could have gone wrong many things and realize that we extinguished without getting to where we are now. In any case, even intelligent life is found,the distance would be such that only a futuristic spacecraft ion propulsion could reach it after thousands of years with current technology, to possibly find that and just left dust, traces of life that existed and which we received signals through space in that place ...

Realistically, if there are more planets no longer with life, but living in the universe, their existence is so unlikely to exist by the time he got to reach the human being, his living period would be over. Are there really " wormholes "? Or does the black holes?

David Losada 2013. PS: For any errors or comments, please leave a comment. 
Recommended Reading: 
Movie Contact 
Documentary Carl Sagan
Bibliography of Isaac Asimov

No comments :

Post a Comment