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New Paper Offers Additional Reasoning for Fermi's Paradox
KentuckyFC writes "If the universe is teeming with advanced civilizations capable of communicating over interstellar distances, then surely we ought to have seen them by now. That's the gist of a paradoxical line of reasoning put forward by the physicist Enrico Fermi in 1950. The so-called Fermi Paradox has haunted SETI researchers ever since. Not least because if the number of intelligent civilizations capable of communication in our galaxy is greater than 1, then we should eventually hear from them. Now one astrophysicist says this thinking fails to take into account the limit to how far a signal from ET can travel before it becomes too faint to hear. Factor that in and everything changes. Assuming the average communicating civilization has a lifetime of 1,000 years, ten times longer than Earth has been broadcasting, and has a signal horizon of 1,000 light-years, you need a minimum of over 300 communicating civilizations in the Milky Way to ensure that you'll see one of them. Any less than that and the chances are that they'll live out their days entirely ignorant of each other's existence. Paradox solved, right?"
And if they're communicating by some mechanism that we can't read? E.g. the equivalent of "subspace radio".
Or maybe it's a point to point via laser (see Niven's Known Universe).
Fascism starts when the efficiency of the government becomes more important than the rights of the people.
Maybe there really is no FTL, and other alien races are as leery of sending out giant seedships that they themselves can't ride in as we are, and are thus still hanging out in their home starsystem.
Maybe aliens are everywhere, aware of us, and simply choosing not to communicate.
Disproving aliens deductively is the opposite of science. The lack of easily obtained evidence for alien life is far from damning given the area that we are capable of observing with any real scrutiny.
ad logicam Claiming a proposition is false because it was presented as the conclusion of a fallacious argument.
True. The calculation of 1000 years seems a bit too long. We can't figure out how to shorten it because we don't know how long we're going to be using broadcast signal based communication as opposed to some other more direct means.
Besides . . . attempting to extrapolate with so many unknowns is, at best, an exercise in postulation. At worst, it is dangerously misinforming.
Actually, IIRC, the Pope made a declaration a while back that there's nothing biblical that bars the existence of extraterrestrial life. For many people who are strongly devoted to one religion or another, even finding a note from their messiah announcing "Just kidding - I didn't think that y'all were going to take me so seriously. Hopefully after I die, somebody will find this and avoid any real disaster," would defer them from their beliefs.
He's getting rather old, but he's a good mouse.
Not necessarily. It may just be that interstellar travel isn't feasible, the ardent wishes of sci-fi writers everywhere notwithstanding. Remember, it's never enough to simply be able to do something: it has to make economic sense if you expect to get anybody else on board, too.
Assuming you can't skirt around the light barrier then that basically means sending small groups of people (or aliens or whatever) across trillions of miles, probably in some kind of hibernated state, in the hope that they'll bump into a habitable somewhere, set up shop, and begin to populate. Any returns on investment will be very intangible indeed- physical goods have to come back the same way they came (meaning it would have to be extraordinarily valuable to merit the shipping and handling on an interstellar ark) and information is cheap. You'd need to expect a very valuable treasure-trove of knowledge indeed for information to start making sense as an expected ROI.
I know many people just assume that interstellar travel is the "next step" in the development of societies but the longer I look at it the less it seems to offer tangible benefits for the people who have to invest in this.
I expect a society thinking in the long-term would obviously see the benefits of spreading one's seed across multiple star systems... but you have to postulate the existence of a society that takes the long view. Considering how easily a society as advanced as ours (not saying we're very advanced: just a society at the same level of advancement as us) is busily undermining its own biome, knows it's doing it, and doesn't care, and took pains to smother other societies which might have taken the longer view, I don't think we should expect many societies to reach the "long-view" stage before they wiped themselves out or got wiped out.
When calculating astrological signs over timescales of millenia, don't forget that due to precession of the Earth's axis the signs all shift by about a month every 2,000 years. So today's Libra is the year 4000's Virgo.
(Except of course that all the dates for the signs are fixed as they were in the time of the Ancient Greeks, so we're already off by a whole month. If you're a Libra the sun is actually in Virgo on your birthday.)
This also means that the autumnal equinox in 4004 BC was somewhere around the end of June.
The calculation of 1000 years seems a bit too long. We can't figure out how to shorten it because we don't know how long we're going to be using broadcast signal based communication as opposed to some other more direct means.
My own contribution to the debate:
As technology advances the limited amount of available bandwidth becomes more valuable, while costs of utilizing it drop. The civilization migrates its bandwidth use from simple, extremely redundant, coding schemes (like AM and FM) to subtle, highly-efficient schemes that are virtually indistinguishable from thermal noise (like OFDM). They also use spacial multiplexing to re-use the same bandwidth over and over at various locations. This buries the few redundant parts of the signal (like the pilot subchannels used for synchronizing the receiver) in interfering noise.
The result is that, after a fairly short time, at a distance they are virtually indistinguishable from a hot black body - and lost in the sagans of other hot things in the galaxy.
Our first AM voice radio broadcast was at the end of 1906. 102 years later we're taking a big step in the transition to OFDM-or-CDMA-everywhere by shutting down "analog TV" and replacing it with OFDM-based digital. AM and FM are already using digital variants to squeeze more out of their spectrum. Any bets on how long until they switch, too?
Once the simple-modulation blowtorches are switched over the few remaining detectably-patterned signals will be soft voices crying in a wilderness of high-noise-floor. If we don't DELIBERATELY send some intended-to-be-noticed beacons we'll again be lost in the background - our own and the galaxy's.
A thousand years? In our case the detectability sphere looks to be only a tad over 100 years deep.
Don't blink!
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
The 1,000 years isn't time from broadcasting to die-off. It is time from broadcasting to narrowcasting (using lasers or some other communications method that directly targets the intended receiver). Once narrowcasting is in use, we wouldn't expect to hear them unless they know we are here and are specifically targetting us.