
There Have Probably Been Aliens - rosser
http://www.nytimes.com/2016/06/12/opinion/sunday/yes-there-have-been-aliens.html?mwrsm=Facebook
======
apsec112
"In other words, given what we now know about the number and orbital positions
of the galaxy’s planets, the degree of pessimism required to doubt the
existence, at some point in time, of an advanced extraterrestrial civilization
borders on the irrational."

This is terribly silly. It reminds me of the Onion talks:

"Step 1: Devise an idea to create a car that runs on compost. Step 2: Create
the car. We’ve already completed Step 1. We’re half way there."

Increased certainty on three of the seven factors is irrelevant, because 99%
of the uncertainty is concentrated in the other four. Specifically, the odds
of abiogenesis are ~1/2^n, where n is the complexity in bits of the smallest
self-replicator. n is bounded below by ~100 or so (or it would have happened
in a lab somewhere), and is bounded above by ~1 million (the smallest existing
bacteria), so we know it's somewhere in there. But where? We have only the
vaguest guesses.

"Specifically, unless the probability for evolving a civilization on a
habitable-zone planet is less than one in 10 billion trillion, then we are not
the first."

"One in 10 billion trillion" sounds like a very large number, and it's put in
italics for emphasis, but in information-theoretic terms it's tiny.
log2(10^22) is just 73 bits. If all that we know about a number is that it's
somewhere between a hundred and a million, saying that X would imply it's
higher than 73 (well technically 73 + log2(#incidences of molecular
combination), so probably a few hundred) is not a disproof of X, nor really
even much evidence against X.

~~~
andbberger
Your assumption that the odds of abiogenesis is given by `~1/2^n, where n is
the complexity in bits' is utterly, completely false.

Statistical mechanical entropy and information theoretical entropy
('complexity in bits') are not the same quantities! But even if they were,
your expression would still be incorrect because living system are
definitionally not at equilibrium - so equilibrium statistical mechanics
(whose predictions you are using to get that expression) does not apply.

No one is surprised when convection rolls spontaneously form as they boil a
pot of water. But equilibrium statistical mechanics predicts that this should
be extremely unlikely as convection roll states have very low entropy. That
is, of all of the ways that the molecules in that pot of water could be
oriented, vanishingly few of them correspond to convection roll states, where
several Avogrado's numbers worth of particles conspire to all swirl around in
a coordinated fashion to dissipate the heat of the burner faster than would
occur just by diffusion.

The origin of life is very much analogous to the formation of convection rolls
in the pot. And I believe is far more common than classical predictions
imagine it to be - nearly everywhere there is an energy gradient in the
universe, you will probably find life.

Citation: I have a degree in physics

~~~
Houshalter
This has nothing to do with physics. He's saying _if_ a first self replicator
requires a very specific sequence (of something like RNA) to form by chance,
then it can easily be incredibly unlikely to happen.

As an analogy, if I make a huge number of random files on my computer and
execute them, the probability of getting a self replicating computer virus is
really low. And one that successfully spreads itself to other computers over
the internet should never happen.

If the first successful computer virus is 100 bits long, then probability of
finding it in a single random search is 1/2^100. Which is just incredibly
small and should never ever happen.

~~~
cookingrobot
Purely hypothetical: where N is the fewest number of bits for a successful
virus.

There could be 10 different ways to make a virus N bits long. There could be
1000 ways to do it in N+1 bits, and a billion ways in N+2.

The relationship between how many possible successful viruses exist to number
of bits doesn't have to scale by any obvious pattern.

~~~
Houshalter
I don't see why adding more bits would make the program significantly more
likely. Yes in theory that is possible, but I don't think it's relevant.

~~~
cookingrobot
Knowing the size N of the smallest possible virus doesn't tell us much about
the probability of a given random string being a virus (as long as it's longer
than N)

There could be a magic threshold where if you're shorter than that you don't
work.

For ex, maybe a valid file has to be at least 100 bytes, or the OS can't treat
it as a file. Any random file 100bytes or longer could have a 10% chance of
being a virus (the actual number depends on how the os works).

This would mean a really high chance of randomness creating a virus, even
though N is 100.

The probability of vitality depends on the specifics of the operating system,
and we can't infer it by looking at the size of the smallest possible virus.

------
throwaway_yy2Di
If you parse the article carefully, the entire argument is summarized as

 _" There are more than 10^22 planets, therefore ETI probably exists[ed] if
P(intelligent life|planet) > 10^-22"._

    
    
        Specifically, unless the probability for evolving a
        civilization on a habitable-zone planet is less than one in
        10 billion trillion, then we are not the first. [...] In
        other words, given what we now know about the number and
        orbital positions of the galaxy’s planets, the degree of
        pessimism required to doubt the existence, at some point in
        time, of an advanced extraterrestrial civilization borders
        on the irrational.

