IEET > GlobalDemocracySecurity > Vision > Virtuality > Staff > HealthLongevity > Mike Treder > Innovation > SciTech
We’re All Alone and No One Knows Why
Mike Treder   Mar 2, 2010   Ethical Technology  

Does this mean humanity is trapped inside an expansion boundary from which we can never escape?

Two years ago, in a column I wrote for Nanotechnology Now, I offered a basic explanation of the Fermi Paradox. As my ideas have circulated on the Web, they have generated a good number of comments, including objections to my reasoning and counter-proposals for our apparent isolation in the cosmos.

But I’d submit that no one has yet come up with any objection or explanation that makes more sense than what I have proposed.

To review, here is the starting point.

We Are Alone

As far as we can tell, we are alone in the universe. That is, human beings are the only technologically-advanced species for whom we have any evidence.

This observation is known as the Fermi Paradox. In 1950, the physicist Enrico Fermi famously wondered, “Where is everybody?” He was referring to the strange silence in the universe, the apparent lack of any advanced civilizations beyond Earth.

Fermi reasoned that the size and age of the universe would indicate that many technologically advanced extraterrestrial civilizations ought to exist. However, this hypothesis is inconsistent with the lack of observational evidence to support it.

So, where is everybody? Nowhere, it seems, or at least nowhere that we can detect.

Many explanations have been offered for this conundrum, with none coming even close to finding consensus. Physicists, astronomers, and philosophers are as far from answering the question today as when Fermi first posed it.

Perhaps the most disturbing aspect of the Fermi Paradox is what it suggests for the future of our human civilization. Namely, that we have no future beyond earthly confinement and, quite possibly, extinction.

But why should that be? Don’t we have a potentially limitless future, with a solar system and eventually a galaxy waiting to be explored and settled?

It would seem so, and yet, the available evidence may suggest otherwise.

Three Propositions

If there are no other advanced civilizations detectable, it must mean one of three things:

1. We are the first intelligent beings capable of expanding into the cosmos and making our presence known. There have been no others. 

2. There have been others before us, but all of them, without exception, have chosen—or somehow been forced—to expand in such a way that they are presently undetectable by our most sophisticated instruments. 

3. There have been others, but all of them, without exception, have run into a cosmic roadblock that either destroys them or prevents their expansion beyond a small radius.

The first proposition, that we humans are unique and special, appears quite absurd. It contradicts all that we have discovered during the last five hundred years about the true nature of the universe and our place in it.

We are not special: the Earth is not at the center of our solar system, the solar system is not at the center of our galaxy, and our galaxy is not at any special position in the universe. Our placement in space and time seems to be random and unremarkable.

Moreover, we humans, along with every other form of life, have evolved to our present state in accordance with natural selection. There’s nothing special about us.

Why, then, would it even be conceivable that earthlings are destined to be the very first species to make a noticeable mark on the universe?

If we reject proposition 1, then we must choose between propositions 2 and 3.

There is a crucial distinction between the second and third propositions. The former relies on choice, while the latter implies restriction by some force or law of the universe.

It seems strange to imagine, as suggested by proposition 2, that all extraterrestrial civilizations would, without exception, choose to expand or exist in such a way that they are completely undetectable to us. If proposition 2 is correct, it requires every one of potentially hundreds, thousands, or even millions of advanced worlds to make the exact same decision. We might expect some to do so, perhaps even most, but all? That defies logic.

So we are left with the third answer. Whatever civilizations have come before us have been unable to surpass the cosmic roadblock. They are either destroyed or limited in such a way that absolutely precludes their expansion into the visible universe. If that is indeed the case—and it would seem to be the most logical explanation for Fermi’s Paradox—then there is some immutable law that we too must expect to encounter at some point. We are, effectively, sentenced to death or, at best, life in the prison of a near-space bubble.

Okay, so that sums up the problem. We are all by ourselves, as far as we can tell, and the explanation that seems to fit best leaves us stuck inside an expansion boundary from which we can never escape.

But now let’s take a look at some of the objections that others have made to my reasoning. Here are a few popular favorites.

Ascension: After a certain point, technologically advanced species move out of the physical realm and into a digital “virtual” existence, living it up forever inside a Jupiter Brain or its equivalent. We can’t see them and they don’t care about us.

Apathy: Similar to the Ascension explanation, the idea here is that species who are smart enough and technologically advanced enough to galactically expand don’t care to. They are happier writing poetry, listening to music, playing video games, or whatever.

Caution: Advanced species realize that human beings are dangerous, that we are psychotic, or that we are too immature for their kind to mess with.

All three of the above objections fall prey to the “everyone does it” fallacy. In order for them to be correct, we have to make the unsustainable assumption that every single technologically advanced species acts the same way. They would all have to make the choice not to expand or not to contact us, and that defies the logic of probability.

Bigness: The universe is so big and the distances involved so vast that all those other advanced civilizations simply haven’t had time yet to reach us. Related to this is the “needle in a haystack” explanation, suggesting that we just haven’t looked in the right place yet. Our SETI scans are not sufficient to do the job.

Fermi himself immediately dismissed this explanation with some quick back-of-the-envelope calculations. Given a reasonable estimate for how many habitable planets there should be and how long the universe has been in existence, it’s easy to determine that if there are any expanding civilizations, there must be many, and that they have had more than enough time to cover the necessary distances. Size is not the problem. We need a different answer.

Difficulty: Expanding into the universe is too hard, requires too much energy, is too expensive, or for whatever reason is not seen as worth the effort.

Again, for this to be correct, you have to assume that every single candidate species makes the same choice to forgo expansion. And if it’s not a choice, but simply a reflection of reality—if expansion is so difficult that it’s effectively impossible—then that proves my original proposition 3.

Invisibility: They’re there, but we just can’t see them. Our instruments aren’t able to detect them even though the evidence is basically right in front of us.

No, that explanation doesn’t work either, and for basically the same reason. It supposes that all advanced civilizations use the same kind of invisible-making technology. Some of them might, or most of them, but every single one?

Rareness: We might not be totally alone, but the number of intelligent species is so few, and the number of advanced technological civilizations so many fewer still, that we are like two or three tiny krill swimming inside an otherwise empty ocean. There is almost no hope that we will ever find each other.

Perhaps, but then you’re getting perilously close to making us “special” again, if not unique.

All in all, it seems clear to me — irrefutably logical — that some sort of cosmic roadblock, as yet unidentified, must exist. Either that or we are in a simulation.

Mike Treder
Mike Treder is a former Managing Director of the IEET.


I favor the ascension hypothesis.  On ‘Overcoming Bias’ and ‘Sentient Developments’  I made a mind-blowing hypothesis that I call ‘The Hall of Worlds’, here is what I said:

“There exists a ‘Hall of Worlds’ which serves as a giant ‘meeting place’ for ‘intelligent entities’ across the universe. The ‘Hall of Worlds’ is a ‘miniature artificial universe’ constructed from ‘inter-dimensional materials’. It is maintained by ‘super intelligences’. The reason humans have little contact with the hall, is that its relationship to the ordinary universe is an uneasy one; The hall is accessible from every point of space and time, but it exists ‘between’ ordinary space and time; once an entity ‘fully’ enters the hall, their ‘freedom’ to re-enter the ordinary universe is severely restricted . Many entities have migrated to the hall, thus, the solution to your Femi Paradox. There exist many ‘Muses’ in the hall, ‘powers’ that specialize in different ‘arts and sciences’. “

They’ve gone to the ‘Hall of Worlds’ Mike.  And it doesn’t make sense for them to travel through ordinary physical space, because this is limited to the speed of light - by the time they reached us we would already have progressed to the point where we too can ascend to the Hall.  The only sensible course of action is for them to wait for us in the Hall.

I’ve read quite a few explanations of the Fermi paradox and I must say I think your logic is pretty solid.  I’m reminded of a similar article Nick Bostrom article in the MIT technology review where he hoped the search for life on Mars turned up nothing for the very same reason.

I have read about singularities and I have seen some of the past singularities being mentioned at

There are six different singularities being mentioned and people might argue on which of the past events to be considered as singularities. Instead of arguing on that, I will just consider them here and see if it helps in this discussion.

I will assume certain things and consider the time taken for each of these singularities to happen.

1) The birth of the universe is singularity number one - time NOT KNOWN/NOT APPLICABLE
2) The occurrence of a ‘perfect’ planet as the birth place of life is singularity number two - (I will consider our planet) - 8 billion years.
3) This most singular of all is singularity number three, the birth of life. - 1.2 billion years
4) The survival of life is singularity number four. - 1.2 billion years
5) The simultaneous combination of an evolutionary process unique to life, a survivable environment, and a life that can survive its own reproductive error is singularity number five. - 1.8 billion years
6) The development of intellect is singularity number six. - 600 million years

Leaving out the birth of the universe and birth of our planet, it has taken 1.2 billion years, on an average, for each singularity to happen.

