The simple answer is no one knows. I believe there is other orgainic matter. I mean think about it. There are billions of stars with planetary systems in our galaxy alone, and we know of atleast of 2 million more in the universe that is visible to us. So what are chances that life is limited to Earth. I don't think there are green people with large heads with super big black eyes that travel the universe in a round ship that travels at light speed to different planets. That is a science fiction understanding. But I definatly believe that there is other life. Maybe not as advanced as us, but maybe they are. It completely depends on the environment. Our Earth is approx. 4.6 billion years old in which it has heated up, cooled down, got life, and then evolved into humans, and the universe itslef is 13.7 billion years old. So if there is another Earth like planet, that species may have evolved longer, and may have a higher inteligence level. I personally think that there might be organic matter in our very solar system. Maybe on Mars, but my bet is one Europa, Jupiter's smallest Gallalain (I know I spelled that wrong) moon. Keep in mind that it is not the smallest moon, it is the 4th largest. The Cassani mission proved what scientists had long speculated- that Europa has frozen water. Scientists think that there is a liquid ocean underneath this ice. But the temperature is that of Anartica! How could life exist? Thats what i thought at first but then I learned that scientists have discovered plant life in the most frigid environment. So if life can exist there, then why can't it exist on Europa? Thats why i want NASA to get a probe out there.
So you need to define alien. The scientific definition or the science fiction definition. The scientific definition of simple life, then yes it is probably real. But the sci fi fantast of interstellar civilizations, then they are simply imaginary. Thats why its science FICTION