We Are Alone

Why I believe there is no other intelligent life in this galaxy

reaction from Eric Smets

Eric is a good friend of mine, who visited my site looking for bridge. He found my article and presented his reaction.

It was written in Dutch, of course, but I have translated it into English and I present my comments in the second column.

Is Herman alone ?
Dear Herman,

I read on your website a number of ideas about the possibility of civilisations in our Milky Way. Very interesting! This is a topic I have been interested in for a long time.

The strange thing is that I too have the idea that our civilisation might well be the only one (or the first), but I am far less certain of it than you seem to be, and that I have reached that (uncertain) idea on the basis of totally different arguments.

Your whole reasoning is supported on three pillars, a time scale, the fruitless SETI and the lack of evidence of "colonising" civilisations.

In my opinion there is nothing right about these three pillars so that the whole reasoning falls down. I am saying, in My opinion. But that only makes the discussion more interesting.

1. the Time scale

A) The time scale for planets

According to you sun-like stars with earth-like planets could have been formed at the earliest some 5 billion years ago. I don't know where you get that number, I have never read it anywhere. Granted that does just mean I don't know and not that it is wrong. But it would be worth while to find some confirmation of that, and I'd like to bet a beer that it does not fit.

Our sun is a Population I star which was preceded by Population II stars and earlier still by Population II stard. Those predecessors have produced the heavy elements that formed the earth. The instellar nebulae were "fertilised" by heavy elements from Supernovae, produced by giant stars that lived for just a couple of million years. As far as I know the first star formation must have been accompanied by a barrage of supernovae. So I am fairly certain there must be population I stars faaaar older than the Sun.

I am really curious to know who will win that pint. But this is perhaps not as important as:

Eric, I did not accept your wager, but you know you can have a beer anytime.

True, the number 5 billion is not a certain one, and it is almost certain far more.

I don't believe I have written anywhere that this is a true number.

But please understand that this only strengthens my argument.

I was presenting a "worst case". In the "best case", alien civilisations did indeed get a head start of several billion years.  Where are they ?

B) The Time scale for civilisations

You accept without further evidence that there is a standard period of 5 billion years between a planet's creation and the development of civilisation. This is pure speculation which is supported by nothing, except that it did indeed take as long on Earth. But Earth is the only example we know and there is no reason to presume that on some other planet it should take as long. Maybe it could go a lot faster, we have no idea!

If evolution on Earth would have gone 0.1% faster, would we be 5 million years further? Could that have been possible? Certainly? Could that happen on some other planet? Why not?

(snip about the history of our planet)

Eric, you have misunderstood me. Nowhere have I suggested that it should always take this long. My suggestion is exactly that if it had happened anywhere else, it is silly to believe that it would happen in exactly 5 billion years, as it did here.

If it did happen as well on some other planet, it is bound to have been faster. So they have millions and probably even billions of years advantage.

Where are they ?

Maybe the famed "Green Bank" formula (is that the correct name) is closest to the truth. You can calculate that there should be between 1 and 50 million civilisations in the Milky Way. That is all we know. We have not learnt a lot more since the time that formula was developed, in any case nothing that gives a greater accuracy to the formula. We have discovered some planets around other stars, but that was something that was presumed already so does not present anything new. I am well aware of that calculation.

But if we are just an average civilisation, there should be between 0.5 and 25 million civilisations out there at a level higher and similar than ours.

Where are they ?


The fact that SETI has not yet found a trace of any civilisation is no argument for me. The collaborators of SETI say themselves that it would be a miracle if they had found anything yet, even if there are many civilisations. (or is that just to get more money for their research)

The search between thousands of billions of natural radio sources in the universe is far worse than the classical needle in a haystack.

Besides, who says "they" are communicating with the only thing that SETI looks for, electromagnetic waves? That is the only method we know, but - as with everything - we will find later other (and more efficient) methods.

SETI is without result. You can draw just one conclusion ... SETI has not found anything yet. But that is no argument.

If there are millions of civilisations out there, some of them must be still in the EM stage, and we should find something from those. But I am not using SETI as a main argument.

3 Where are the colonists

Colonising is a bad European habit. Who says extra-terrestrials would do this? Another unfounded presumption.

Colonising is not a European habit. Humans started from Africa and reached the last barren lands (the Maori in New Zealand) 1200 years ago.

I believe that any species that attains a level of civilisation can only do so with an urge to colonise. And that urge will not stop when the home planet is full.

