The Straight Dope on Fermi's Paradox...

This is something I have wondered for some time. What is the solution to Fermi’s Paradox? In case you don’t know, this is the seeming paradox that there are probably other advanced alien extraterrestrial races. But none of them have tried to contact us thus far.

Actually, I must insert my opinion as I start this discussion. I contend that considering how much older some planets are than ours (I think some of them are billions of years older than us), clearly some of the more advanced ones have to be at least aware of us. So why don’t they contact us? So I guess my question is two-part then.

BTW, I am familiar with the Wikipedia article on Fermi’s Paradox. But I am looking for some fresh ideas here perhaps not included in the Wiki article. (But if you must bring up the Wiki article, may I start by saying I find the “Zoo Hypothesis” very interesting–although it doesn’t make much sense to me really :confused:.)

Thank you in advance to all who reply:)

Szilard’s Riposte: “We are here, Enrico, we’re just disguised as Hungarian Jews.”

If you received an episode of Tool Academy on your radio telescope, would you want to respond?

You have to flesh it out a bit more before the paradox becomes evident. First of all, even at very conservative estimates, there should be a few civilizations per galaxy, or so (possibly millions or billions of civilizations). Second, it would only take a few tens of millions of years for a civilization to colonize the entire Galaxy. Third, tens of millions of years is not a very long time at all, compared to the time it would take a civilization to arise on its own on a planet, so for the vast majority of planets, one would expect civilization to come from elsewhere.

All that said, I’m not sure of a resolution, either.

Maybe they already have contacted us and have been doing so for millions of years? Perhaps unusual weather patterns or seemingly random solar flares are their way of communicating information but we’re not advanced enough to notice it. Our current knowledge frames these as “chaos theory” but maybe 10,000 years from now, these events will be recognized as alien transmissions from another galaxy. Since aliens can’t use radio waves (speed of light is too slow), they use some kind of “quantum entanglement” to ping us.

For example, a person born before Darwin might look at bees wiggling and determine they’re just meaningless random body movements. But recent scientists have decoded their sequence to determine they are actually communicating the location of flowers. The information content in the bees body movements have been there all along – we just didn’t notice the patterns.

Maybe we are constrained in thinking that aliens will contact us via radio waves. (This is our bias because radio waves are what we know.)

*Yes, I realize that “entanglement” in physics says information can’t be transmitted this way but I don’t have a better word for this.


People forget the time factor.

Civilizations have to be in the same place at the SAME time to meet. Unless the galaxy is absolutely overrun with with advanced civilisations that requires at least two more things.

The civilizations last 10s if not hundreds of millions of years.

They go nearly everywhere. Not only that, they either colonize there or hang around for 100s of millions of years until the local ape’s learn to make radio’s.

Personally, I think intelligent life is not particularly rare. But throw in the time problem and IMO it quickly becomes rowboats passing in the night in the Atlantic.

We obviously don’t have a solution yet. But a few ideas I like:

The aliens only check in every five million years or so, there being so many planets to visit, so we are just between visits.

One planet is pretty much like another, so they are not interested in seeing the equivalent of their millionth tourist trap.

They’ve downloaded themselves into robots, and live in space where there is more room.

They are a billion years ahead of us. Would you go out of your way to have a conversation with an ant?

They really believe in the prime directive. Look at what happened to various human cultures when the Europeans dropped in. Just the knowledge that advanced aliens exist would have a tremendous impact, much of it bad. (Why build a LHC when you can find the answer in the interstellar equivalent of Google.)

In my SF universe, the aliens only make contact once a civilization makes a successful interstellar flight. They figure that the planet has to be more or less united to do this. (In my universe you only find the secret to ftl travel after you build a really, really big collider - interplanetary size, millions of miles long.) I also have a justification for a Star Trek like galaxy with everyone at more or less the same technological level. Which doesn’t mean anything but that I had to think about this to get it set up to be somewhat supportable.

ETA: Most of my reasons are optimistic ones. If you want to be pessimistic (intelligent races wipe themselves out) there are plenty of solutions.

Adding to the time factor is that we’ve had no real ability to even attempt to find any communications for all but a tiny fraction of our history. Our technology may be too primitive to detect the Cosmos-net. Maybe ET has a Prime Directive. Maybe we’re not worthy. Maybe ET just isn’t hungry enough yet.

