Our sun-system ends around 100.000 times as far away as the earth is to the sun. This x100.000 would be around the diameter of the Milky-Way. 25x from that away is our neighbour-galaxy, the Andromeda Galaxy. Our galaxy with all his neighbour galaxy's moves in a Galaxy cluster, our Galaxy cluster is called 'Virgo cluster', he has approximately 200.000 of all those galaxy's in itself. And these clusters move in so called 'Super Clusters'. And this is already the end of what we know about how big our universe is. The Super Cluster has thousands of thousands of galaxy's with all the stars and all the planets in it. Think about how much sand grains there are on a beach, in the Desert, in the whole world. And now think about the fact, that there are way more planets in the universe than sand grains on the earth. Who thinks there is no extraterrestrial life out there now?
Extraterrestrial life is life that does not originate from Earth. Although some people expect extraterrestrial life to exist, there is no unambiguous evidence for its existence so far. See also: Is there an intelligent form of life in the universe? (beyond Earth).
Yes, I believe that we are not alone in the Universe. I also must point out that I'm an atheist, so I don't believe in God - there is no religion that could cloud my views on that matter. I'm not afraid that contact with intelligent alien races may destroy the foundation of my faith... cause it doesn't exist.
I believe in science, and math says that 'yes, there is the possibility that we aren't alone'. Though I think the reason why we haven't found any evidence yet is that we aren't technologically advanced enough to find it (but that doesn't mean we won't find it in the future). Of course it doesn't mean that this extraterrestrial life is as advanced as we are, but there could be a planet flourishing with microscopic life, or a planet with creatures resembling Earth's long extinct dinosaurs. It would be really arrogant of us to think that we are the one and only life form existing in the incomprehensibly vast Universe with billions of planets and stars.
In the end however I really enjoy the idea of technologically advanced alien species observing us from the safe distance and waiting for the right moment to get in contact. Imagine the possibilities!
I'm sure the universe is full of intelligent life. It's just been too intelligent to come here.
― Arthur C. Clarke
Every day astronomers are finding more planets among the distant stars. There is no proof yet of actual life, but most scientists feel uncomfortable about the Earth having the only life in the Universe. The problem would be at what stage or stages of life are out there. Finding life in the narrow band of our technology would be difficult.
Statistically it is almost certain that there is other life on other planets somewhere in the Universe. What is less certain is whether or not there is any intelligent life. We only have a sample size of one when it comes to planets that support life, so we have no idea how likely it is that self-awareness will develop at some point in the evolutionary history of a planet. It only took 500 million years or so for life to appear on earth after it solidified, but multicellular life didn't evolve for another few billion years, and the development of high intelligence happened only yesterday in evolutionary time. For this reason it's reasonable to assume that the development of intelligent life is much less likely than the development of life in general. However there is obviously much uncertainty here.
Regardless of how likely there is to be intelligent life out there, it's very, very unlikely that that life will ever visit us due to the universal speed limit of 300 000 km/s
From a scientific standpoint, I neither believe nor disbelieve. I have simply not seen any proof of extraterrestrial life. We can go on and on about how big the universe is and therefore how "likely" it is that there is extraterrestrial life out there, but we've barely begun exploring our own solar system, never mind any of the rest of them, so we really don't have a big enough observational sample to say whether life-conducive conditions are as common as dust in the universe, or if our planet is an entirely unique "snowflake," and life is an anomaly peculiar to this one place.
And Dave Todd, I must point out that I'm a Catholic, so I do believe in God, and doing so does not cloud my views on the matter either. I'm not afraid that contact with an intelligent alien race will destroy the foundation of my faith, because there's nothing in my faith that says that we're the only intelligent species.....or that we're not the only intelligent species. It remains to be seen.
If there are technologically advanced alien species out there observing us, I hope they are benevolent. In our own human history, when technologically advanced cultures encountered less technologically advanced cultures, things usually didn't turn out very well for the less technologically advanced cultures. Technological advancement doesn't require sophisticated morals or ethics, just enough sense of self-preservation not to trigger an extinction-level event, like full-scale nuclear war.
Considering the number of planets that have been found so far, I think the possibility of finding extraterrestrial life to be extremely likely. However, intelligent extraterrestrial life maybe not so much. Earth has had some one hundred million different species on it, but only five created tools and manipulated fire and only one of those species exists today. It doesn't sound likely that we will be hobnobbing with Vulcans anytime soon.
Scientific studies show that there are signs of real extra-terrestrial life. Sure, aliens have been in fictional movies, games, etc., but somehow they have become real. For one, I've heard there has once been organic alien life inside of 3 asteroids. This came to be because some water slipped through into the asteroid, waiting to be consumed by the alien bugs. Another thing I've heard about is that in the clouds of Venus, there is bacterial life present. A scientist suggested that there is life on Venus, and, obviously, he/she is right. Venus's clouds also are similar to Earth's conditions, giving out more proof.
I believe that it is certainly possible. The universe is so vast that there has to be some form of life out there, sentient or otherwise. God has the power to create life anywhere He sees fit, so it is possible. We just have to keep looking until one of us discovers the other. It just doesn't seem too likely that we are the only living beings in the entire universe.