Besides, there will be enough planets in the Milky Way to "terra-form" (if they would want to), unable by themselves to form life, so that "they" don't have to demolish the existing civilisation (or its potential). If we assume that life springs everywhere, the first civilisation to reach other planets will not find any barren planets, but lots of planets with early indiginous life. No matter how well they will treat such a life, it will not be allowed to develop into a fully fledged civilisation, because its evolution is irrevocably shattered by the aliens.
We find no trace of colonisation in the Milky Way. Of course not: see SETI. We don't know where to look or what to look for. I agree with that statement. Intra-stellar communication, if it exists, would be even more difficult to find than random emissions from TV or similar.
No trace of colonisation on Earth? Maybe not. I am not a fan of von Dänike and others, but when you read that kind of books, you cannot escape a number of question marks that remain. I got the same feeling when I was standing in the great pyramid. I would not be surprised if this great building were built by extraterrestrials. The presumption that the Egyptians could build this 4600 years ago is as unlikely. There are a lot of earlier examples that clearly show that the building of the pyramids was just the end product of a set of things by trial and error. To presume that extraterrestrials built the (earlier) pyramids at Saqqara is far more unlikely.

But I am not talking of colonisation 5000 years ago. Rather 2 billion. When the highest form of life on earth was some bacteria.

Besides, who says that further evolved civilisations would prefer the natural habitat of a planet, where one gets half a sea or a blob of magma over oneself every other minute. Mayve they are more confortable in biospheres in space. We too have left our natural habitat (caves and trees) long ago. Evolution will no doubt continue. Where would they get their minerals ? Why was Earth not mined of all metals several billions of years ago ?
But true, those are speculation as well. Again, the fact that we don't see traces of colonisation is no evidence there are no further evolved civilisations.

Or are we alone after all.

You see, your arguments are too insecure to draw any conclusion. But there may be others.

You pass too easily on two presumptions :

- lots of planets (1 million) could be susceptible of life

- intelligence is the normal closing of evolution on a planet

But is that as certain as all that? Maybe each of  these elements is less certain and both together are so exceptional, that we are indeed alone.

I have not made those presumptions, others have.

These presumption, much less than those above, are provable or disprovable.

I have used the arguments above (which you have not really disproved, in my opinion) to draw the conclusion. A further conclusion is that one or both of the presumptions is indeed false.


A planet capable of producing highly developed life may well be a great rarity. You don't have to look all that far. Of the many dozens of planet-like bodies in our solar system, only one has managed it. Mars may well have kept the appearance for some hundred millions of years. Life on Europa or Titan? Possibly, but not highly developed.

Although I am in general in agreemement with your conclusion, I cannot let this argument go unchallenged: This only proves that on any star, out of dozens of planets, there must almost certainly be one in the correct spot to sustain life!
A great deal of factors have had to co-operate in amazing fashion to keep this unstable condition going for 4.5 billion years! You are trying to explain how it can be possible that we are alone - not proving it. I agree with the explanation, I believe I have added a proof (see above)
- a central star, not too big or too small, gently stable for billions of years, in the beginning a bit weaker than not, so that the greenhouse effect, stronger on the young earth than now, would not boil the earth off (see Venus); then matured and 10% stronger when the chlorophyl had pured the athmosphere, so that the Sun prevented Earth from getting into deep freeze (see Mars). Coincidence! Well, again I could counter by saying that if the Sun had been weaker, maybe Venus would have developed life, or stronger, Mars.

I have never heard about this changing of the sun, but it cannot really be a very strange phenomenon, the Sun is quite ordinary in the Milky Way.