Here I will take Kardashev’s Type-1, Type-2 and Type-3 civilization concepts and see how much time is required to pervade galaxy. Assuming that we are almost type-1 and that we need two more singularities to reach type-3 civilization, we need 2.4 more billion years.

So a planet, once it is formed, requires 6 singularities and 7.2 billion years to pervade the galaxy. Considering 13.7 billion years as the age of the universe, this looks feasible. So Rareness may not be applicable.

So, I am also left with the only option which is to conclude with the third proposition. Or somebody can find flaws in my arguments and see if we can conclude otherwise?

“We are not special: the Earth is not at the center of our solar system, the solar system is not at the center of our galaxy, and our galaxy is not at any special position in the universe. Our placement in space and time seems to be random and unremarkable. “

Maybe, maybe… writes

“Mathematicians have proposed an alternative explanation for the accelerating expansion of the universe that does not rely on the mystifying idea of dark energy…One potential issue with this idea is that it might require a big coincidence. For the universe to appear to be accelerating at the same rate in all directions, we in the Milky Way would have to be near a local center, at the spot where an expansion wave was initiated early in the Big Bang when the universe was filled with radiation.”

mjgeddes, would you mind if I have a little fun with your fascinating post? I mean no offense by it, but I’m struck by some similarities I’ve seen elsewhere. I’d like to substitute some of your words with others, so that the resultant message sounds like it comes from a certain religion. The resultant paragraphs do not match that religion’s teachings 100%, but it’s not terribly off.

“There exists a ‘Garden of Time’ which serves as a giant ‘meeting place’ for ‘intelligent entities’ from around the world. The ‘Garden of Time’ is a ‘miniature artificial universe’ constructed from ‘inter-dimensional materials’. It is maintained by ‘angels’. The reason humans have little contact with the garden, is that its relationship to the ordinary universe is an uneasy one (i.e. death is usually needed); The garden is accessible from every point of space and time, but it exists ‘between’ ordinary space and time; once an entity ‘fully’ enters the hall, their ‘freedom’ to re-enter the ordinary universe is severely restricted, with one notable exception, Elijah the Prophet. Many entities have migrated to the garden, thus, the solution to your Fermi Paradox. There exist many ‘Muses’ in the hall, ‘powers’ that specialize in different ‘arts and sciences’. “

They’ve gone to the ‘Garden of Eden’, Mike, and “Eden” can mean “Time”. And it doesn’t make sense for them to travel through ordinary physical space, because this is limited to the speed of light - by the time they reached us we would already have progressed to the point where we too can ascend to the Garden. The only sensible course of action is for them to wait for us in the Garden. “

We may be completely alone in our Hubble volume but in no way special if the following condition holds. In the overwhelming majority of Hubble volumes in which primordial life arises, it does so only once: the genesis of information-bearing self-replicators is sufficiently thermodynamically improbable as to make two or more mutually accessible civilisations vanishingly rare.

Perhaps the sky is full of electromagnetic transmissions, but we are still too stupid to extract them from noise.

Or, there is some interstellar transmission technology so much better than electromagnetic waves that all civilizations switch to it as soon as they discover it. We may be thinking that we are alone because we don’t hear far drums.

I had never thought of the simulation theory as an explanation for the Fermi paradox, but it is certainly a possible explanation.

@ mjgeddes and veronica

So is this what we have to look forward to? A “timeless” wait in the hall? Not very encouraging. Yet this idea also incorporates Plato’s ideas of souls waiting to draw lots for reincarnation, and the muses may well be angelic?

I’d have to go with “bigness” and “rareness”. To quote Douglas Adams, “Space is big. You just won’t believe how vastly, hugely, mind- bogglingly big it is.” And if we took a journey on board the trusty old starship Enterprise, whose five year mission may be to travel at up to ten times light speed : this would still only give us 50 light years distance. Our galaxy the Milky Way is 100,000 light-years across, (allegedly). Talk about needles in haystacks.

Yet if we could advance enough to subscribe to broadband sub-space transmissions, we may find there is a whole chatter-verse out there? Of course, this may just all be gobble-dee-gook to us, which is why you should always pack your babel fish.

Point 3 should not be discarded lightly however. Although I do think we have all the time in the universe to evolve, if we take care or ourselves.

@ Mike

Quote : “Perhaps, but then you’re getting perilously close to making us “special” again, if not unique.”

But can’t you see that you are special, that we are all special? The ability to even contemplate and question these very ideas proves how special we all are, (although I also think cats are smarter than they let on?) Geeez.. I mean, it’s enough to make you religious : Mike, repent and atone, take up the good book. We may well be living in God’s simulation, like a giant fish tank : travel far enough and long enough and you may just bump your nose into glass?

Douglas Adams Quotes - The Quotations Page

Option 1 does not say we are ‘special’ it simply says we are the first.

Why is that so hard to believe ?

The probability of being the first is the same probabilty as being the 688790320167821207-th.

Proposition 2 may have a level of refinement applied, namely, that they are detectable and even detected but the forced silence is conspiratorial. All evidence of any extraterrestrial intelligence is suppressed, censored, covered up. I’m not saying this is likely or true, but it is believed and should be presented as part of the 3 propositions. I thought proposition 2 was the best fit.

There’s a perfectly reasonable and universal incentive for other civilizations to end up with invisibility:  non-invisibility means inefficiency.  A signal that can be distinguished from noise isn’t compressed enough; radiating energy that we can detect over here on Earth means it’s being wasted.  Civilizations probably only have a window of a few centuries between the development of radio and the level of efficiency at which they’re not detectable through our currently available methods.  They’re not hiding from us; they’re just avoiding waste.


I see little or no similarity.  The religious picture is the exact opposite to the one I put foward actually, a narrow, human-centric view of reality, further, there’s a huge gulf of difference between supernatural and natural concepts.


If ascension was so attractive and blissful, it is likely that everyone without exception would do it.  Image something like the equivalent of a sort of galactic internet multiplied by a million where the accumulated wisdom and bliss of eons of intelligence life was at your disposal if you went to this place, by constrast, remaining in ordinary meat-space would leave you completely cut off and alone from galactic civilization.  There’s no way anyone would choose to remain in meat space, given such a choice. 

According to Tegmark and the Many Worlds View (controversial but supported by many leading scientists), there *does* exist a platonic, timeless multiverse where all possibilities are realized.  In that multiverse, given an infinite universe there have to be an infinite number of intelligences.  And, given the emergence of super-intelligence in the future, the logical course of action is to try to emulate (compute) the ‘Multi-verse’ view.  This emulation would be ‘The Hall of Worlds’.  It is almost obvious that it has to exist.

The ‘Hall of Worlds’ is all around us.  We just need the right access key to enter.  I think there’s a good chance I’m right.

I suppose this might fit under heading no.2:

Unless I missed something, at our present capabilities our ability to detect any alien intelligences would depend on several assumptions about their behavior:

1. Foremost, that they would expand across the universe with no more thought of the consequences than would bacteria, filling every available niche *without exception*.
2. They would be deliberately broadcasting powerful signals using a technology we understand, and which we could detect.  As far as I know we still wouldn’t have very good odds of singling out an Earth-level civilization’s signals from more than a couple dozen lightyears away.
3. They would build artificial structures of a Dyson Sphere scale or even larger.  Again if they haven’t we would not likely see any sign of them from more than a few dozen lightyears away.

Charles Stross recently wrote a piece explaining how unlikely it was that, even if it was placed directly on the Earth’s surface, a life detector would have discovered a human-habitable world here, given all the span of time in the universe it might have wandered by.  See, frankly, this moment in time *is* special, that for less than two centuries, there’s been a capability to even go looking for aliens.  It’s distinctly possible that this universe could be teeming with life, but there just doesn’t happen to be any in this particular dozen-lightyear bubble, during this particular century.

When we’re capable of definitively ruling out Earth-level civilizations across a significant portion of the galaxy, then it might be time to start taking this question a little more seriously.

@Max Kaehn - very good point!

mjgeddes writes: “veronica, I see little or no similarity. “
In my opinion, I think it’s close enough.

I have a few questions on your hypothesis: “And it doesn’t make sense for them to travel through ordinary physical space, because this is limited to the speed of light - by the time they reached us we would already have progressed to the point where we too can ascend to the Hall. “

a) Why doesn’t it make sense for them to travel through ordinary physical space? Asked half-seriously, wouldn’t it be worth it (for a guy) to see any one of these women?—>

b) Also, why would it take time to reach us? Can’t they just reach us at any point in time (and maybe space) that they’d like? This assumes that “their ‘freedom’ to re-enter the ordinary universe is severely restricted,” but not completely restricted.

c) What’s restricting them, anyway?

d) On the words, “The reason humans have little contact with the hall, is that its relationship to the ordinary universe is an uneasy one”—did I guess right that this “uneasy” relationship is that death is required?

A very simple and parsimonious answer to the Fermi paradox is that we are *locally* first.