~~~
ekianjo
That was extremely shallow from the nytimes.

------
andrewstuart2
Probably. Assuming they're correct. Our planet is 12,742km in diameter, yet
we've only drilled 12.262km deep [1] (and we were wrong about how hot it was
gonna be), and sent a human down ~10.900km [2] (and we still can't decide how
deep we've actually been). Do we really think we understand the probability of
alien life on another planet _that_ well, given the amount of data we have on
those planets, and that we're constantly proven wrong on our own?

And yet (either way) I'm not sure it really matters. No human has left our own
planet for longer than 437.7 days [3]. Say they're right, though. If an alien
race exists, we're still a ways from being able to do anything about it.
Unless we can make it there in 1.198 years. If that alien race can make it
here, awesome. Let's talk then. If they can make it here and are hostile, then
it's been swell. See you on the other side. Probably.

[1]
[https://en.wikipedia.org/wiki/Kola_Superdeep_Borehole](https://en.wikipedia.org/wiki/Kola_Superdeep_Borehole)

[2]
[https://en.wikipedia.org/wiki/Bathyscaphe_Trieste](https://en.wikipedia.org/wiki/Bathyscaphe_Trieste)

[3]
[https://en.wikipedia.org/wiki/List_of_spaceflight_records](https://en.wikipedia.org/wiki/List_of_spaceflight_records)

~~~
nielsbjerg
You got the units of the borehole wrong, it's in meters not kilometers.

~~~
andrewstuart2
Well, we've certainly drilled more than 12 meters. :-P (Note the decimal
point: 12.262km; I just converted to km to keep it consistent with the other
measurements I cited)

Could be confusing if you're used to the inverse comma/period from what we use
in the US (comma=thousands, period=decimal).

~~~
gh-lfneu28
Would be far less confusing if you'd just written "~12km" and "~11km". The
meters add little to the point you're trying to make.

~~~
andrewstuart2
Well, that's probably true, but it was late and I thought the higher precision
would help add to my point. Too late to fix it now, though. :-P

------
Houshalter
>unless the probability for evolving a civilization on a habitable-zone planet
is less than one in 10 billion trillion, then we are not the first.... the
degree of pessimism required to doubt the existence... of an advanced
extraterrestrial civilization _borders on the irrational_.

After working with probability theory and combinatorics a bit, you realize
probabilities much smaller than this occur naturally all the time. It might be
hard for people not familiar with that to appreciate this, and be wowed by
such a small number.

The thing is that independent probabilities multiply together, and so approach
0 exponentially fast. The probability of winning the lottery is of course very
small. But there are so many people, that someone wins a lottery every day.

But the probability of winning the lottery twice is really small. The set of
people that have won twice is a very small set indeed. And the probability of
winning 3 times is so small that we should expect it to be a sure sign of
corruption of the lottery, or intervention by supernatural forces. It's also
about 1 in 10 billion trillion.

It seems to me that the evolution of intelligent life from nothing, also
requires many things to go right. We don't know what all these things are, and
we can only guess what their probability is. But if even a few of them have
relatively small probabilities, then the probability of _all_ of them
happening could easily be much lower than "1 in 10 billion trillion".

There are many candidates for this so called "great filter". Some ideas I
think are plausible are the evolution of multicellular life. The Earth was
around _a very, very_ long time before multicellular life formed. And it's
believed to have required some weird coincidences like a parasite evolving
into mitochondria.