- Plate tectonics, like you say, must have influenced the evolution of life. But it also had great influence on the Earth's general condition. Without it, and with continuing erosion, Earth would be as smooth as a billiard ball, so that no centimeter land would surface. Vulcanism (a consequence of Plate tectonics) keeps the greenhouse at a good level, not too much (Venus), or too little (Mars) There is plate tectonics and vulcanism on other planetary bodies in our solar system, and nothing to presume not on planets around other stars.
- You correctly name the Moon. But you forget one effect. Our giant moon keeps the earth axis straight, like a gyroscope. Without it the axis would wobble a lot more, up to 180°. Which would influence climate so much that life would be impossible. Strange argument. Our axis is tilted at a greater angle than most planets (except Uranus, which must have been hit by something really big). The number of ways life has adapted to seasonal changes makes me wonder if the reverse is not actually true : through the moon, the earth has wobbled more, not less!
Aside, why are you no fan of the theory that the moon was formed from the collision between the proto-Earth and another proto-planet? I am not a fan of anything, I don't want to explain the moon, I use its existence as an explanation of why we are alone, not as proof of it.
- Lots of water, but not too much so that everything is under water (Europa) I don't want to presume that water-carbon based life is the only possible solution
- The phenomenal way the Earth succeeds in keeping a stable climate, hundreds of millions of years long, with a mean temperature within narrow borders, which should be very unstable. It is so complex that science can not resolve it. 20 years ago scientists believed Man was the cause for global warming, now they are not as certain any more. I believe life itself is the main stabilising effect. Nothing I would want to presume could not also happen around other stars.
- Cosmic effects should not spoil it. Earth's orbit can not change to much. Another star passing could disturb that quite a lot. No Hypernovae in the vicinity. No Supernovae too close. Those factors may contribute, but I'd rather think they would account for only a small percentage of failures.
- Now and again a good knock from a planetoid or comet impact, but not too frequent. Nice coincidence that Jupiter is there to protect us from most of those nasty things. Again, there is no evidence that giant planets would not do the same in most planetary systems around other stars.
It is amazing how all these factors must co-operate to keep this condition. I cannot shed the opinion that there could be an amazing coincidence which makes Earth unique, even if there are hundreds of millions of planets in the Milky Way. I agree, but most of the coincidences can be explained. My argumentation started with a "proof" of alone-ness, and all these facts merely explain how this could have happened. They don't prove the uniqueness in any way.

Consciousness and Intelligence

I am not certain that higher forms of life would automatically evolve to intelligence of human measures. Maybe that too is a big exception! We don't have to look far: from the millions of forms of life only one has managed to become intelligent. That proves it is highly exceptional.

Nothing exceptional: the species Homo is not the only one to evolve to intelligence, merely the first one! And knowing our species, we shall make damn sure no other species copies it.
You probably know the theory that explains that our ancestors had a free and simple life style in the tops of trees, until plate tectonics (again!) cruely disturbed their lifestyle. East Africa started to secede, with high mountain ranges as a result, which turned East Africa from Forest into Savannah. our ancestors were forced into a different lifestyle, which eventually led to humanity. If it were not this, then certainly something else. Change one thing in plate tectonics and the intelligent life form that would colonise the Galaxy might well descend from the South American giant sloth.
You correctly assume that man does not differ substantially from animals. But there is something strange about our intelligence. If you award some number to the degree of intelligence and plot this from lower animals to apes and finally man, that line goes gently up and then jumps to us, without anything in between! For two reasons:

- if it is exponential, then use a different scale and it becomes linear again

- maybe the absence of anything in between is because the intervening species could not compete with the highest intelligence.  In the African steppes, there is no animal with a necksize between that of a normal animal and a giraffe - they got eliminated and only the longest neck survived.

I once saw such a diagram in a book of a paleo-antropologist, but only concerning the hominids. Horizontal at australopithecus, then a jump at Erectus, a few more steps and then a problem, because the page was not high enough to present human intelligence. I am certain that other scientists will disagree.

But again, what does that prove?

It might be an explanation, but not a proof.


The series of coincidences needed to create an intelligent civilisation are so unimaginatively large, that the chances may well be very small. That is why we may well be alone in the Galaxy, but that does not need to be the end of it.

You write that a civilisation would need 1 million years to colonise the Milky Way, travelling at 10% of the speed of light. At that speed you are not allowed to stop too many times to colonise a planet along the way, and you would have to start off in billions of directions at once, or you cannot get there by far. Ever heard of geometric progression?

If there is no limit to birth control; how long before a colonised planet needs to start sending out colonies of its own?

I had put it at 10% to be conservative, I actually believe it could be faster. But even at 1% of the speed of light, it would take a "mere" 10 million years. If we are merely the first of many, I think we would have far more advantage than that.

If we are alone, of course, we need not hurry...

But if we can believe Stephen Hawking, pure speed may not be the only method of travelling through space-time. If that is true and technically feasible, mere tens of thousands of light years would not pose a problem. But also not barriers of millions of light years.

In which case we must think Universe, not Galaxy.

Would we be alone then ?

Speculation I don't need to prove my point.

I am quite willing to do the same for other writers who would like to present their ideas.

by Eric Smets, Zandhoven, Belgium and Herman De Wael, Antwerpen, Belgium

written 1999-11-07

weRalone@email.com / Copyright ©1999