Is there life beyond Earth?

First of all, it is important to define what is meant by general"extraterrestrial life". Normally, they are including littlegreen men in spaceships with front-drive Wharp. But that probably would bethe "highest level" of extraterrestrial life. It had completed astage of development the people ahead of us. Because with the currentlyknown laws of nature and technology, but are denied human interstellar travel,but the distances are too great.

Extraterrestrial life is not necessarily intelligent. Life - that could bebacteria, plants, fungi, animals and us be unknown creatures. It is quitepossible that there were bacteria on Mars again. And the Jupiter moonEuropa might harbor simple life forms. Even the simple discovery of bacteriaon another celestial body would be a scientific sensation - but it would makeour uniqueness one more time in question.

For a long time, scientists thought that life somewhere in the universe is veryunlikely. Prerequisite for this is, namely, that there are planets ormoons that orbit at a suitable distance to a star and have a hospitableclimate. But the existence of so-called extrasolar planets (planets ofother star) has long been regarded as very unlikely. Only in recent yearssucceeded in repeatedly to demonstrate extrasolar planets in our immediateenvironment indirectly. This was another major breakthrough in astronomy.

It can therefore be assumed that some planets "normal" in our MilkyWay. It houses about 100 billion stars. If only every 1000th of aplanetary system and if there were life on every 1000th of them, there would bealone in our galaxy 100000 animated planet! And when you consider that itin turn upon billions of galaxies in the universe, it could be trillions oflife-bearing planet. If only every 1000th intelligent life has broughtforth these are still trillions of civilizations. And if there were any1000th technologies owned by them, which could overcome the familiar confinesof space and time, there would, in principle, one billion species ofintergalactic space tourists who might visit our little earth. Of course,the assumptions in this calculation are completely arbitrary - it could beevery 100th or 100,000 each.

A simple consideration shows that it is purely statistical two likelypossibilities for a second man in space: If there are in our Milky Way andabout a hundred billion stars in the universe contains billions of galaxies, sothese are 10 to 22 stars, which are 10 sextillion stars. Let usassume that the probability of intelligent life in a star system would berelatively high, eg One in a billion. Then there was the universe 10quadrillion (10 ^ 13) intelligent civilizations. If they are relativelylow, so for example 1 to 10 to 30, then humanity would probably unique inthe universe. The probability that the huge number of stars, theprobability of intelligent life, just keep the balance, so that only a fewplanets in the universe are civilizations, is extremely low. This meansthat statistically we are either unique or there are many civilizations in theuniverse.

Even if the latter is the case, then the question remains whether we get our"extraterrestrial brothers and sisters" (or there may have verydifferent gender?) Ever seen, because we are separated by space and time.Thecosmic distances within our galaxy amount to thousands of light years in nearbystars is still around 10 light years. Even these "small"distances by means of our physics can not be overcome. And even ifextraterrestrial beings have the knowledge of natural laws that go beyond thelimits of our physics, only a small time window exists for a reciprocal visit. Thecivilized man has existed since a few thousand years, and we do not know ifthey will see the year 3000. A few thousand years is not much when youconsider that the universe is billions of years old. When the expeditionreached the Andromeda Galaxy some day our earth, it might be too late.