Another candidate is the evolution of intelligence itself. Most animals aren't
intelligent. Intelligence doesn't actually seem to be very correlated with
fitness beyond a certain point - and reducing brain size is actually
beneficial. Animals with brains were around for a very, very long time before
anything like humans appeared. Some scientists believe that humans required a
really weird set of conditions to evolve. There are theories that we are a
case of accidental runaway sexual selection, like the peacock's feathers.

And there are many other factors we can't possibly know, that might be unique
to Earth and rare on other worlds. We also don't know a huge amount about the
evolution of early life. Getting from RNA self replicators to the complicated
machinery of the most recent ancestor was no small feat.

------
ChuckMcM
I can't recommend "The Vital Question" by Nick Lane enough for people who are
really interested in the question of life elsewhere. It does such a wonderful
job of show how mechanically "life" can be started as a way of simply reacting
chemicals to a lower energy state. It neatly ties together biochemistry and
geochemistry in a very plausible (and testable) way.

Given the analysis, I would expect that bacteria and archaea, are present on
any world with liquid water and a threshold amount of heat. Which would
include Mars, Europa, and probably Io as well. There are a number of forms of
bacteria living in the ionosphere which could be dropped on to Mars and they
would do just fine there.

The odd bit comes from the origin of _eukaryotes_. Which, according to Lane,
might arise if archaea were endosymbiotically living inside bacteria. That
works but he doesn't offer any suggestion of what caused it to happen the
first time. And he makes a reasonably good case that what ever it was that
caused it, happened exactly once in the 4+ billion years of the planet and 3+
billion years of bacterial life roaming around.

~~~
Lost_BiomedE
I read his book 'power sex suicide'. Here is a good summary:

[http://ronbarak.tumblr.com/post/25996121029/life-is-it-
inevi...](http://ronbarak.tumblr.com/post/25996121029/life-is-it-inevitable-
or-just-a-fluke-by-nick)

In the book he expanded on what was needed to make the jump to complex life
and his opinion on how unlikely it was. He made a case for how only a
relatively small time window was available for it to happen at all.

I second the rec!

------
twright
Here's a Drakes Equation visualizer I made. I know it doesn't address certain
factors but it's fun to play with as a thought experiment. Even with some
optimistic numbers there's not that much out there.

[https://tristaaan.github.io/ngDrakesEquation/](https://tristaaan.github.io/ngDrakesEquation/)

------
houseofshards
Content of the article is pretty information, but worst clickbait title of the
year. At the risk of alienating some fraction of HN community (no pun
intended), I'm going to say this is what you get when trying to chase the
likes of Gawker (again, no pun intended).

~~~
rl3
The irony here is that Gawker's relevant clickbait is actually far superior:

[http://io9.gizmodo.com/11-of-the-weirdest-solutions-to-
the-f...](http://io9.gizmodo.com/11-of-the-weirdest-solutions-to-the-fermi-
paradox-456850746)

~~~
mrob
I read a good short story recently about a weird Great Filter:

[http://www.begoodenough.com/the-great-
filter/](http://www.begoodenough.com/the-great-filter/)

~~~
amasad
The first movie that I think plays around with the idea of a Great Filter (not
quite; but close) is The Forbidden Planet, a 1950s scifi. The basic idea
without spoiling it is that enhancing their own intelligence also made
powerful their lizard brain of sorts. I assume freudian psychoanalysis was big
in the 50s so they called it the ID in the film.

------
skissane
The universe is so big, that I think it's very likely that somewhere out there
are, there are many other intelligent civilisations, in distant galaxies–but
so far away we'll never be able to visit them, never be able to communicate
with them, we'll likely never even know of their existence (not in a million
years–and I mean that literally.)

In the long-run (of millions of years), the two most likely outcomes for
humanity are extinction or galactic colonisation. If we do colonise the
galaxy, we'll prevent any other intelligent species from evolving within it
(by fully occupying that ecological niche.) If we go extinct, we'll leave that
niche open for another species to maybe one day occupy as we would have failed
to do. The galaxy is likely a natural hard limit for our species, since while
interstellar travel is difficult it is arguably possible (not with present day
technology and economics, but potentially within a few centuries from now),
but intergalactic travel is likely never going to be possible.

