A New Take On the Fermi Paradox

TravisTR points out some new research that aims to update and supplement the Fermi paradox — the idea that if intelligent life was as common as we expect, we should have detected it by now. The academic paper (PDF) from scientists at the National Technical University of Ukraine is based on the idea that civilizations can't expand forever on their own. The authors make the assumption that an isolated civilization will eventually die out or go dark through some other means, which leads to some interesting models of intergalactic colonization. "In certain circumstances, however, when civilizations are close enough together in time and space, they can come into contact and when this happens the cross-fertilization of ideas and cultures allows them both to flourish in a way that increases their combined lifespan. ... Bezsudnov and Snarskii say that for certain values of these parameters, the universe undergoes a phase change from one in which civilizations tend not to meet and spread into one in which the entire universe tends to become civilized as different groups meet and spread. Bezsudnov and Snarskii even derive an inequality that a universe must satisfy to become civilized. This, they say, is analogous to the famous Drake equation which attempts to quantify the number of other contactable civilizations in the universe right now."

Comments

My take

[Black Parrot]

Them that advertise get eaten.

Re:My take

[nitehawk214]

In spite of all that, you still think "them that advertise get eaten"

Fascinating.

No no, he is saying we will send advertising executives to the alien overlords as sacrifices.

Maybe it's as simple

[Anonymous Coward]

As the speed it would take to get nearby stars in a short period of time is just not physically possible no matter how advanced you are and no civilization has yet wanted to spend 500 years getting here.

Re: Maybe it's as simple

[Chris Burke]

No it doesn't. It merely assumes that a majority of them would eventually become wealthy enough to afford to create a colony or two and would do so just as their parent did. You can give each colony a thousand years to mature and still fill the galaxy pretty damn quickly.

Right but the very fact that they are wealthy and advanced enough to create multi-generational colony ships makes me wonder why they would want to. The only obvious one is population growth exceeding the capacity of their world, but look at our world (as we naturally must for all such predictions): The richest portions of the world are the ones with the lowest population growth, including negative. People traditionally had many children because of 1) lack of birth control 2) needing extra labor for their farms 3) high mortality rate among children from illness etc. That only leaves culture as a reason to reproduce beyond replacement rate, so sure maybe the Space Catholics will have population issues but otherwise it seems plausible that wealthy and advanced civilizations will stabilize not grow unbounded.

Then what? Resources? To even make the colony ship work I'm going to assume they have a Mr. Fusion, and once you have that you can do a hell of a lot with the resources of just one system (especially given a bounded population) and every energy-intensive recycling technique is suddenly much more feasible. Sending a small fraction of the population off in expensive colony ships is only going to exacerbate a resource problem anyway. Exploration, sense of adventure? Explorers are people who want to explore, not people who want to maybe enable their great-great-grandchild to explore.

I'm not saying it isn't possible. I'm saying that the answer to the Fermi "Paradox" could be as simple as: Maybe the assumption that civilizations will engage in exponential galactic colonization endeavors is wrong.

Re: Maybe it's as simple

[thesandtiger]

Even if you posited a 10000 year development time before a colony could successfully send out just 1 other colonizer, and another 10000 year development time before it could send out another, you still wind up filling up the galaxy REALLY fast. Even if 9/10 of those colonies fail to sprout (so let's call it, effectively, 100k years per new colony), in just over 5 million years (a cosmic blink of an eye) you have over 10^15 colonies. Even if it was 1 in 100 colonies that succeeded, you're still just talking about 50 million years.

Look at human history over the last 5000 years - we've gone from pre-technological to being on the verge of being able to break out of our solar system (relatively speaking, assuming we survive, we should be able to get out of town within the next 100000 years if we aren't dead). A colony on a future world would have all that technology and knowledge already developed - I'm going to say that, if we do get to another world, it'll take us WAY less time to fill it up and move on than it will take us to do this.

I have a better paradox

[blair1q]

If they are as intelligent as we think they are, won't they take one look at us and pretend they're not home?

Basic assumptions

[icebike]

The bit quoted as "Eventually die out and go dark" apparently comes from this quote in the second link:

Their approach is to imagine that civilisations form at a certain rate, grow to fill a certain volume of space and then collapse and die. They even go as far as to suggest that civilisations have a characteristic life time, which limits how big they can become.

However, this deals only with civilizations and not intelligent beings. The Civilization may collapse, after expanding to multiple worlds, but that does not mean that everyone on these planets dies. The would live on to create new civilizations.

Using an admittedly imperfect Earth analogy, the collapse of the Roman or Mayan empires din not lead to the extinction of humans, merely a pause in the development of civilization among that species, (us).

So EVEN if the basic assumption is correct, you would still expect to see many inhabited worlds, populated with remnant people having "arrival myths".

They may have once held knowledge of how to build ships, but deciding instead simply to sit tight, and not draw attention to themselves for a long enough period for any ship building knowledge or desire to wane. But new civilizations and technology would sooner or later arrive on these worlds.

When you start with a flawed and pessimistic assumption, it seems natural that you might arrive at a dismal conclusion.

Re:Basic assumptions

[HiThere]

But by the time the civilization collapses it's used up all of the readily available hydrocarbon deposits and metal deposits. (Civilization may require readily available copper deposits to be jump-started.)

So unless you can read the old CDs...or whatever storage medium replaces them...you can't learn enough to make a technological civilization out of what's left. You can probably go quite far with ceramics, glasses, etc., but none of those lead to electronics. And if you can't get to electronics you can't extract specialized materials out of low-value ores. (Well, possibly you could fractionally distill them...but just try doing that to extract iron. Zinc [zinc oxide?] you could get that way, though. Even if you get them that way, you get compounds, not metals. You need electricity to extract most metals from their compounds.)

