Letters to the Editor
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The frequency of ET sightings is directly correlated to the price of camcorders
When cam corders were very very expensive, people claimed to see space lobsters all the time. Now when it's easy to have evidence, alas all the space lobsters are gone.
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read this a few months ago...
It really makes sense... by under pricing energy for 150 years we are risking out ablity to boot strap our selves into the solar system. Once the cheap energy is gone...
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he's not the first to think of it
He's not the first to think of it. Names escape me at the moment, but more than one science fiction author has noted the possibility as well.
Although it's usually phrased something like "perhaps few civilizations successfully make it past the 'bootstrap' phase, using planet-bound resources to get themselves to the point of being able to tap into off-planet resources".
It's a depressing thought.
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I Love Lucy in Space
There was a really interesting bit on NPR a couple weeks ago dealing with the transmission of radio broadcasts into space. Here's the link:
http://www.npr.org/templates/story/story.php?storyId=89700174
Basically (if I understand this correctly), as her voice was transmitted across space, it gets drowned out by the echo of the Big Bang. By the time, her voice reaches the edge of the solar system, it's just a whisper.
By the same token, the technology we use for broadcasting today is different than before. So, we're contributing nearly so much noise pollution into the solar system as before. In other words, our broadcasts aren't so "broad" anymore.
If that's the case, couldn't the same be said of alien civilizations? And, wouldn't it be a lot less depressing?
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More Likley, There's No Reason To Go Far Offworld
Even if you had the technology to travel interstellar space, would you use it? Unless you can somehow master faster than light travel, which is impossible according to Einstein, it would take years to physically reach distant solar systems. Who wants to spend years couped up on a spaceship?
Most of our technological progress over the past 50 years has involved making increasingly complex, ever smaller computing devices. We're now seriously considering the construction of devices where individual atoms might be used to store information. I'm sure subatomic computers will come after that. Instead of expanding out into space, our technology is focused on exploring and exploiting ever smaller spaces. It's conceivable that a sufficiently-advanced civilization could squeeze all of its knowledge into something the size of a sugar cube.
With that kind of technology, who needs space?
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Plenty of methane on Titan
I'm probably a sucker for responding seriously, but even if you assume that spacefaring species will rely on chemical propellant, it's unlikely they will be limited to their home planet for resources. Saturn's moon Titan has a sea of methane. It is little use to us here, but could probably be converted into refueling stop once you seeded it with self-replicating robotic pump attendants (metaphorically speaking).
The Fermi paradox is interesting, though. If it were just limited to civilizations expanding or exploring at a reasonable rate, there might not be much of a question. But assuming sufficient technology to build self-replicators, even a small initial population could set off an expanding sphere of robot probes converting all matter in their wake (an old idea). Maybe few advanced civilizations would do something so pointlessly destructive, and maybe the others eliminate such viral propagation when detected (an old rebuttal).
It's also possible that they are here already but not tromping around like elephants. You can probably embed more sentience in a grain of sand than we have on our whole planet.
It's also possible that we really are among the first and others have not reached us. Once the galaxy is lousy with intelligent life, it may be very unlikely for a species to evolve naturally the way we did.
Old stuff, all of it, but pretty cool questions nonetheless.
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UFO sightings
there have been multitudes of UFO sightings over the centuries. Just because you personally haven't seen one doesn't mean that other people haven't. Many of them have been quite well documented. The History Channel discusses this subject all the time.
perhaps the extraterrestrials communicate via some means other than radio waves which is why we haven't heard them. Or as others suggest maybe their signals are too faint or there's too much other noise out there.
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Speeding is one problem, slowing down is a much bigger problem
1/2kv^2 that exponent messes with you big time. Assuming that in order to brake you have to apply thrust in the opposite direction as your current motion. You would need the amount of fuel energy squared to slow down again unless you knew how far you were going and applied reverse thrust at the halfway point effectively multiplying your travel time by several orders of magnitude.
We will never ever ever ever ever ever not ever find any credible evidence of any intelligent civilization anywhere. We are for all practical purposes, alone and unique.
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Power functions
Radiation is an inverse power function. So close in, the earth appears hundreds of times more radioactive than it really is, because of all the EMR throwing off from radio, TV, radar, microwaves, powerplants and such. But that perceivable power attenuates very quickly as an inverse square of the distance. Otherwise any sufficiently advanced homeworld would look very peculiar to our radio telescopes in that their planet would look like a close distance Quasar or something like that.
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SETI and probabilities
While the size and age of the universe makes it likely that multiple technologically advanced civilizations exist, the same size and age of the universe makes it unlikely that any two of those civilizations will find each other, no matter the energy costs.
The most likely way for one to find another is the "beacon" approach, which is essentially what the SETI project is looking for (and the basis of the book and movie Contact*). In this an advanced civilization emits radio signals, possibly inadvertently, which another civilization receives. This is most likely because it doesn't involve actual travel, and since the beacon is omni directional the sending party doesn't have to know which direction the receiving party is. Unfortunately, due to the inverse-square law, the further you get from the beacon, the lower the power of the signal gets, until it's indistinguishable from the general background radiation bouncing around the universe. Thus, we could be pointing our nice big radio telescopes at a star with an advanced system blasting out radio signals (and have been long enough for those signals to reach us) and we'd never even know it.
Barring a beacon, a group would need either a directed signal, chance, or some kind of directed search, but it would literally be a shot in the dark, without knowing if someone was going to be there to receive it, or even listening in the right way, which is a very low gain to cost ratio. Given the vastness of what's out there, it gets extremely unlikely. Chance is the most likely that two civilizations will find one another, but given the odds that there may be many civilizations out there, chances are actually against us being one of the ones that meets up with someone else. We aren't exactly cruising around the galaxy having only had two objects even get barely out of our own solar system, and if there is someone out there flying around, the would have to decide to head our way and with all the places out there for them to go, what would make them come this way?
Granted, if we can actually prove some of the theoretical ideas like faster than light travel or wormholes, this could change the probabilities somewhat, but right now we don't really know that those things are possible.
* Contact, both the movie and the book, was somewhat interesting that it left open to the reader/viewer if there was any actual extraterrestrial contact. Certainly, some of the characters felt there was, and some did not.