Even if these authors are right that other intelligent life once existed in
this galaxy, it's almost surely extinct by now. If that's true, it makes their
conclusion profoundly pessimistic – the more ruins of dead civilisations this
galaxy contains, the greater the likelihood that we'll meet the same fate as
they did.

I think we'll always be alone in the universe. And it's probably better that
way.

~~~
chmike
Why do you believe it is surely extinct by now ? Why do you believe that
colonisation of the galaxy means eliminating all other advanced civilisations
and life form ? Are you russian ;)

Your reasonning is based on many assumptions. Look at us. When did we discover
how to fly ? When did we landed on the moon ? Human evolution in science and
technology mastering is evolving exponentially. Things can happen much faster
than we thought.

Another question is why is the UFO phenomenon consistently discarded in the
reasoning ?

~~~
skissane
I'm not suggesting our species will go on a genocidal rampage through the
galaxy. Rather, I'm suggesting that if we manage to spread through the galaxy,
we won't encounter any other intelligent life, and our galactic colonisation
will prevent any other intelligent species from evolving in this galaxy since
we'll be fully occupying that ecological niche, just as being the dominant
species on this planet makes it much less likely that other species (such as
chimpanzees) will evolve to our intelligence level. (Galactic colonisation
might plausibly result in speciation of homo sapiens, however.) It's extremely
unlikely for two intelligent species to evolve within a single galaxy at the
same time; if other intelligent life ever exists in this galaxy, it is almost
certainly many millions of years older or younger than us. Any civilisation
following our present trajectory is likely to colonise the galaxy within a few
million years. Since we are here, no species before us has successfully
colonised this galaxy, which implies either we are the first, or the others
have already gone extinct before reaching that level.

I discount UFOs because I believe the alternative explanations–such as natural
atmospheric phenomena, secret testing of military aircraft, confusion,
hallucination and delusion–are collectively much more probable than the
hypothesis that extraterrestrials have visited us.

~~~
chmike
> I discount UFOs because I believe the alternative explanations–such as
> natural atmospheric phenomena, secret testing of military aircraft,
> confusion, hallucination and delusion–are collectively much more probable
> than the hypothesis that extraterrestrials have visited us.

I understand but the reality is undetermined. So assuming that UFOs are not
real or ET manifestation is taking a risk of error.

My knowledge of the UFO phenomenon is different as I'm very close to the
author of the following articles
[1]([http://www.meessen.net/AMeessen/Propulsion.pdf](http://www.meessen.net/AMeessen/Propulsion.pdf))
[2]([http://www.meessen.net/AMeessen/Evidence.pdf](http://www.meessen.net/AMeessen/Evidence.pdf))
[3]([http://www.meessen.net/AMeessen/Production.pdf](http://www.meessen.net/AMeessen/Production.pdf)).

While I agree that a priori we don't know if we can attribute any reality and
seriousness to the UFO phenomenon, these studies shows that we should. The
author applied the inductive process. If the UFO phenomenon is real and the
manifestation of unconventional flying objects, they must respect the law of
physics that we know. The author investigated the a priori uncertain data to
determine if it is possible to explain what is described by using the law of
physics that we know and are valid in our environment (air, water, etc.). The
only liberty degree accepted is that since the UFOs may not be of human
origin, they could use the laws in an original way not yet known to us.

The referenced articles describe the result of this study. The conclusion is
that it is possible to explain the propulsion mechanism of UFOs and its
described properties. The mechanism is not yet used by humans and require a
supraconducting surface at room temperature and above.

This is a theory explaining the observed phenomenon. The normal scientific
process should now be to test that theory. This is the work of an
experimentalist, not a theorist.

Of course this doesn't tell us anything on the real origin of the phenomenon.
But its theorical validity give credibility to it. Since many reports signal
the presence of non human looking beings, this give credit to the ET origin.
Finally, supraconductivity at room temperature is not yet mastered by humans.
I suppose it would be known by now if it was the case.

Why do these ET behave as they do ? I have no idea. One thing to keep in mind
is that the rules and optimal strategies may be different once space travel
and energy is not a problem anymore. There may be no benefit in colonizing the
galaxy. There is enough space for everybody. My conclusion, influenced by the
results of the author is that what matters is to be able to ensure the
survival of ones civilization. This means that scientific and technological
advance is primordial and determinant as we can see with the war in Syria. We
can also see that colonizing doesn't work unless the population is fully under
control. This may give credit to the abduction side of the UFO phenomenon, but
I'm much more careful on this subject because we have much less data and
independent data sources.

------
jkeler
> a probability for civilizations to form of one in 10 billion per planet was
> considered highly pessimistic

I think people underestimate how low probabilities can really be. According to
wiki the shortest self-replicating RNA is 165-bases long. Even if you convert
all observable universe in RNA this is still not enough for this RNA to form
by chance (4^165 is much larger than number of atoms in observable universe).

