Nick Bostrom wrote an interesting article for the MIT Technology Review about how he hopes that the search for life on Mars finds nothing. In it, he reasons that inasmuch as we haven't come across any signs of intelligent life in the universe yet, advanced life must be rare. But since conditions for life aren't particularly stringent, there must be a "great filter" that prevents life from evolving beyond a certain point. If we are indeed alone, that probably means that we have made it through the filter. But if life is found nearby, like in our solar system, then the filter is probably ahead of us, or at least ahead of the evolutionary stage of the life that we find. And the more advanced the life form that we find, the more likely that we have yet to hit the filter, which implies ultimate doom for us.

But I wonder about some of the assumptions in this argument. He argues that intelligent ETs must not exist because they most certainly should have colonized the galaxy via von Neumann probes but apparently have not done so because we do not observe them. It seems to me, however, that it is certainly plausible that a sufficiently advanced civilization can be effectively cloaked from a far less advanced one. Mastery of some of those other 6 or 7 spatial dimensions that string theory predicts comes to mind. Or invisibility via some form of electromagnetic cloaking. And those are only early 21st century ideas. Imagine the possibilities of being invisible in a couple hundred years.

Then there is the programmed reality model. If the programmers placed multiple species in the galaxy for "players" to inhabit, it would certainly not be hard to keep some from interacting with each other, e.g. until the lesser civilization proves its ability to play nicely. Think about how some virtual reality games allow the players to walk through walls. It would not be hard to maintain multiple domains of existence in a single programmed construct!

Thoughts???

I totally agree. I feel like we humans (myself included) really have trouble thinking beyond a 50 year time frame, so we always speculate using contemporary physics and ideas. Scientists especially seem to be prone to this - I always hear things like the limitations of the speed of light and time travel being described as factual concepts, rather than "limitations based on our current understandings."

I think for the most part we are afraid of the possibility of life on other planets or from other solar systems. It seems most logical that there is other intelligent life out there somewhere even if we aren't presently aware of them. I think it is even scarier to think of intelligent life out there somewhere that is even more advanced than we are. We want to expect that they would look like us but that may not be even near what they look like. If they are more advanced than we are then we would be afraid of what their objective is by visiting us. I think this is why we are afraid of U.F.O.'s now. We know that they are more advanced than we are simply by virtue of how they travel. Since we don't have the kind of air travel that they do they must be more advanced. I think the government knows that most people are afraid of U.F.O.'s so they cover up reports of sightings. I really don't think that is a good idea though because at some point we are going to become aware of why U.f.O.'s are visiting us. I used to not believe in U.F.O.'s until I saw one (actually two were involved)some years back. I am interested in why they do examinations on various people when there is an abduction or about cattle mutilation stories.