(a)  If life was far far better in the hall, then the temptation to leave ordinary space would be too great for anyone to remain here long, remember I am assuming that in the hall there is infinite wisdom and bliss, including all the female forms one could ever desire 😉

(b)  I assume it’s largely a one-way trip, they can leave ordinary space at any point in space/time, but mostly can’t reenter (see below).  They can’t use the hall to get to us. 

(c)  Conflict with relativity theory.  If two aliens from opposite sides of the galaxy could meet and converse immediately (for example), they could only do so outside ordinary space, and could not re-enter ordinary space at the times they left (otherwise causal influences could travel faster than light).

(d)  I meant physics , see above, there is a conflict with relativity theory (no faster than light) unless there are some serious restrictions.  That’s why the meeting hall (if it exists) would have to be an artifical universe outside ordinary physics, and there would be serious limitations on leaving after you’ve entered.

Civilizations probably only have a window of a few centuries between the development of radio and the level of efficiency at which they’re not detectable through our currently available methods. They’re not hiding from us; they’re just avoiding waste.

The cosmic roadblock may be this: (“Why the demise of civilisation may be inevitable” on The article says that complexity theory seems to suggest that beyond a certain point advanced civilizations become so fragile that collapse is inevitable. Seems perfectly reasonable if you look at how our ‘civilization’ is progressing.

You didn’t consider the “first mover wins” hypothesis:

1. Civilizations are unlikely to get intelligent at the same time, there will be multi-million-year differences just because mind and geology/evolution don’t run on the same time scales. The chance of two civilizations going expansive at exactly the same time is close to zero.

2. A multi million year gap will be, saving some existential disaster, plenty sufficient for our very posthuman descendants to overrun the local galaxy and own it completely.

3. A random first mover couldn’t be expected to have humane values. They would have breezed through our neighbourhood, disassembled the planets for mass, tapped the sun for energy, and too bad for the lemurs or whatever our ancestors were at that point.

4. Only the first mover’s viewpoint contains observers. Ergo by anthropic reasoning, we are the first.

I had never thought of the simulation theory as an explanation for the Fermi paradox, but it is certainly a possible explanation.

Not surprisingly the problem has been over simplified and the possible solutions as well. It all boils down to the odds that advanced civilizations would develop with the same priorities that are being assumed that they would. There are a myriad of reasons that would prevent our detection of an advanced species in the cosmos and they include all of the reasons given and more. Just one for example, let’s say there’s an intelligent group on an undetected planet just beyond our solar system. They are at the level of say, ancient Greece. Now compared to them, we are the advanced spacefaring civilization but we haven’t discovered them yet and probably won’t for decades. Where are the bases on the moon and the space hotels we’re supposed to have by now? Where’s that PanAM spaceline that I saw in the 2001: A Space Odyssey promos?

Since it appears that there are no current advanced civilizations in our solar system, then if there are any anywhere they have plenty of places to go besides our direction. They may also have myriad of constraints on how travel is done, who does it, why, where, when, and on and on.

In the end I don’t believe scientists really care about finding life in the universe anyway. As for the Max Tegmark idea of a multiverse, I met Max once and he’s pretty good guy. I don’t think it would be accurate to call any place “timeless” however, due to the fact that it is impossible for time not to exist. Something may go on forever, or never change but time would still exist, it’s just that the thing or place in question would not change over time…

haha, cosmic roadblock. I think it’s time to realize what is really going on here. Obama is most likely going to announce Disclosure very soon. Anti gravity and what not. Lots of news coming out. Keep your eyes peeled. the mainstream hasn’t seem to have been reporting it. lately.

Are we alone in the universe?...Are we alone on the planet???

When we look at stars from earth we are looking at the history of that star; as it happen from the point of time that it took that light to get to us. I agree that we are not unique and I would also think the same of every other civ out there.  So lets say that all intellectually life started around the same time 1-2 billion years ago. Now lets say that the fore runner of the universe hit stage 2 or 3, 500million years ago; if their home galaxy was 501 million light years away and assuming we have the technology to see traces of their advancement would not see it next year and not presently.  Just a thought.

I still thing the bigness theory is the true one. Take us for example, we
have been broadcasting radio waves for around a hundred years. For anyone to hear those broadcasts, they would have to be no further than one hundred light years away. It would be another hundred years before we would hear any reply. Another thing, not only does it take an awful long time for a signal to cross such distances, but signal strength weakens the further it must travel. For us to detect a signal from another species it would not only be very strong but aimed directly at us. Why would an alien civilization choose our solar system in particular to beam such a signal toward us?

Here is just an interesting thought…

What about the thought that it is unusual to have the human philoshophy of the ego. We largly consider ourselves as discontinuitus beings from the rest of creation. However there is a small part remaining in us that feels a need for continuity, for instance, connected to Mother Nature or God.
If we consider the ego is an unusual development we could suppose the rest of the life in the universe may feel less egotistical and know that they are already connected to all life. They would have no need to speak with us physically.
Who knows, perhaps we will be cured of our ego by merging our brains with computers or biolgical connections. Perhaps the ego, if not rare amongst advanced life forms, is only a temporary phase.
We may look back on this ego phase and say, “Oh my, how silly we were.”
I can think of my own pro’s and con’s to this idea but it’s interesting.

“but signal strength weakens the further it must travel.”

Aye, “signal entropy”.
Did you ever think of how ETs might turn out to be boring creatures? perhaps aliens will be discovered to be similar to Midwestern used car salesmen.

As I recently told a friend:

Regarding truly intelligent life on other planets:

The Bible isn’t clear on this, but, personally I don’t believe it exists because:

1)    Sin has tainted the entire universe.
2)    Other life could not evolve “by accident”
3)    I don’t think God would create sentient life on another planet and have it come under the subjection to sin caused by our race. That just doesn’t seem just.
4)    Man holds a unique place in the universe. Would Christ have had to die for another race as well?

Having said this, I could easily be wrong. My faith doesn’t depend upon this point, but it is obvious that many a secularist and evolutionist finds encouragement in their faith from the idea of intelligent, extraterrestrial life.

We are not alone - God is indeed here with us, and the resurrection even proves that He has intervened in our time and space when he visited our planet.

>>Invisibility: They’re there, but we just can’t see them. Our instruments aren’t able to detect them even though the evidence is basically right in front of us.
No, that explanation doesn’t work either, and for basically the same reason. It supposes that all advanced civilizations use the same kind of invisible-making technology.<<

No it doesn’t. A multitude of *advanced* civilizations could have quite plausibly come up with a multitude of “invisible-making” technologies.

I didn’t read all of the comments, but I wonder: How many of you are aware that what you are engaging in is metaphysics? I realize that this word has been anathematized by the atheist hegemon that occupies the commanding heights of the scientific world, but there is little difference between the speculations presented here and those of Plato, Aristotle and their philosophical progeny. It is most interesting to note the lacuna that exists regarding the most obvious explanation for the fact that we appear to be alone and that that aloneness or the alternative diversity do not rule out that possibility.

Odd that no one here has mentioned the Anthropic Principle.

The idea that we’re in an unremarkable situation is somewhat outdated - many a scientist has marveled at the unique conditions which enable our universe itself and intelligent life to exist. See Paul Davies, Guillermo Gonzalez, etc.

Yes, it’s statistically impossible, as calculated by Lee Smolin et al, but seems to be a huge clue pointing to our origin and purpose. Hint: Anthony Flew realized this.

I suspect that the true answer is that the Universe is a hostile place that manages to kill off species before they can reach other worlds. There have been a number of Mass extinctions on Earth - we aren’t immune to them.

Here are the things which will wipe out humanity given enough time.

1. Impact event - if you look at the moon there are too many large craters - meaning the big impacts are more common than we might hope. A comet like 109P Swift Tuttle would do us in nicely. Just a matter of time till we get hit. There is strong evidence that the fall of the Roman Empire and the start of the dark ages was precipitated by a double impact in the Gulf of Carpentaria North of Australia around 535AD

2. Super Volcano - the last one 75,000 years ago almost wiped us out.

3. Near by Super Nova - give it enough time and we are gone.

4. Gamma Ray burst aimed at us.

There are more but that is enough.

You assume too much.

Perhaps the Ascension hypothesis is correct.  It’s not that all civilizations somehow “choose” to go this route, it is that this route IS the ultimate goal of all civilizations.  They may not be invisible but we currently do not have the correct technological means to detect them.  They do not reveal themselves to us, not out of apathy but because that is part of the game; we must figure it out for ourselves.  To make obvious and direct contact is a “proof” of the concept and removes our free will, our ability to decide.  (If I ask you to decide if you want eggs or toast for lunch and then tell you we have no eggs, I’ve effectively removed your ability to choose.) 


Well, in one regard we are special even if trivially so. By definition, we are at the mathematically exact center of the “observable” universe.

Ward and Brownlee (“Rare Earth”) and Gonzalez and Richards (“The Privileged Planet”) have developed lists of other ways we might be unique.