~~~
qaq
Given enough time anything can form out of random fluctuations if it has >0
probability no matter how small.

~~~
Houshalter
"Enough time" can easily be longer than the age of the universe. A million
monkeys typing on keyboards will eventually write shakespeare. But it will be
longer than the universe before they even type a single sentence of it
correctly.

~~~
titzer
You are postulating the existence of only a single universe, ours. But there
could be any number of universes, and so far we have no scientific way of
testing that. The anthropic principle and the possibility of multiple
universes puts all probabilistic arguments to dust: anything with non-zero
probability happens in an infinite number of universes.

> A million monkeys typing on keyboards will eventually write shakespeare. But
> it will be longer than the universe before they even type a single sentence
> of it correctly.

All it takes is _one_ tiny selection force to blow this argument out of the
water. For example, if only _a single_ correct letter is retained from each
attempt, the problem gets exponentially easier with every iteration, making
the expected time to generate any work linear in its length.

~~~
Houshalter
I agree with you completely about the anthropic principle. But we are talking
about the probability of aliens. If the anthropic principle is true, then we
should expect aliens to be really really unlikely.

------
madaxe_again
The most likely reason that nobody seems to be out there is the great filter.
The author asks if our civilisation will last millenia or millions of years -
but I think a more apt scale would be decades or centuries.

It just seems pretty obvious that we have an ever increasing set of
opportunities to extinct ourselves, and therefore the probability of a
civilisation ending disaster only grows.

All the aliens either blew themselves up, starved, or are the kind of
incredibly boring, mind-numblingly conservative people you wouldn't invite to
a local cluster cocktail party.

Oh, either that or civilisations tend to disappear up their own simhole.

~~~
XorNot
Conversely, by 2025 there might be living humans on Mars (if Elon Musk gets
his way). And while that's not enough to form the basis of a backup
civilization, I'm somewhat more interested in the effect on global zeitgeist
it's likely to have. The feeling of the times is, I feel, an underestimated
factor in how democracies pick their priorities - and the early 21st century
has been very down on itself trying to figure out practical, post-conflict
economic realities.

~~~
sangnoir
> And while that's not enough to form the basis of a backup civilization

Or that might accelerate the end of civilization due to our inherent tribalism
- the US isn't quite a backup of Europe as a 16th century European would have
imagined. Who is to say there won't be a Planetary Mutually Assured
Destruction?

 _The Expanse_ (books and TV series) explores some themes around planetary
identity & politics in a fictional future where Mars and the outer solar
system has been colonized and Earth is seen as a meddling 'old country' by
some.

------
Udo
It's true that so far every step of the way we have found environmental
factors that are generally in favor of life. However, there are still many
factors we don't know anything about. Somewhere between the possibility of one
of these remaining factors being extremely unfavorable to life and us just
being in a very isolated location, there should be an explanation for the
Fermi paradox we're actually experiencing.

Sensationalist title aside, the article actually plays it extremely safe, by
asserting a very high probability of extraterrestrial civilizations having
been existed somewhere in the past.

But even so, there are potential problems where that might conflict with
observation. I'm not generally a fan of these "alien civilizations must
construct huge machines and must have a huge energy output" assertions,
_however_ , all it would take is _one_ of the previous civilizations to have
built _something_ we can recognize. Sadly, nothing has been found, neither
artefacts such as probes, nor radiological evidence in the sky.

Now, there are many possible reasons for why we haven't found anything yet,
first and foremost being that the galaxy is vast in both time and space. But
if I forced myself to be especially pessimistic, I would say that the
probability of abiogenesis might be way smaller than even our bleakest
estimates.

------
sktrdie
By pure probability, if we're the first intelligent species here on earth
(that is able to build radio communicators) out of what, ~4 billion species
that ever existed, what are the odds of us being the first in the entire
universe?

My logic is that intelligence (as defined above) is clearly rare here on earth
where life is prolific, hence by no means a certain development of evolution.
I wouldn't be surprised if we're the first in the universe where the
conditions are certainly less hospitable for life.

This game of probability doesn't only depend on the sample size, but also on
what you're looking for. For instance, you can say that if you find a _purple_
grain of sand, and you know there are trillions of other grains, then you'll
be sure to find other _purple_ grains. But what if the purple grain has
written on it "hello how are you" by sheer chance. You'd probably never find
another grain of sand with that same writing.

And then you can say, "us being the first is egocentric". Well, but we're the
first (on earth) when it comes to building radio stations, so we clearly won
that lottery big time. Is it such a stretch to say we won the lottery in the
universe as well?