I'm not sure you get a second chance at a technical civilization.

Re:Basic assumptions

[icebike]

But again, you assume collapse due to material exhaustion, which, even for a very OLD civilization would not universally be the case, especially one that migrated to other planets.

Why would a planet be colonized in the first place if there were insufficient materials for self support?

By the way: There is no exhaustion of copper or metals, as any gaze into a junk yard will reveal. In fact we make mining significantly easier for future generations by concentrating all of our waste materials. And any civilization capable of interplanetary migration would be been off hydro-carbons as a primary energy source for eons.

Hyperspace Bypass

[schmidt349]

What do you mean, you've never been to Alpha Centauri? For heavens' sakes, mankind, it's only five light-years away. Look, I'm sorry, but if you can't be bothered to take an interest in local politics that's your own lookout. Energize the demolition beams.

Apathetic bloody planet... I've no sympathy at all.

Alternative Interpretation

[camperdave]

Here's an alternative: Perhaps we are the First. Perhaps humanity is the first culture to rise to the point of being able to leave their home planet, even for a short while.

Some more thoughts on the subject

[erichill]

There's been a lot of argument that "close in space *and time*" is precisely the problem. In the cosmically vanishingly small time of a million years ago, we weren't very interesting. If we're still around in a million years, we probably wouldn't want to detectably approach anyone at the level that we're at now. There's also evidence that we're heading towards "going dark" as a result of using more efficient communications so there will be an inner surface to our radio sphere of influence. There may be other things to look for, like the gamma ray signature of antimatter powered interstellar vehicles. We wouldn't see anybody on a ballistic trajectory. I'm rather taken by arguments that suggest that really advanced cultures won't want to be very spread out because of communications latency. See, for instance, this by Cirkovic and Bradbury.

As already mentioned, there is the possibility that we're the first [in our light cone].

Communicate first?

[CdBee]

I'd have thought, however risky we are to meet, any civilisation that's aware of us and monitoring would probably start with a generic 'hey guys, want to chat? Check where this signal is coming from if you want to know who we are'

it might not only be human society that thinks turning up unannounced is poor form.

Why are we assuming E/M transmission?

[sconeu]

Perhaps advanced civilizations are not using EM transmission (radio/light), but some other form of communication that we are unable to detect.

Yes, Trek is fictional, but to use it as an example: We wouldn't detect Starfleet because they use "Subspace communications" instead of radio.

It's time and distance as much as anything else

[Todd Knarr]

We generated our first real radio signals sometime around 1894, give or take. That means that we are completely and utterly invisible in the radio spectrum to any civilizations more than about 116 light-years away from Sol. Our radio signals simply haven't had time to reach them yet. And the same thing applies in reverse: if an alien civilization began transmitting radio signals 200 years ago but they're more than 200 light-years away from us, we won't be able to see them because their signals haven't had time to reach us yet.

That defines the outer edge of the visibility shell. There's also an inner edge. As a civilization develops, it eventually stops transmitting radio signals as it first gets more efficient at transmitting radio (moving from pure broadcast to directed transmissions and then refining their ability to direct the transmission into tighter and tighter beams) and then starts using things other than radio. If you start listening after the last of their detectable broadcasts has passed you, again you can't see them.

So when you're asking "If there are as many civilizations out there as the equations predict, why can't we detect them?" you also have to take into account the fact you're likely only physically able to detect a fraction of the civilizations that may exist. The rest are either too far away for their signals to have reached you, or they've been around long enough that you weren't listening when the last of their detectable transmissions passed your planet.

Bandwidth efficient communication looks like noise

[Ungrounded Lightning]

My own take on the Fermi paradox comes from the observation that modern radio communication systems - spread spectrum and ODFM - approach the Shannon limit of the bandwidth's information carrying capacity. As they do that, they approach the appearance of pure noise.

Earlier transmission systems, such as AM, FM, and analog broadcast's AM/FM hybrid, involve massive inherent reundancy and low bandwidth utilization. This makes their existence detectable (even if not fully decodable) at interstellar distances and at the resulting far worse signal-to-noise ratio than their intended receivers experience. Spread-spectrum and OFDM systems (and no doubt others yet to be invented) fill their assigned bandwidth with a close approximation to white noise, with only a small amount of redundancy to allow the receiver to detect the existence of the signal and synchronize with it. (Even the redundancy from the forward error correction is sufficiently complex that at appears as noise if the particular scheme is not being looked for.) This is why, when the signal-to-noise ratio of a digital signal becomes excessive, the reception drops out completely rather than becoming noisy.

Bandwidth is limited by physice, but the potential valuable uses of it are limited only by imagination and cost. So other radio-using civilizations seem likely to follow a similar path of squeezing as much information as technology allows into their signals.

If this is the case, the L term in the Drake equation ("the length of time such civilizations release detectable signals into space") becomes a measure, not of the lifetime of the civilization after it begins to use broadcast radio, but of the time from such use to the time it is supplanted by highly-efficient but not-readily-detectable shannon-limit-approaching signals.

When estimating the number of intelligences in this galaxy using the Drake equation, L was ballparked at 10,000 years. But consider broadcast TV here on Earth (the main telltale, emitting far more power per station than audio radio): Excluding early experiments the first regularly scheduled TV broadcasts started in 1930 - and the Analog Cutoff (where most high-power analog TV stations were shut down to free the bandwidth for other purposes) is in progress now, with the US terminating all full-power analog TV broadcast in 2009, just 80 years after the first signals from that first broadcast-service station.

So I have no feeling of loneliness just because we haven't happened to hear any civilizations in the narrow time slot when they might send DETECTABLE broadcasts.

You'll go blind

[Hognoxious]

What do you see if you close your eyes and rub hard?

I don't see anything, but my hand feels sticky.