@Max Kaehn’s point that being visible is being inefficient is extremely insightful.  Indeed, there is supporting evidence for the point here on earth.  Invisibility of intra-species communication has selective advantage not only because it is more efficient, but because it is more reliable (as a communication channel):  it is less subject to interference.  Example from nature: whale calls inaudible to predators.  Example from engineering: CDMA (code division multiple access) radio communication, which hides any particular signal among many signals using digital coding to pseudo-randomize frequency hopping.  The aggregate of all the signals appears to be noise.

You walk into a jungle, and all you are likely to see, unless you look very long and hard, are plants and trees.  You conclude that you are the first big animal in the jungle, reasoning that if there were any big plant-eaters present they would have long since have overrun the jungle and eaten all the plants. However, you are ignoring Darwin.  There may be big animals present that eat the plants, but they try to keep hidden to avoid the predators that eat them—keeping their overall numbers down.  The predators try to keep hidden to make it easier to catch their prey. Groups of advanced civilizations should be compared to living organisms inhabiting a jungle—this is the correct answer to Fermi’s paradox. Of the three options presented, I choose option two.

I would like to expand on my last post. The odds of it being insufficient technology which leads to our demise are much much higher than the odds of it being ‘runaway’ boogie man technology - the ‘Skynet’ - ‘Terminator’ end or the ‘Gray Goo’ of nanotechnology which does us in.

Artificial intelligence is here - but it doesn’t look like Skynet - and it is never going to wake up and become self aware; doing a ‘kill smash destroy’ goosestep on the world.

The singularity of machine intelligence passing us by never happens because it can’t; if you study the design of the human brain from an engineering standpoint you are forced to admit that we can’t do better with the materials which exist in the universe.

Neurons pack as much computing power into as small a space as can be done. At the scale of neurons the insulation thickness of the cell walls are so small and the capacitance of the circuit thus becomes so great as to affect the speed with which electrical signals can be sent along the neural ‘wire’. At small enough ‘line widths’ capacitance begins to swamp every other effect and the computing density of circuits becomes limited.

Nor are mechanical nano-computers going to replace electronic switching because of reliability issues. Mechanical is the least reliable technology - electrical mean times between failures are much longer- and biological MTBFs are far longer still. Imagine building an electronic device with trillions of components and a system MTBF of more that 70 years like a human being. Not going to happen.

The ‘Gray Goo’ is never going to happen because it can’t. In the real world nothing exists in size between chemical molecules and virons. The reason for that is that on the atomic scale gas molecules look like cannon balls moving at a thousand feet per second. The only way to survive their impact is by either being too small and strong or too large and strong to be destroyed by the impact of those cannon balls. Nano tech of intermediate size can only exist in a vacuum; exposure to the air destroys it. Hence - no ‘Gray Goo’.

By the way in my previous post I left out Ice Ages periodically destroying civilizations. We live in a golden age - a metastable climate between the Earth’s two stable states of very hot and Ice Age. Man made ‘Global warming’ isn’t going to do us in, but another naturally occurring Ice Age sure will.

The Universe is out to kill us - we don’t grow strong enough to fight that off - we die. End of discussion.

It was not too long ago that folks debated whether or not exoplanets existed.

Now we have cataloged hundreds of them.

We need more data.

The size of the universe works both ways.  There may be millions of intelligent species out there but they are too far away for us to ever encounter.

Say that you are the last person on Earth and you live in New York.  You walk around the deserted landscape for decades and never meet anyone.  Unbeknown to you another person is doing the same thing in Australia.  You’ll never meet so as far as either person is concerned each is the only person on Earth. 

If we are the only intelligent species in the galaxy we live in, even if the universe is full of intelligence, we are effectively alone.

This is what I think of when someone uses the size of the universe as an argument for alien life.  Sure, probably is true.  But it also mitigates the chance we will ever meet anyone.  And that’s the real issue.

I’m surprised no one has mentioned the Prime Directive.
Specifically, I can imagine a combination of Ascension for most all species, many of which do communicate with each other. They form a community that prevents the remaining ‘invasive species’ from overrunning the universe.

And it could be that Saberhagen was not just a great science fiction writer, but a prophet, and that Berserkers are real.

And by now, they know we’re here…

Speculation about other intelligent species in the universe is all very well, but I stubbornly believe that we won’t meet them… until we do.

Maybe there is life, maybe there isn’t.
We have only one example in our solar system where there is any known life. Our planet has almost been blanked a few times but we have never reset to zero. Each time, life gets more robust, more complex.
Contrary to the Doomies, I think life is better now than ever. People say our civilization is evidence of our doom… what?!? Somehow long lives, vast amounts of diversions, massive human controls on many diseases (and, if you need an example or two, smallpox and polio) and the biggest problem of the poor in our country is that they have too much food. Considering that, for the vast majority of our species time on this planet, we have been starving - what are you complaining about
Maybe the reason we cannot see ‘them’ is because of the aforementioned efficiency argument and the fact that they don’t want to hang out with so emo and whiney a race as ours.
So, if an advanced alien race is reading this, I would be happy to go with you and actually present our species in a positive light.
If there is no one out there and we truly are alone, then we all still have each other. And that makes it that much more important that we get out to space.

Proposition 1 is not absurd.  It is the correct answer.  The evolution of bacteria into intelligent life is not trivial, it is nearly impossible.  We are the first.

  Perhaps the most serious work on possible contact with extraterrestrials was Robert Temple’s SIRIUS MYSTERY, especially the section on the Dogon and Bozo peoples remarkable knowledge, itself a possible link to Pharaonic Egypt. Attempts to debunk the Dogon’s knowledge have been directly denied by the possible contaminators (i.e. the White Fathers missionaries, etc.). The earlier tales about creatures coming from the sea (Oannes) are interesting, as the name for them means “repulsive”.  Even smarmy Carl Sagan thought this story merited investigation.

“Moreover, we humans, along with every other form of life, have evolved to our present state in accordance with natural selection. There’s nothing special about us. “

This statement being true as far as it goes, does not speak to the inevitability that somewhere some species would be first.  It is as likely to be us here and now as at any other given point in time and space.

I think that you’re sort of dismissing many of these counter-explanations as if they’re mutually exclusive, but they’re not.  For example, you dismiss Ascension, Apathy, Caution and Invisibility on the “everyone does it” fallacy.  But it doesn’t have to be one or the other of them; it could be all of them.  Some civilizations are invisible due to Apathy, some due to Ascension, some due to Caution and some due to invisibility.  We can also add Bigness and Rareness to explanations why we haven’t seen them yet.  As we add each one of these explanations to the equation, the probability we’d have seen something by now gets smaller and smaller.  Add to that the fairly short amount of time we’ve been looking, it doesn’t seem too improbable that we simply haven’t seen intelligent life by now by pure chance.

And we might add other explanations too, for example Slowness.  Your Propositions 2 & 3 both assume that there is some sort of fast-track to evolution and technological advancement that we missed out on.  But what if the time period we took is in the ballpark of all other intelligent species?  Perhaps the vast majority of species are about at the level of advancement as us.  If one objects, “are ALL species to have advanced at the same rate?”, we might respond perhaps there are some species that have evolved faster, but they are rare outliers and aren’t detectable due to one of the reasons above.  Perhaps the rate at which species advance is distributed like a bell curve and we’re somewhere in the middle, perhaps we’re even in the front.  The percentage of advanced species that are way ahead of us might be extremely small and thus unlikely that we would’ve detected by now.

Since we are looking at probabilities, these explanations can all be added to one another. And though individually they’re not strong enough to explain why we haven’t observed advanced species by pure chance, in combination they might be.

My other thought is that maybe interstellar travel is pointless.  Perhaps at some level of technological development there is no need to go anywhere.  Perhaps there is interdimensional or time travel that makes travel over long distances totally pointless.  Or there is nothing in the universe that an advanced civilization can’t get without leaving home at all.

I guess that would be one of the barriers that the post is about.

On bigness again, Fermi may have made some bad assumptions about the size and age of the universe.  It’s very much larger than he thought, and life on Earth took a significant fraction of the age of the universe to evolve.  Also, traveling between galaxies is harder than traveling within a galaxy.  If our galaxy happens to be empty it would be very hard to get to us across intergalactic space.

We would only be “special” in the sense that civilizations can be very far away from each other.  There could still be countless numbers of them.  There’s no reason why the universe can’t impose isolation upon us by its sheer size.

Our assumptions about the frequency of life and intelligent life are just assumptions.  Instead of looking for reasons why we’ve met no one if these assumptions are valid, maybe we should look at the assumptions themselves.

There’s no reason that the universe owes us intelligent life near enough to talk to.  Rare intelligence may make us “special” but I don’t see why the universe must make intelligent species as plentiful as the stars.  If we are going to make assumptions and plug numbers into the Drake equation we can get any answer we wish.  The universe has a way of ignoring us.

