As a certified (or at least, certifiable) astro-nut, I`m convinced that we aren`t alone in the Universe.
With our galaxy of 100 million stars, multiplied by at least the same number of galaxies in the Universe, it seems ridiculous to assume that the same conditions that arose on Earth over the past 4 billion years didn`t get repeated many times over in other places. And that only accounts for life similar to our own. There are possibilities of life based on materials other than carbon. All that is required is a system of energy production that doesn`t require oxygen.
Anatomy would be almost anything that is suitable for the circumstances in which they live. We evolved due to the environment of the world to give us height, speed, intelligence (um ...), steroscopic sound and vision (this is a DVD forum after all!), a sense of smell, taste and touch. What senses and anatomy might evolve for creatures living on very high gravity planets, or very low. Or on planets which orbit stars that emit powerful radiation, or give off light in wavelengths other than what we see in.
Over the past twenty or so years we`ve also discovered just how resilient life can be - living under the surface of salt flats, or at oceanic thermal vents at the bottom of the sea. Places where there is almost no light, and no oxygen.
The more contraversial question regards whether there have been any living creatures from elsewhere that have come to visit Earth. My imagination and curiosity want the answer to be yes, but I have to say that my reasoning says, probably not.
Assuming for a moment that the lightspeed limitation cannot be broken, any journey across the galaxy would take decades at best. A starship travelling to the nearest star would need four years at lightspeed (an unattainable speed) to get there. In all probability, we would need a fifty years to cross that distance in any practical spacecraft design. And Proxima Centauri is not likely to yield life. So any journey that would reach us from a more likely candidate star would take centuries. Not impossible, especially if time is not perceived in the same way by our theoretical aliens, but still pretty unlikely.
If we could travel faster than light (Einstein`s limitation actually states that it requires an infinite input of energy to attain a speed exactly equal to the speed of light, so travelling FASTER isn`t theoretically impossible, just very improbable. This takes us into the realm of probability mechanics and quantum physics which, to say the least, wasn`t my strongest subject at Uni) then there seems very little restraining aliens for coming to Earth to study us strange bipedal water sacks. So where are they?
The most convincing bit of "evidence" that we are alone in our *local* neighbourhood comes from radio astronomy. With the exception of the big "Wow!" yome years back, there have been no signals detected that could be considered indicative of intelligence. We`ve been chucking out high-power radio frequency transmissions into the ether for over seventy years, which means that anyone in a region of space comprising basically one and a half million cubic light years could have heard us. And in all our searches looking at nearby stars, we`ve never heard a thing. That means no-one in the neighbourhood is transmitting on a signal that we can detect.
The chances of us being the first kids on the block is remote. Don`t forget that us mammaly have only been around some 100 million years, double that for good measure and you can realise that we have only been evolving towards intelligence for 200 million of the 15 billion years the Universe has been in place, roughly 1.33% of the time. It would seem logical that if we could develop in the 4.5 billion years since the Earth formed, why couldn`t others develop earlier in the history of the Universe? So they should be there.
My opinion is, they are there, but not nearby, and not communicating on a level we can detect or understand. They may be aware of us - we`re not exactly hiding ourselves under a blanket - and are ignoring us, or studying us from our transmissions, or slowly, carefully, laying their plans (oops, sorry, had a Richard Burton moment there).
Of course, they may also be watching us like dispassionate documentary cameramen, watching the wildebeest happily watering blissfully unaware that the leopard is fifteen feet away and about to pounce ...
Who said paranoia couldn`t be fun?
