I think there are pretty high chances that extraterrestrial life exists somewhere else in the universe, if not in our own galaxy. It’s estimated that there are about 8 billion Earth-like planets only in our galaxy, so, if we’re alone, it really seems like an awful waste of space 😉
Cartoon aliens are pretty much the product of our imagination. There is no reason for ET life to be looking like that something we can even start to imagine… I think (and a lot of astro-biologists also think) it’s likely it’ll be carbon-based, but even that is based on what we’ve seen on Earth. Maybe the conditions where life has developed away from our blue planet are SO drastically different than on Earth, we can’t possibly imagine what life is like over there…
A conservative statement would probably be that bacteria-like life is the most wide-spread, but who knows, really!
Yes, I believe there is a high chance of their being aliens. Now, will they look like the ones we see in films and cartoons? We just don’t know. Already there are a huge range of species of life on Earth, so who knows what life will look like on other planets where environmental conditions are different. For example, we believe that an excellent place to look for life are on some of the moons of Jupiter and Saturn. In particular, the moons Callisto and Ganymede appear to be covered in ice with a liquid water ocean underneath. If there is life there then it will have evolved to live in water, so it could look like some sort of very deep water fish that we see on Earth. Or it could look completely different! Here’s hoping that we send a space probe to these moons in the near future so that we can try and find out!
Just like the other guys, I think it’s very probable that there are aliens, just that we have yet to see them. Because we haven’t found them yet (and they haven’t found us) we have absolutely no way of knowing what they’ll look like, so right now we have to leave that to the imagination and cartoons!