Easy–the flaw in Fermi’s Paradox is the unstated assumption that aliens think like us.

Who says they have any interest in exploration/communication? What if we’re unique that way.

Fermi’s paradox isn’t a paradox until you state as given that aliens have our motives.

It’s not about having the technology. Fermi’s Paradox is not about being able to pick up radio waves or entanglement waves or whatever: It’s about the fact that we haven’t picked up any of them waving at us from across the room. There’s been enough time for aliens to not just blanket the Galaxy with radio waves; there’s enough time for they, themselves, in the flesh, to have filled the Galaxy.

There are 2 interpretations of Fermi’s Paradox in the wiki article. One is “in the flesh” and the other considers (for argument’s sake) that space travel is too difficult which leads to the other interpretation: “why haven’t they contacted us?” It is the 2nd interpretation of communication I was responding to. The OP also considered this version when he asked, “So why don’t they contact us?”

There’s also the possibility that we ***are ***the aliens . . . or at least a product of them. Similar to Intelligent Design, except at the hand of aliens, rather than a deity. We may be nothing more than a science class project.

But I think a more likely explanation is an enforced Prime Directive. If their species is advanced enough to get here, they may be wise enough to leave us alone.

They don’t contact us because they’d need a ludicrously large device pointed our way for us to pick them up. And they won’t hear our weak signals. We couldn’t even detect a clone earth if they were right next door.

They haven’t colonized the galaxy because that is absurdly uneconomical. I would guess that most civilizations would find themselves stranded on their home planet after using up most of its resources. If not that they’d probably invent a real life matrix before undergoing a galaxy wide colonization project. Imagine trying to terraform billions of planets.

I prefer invoking the anthropic principle. That is, intelligent life is so hideously unlikely to exist that there’s only a 1 in 10[sup]100[/sup] chance of it appearing. However, in universes in which there is no intelligent life, there’s nothing to observe that there’s no intelligent life, thus, we live in the 1 in 10[sup]100[/sup] universes which intelligent life exists but it’s highly unlikely that any other intelligent life would also arise.

There’s always the theory that haven’t contacted us because we’re made of meat.

They likely would have some sort of passive stealth monitoring device.

While I await the findings of various planet-finding satellites (both in orbit now, soon to go up, and on the drawing board), so as to get an idea of how common “class M” planets are, you’d think that a world with Earth’s potential for life (say they visited 1 billion years ago, when there were few megacellular life forms, but their models clearly showed a definite possibility of same somewhere down the road) would be of intense interest to them.

Or wise enough to not get noticed (assuming Stealth in Space is possible). We are pontificating into a void of information-fun to speculate about, but nothing that can get resolved one way or another.

The problem with Fermi’s paradox is that it makes a lot of assumptions. For one thing, most basically, why do we assume that these intelligent civilizations either can or want to colonize the galaxy. Maybe nobody has figured out how to get around the light speed limit and doesn’t want to bother with ships that will take hundreds or thousands of years to get to another planet. Maybe all the aliens have moral/religious objections to space travel. Maybe they’re just not curious about the universe around them. Maybe once a civilization discovers nuclear weapons, it blows itself up. Maybe we’re just the most advanced civilization in the galaxy.

Both interstellar travel and interstellar communication take tremendous amounts of time and energy. To try and communicate with say the 1000 closest stars similar to the sun would be extremely costly. The round trip for messages between civilizations is 10 years plus. How many round trips before you have anything like communication? It is easily believable that it is just to hard to communicate or travel between stars.

Take a 16 ounce cup and place it open side up somewhere in any of the oceans of the world.
If we all started throwing pennies into all the bodies of water, how soon will it be before a single penny lands in the cup?

I had heard somewhere, and it may be in the Wikipedia article for all I know, that a possible solution to Fermi’s Paradox is to try to see what he was trying to teach his students with it – namely, if you only have wide probabilities to input into an equation, you soon reach the point at which no conclusion is possible.

Really, look at the paradox. It starts off simple, how many galaxies, sun -like stars, how many earth-like planets (assuming those are requirements), those are fairly easy determinations, and we can estimate our errors.

Then the later terms, odds of life evolving, odds that it develops intelligence, odds that it develops an advanced civilization, odds that it has the resources to communicate, odds that it exists long enough. Those are really wide guesses. They muddy the equation. The equation itself, that’s perfect, … outside of being useless for producing an answer. :wink: