well but science is not total truth, i means if something is not scientific proven doesn't mean its not true or not exist. But means its not yet understood by science...

And the chances of earth being the only one, its so so small as you can calcultate. and since matter is all arounds, its a matter of randomness, so im almost 99 sure there is. Its logical. And there is microbiology on marth and other, what proof life existed some time ago, so, there must be other planets in the same conditions.