~~~
EndlessSky
I'm not sure you can draw the conclusion that since there is one intelligent
(as defined above) species, out of many on earth, that intelligence is
unlikely to develop.

The main issue I see is that there were other species that were close to as
intelligent us, but we out competed them and they went extinct.

I wouldn't be surprised if there was a sort of "first one wins" effect where
the first species to reach a certain level of intelligence quickly (compared
to the time it takes to evolve that level of intelligence) comes to dominate
the planet wide eco-system on a level far beyond every other species, thus
preventing the development of other intelligent species.

~~~
sktrdie
Even if we outcompeted the Neanderthals (or other very intelligent species),
they were still very close to us in the tree of life (they were cousins). For
a trait to be a high probability outcome of evolution it needs to happen
independently in many different species - take binocular sight for instance
which happens in all kinds of very far related species.

Even if our close relatives had similar intelligence and we outcompeted them,
it's still safe to say that intelligence (as defined) appeared in only a small
branch of the evolutionary tree.

Why don't we see species underwater building radio stations? There's lots of
life diversity underwater and they certainly weren't in our "competing" ground
(being underwater) so they could've developed intelligence independently...
but didn't. That's my point.

~~~
EndlessSky
One species having binocular sight does not significantly effect the
evolutionary advantage of binocular sight in other species.

And define what you mean by "high probability", I would agree that
intelligence (as defined as building radio communications) does not have a
high probability of evolving compared to binocular sight.

What I am getting it, is I would not be surprised if intelligence (building
radio communications) was like a race. A race only has one winner. Just
because a race may have a thousand contestants, does not mean that the
probability of there being a winner if 1/1000\. Rather the probability of
there being a winner goes to 1 as the duration of the race increases.

Or its like concluding that because life only appeared once on this planet,
its very unlikely that life could have appeared at all. Another hypothesis is
that once life appears, it makes it very difficult for new life to appear by
preventing the conditions that lead to abiogenesis. For example maybe chemical
evolution can not occur, because in all places where it would the are living
organisms that interrupt the process because those chemicals are useful to the
organism.

Similarly, I Humans have an unprecedented degree of control over the
evolutionary trajectories other organisms. Maybe other apes, if left alone for
hundreds of millions of years would evolve into a species that develops radio
communications. But organsim's need evolutionary pressure to evolve, and
humans really, really like preserving species. If a species of apes start
dying off due to some evolutionary pressure, rather than let nature take its
course and let the apes which can survive that pressure out compete the
others, humans will intervene to keep them around, and as a result they will
remain stagnant evolutionary.

------
wtbob
> Specifically, unless the probability for evolving a civilization on a
> habitable-zone planet is less than one in 10 billion trillion, then we are
> not the first.

And … nothing is provided to indicate that said probability is higher than
that.