Rejecting us as “special” is simply a philosophical objection, not one based on observed fact.  The only fact we have is that we haven’t met anyone yet.  There’s no way to prove whether we are alone given the size of the universe.  We can only disprove it.

Seems to me that….

“3. There have been others, but all of them, without exception, have run into a cosmic roadblock that either destroys them or prevents their expansion beyond a small radius.”

defies logic in the same way that .....

” it requires every one of potentially hundreds, thousands, or even millions of advanced worlds to make the exact same decision. We might expect some to do so, perhaps even most, but all? “

Perhaps 3 might hold true anthropomorphously speaking, but what of advanced intelligences that have become semi/non-biological in nature.

As Giulio Prisco and ilk postulate the messages may be there but we are not able to find them with current technology.

What I like about this problem is that it clearly demonstrates the limits of logic and statistics. Until we have empirical evidence, all of the possibilities are false, no matter the likelihood. One of the great fallacies of modern man is that all knowledge can be acquired through logical means.

This link might be of interest:

The first proposition, that we humans are unique and special, appears quite absurd. It contradicts all that we have discovered during the last five hundred years about the true nature of the universe and our place in it.

This is a major over-extension of the anthropic principle that gets made frequently.  It should not be ‘you are not unique’, but ‘the probabilities that led to your existence are not unique’.  It says nothing about what those probabilities actually are.  We could very well be first (at least in the Milky Way) depending on the probabilities.

The marble analogy is a poor one, since the probability of each marble being in the jar is already one and is time independent.

There are different ways of knowing.  Standard mathematically-based scientific disciplines comprise ONE way of knowing, one set of cognitions that lead to knowledge.  If scientists would bother to learn some history and bother to investigate how certain other civilizations explore the world, they might learn about these other ways of knowing.

There are other civilizations “out there” and people involved in today’s “standard science” simply have not yet developed the forms of cognition needed to cognize their existence.  I anticipate that the Chinese and the Indians (in India) will eventually be the first two countries to announce contact with distant civilizations because these two countries have acquired standard Western scientific ways of thinking and also are resurrecting and learning to exploit certain other specifically Asian traditions that have uncovered additional higher ways of human cognizing, ways that will lead to our being able to perceive the existence of other civilizations “out there.”

Civilizations and species strive towards stasis.

All the utopian (and dystopian) novels are aimed at a achieving a static society.  China developed gunpowder centuries before the Europeans.  The Europeans used gunpowder to conquer the Chinese. 

The idea of actively pursuing change as a good thing is relatively recent in human origin.  And change, at any level, is constantly being fought against.  No nukes.  NIMBY for windpower.  No more dams; they endanger the (insert any species or subspecies of rodent or insect here.)  No offshore drilling.  No oil, period.  No nano-tech.  Etc., and so on and so forth.

The leading agent for change in the world is the United States.  Impede us and our way of life, and soon thereafter, the world reverts to a place where change doesn’t occur.  And space travel never happens. 

Even today, the primary argument against space travel is, “Why should we spend money on space when people are starving on Earth?”  Or dying in tsunamis, or whatever.

And the argument resonates with many, if not a majority of people.

Regarding your comment, Harold, on people’s striving for stasis.  It is simply not true.  If you read Buddhist texts starting from approximately 200 years before Christ, you will see that the entire Buddhist philosophy and Way (of living) are based on constant inevitable change. 

As far as the West goes, those theories and ways of life based on Platonic thinking strive for stasis.  But Plato is just one Western philosopher.  Heraclitis, for instance, believed life rested upon constant change.  These facts about stasis and change were quite extensively discussed in the 1920s and 1930s in European philosophy when philosophers began to be especially interested in the philosophy underlying scientific thinking and how this thinking has played out in the technologically-oriented West.  The writings of Martin Heidegger are especially relevant in this regard.

I sometimes get the impression that modern day scientists have no acquaintance at all with any philosophy or history.  There are FACTS in history and facts about philosophical developments over time.  Before claiming that everybody strives for stasis, you should first check the historical and philosophical facts.

Relax, according to physics and the “Hisenberg Uncertainty Principal”, aliens both exist and don’t exist at the same time unless we observe them.

In the famous thought experiment of “Schrodinger’s Cat”, The cat is both alive and dead at the same time. If the cat is alive but not capable of solidifying it’s own fate into reality then we can assume it takes a being that is capable of a special level of self awareness and respect for the truth. When I say “respect for the truth” I mean both a general sensitivity and a specific predudical understanding of mathmatics. This is shown to be true because we are beholden to the “Hisenberg Uncertainty Principal”. For example, if we solve for “p” for position, then we repect the fact that p = 5, no matter where in the universe “p” is. Even if we later find “p” in a derivative equation of the second order such as “v” for Velocity.

When people talk about aliens capable of long range communication or space travel we assume the aliens must also have this special ability.

The bible tells the story of the fall of man in the garden of eden which is sometimes interpreted as the birth of the Ego.

a) The knowledge of good and evil.
b) The knowlege of Self vs. Others.
c) The understanding of continuity with God or nature VS. discontinuity of the self, meaning the separation from the life giving creator or force.
d) The need for a redemption program so that we can either be reunited with God or consiquently experience death as a permanenty increased state of discontinuity.

Therfore, this higher learning is largely understood to be a tragedy of sin and death. Should we assume that other civilizations should be more than animals? If it is such a terrible and rare event why do we think aliens would have also then developed an ego and have become sensitive to mathamatical truth?

According to “Schrodingers Cat”, as animals they would have no way of taking a measurment of a particle or wave. They do not solidify their own existiance out from statistical probability.

As I recall, somebody did some analysis of the “lifetime of civilization"parameter in the Drake equation and plugged in a value from the (terrestrial) historical record.  The average lifetime of a terrestrial civilization is something like 150 years.  If you use that as a baseline, you get a very small number of civilizations that are present at any one time.  This is a specific case of scenario #3, where it’s very difficult-to-impossible for a civilization to persist long enough to perfect interstellar travel, even for a bunch of von Neumann machines.

I’m also less inclined to rule out scenario #1.  Since we don’t know the necessary conditions for the emergence of life, to say nothing of the other great leaps forward in complexity, it’s hard to draw any conclusion about how special or ordinary our situation is.  How many stellar systems have planets in the goldilocks zone with stable orbits?  How many have a big moon to stabilize their rotation over geologic time?  How many survive without something bad happening to their plate tectonics?  The geologic record is littered with close calls for our planet—who’s to say that we aren’t at the far end of a very long tail?

Finally, there’s a plausible variation of scenario #2 that bears mentioning:  The successful civilizations are the ones that learned to shut up before somebody found them and decided to shut them up.  If this is true, then you don’t need to have civilizations that all decided to be invisible in the same way; you merely need civilizations that recognize the need to be invisible and leave it at that.

Bottom line:  This is always fun to talk about, but we simply don’t know enough to draw any conclusions yet.  Hopefully we’ll have a lot more data in another 30 years, as our ability to image other stellar systems gets better.  Meanwhile, anybody who claims to have gamed out all the possibilities is likely to be disappointed and/or embarrassed.

Fascinating discussion. Of the various objections to Mike’s position, the following strike me as most promising: Joseph K’s observation that you can combine the various objections (ascension, apathy etc) to reduce the probabilities sequentially, Steve Reynold’s reminder that the advanced civilisations may be communicating (in which case you can’t treat individual observations as independent random events), and David Pearce’s support (last year) for the “rareness” hypothesis on the grounds that the emergence of life may just be very, very improbable.

For my part I want to add two further considerations. One is that just because empirical evidence over the past couple of centuries has undermined the idea that we are special, we should not replace one orthodoxy (special) with another (not special). Perhaps we should see the failure of SETI to deliver results so far as evidence that we are more special than we thought (essentially Pearce’s position, I guess).

The other thing I want to add is a question: what are the policy implications of all this?

I believe all three of your propositions could be effectively correct simultaneously.

We are certainly the first in our local region of space. If others within a few hundred light years were broadcasting inefficient radio broadcasts in all directions we’d see it.

The second is true in that expansion and technology after a certain point becomes efficient enough that we are unlikely to detect it unless it is direct straight at us.

The cosmic roadblock may be the difficulty in finding habitable planets that we could travel to. When we get around to sending out probes to all the planets within 100 light years we may find that they are all a bunch of Venuses and Marses. Too much atmosphere or too little and not the right composition. High oxygen content is likely the result of a few hundred million years of photosynthesis. I think our expansion into the universe would be exceedingly slow if we find the average distance between habitable planets is 500 light years throughout our galaxy.

If it is 500 light years or 5000 light years, it’s possible that every single one of those planets is inhabited and the population is in a constant cycle of expansion and collapse a.k.a The Mote in God’s Eye. Expanding into the universe may be more difficult than we imagine.

You seem to have proven, by induction, that case number one which you discard for philosophical reasons alone, is the likely one after all.

Why is it so hard to believe that we are the first complex thinking lifeforms in this galaxy?

Arguments/conditions for:

A) the speed of light is in fact the speed limit.  No functional FTL possible.  This allows us to ignore other galaxies for the most part as it would take a REALLY advanced race to bridge those gaps at c.

B) Complex life on earth required TWO miracles.  Replicating chemicals was the easy one.  Mitochondria were the second miracle.  It could well be that single-celled life is spread throughout the galaxy but the leap to higher energy forms is extremely rare.

C) The earth-moon system is VERY unusual.  Perhaps even single-celled life is rare unless the constant stirring of tides accelerates its formation.  We will know the answer to that soon enough, certainly within a century or two.

D) And, with a nod to your other points, perhaps thinking lifeforms that survive to leave their solar systems are rarer still, due to self-made existential dangers.  Remember, WE haven’t crossed that bridge yet.  At this point there might be ZERO space-faring races in the galaxy.

Fermi’s point was that given maybe a million years, humans would expand throughout the galaxy, and that a million years is an eyeblink so why hasn’t someone else done it?  It does seem like we are the first, or have the potential to be the first, or at least the sole successors to some extinct predecessor.  You inability to come up with anything other than deus ex machina as an alternative is rather unconvincing.

I beg your pardon, but I find your contention that there is intelligent life on Earth to be nothing short of preposterous.

Another possibility is that technological life is a relatively recent phenomenon in the galaxy.  If we start from the assumption that we are not special, then it is reasonable to assume that we are also typical in the timing of our development.

The first generation of stars to form, known as population II stars, did not have significant quantities of the heavier elements that are necessary for our, and if we are typical, all life.  So, of the 13.5 billion years of the universe, the first 10 billion or so could not support life.

Our sun is 4.57 billion years old, and is typical of population 1 stars which have the elements needed for life.  The Earth’s protective magnetic field formed 3.5 billion years ago, coincident with the formation of the earliest life on Earth.  If we are typical, the first primitive life in our galaxy couldn’t be much older than that.

If we assume that the length of time needed for our evolution from first primitive life to a technological civilization is in the middle of a narrow bell curve, it is not unreasonable to believe that the window of possibility for intelligent life in the galaxy only opened recently.

If we further assume that the rise of technological life develops at a very consistent rate, it is entirely plausible that the oldest civilization in the galaxy is only a few million years ahead of us.

If life is relatively rare, with perhaps a few dozen intelligent species in our galaxy; and if life couldn’t exist anywhere until roughly 3.5 billion years ago; and it takes roughly 3.5 billion years for it to evolve to intelligence; then the oldest galactic civilization might not be that far ahead of us.

If you start from the assumptions that we are not special; that life and intelligence evolve at a very consistent rate; and accept that life has only been possible relatively recently in the history of the universe; then you can not assume that other civilizations must have developed sufficiently far ahead of us to have spread to all parts of the galaxy.  The Fermi Paradox’ implicit assumption that if intelligent life exists, it must have a wide age range may be false.

Give it a couple of million more years, we’ll bump into them.

You’re leaving out one elegant explanation which has the support of one big-name physicist.  John Wheeler, who coined the term “black hole,” understood quantum physics a little differently from the consensus view (which is known as the “Copenhagen Interpretation”).  Most quantum physicists agree that an “observation” causes the “quantum wavefunction” to collapse into what we perceive as reality.  Wheeler argued that the entire universe existed as an uncollapsed wavefunction from the moment of the Big Bang until the first “observation” collapsed it.  (In today’s terminology, the universe is a quantum computer programmed to try every one of an infinite number of combinations to find the one where “intelligence” exists.)  Wheeler called this speculative notion the “Participatory Anthropic Principle.”

Whether or not you agree that the PAP is real or possible, you pretty much have to agree that it perfectly explains the Fermi Paradox.  According to PAP, you and I, reading this email, are the “output” of a universe-sized “computer” programmed to produce intelligence.  That’s why we don’t detect any other intelligences.

To clarify, I went back and reviewed your article and found the relevant quote:

“Fermi himself immediately dismissed this explanation with some quick back-of-the-envelope calculations. Given a reasonable estimate for how many habitable planets there should be and how long the universe has been in existence, it’s easy to determine that if there are any expanding civilizations, there must be many, and that they have had more than enough time to cover the necessary distances.”

Fermi’s error was to use the age of the universe as a factor.  The correct factor would be the age of the universe minus the time required for conditions compatible with any life to develop minus the time required for primitive life to evolve to a technological civilization.

A religious, or spiritual, view of the universe does not, per se, need to be anthropocentric.
  Medieval Christians looked out on the night sky and felt they were on the “outside,” looking in at the lights of the City of God..
  the idea that God would deign to come to those He created is called the big “humiliation” in Christian teaching.
  The Christian view of things includes all sorts of room for infinite stuff out there, beings we know little about, stuff that isn’t our bailiwick.
Mainly, that “this isn’t all there is,” which seems a rather universal human response to this world, this universe. A scientific fact, of sorts, for which it is difficult to account unless there IS something beyond, ....
the narrow view is that which rules out anything else than our material experience….
it seems that humans, as far back as history goes, have believed there is much else.
There also is much documentation in history of experiences with non-material reality, of some sort of super-Reality that undergirds the world we see
Modern physics seems to buttress many of these ideas, that the material world is somehow contingent on something Greater; or perhaps, Someone greater..

Firstly, I think recent observation of other planetary systems have shown that ours actually is quite special, something of a freak. Most have extremely large gas giants close to the sun, taking up the habitable zone

And our location in the galaxy is also a big factor. Life is likely only to survive out on the edges.  Stars are messy, they end to explode, sending waves of radiation out.

And our star happens to be single. Most starts are in binary or trinary systems (not counting thoses in clusters to begin with). Planetary orbits in binary/trinary systems would not be conducive to life.

And why did life emerge on land? Probably in a good part thanks to tides, which are mostly the result of having a freakishly large Moon. It’s hard to have a technological civilization if you are aquatic. Ask the dolphins about that one.

There probably is life elsewhere, but I think even as immense as the galaxy is, we are probably the only ones in it.

Beyond that, let’s not get too cocky. It’s pretty obvious to those that have studied history that Western civilization is in decline. And while one of the civilizations primed to replace it does show an interest in space travel and astronomy, the other doesn’t…I think (thankfully after I’m dead) we’re due for a new Dark Ages. I would not be surprised to see a cycle of this repeated elsewhere - life is not really rational.

From a Bayesian mathematical perspective, the fact that we haven’t yet observed other civilisations should definitely (if we are processing information rationally) reduce our assessment of the probability of us ever expanding into the universe ourselves, but the extent to which it does depends on how unlikely this “observation failure” is if there is no insurmountable “roadblock” as posited by Mike. Arguments along the lines given by the various comments lead me to think that this may not be as unlikely as Mike considers it to be, in which case perhaps we shouldn’t be so discouraged.

I agree with JeremyR that we shouldn’t get too cocky. In fact let’s be guided to the following aphorism quoted by the World Future Society on Twitter earlier today, and which I very much like: “Ridiculing idealism is shortsighted, but idealism untested by pessimism is misleading.”

Perhaps a little economics is in order: biological species are constrained by scarcity.  This implies that a cost-benefit analysis is in order.  Ignoring the cost of locating Earth from a planet millions or billions of light years away, what would be the benefit to the initiating species?  By the time Earth was located and information was returned to the home planet, civilizations would have come and gone, and perhaps the initiating species would have long since disappeared.  In other words, size matters.

The Reapers are real. Now if you’ll excuse me, I have to be going.

So we have:

  Bigness: The universe is so big and the distances involved so vast that all those other advanced civilizations simply haven’t had time yet to reach us. Related to this is the “needle in a haystack” explanation, suggesting that we just haven’t looked in the right place yet. Our SETI scans are not sufficient to do the job.

Fermi himself immediately dismissed this explanation with some quick back-of-the-envelope calculations. Given a reasonable estimate for how many habitable planets there should be and how long the universe has been in existence, it’s easy to determine that if there are any expanding civilizations, there must be many, and that they have had more than enough time to cover the necessary distances. Size is not the problem. We need a different answer.

Not quite.  If we postulate a big bang, then the earliest universe, counting elements only, was made up of hydrogen and helium.  All biological life that we are aware of needs heavy elements. Those heavier elements did not appear in the universe until they were created by fusion in the 1st generation stars. 

It probably took at least a billion years for the 1st stars to form after the big bang. If the big bang occurred 14 billion years ago, that takes us to 13 billion years. If the first generation stars lasted 5 billion years, and then went nova, give or take, that gets us to 8-7 billion years. Our sun is thought to be a 2nd generation star, and it is postulated to be about 5 billion years old. If so, then that means that the heavy elements created in the 1st generation stars can lie around for a long time before is its accreted into another star and planets.  Even if we assume that it took a billion years of floating around before a 2nd generation star was created out of the material of the 1st generation star, that gets us to 7-6 billion years for the formation of a 2nd generation star. That puts us awfully close to the sun at 5 billion.

