SETI

I am certain that there is extraterrestrial life out there and I am pretty sure some of it is intelligent.  The universe is so vast and the number of planets so enormous that anything else strains credulity.   But the distances are so vast and the number of dead planets so enormous that the chances of us discovering them or them discovering us is so small that the possibility of that happening also seems pretty small.   The distances are enormous.  Most of the stars we see are hundreds of light years away and those are our nearby neighbors.  Our galaxy is over 100,000 light years across.  The nearest big galaxy, Andromeda, is 2.5 million light years away.   The laws of physics that we know preclude travel faster than the speed of light.  To send a fleet of a million probes, to visit every star in our galaxy, traveling at light speed, would take half a million years.

But, you ask, isn't it possible that there's a way to travel faster than light?  You'd have to do this by warping space through a higher dimension, most likely time.  We know a little about this: Galaxy-sized masses warp space enough that light is curved a few micro-seconds of arc.  Enough to detect with powerful instruments, but the space-warp available from this is not actually any faster than the speed of light.  I remain hopeful that some unknown technology allows us to do this but we are very far from any plausible breakthrough.    Let's say that such a breakthrough occurs--we can go 1000 times faster than light--our million probes would still take at least 500 years to visit every star.    Even at 1000 times light speed, our nearest star is a day and a half away.

What if some other intelligent species is out there, looking for us?  If they already have 1000x light speed travel and did a search using a million probes to find us, they are at least a few hundred years more technically advanced.  Could we, using the highest technology available to us, successfully hide from the best technology the 18th century had to look for us?  Of course we could.  We could paint an orbiting telescope flat black and spy on them from space.  We could find places where they aren't and send a lander--appearing at worst to be a meteorite.  We could send out drones from that lander to watch from a distance.  We'd design the drones so they'd easily be mistaken for a bird or some other creature.

Or you point out that we're sending out massive quantities of radio waves.  That's true, but each of these signals, on an interstellar scale, is pretty weak, and while individually coherent, from 100 light years away it's likely just a bunch of incoherent noise, and compared to what the sun generates, pretty weak at that.   It may be enough to help them find us--but the waves only travel at light speed, which means the probe that detects them must be within a sphere about 100 light years in radius of us.  It shortens the search, but only a decade or so. 

The bottom line is that an intelligent extraterrestrial that wants to hide from us, will successfully hide from us.  If they want us to see them, we will.   Searching for ExtraTerrestrial Intelligence is basically a fool's errand at this point in human development.  Once we have the technology to actually embark on the faster than light search, this may change.  But for now, if they're looking, they're gonna find us, whether we're helping or not.

That said, I certainly don't object to privately funded SETI projects.  There's lots of peripheral research being done, some of which may prove useful regardless of whether there are extraterrestrials involved or not.  The SETI Institute in California does lots of space-related research, lots of it interesting and potentially useful, and as far as I can tell, only a small fraction is actually in pursuit of aliens.  It's just that I think there are better things to spend my tax money on.   On the other hand, I think the search for extraterrestrial life in the solar system is a worthwhile goal.   We're still in the early days of exploring the solar system and it's entirely possible that there's life on one of the moons of the gas giants, or much less likely, on Mars in the dim past.  Odds are very unlikely that it's even multicellular life but whatever it is, we'd like to know about it.   (life has existed on earth for well over 3B years.  Multicellular life for less than 1B)

addenda 18Dec2017
Over the weekend, the pentagon's own UFO research organization came to light.   There are lots and lots of UFO sightings, many of them by completely credible people.  I've seen two myself.  One turned out to be a rocket launch from nearby Vandenberg Air Force Base in unusual atmospheric conditions, which left a long glowing trail.  The other was almost certainly a meteor falling close enough that I could see it tumble and burn, but it might have been falling space debris.   Strictly speaking, there was a time when, for me at least, they were unidentified.  I know someone who managed to get a flying saucer photo published: it was a lid from a cooking pan, tossed in the air and spinning fast, and in poor focus.  An at least superficial investigation should be easily available.  A central clearing house can quickly dismiss the vast majority for what they are.  Occasionally something mysterious does turn up, and these should be investigated.  Yes, there are plenty of cranks in the world