------
sleepychu
I'll agree that aliens might exist far away from us in space &|time, but so
what? I'd argue there's no practical difference between being alone in the
universe and our local galaxies.

~~~
chmike
Why do you believe there is non difference ? Do you believe they didn't vist
earth yet ?

------
imh
One in 10^22 seems really easy odds to beat. Basically anything should happen
more often than that, right? But if we choose a random 16 letters, the odds
that they spell "unscientifically" is less than that. If we gave 16 letters to
each of the 10^22 stars, we expect the word to happen on only one star, if
even that. It's not too hard to argue that life is more difficult to get by
random chance than the word "unscientifically", so we can't simply argue that
"of course life will happen with those odds!"

------
ulmus
In estimating a probability for the occurrence of life in the universe, the
authors essentially claim to know the probability of their own existence.

For me, that's a red flag. I can't know the probability of a phenomenon which
my existence depends on just by observing my existence alone, because I can't
observe all of the cases where the phenomenon does not occur and I do not
exist.

~~~
lisper
The quantity of interest in any probability problem can always be re-cast as
the conditional probability of the event given that the person asking the
question exists, which is necessarily 1.

~~~
ulmus
Pardon me, but I'm not sure what you mean by quantity of interest. If the
quantity of interest can always be re-cast as a value which is necessarily 1,
isn't "quantity of interest" the same for all probability problems?

~~~
lisper
Sorry, I wasn't very clear.

> the authors essentially claim to know the probability of their own existence

The "quantity of interest" is the probability of aliens, but not the
probability of aliens in all possible worlds, but rather the probability of
aliens in _this_ world. In _this_ world, the probability that the authors
exist is 1.

~~~
ulmus
I respectfully disagree. I claim the probability of human existence could have
been less than 1, just as the probability of heads when tossing a fair coin is
less than one, even when heads is observed as an outcome. We simply can't
observe "tails" in this case.

~~~
lisper
You are confusing two (perhaps three) different things. The probability of a
fair coin landing heads is 1/2 before the coin has been flipped. After the
coin has been flipped, the probability is either 0 or 1. You may not know
which it is, but it is definitely one or the other (assuming classical
mechanics).

Now, if you are being a strict Bayesian then the probability of the coin being
heads is never quite 0 or 1 because there is always the possibility that your
eyes are deceiving you, or you are suffering from delusions or some equally
unlikely contingency. But I assume that's not what you mean, and that you
accept that humans do in fact exist in this universe, in which case the
probability that humans exist in this universe is exactly 1. P(A|A)=1 by
definition.

------
dacompton
There have been aliens -- and they don't care about us.

To assume that a collection of beings which have obtained the ability to
travel amongst the stars would focus their attention on a single species on a
single planet is fundamentally selfish.

What resources does our earth contain that are not (more easily) obtainable
elsewhere? If Drake's equation "holds", then what novelty do _we_ provide?

~~~
Houshalter
There are many reasons alien races would interact with primitives.

Morality - they might be utilitarian and desire to relieve the suffering of
other sentient beings. Or force their weird alien morals onto them.

Competition - we might not be a threat now, but given a sufficiently long
time, we could evolve into one. If they really don't care about us, it would
cost them very little to exterminate us early.

~~~
chipx86
I see these mentioned a lot, and sci-fi is big on the latter. The one I rarely
see come up is "entertainment."

If we were traveling amongst the stars today, with our values and morality as
they currently are, and happened upon a world of what we'd consider to be
primitive life, we'd probably scoop some up and put them in a zoo, or
broadcast them on TV. We'd want to study them, learn what makes them tick,
maybe try to see if communication was possible, but in the end, we'd get
entertainment value from them.

Even if we left them be and studied from a distance, the human race would be
fascinated. New life! A new place! We like new things. The news would cover
these creatures ("Are they a threat to humanity? News at 11."), they'd be
woven into stories and shows and movies in one form or another. If we could
safely bring them back, people would want to see them in person.

We'd get a lot of entertainment value out of these new creatures. We're a
curious race who manages to get bored of spectacular things quickly, which is
a large reason we continue to innovate and push forward.

There's no way to know for sure what would motive another intelligent race to
advance to the point where they'd reach for the stars, but if any of them
shared a degree of curiosity, I doubt they'd pass us up if they found us. We'd
be something new for them.

Maybe we'd end up in their stories, their drawings, their videos, or even
their zoos. Maybe they'd be interested in how we smell, or the way we dress
and decorate ourselves, or the things that we watch on TV. Our languages, our
fights, our culture. Or maybe just the way we go about our business, missing
some big cosmological truth that's so obvious to them, as if we're adorable
little children.