Since life, in theory, needs the heavy elements, than the earliest it could have got its start was probably about 7 billion years ago. Since it took us about 5 billion years to reach the point where we can ask these questions, we can assume that any other life follows the same pattern. So, at most, any other life can be about 2 billion years ahead of us.

What that say is that any other life farther away then 2 billion light-years will remain hid to us. I admit that creates a big area, but it takes 86% of the universe out of the picture. That’s a lot of universe.

If we assume that all other life got about the same start we did when we did, within a couple of million years, then we have to limit our search to within a couple of million light-years.  The Andromeda galaxy is the closest at 2.5 million light-years, so they are out of the picture. We are limited to our own galaxy.  So, how many other life forms in the galaxy got a couple of million years’ head start on us?  The evidence points to not many. 

And, if we bring the number down to a 100,000 year head start, or a 10,000 year head start, we have t circumscribe our search even further. How many habitable planets hare there within 100,000 light years, or 10,000 light years?  Probably not a lot.

So, the age of the universe matters much.  I disagree with Fermi, respectfully.

The most logical answer is that “...all that we have discovered during the last five hundred years about the true nature of the universe and our place in it…” is not really correct.

When we have exhausted all the possibilities, the wise will realize that God has been right all along, the foolish will still be denying the evidence for his existence exists.

To which we must add:  E = mC2; E/c2 = m.  As the energy increases, the mass increases. So, a spaceship cannot travel at the speed of light because its mass would increase to infinity.  Without the ability to travel at the speed of light, space exploration is limited indeed.

That leaves us to looking for old episodes of My Favorite Martian on just the right frequency at just the right time in a sea of almost infinity.

Like others have said before, perhaps a combination of these possibilities is responsible. I see no reason to believe they are mutually exclusive.

In regards to your jar with a thousand marbles - We don’t need to be marble number 1 in order to have trouble detecting other civilizations. Perhaps 1000 intelligent civilizations will arise in our galaxy. Let’s assume that we are the 200th such civilization to do so. Fully 4/5 of those left have yet to come, and perhaps the 199 are missing due to any one of the responses you’ve received, and perhaps others we haven’t come up with.

Your dismissal of the first possibility is premature. We accept as true many things that are unlikely - why is this possibility any different? I hope it isn’t due to some fanatical avoidance of any sort of religious explanation.

Or perhaps it’s just you who is in a simulation, and all of us are merely programs designed to convince you otherwise.

In response to rareness, you say:

Perhaps, but then you’re getting perilously close to making us “special” again, if not unique.

Not really.  In astronomical terms, we would be rare if we were unique in our galaxy, even though there could be hundreds of billions of other advanced species spread throughout the universe.  That’s really not all that close to “special” or universally unique.

It seems quite unlikely that we would be alone.  So much space, so much potential. Perhaps a hybrid combination of proposition #1 and #2.
We have come so far trudging through a history of violence. For as long as there have been civilization, the technologies we have developed have often been in support of warfare, technological advance built by various forms of slavery or caste. Were not the pyramids possible because of forced labor? Was not NASA as much about developing ICBM capability as it was about exploration?
What if on other planets different intelligences emerged that were on par with intellect, say social or empathetic intelligences? And what if, because the other intelligences were so strong, the technologies developed were not in support of warfare? Perhaps reaching out beyond their planet was not a priority. We come from carbon and build technologies of steel and metal and silicon. What if other intelligences build technologies of the the planets themselves, like the termites in the Dennett video only with a reason in mind?
Perhaps they have detected us but do not wish to be known to us or engage us. What if they are waiting to see if we evolve or die?

The inhabitants of Easter Island had the same issue. An isolated Island, with their original migration lost in legend, the Easter Islanders had come to believe theirs was the only land in an otherwise empty water-world.

What a shock when the first Europeans rolled up, and they found it was just that their technology and resources (Easter Island had no trees as they had chopped them all down) were too limited to enable them to look far enough to find others.

The galaxy is huge. Any thoughts about aliens contacting the Earth presume a capability to overcome two key things: distance and gravity.

Science fiction gives us wormholes, warp speed and hyper-space jumps, but if those things aren’t possible, travel over long distances becomes extremely difficult. This would become an extreme limiter consistent with the “Cosmic Roadblock” idea.

Another problem is gravity, or the lack thereof. Without gravity, or at low gravity, bones deteriorate quite quickly. Star Trek gives us countless planets where the gravity is the same as Earth’s, and they manage to replicate gravity perfectly aboard the Enterprise and other ships. But how likely is that? What if gravity cannot be replicated so easily?

It is difficult to image any species developing in a gravity environment then being able to adapt to a limited gravity environment for the periods required for space travel (using centrifugal force etc would appear to be less than fully optimal, on trips taking years or decades). And when the travellers get wherever they are going, unless the gravity is essentially the same as at their origin, it is difficult to see how they could successfully colonise the place.

Gravity, and its effects on our physiology, may turn out to be the greatest roadblock. Unless a species can develop a technology to alter magnetic fields to meet their requirements, viable long term space travel and colonisation may be virtually impossible. The deforming effects of a long term non-standard gravity, plus the effects on reproduction could well be another Roadblock. Add radiation etc, and it starts to become a tough undertaking, and unless it is possible to colonise and/or return with resources, after a while it must seem like a futile undertaking: there needs to be a point to maintain a sustained effort..

Either the roadblock idea, or Easter Island syndrome (ie that we really are in a backwater and either one has bothered to come here yet, or they are disinclined to return) makes the most sense to me.

Perhaps it’s because we’re made out of meat.

Mike Treder’s first point, that it is absurd to say we humans are unique and special, is made too easily.  He suggests that it contradicts all that we have discovered during the last five hundred years about the true nature of the universe and our place in it - but the simplest way of countering this is to say quite the reverse.  Everything we have learned reinforces the argument that humans are unique and special.  The “evidences” are not relevant to the argument being made: the Earth is not at the center of our solar system (does this really matter?), the solar system is not at the center of our galaxy (should it be if humans are unique?), and our galaxy is not at any special position in the universe (how would we know if it were?). He also argues that “humans, along with every other form of life, have evolved to our present state in accordance with natural selection” - yet it has not been demonstrated that natural selection is capable of doing anything more than fine tuning.  The debates among evolutionary biologists, including the ineffectiveness of natural selection, appear to have been missed by Mike.  Why not reflect on the uniqueness of the Earth in the Solar System?  Why not ponder the inhospitable nature of all the planetary bodies discovered outside our Solar System?  Let’s stop imagining that we have all the answers about evolutionary transformation - the proposed mechanisms do not deliver complexity.

Pellegrino and Asimov answered this in the intro to “Flying to Valhalla”.

It’s sort of a combo of #s 2 & 3. 

Since it’s only reasonable to suspect that some dominant races evolved from predator stock, and will wish to dominate or eliminate all others, then the only responsible decision is to assume that other races will also realize this. And take precautions. One precaution one race might take is pre-emptive destruction of all even potentially advanced life-bearing planets. Since one might do this, all races must.

So all responsible races will immediately launch planet-busting missiles at any such planets; kinetic 0.92C, a few tons, and that’s all she wrote.  If we have any hope of survival, we must set up our automated near-solar orbital factories turning out the anti-matter fuel, rail-gun launchers, and highly accurate missiles immediately. 

And then hope we have enough time to disperse and hide quietly on unlikely planets in other solar systems before the first incoming arrive.  There may be little time; at .92C, you get about 1/12 of the apparant time from detection to arrival.  When you see the gamma wake at 1 ly out, it’s actually only a month away.  And so on.  When it seems to be 5 minutes away, you have time to bend over and kiss your bippy good-bye before the strike punches a 100-mi. radius vacuum tunnel in the atmosphere, and breaches the crust and causes a huge rebound of molten rock that will rain down around the globe. 

Even the cuccarachas will have it tough.

Since Mathematics are the same everywhere in the Universe, and the Physics and Chemistry that use the math are the same everywhere in the Universe, it makes sense therefore that Biology that is based on the underlying and consistent math, physics and chemistry will also be the same everywhere.  Indeed, why would it not be?  Because the distances are so huge, we are just not technically capable enough to find everyone… yet.  But, I think we will.  Eventually.

Interesting statement Gloria. “Regarding your comment, Harold, on people’s striving for stasis. It is simply not true. If you read Buddhist texts starting from approximately 200 years before Christ, you will see that the entire Buddhist philosophy and Way (of living) are based on constant inevitable change. “

So, from that, we can conclude that all the great advances in science and technology must have come from Buddhists.  Or, at least a whole lot of them.  Or maybe even some of them.

Off the top of my hrad, I can’t think of any.  Perhaps you can supply the list.

