Life from space
According to some scientists life has always existed in the Universe just like the Universe itself has always been there. This is called the “panspermia” theory. At the beginning of the 20th century a Swedish chemical scientist, Svante Arrhenius, assumed that the simplest life forms move constantly through space, thus colonizing new planets. Therefore, according to this scientist life goes from one planet to another in the form of spores or germs, moved by the pressure of star solar radiation towards new planets on which to glide and evolve into more complex organisms. Actually we know very well about space conditions. In fact there are different kinds of radiation (ultraviolet rays, gamma rays, x-rays), temperatures ranging from near zero to extremely high near the stars. These conditions would kill any form of life, even if it were protected by layers of very resistant material. Some researchers then supposed that these “spores” may have traveled within huge meteorites in which traces of organic compounds have in fact been found. Yet in this case the problem would arise when the meteorites entered the atmosphere: both the friction temperature and the impact with Earth would be fatal for these particular germs.