Maybe we'd provide just enough entertainment value to be worth a quick trip.
Or a long stay.

~~~
XorNot
If we discover intelligent alien civilization, there'll be a massive effort
put into simply tapping into their culture. Their internet, TV, magazines,
history, everything we can our hands on. The sheer volume of cross-cultural
exchange which would be suddenly and immediately valuable would be enormous.

------
dmfdmf
If you are interested in these issues a great book to read is called "Rare
Earth:Why Complex Life is Uncommon in the Universe" by Peter Ward and Donald
Brownlee. They make a convincing argument (to me anyway) that bacteria and
simple life forms are probably common in the universe but animals and complex
life with intelligence might be exceedingly rare. We, quite possibly, could be
the only intelligent life in the universe.

------
noiv
ITT, people start with the assumption live is something incredibly special.
Another way of thinking assumes live emerges everywhere an energy gradient and
some matter exists.

Maybe we are not special at all.

[https://www.quantamagazine.org/20140122-a-new-physics-
theory...](https://www.quantamagazine.org/20140122-a-new-physics-theory-of-
life/)

~~~
drjesusphd
So where is everyone?

If intelligent life is at all likely, there ought to be many civilizations
that have had millions of years technological head start on us. Given one
species with galactic ambitions, but technology only modestly beyond ours, it
would only take them one million years to colonize the entire galaxy. So why
do we not see any evidence whatsoever?

This is the Fermi Paradox.

~~~
noiv
Well, maybe intelligent does not necessarily include expansive.

------
logicallee
Protip: if the greatest possible discovery in astrobiology is confirmed
scientifically, you won't hear it first in a New York Times article whose
title is "Yes, there have been aliens"...

------
lumberjack
What I always don't get about this, is the omission of the probability of life
emerging. We know it's possible but do we know how likely it is?

------
bufo
About Drake's equation: [https://xkcd.com/384/](https://xkcd.com/384/)

------
ommunist
What these guys clearly omitting is that our planet could be the host of not
only human civilization. At least in the past.

------
slowmovintarget
No cookies, no article. Couldn't read.

Comments seem sufficient for me to realize I needn't have bothered.

------
SFJulie
No they have not been any aliens until proven so...

Science requires a theory and experimental validation.

The existence of aliens has been postulated by a crazy monk that also invented
the concept of monads. It is much more metaphysics (religious thinking) than
physics.

It strikes me as odd that most of flawed science is coming with the same flaws
as religious thinking.

~~~
coldtea
> _Science requires a theory and experimental validation._

You'd be surprised. That's 19th century thinking about science, and not really
how science works in practice most of the time.

~~~
SFJulie
Well, that is at least what made relativity and quantum mechanic successful.

And yes there has been a lot of flawed science in the XIXth I am aware of it
... like the theory of the ether that Einstein dispelled through
experimentation, or the superiority of some "races", or the morpho-
psychology...

------
JoeAltmaier
So you can publish papers by making up numbers?

------
artur_makly
i love u guys. really great discourse. thank u.

------
jstanley
Title is mild clickbait. There's no evidence for the claim, just a persuasive
argument that it's probably true.

Interesting nonetheless.

~~~
SonicSoul
it's not mild clickbait. it's the definition of click bait. it states a very
controversial conclusion, as if the argument is finally settled, while the
body has little new information and fudges around with statistic that "it's
likely probable that there is or once was another species".

~~~
hudibras
Since this is published in a newspaper, the terms that are generally used are
"headline" or "title," not "click bait."

~~~
pbhjpbhj
Their media kit claims 78 million online viewers vs. 5 million _wealthy_
newspaper audience. I think more people click to read the article than turn a
paper page to read it. Newspapers are online media companies now that happen
to also produce limited paper versions.

Perhaps I'm missing your point?

------
theaeolist
I enjoy these quasi statistical arguments. Can anyone remind me what is the
probability that God exists, or that we live in a computer simulation?

~~~
noiv
Did god invent humans or was it the other way round?

~~~
amasad
See Isaac Asimov's the Last Question for a recursive god human relationship

------
dandare
m - km, fix the units

