- It has been shown, that one-cellular life forms can survive crashes (like meteor) and space (NASA had a rock on their space ship for 365 days, some others have crashed rocks - in both cases, some bacteria have survived).
- Meteors and other space bodies bounce off from earth atmosphere - which means, they can come to as low as 3600 km and then bounce off. Sometimes, space rock will crash on Earth, but so strongly, that Earth soil will be blown back to Cosmos - by news, some part of it is by all calculations probably already travelled to many star systems (the one thrown away by event, which probably destroyed dinosaurs - this is good basis for space reptile myth:)).
- If you consider movement of Sun around Earth (relativistically speaking to get simplest model) you see that bacteria there must survive very high and low temperatures, which happen up there. As air flows also up, bacteria can live also in atmosphere - and they do live everywhere they can.
Now, you see the definite mechanics, how life can travel away from earth - some sensitive bacteria can see it's path to Alpha Kentauri and go with a space rock, and hibernate for 160 000 years Earth is 4.5 billion years old, life here is 3.6 - with 25 million small meteores per day (mostly dust) and still many per year, if you put Earths history into a hour, then it would be 1200 years per second - asteroids would fly in all directions. If it's cold at the middle and hot around it, going through Earth atmosphere, and contains water and organic elements, asteroid can grow some bacteria when in ideal condition; then some stone can blow this asteroid up and life will travel.
The array will sometimes send some DNA parts (bacteria can just pick them up and try, so much of random DNA on other planets will be checked out, if there is compatible DNA-based life) and sometimes some amobea (all Earth DNA shares some primitive parts of our genes). This primitive part might be enough to make up a planet - compunds of air and our atmosphere has been built by life. Cosmic evolution would guarantee that after some time, forms it creates on similar planets are similar - this is highly probable that once we get to cosmos, we will find humanoid, reptiloid (in instance dinos didn't die out somewhere) and maybe insect-life conscious life forms.
Now, consider the probabilities in case life *can* travel:
- Consider that we have a planet and divide it to eight parts with same size.
- Consider that we take one part and find life.
- Probability that life first appeared on that part is 1/8.
Take an unit, which is km2a - square kilometer or other size measure multiplied with time measure. For one km2a there is some average probability that life would appear. Lets take average probability of life appearance in space for 1 km2a as P, average probability of life appearance on Earth for 1 km2a as p.
Now lets say that if earth is x square kilometers in size and t square kilometers old, then e = x * t * p (probability of life appearing on Earth, not coming from other place, is x times t times p).
Now lets make a list of all planets, from where life could have travelled to Earth, multipliing their size and age, and multipliing the result with probability that it got to Earth from that place, and including life-supporting asteroids and other space rocks. Lets add the result of this multiplication together, to get age-size of our neighbourhood, and lets call this E.
Now the probability that life appeared first on Earth and not on some other planet is e / E - almost non-existent.
Edited by Daughter of the Nine Moons, 16 November 2012 - 05:45 PM.