Buddhist strive to make changes necessary to reach Nirvana, after which, there are no changes, for perfection has been achieved.  Stasis.

There appear to be over ten million species on this planet.  Of that incredible multitude there is exactly one species that figured out how to communicate in a written language, mine coal, refine metal, generate electricity on a large scale, transmit radio signals and build rockets. 

(A shout out here to electric eels and electric catfish that organically generate electric power.  They’re rather weak in the mining, smelting and rocket departments, though.)

We are therefore demonstrably a one in ten million chance.  And that is the lower end of our specialness.  One in a hundred million?  One in a billion?  One in ten billion?  One in the galaxy?  Quite conceivable.

Besides Berserkers, there are also the machines of Revelation: Space (Alastair Reynolds) to consider.  They wipe out any instance of civilizations that go FTL, and idea clearly related in the book to Fermi’s Paradox.

Actually, David Tyler’s post is a very good response.

If by ‘special’, you mean: “Placed in the center of the universe, the center of the galaxy…” and other silly arbitrary measures then no, we aren’t special.

If by ‘special’, you mean to say that our existence is incredibly unlikely, then yes, of course we are special. There are a multitude of coincidences that allow our planet to even support life, and a million others are required for the evolution of intelligent life.

‘Until we have empirical evidence, all of the possibilities are false, no matter the likelihood. One of the great fallacies of modern man is that all knowledge can be acquired through logical means.’

Dadvocate, while I agree with you about our limits to knowledge I don’t think anyone is claiming to know anything here (with the possible exceptions of the Christian folks who posted). But speculation is fun sometimes especially on such an intriguing question, is it not? And then again, sometimes our path to knowledge begins with the first tentative speculations we make.

To throw my two galactic cents into the ring we might be the only intelligent life in the universe, because the creators of the universe only wanted one. Before the aforementioned Christians feel their little hearts go pitter-patter notice I said ‘creators’. It has been postulated that it’s not actually that difficult to make a universe (we may have done it already) and it may be that a lot of universes are made by aliens for experimental or other purposes. This is similar to the simulation argument except If it’s as easy to make a universe as postulated then we are not living in a simulated universe which in any case is unlikely to contain any intelligent life as simulations are not intelligent but only appear to be according to the software used ie a simulated universe is a zombie universe as in video games. The only possible way a simulated universe could contain intelligence is if minds were uploaded into it and that notion has its own difficulties.

Extending what the last few posters have said…

Let’s go with Mike Treder’s number of 250 million potentially habitable planets within 50,000 light years of us as the physical limit of our ability to detect an advanced civilization.

That is actually not such a large number.  Not when you apply these correcting probabilities:

What is the % of those planets that have remained free from catacylsmic bombardment for the billions of years required to evolve intelligent life?

What is the % of the remaining planets which do not exist in a region where a supernova or a gamma-ray burst or a catastrophic solar variation of their home stars have not occurred in the billions of years required to evolve intelligent life?

Of the % of remainiing planets, how many actually evolved complex life forms?

Of the % of those planets, how many evolved intelligent, tool-using creatures?

Of hte % of those planets, how many of those creatures managd to survive and weren’t wiped out by natural disaster or other predators?

Of the % of those planets, how many of the intelligent tool-using creatures developed complex civilizations capable of accumulating knowledge and developing advanced technologies?

Of the % of those planets, how many avoided destroying themselves through war, resource depletion, or societal collapse?

Of the % of those planets,  how many developed the urge to expand outwards and seek other civilizations, or who use engineering on a vast enough scale to be detected by us here on earth?

And so on.  The Fermi Paradox at its core assumes gigantic numbers for potentially habitable worlds.  Given a big enough starting number, the percentages above don’t really matter.  Any tiny percentage of each one would still result in an immense number of advanced civilizations if the starting number is in the hundreds of trillions.

But if we start with a number as small as 250 million, those percentages DO matter.  If each question above had a 10% chance of being answered in the affirmative, the number of civilizations we would expect to be detectable would be less than one.  I suspect some of those questions above have probabilities significantly lower than 10%.  For example, as Dark Helmet pointed out above, out of the millions of species on this planet, only one developed civilization.  For all we know, it could be quite common for complex life to evolve, but millions-to-one that intelligent, tool-using civilization develops. 

I think some people assume that evolution is the inevitable march from simple and dumb to complex and intelligent.  But there’s no reason evolution has to result in high intelligence.  There’s no ‘optimal’ path for evolution.  It’s a random walk in response to changing environment.  It doesn’t need to result in civilization.

How many exo-planets featuring appreciable amounts of liquid water have we identified?  I’m guessing that number is closer to zero than 250 million.  I’m not aware of any, but if I’m wrong please correct me.


We don’t have a good way to detect water around exoplanets right now.  The only way we can currently detect extrasolar planets is to measure the gravitational wobble of the parent star, which generally only works with very massive planets or planets orbiting very close to the star, or by measuring the dimming of the star as a planet occludes some of the light as it passes in front of it.

The Kepler telescope is using the second method to look at a group of about 150,000 stars.  It takes about three years for that telescope to find an earth-sized planet orbiting a star like the sun (it takes tha tlong because such a planet would orbit in about a year, and we need to see three orbital transitions to confirm it). 

Kepler has only been watching those stars for a year or so - it’s already detected quite a few planets, but they’re all close to the star and orbit in days or weeks and not years.  But within two years, we should know how many planets are out there in earth-like orbits.  Once we know that, and know when to look for their crossings, we may be able to use other telescopes to look at the change in the light spectrum as the starlight passes through the planet’s atmosphere and hopefully detect water vapor.

That said, there’s no reason to believe that water is rare, and lots of reason to believe that any planet that is as warm as Earth will have plenty of liquid water.  So far, we’ve found large quantities of water on Earth, the Moon, Mars, and many satellites of the outer planets.  Enceladus and Europa have liquid water oceans inside them, and many other outer solar system bodies are really just frozen ice balls.  It’s safe to assume that water isn’t the problem.

Not to quibble, but ice isn’t water.  Maybe there’s plenty of ice out there, and that’s good news for space exploration.  Advanced civilizations can turn ice into liquid water.  However, ice isn’t very helpful in the evolution of intelligent life as we understand it.

Case in point:  of all those accumulations of ice in the solar system, how many have served as the breeding ground for intelligent life in the last 4.5 billion years?  To the best of our knowledge: zero.


We have now found evidence for liquid water on four bodies in our own solar system.  I think it’s reasonable to assume that liquid water will be found on the majority of planets within the temperature range of liquid water. 

Dark Headspace;
The secret of making liquid water out of ice has been discovered!  You’re getting warm if you suspect temperature has something to do with it ...


What if ETs turn out to be similar to okra, only tasting much worse? then we wont be able to communicate with them nor eat them. The reason I’m so cynical about this is because so many people (often rightwing paranoids) think ETs, ‘globalists’, the Illuminati- and so forth- are out to get them; they take it all too seriously.

Dan H., we have four major bodies in our solar system that are arguably life-friendly distance from the sun:  Venus, Earth, Luna and Mars.  One and only one has liquid water.  The temperature zone for liquid water is actually fairly narrow on the scale of galactic temperature variation.  I’m not saying water is vanishingly rare, but I would argue that it’s not all that common.  Or more accurately, I would not assume that water is common.

The point is:  Earth is pretty darn special in a variety of ways.  Even so, in 4.5 billion years Earth has yielded only one species theoretically capable of interstellar communication. 

Going back to Treder’s dismissal of his first proposition:

“The first proposition, that we humans are unique and special, appears quite absurd. It contradicts all that we have discovered during the last five hundred years about the true nature of the universe and our place in it. “

I would argue the opposite.  What we have learned in the last five hundred years suggests that the human species is absolutely unique and special.  Of course, I would argue that the existence of the universe is unlikely in the extreme.  That anything exists is an incredible long shot that happened to come in.  Random factors have operated in our favor.

Brian H.:  You mean that phase changes in matter are temperature-correlated?!  This new learning amazes me!  Explain again how sheep’s bladders may be employed to prevent earthquakes.


You all try so desperately to find answers to why we exist. So badly that your life is passing you by. This world like someone pointed out is incredibly lucky so to speak to have life on it. Wether you believe in god or believe the world appeared from molecules. At the end of the day that’s what it is “belief” or hope. There will never be answers to find. Ever. This is all scientific mesh of people trying to sound intelligent or act like they know what they are taking about. Some crackpot comes up with a theory and without evidence you all jump on the bandwagon. I chose to believe their is a god not because of delusions or because of facts. But because of the two choices presented to me which neither have conclusive proof nor will not until our physical bodies die I choose to believe that this world is create by one much powerfuller and wiser than we can ever comphrend. We are not alone we have eachother if we can only be happy with what we have now we have no reason to waste our lives seeking others.

Next entry: Water and Wrenches, Belts and Suspenders

Previous entry: A General Intelligence Oriented Architecture for Embodied Natural Language Processing