Les. Whilst opinions are free and everyone has one, for someone who spends alot of time looking at other galaxies, and knowing how many planets are within our own galaxy... don't you think there is more than a 'slim' chance, that quite a few of the thousands of other galaxies out there have planets, and that a fair few of them would be able to sustain life, and of that few, at least a couple WOULD sustain life... It seems incredibly likely to me...
On the topic of "why would they cover it up"
A few reasons..
1 - world wide mass hysteria. The majority of humans are somewhat naturally fearful of the unknown, if you were to tell them that 'the unknown' were technologically superior to us, could travel across the expanse of the universe and had something of an interest in our planet for whatever reason...
2 - Religious denunciation. At least a few people probably wouldn't take nicely to relative proof of other life, hence denouncing the belief structure of more than a few religions...
They both seem perhaps a bit far fetched, but its late, i've been at work too long today, i really need to get home, and have a coffee... I'm somewhat sure that if a secret was ever going to be kept, NASA and their corresponding political backers would be up to the task...
I am however with you on the fact that the videos and stories of abductions are a load of crap, most of the videos can be explained/have been doctored...
Crop circles - eh... take them with a grain of salt.. That most recent one was fairly impressive how it depicted Pi in a circular pictograph. but IMHO - elaborate fake.
The idea of other life to me seems only natural. The idea that they come here and poke and prod at humans. thats a load of crap...
EDIT : Good to see you Ron!
