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Number of ET Civilizations In Our Galaxy Is 37,964
KentuckyFC writes "The famous Drake equation calculates the number of advanced civilizations in our galaxy right now. But the result is hugely sensitive to the assumptions you make about factors such as the number of habitable planets that orbit a host star, how many of these actually develop life and what fraction of these go on to become intelligent etc. Disagreements about these figures leads to estimates for the number of advanced civilizations ranging from 10^-5 to 10^6. Now an astronomer in Scotland has worked out how to make the calculations more precise so that different theories about the origin of planets, life and civilizations can be compared. His calculations say that the rare-life hypothesis predicts only 361 advanced civilizations in the Milky Way now. However, the so-called tortoise and hare hypothesis predicts 31,573 and the theory of panspermia says that there ought to be 37,964 extraterrestrial civilizations more advanced than our own in the Milky Way."
Make that 37,965. My colleague surely has one growing in his tea cup.
yuck.
...of spurious precision.
Should give us plenty of room to screw up without affecting anyone.
The simple truth is that interstellar distances will not fit into the human imagination
- Douglas Adams
I'd be interested to know where the best place to look for ET civilizations is. A common science fiction theme, found in plausible for in Niven's Known Space universe and Vinge's rather implausible A Fire Upon the Deep has civilizations getting out of the core as fast as possible, settling the fringes of the galaxy. The increased speed of stellar activity in the core would make for a risky place to build lasting civilizations. Would everyone better than us be at the outskirts?
1.
And it is as valid as this astronomer's estimation.
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The "famous Drake equation" is NOT meant to calculate anything, it's meant to start a conversation on what the parameters of intelligent life probability are.
On the other hand, the famous Fermi Paradox tells us that we're alone in the galaxy. And considering that's a direct piece of data, I tend to believe this view. People like to wave their hands and say, but, but, WE'RE here! That means that there "just have" to be more! Why are we so unique? This is the Sagan argument, and it's answered by the Anthropic Principle.
And yes, in this case, absence of evidence *IS* evidence of absence.
Sometimes it's best to just let stupid people be stupid.
No mention of species less advanced than us, but there are apparently 37,964 more advanced. I wonder why that is... Other civilizations must look at this backwater hick-world and laugh.
Admit it. You post strawman arguments as AC so you get modded Insightful for refuting them, rather than Troll
We just don't have a clue.
The number of things we don't have a clue about is staggering.
Counting the number of earth like planets is just plain silly. If life can only start in space and then find a planet, earth might be totally unsuitable for the first start. It also presumes life can only exist under earth like conditions yet we KNOW that even life on earth varies widely. If some species can survive on the bottom of the ocean outside the influence of the sun, is it impossible to imagine a lifeform that exist in space itself?
No, I am sorry but until we can actually go and look our estimates of the number of civilizations is between 1 and 1+.
MMO Quests are like orgasms:
You may solo them, I prefer them in a group.
But we have no definition of advanced.
Look, just because an alien civilization has been around longer than we have, doesn't necessarily mean they will be more advanced than we are.
Maybe they could have been around one million years before us, but are stuck somewhere between Mesopotamia and Rome.
I'm god, but it's a bit of a drag really...
I follow the Mass Effect way of thinking. A handful of civilizations, each with dramatically polarized stereotypical traits, and who speak English with perfect North American accents, regardless of the structure of their mouth(s) and/or vocal cords (assuming they have them...).
Admit it. You post strawman arguments as AC so you get modded Insightful for refuting them, rather than Troll
Because a species of intelligent dolphins would surely be detectable from their radio transmissions.
No. That entire line of thought is based upon the incorrect assumption that WE are the model for all other species.
We're almost unique on Earth. Where we share DNA with every other animal. Why expect that from creatures who evolved on a different world?
Not to mention the incredibly SHORT time we've been looking over an incredibly SMALL portion of the galaxy.
Your entire argument is based upon another species developing the exact same technology that we have ... and using it in a fashion we can detect ... far enough in the past ... but not too far in the past ... so that we can detect it ... using the technology we have ... during the time we have been trying to detect it.
Yeah, like that "proves" anything.
You have no theory, as it stands it is only a hypothesis.
Free Martian Whores!
I am a polar bear. Don't bother to ask me how I managed to get on Slashdot and post this, you would never believe it.
However, I have been doing some estimations of my own. I have always wanted to figure out how many polar bears there are in the world. In my neighborhood here in the arctic, there aren't too many polar bears. About 350. I estimate that we roam over 20 square kilometers. Now, based on some observations I made from the bottom of a well, I figure the earth is around 500 million square kilometers. I haven't actually been outside of my corner of this world, but I imagine everything must be like it is here, and life must be exactly like it is here. I have no evidence to the contrary.
So, I figure there must be 25 million times 350 polar bears or 8.75 Billion of them.
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But, the diameter of the milky way is about 100,000 light years - so, if we assume that pre-Galileo civilization was oblivious to ET, we as a species are only aware of civilization signs within 400 light years or so.
So, if there are 40,000 civilizations within a 100,000ly diameter, then there are approximately 2.56 civilizations within a 800ly diameter.
Personally, I feel like Earth represents the .56 of a civilization in that scenario...
That reminds me of this article from the Onion.
today :
http://edition.cnn.com/2008/WORLD/europe/10/20/britain.ufo.sightings/index.html
Read radical news here
If we ask "where are they?", could it not be possible that NO advanced civilisation could make it to interstellar travel, given how difficult it would be to maintain a survivable environment, enough resources for the trip, and so on? After all, we can look in out neighbourhood and conclude that life is not abundant in the vastness of space, so it must need some kind of special environment to develop and grow. No matter what type of environment a civilisation may develop under, it's unlikely to be one easily recreated on a spacecraft.
Oh, now I read the wiki I see this has already been considered. Well, there's no evidence that our TV signals and such would be powerful enough to reach beyond the solar system. All our deep-space communication is done to a very precise point. Same goes for the Arecibo message, and that has many years to travel before it reaches its destination. These other civilisations would have to be millions of years ahead of us for us to hear them now.
How many of that have stargates?
Michael Crichton criticised the Drake equation years ago:
http://www.crichton-official.com/speech-alienscauseglobalwarming.html
My personal guess is that there are OVER 9000 civilisations out there.
Squirrel!
Was anyone else just a little sad that the bitches didn't arrive on the 14th a few days back?
No kidding. Our current estimates of the number of stars in the galaxy only go to about one significant figure, with upper and lower estimates differing by a factor of two. That puts a pretty serious cap on the precision of his answer.
One of my peers is an astrophysicist. Nearly all of their calculations are done to ONE significant figure. It ends up that they typically just add up exponents. The numbers are usually so huge, eg. 1E27, that they can get away with this.
:)
When you are dealing with orders of magnitude like these, it is usually acceptable in the scientific community. Whether this de-facto standard *should* be so acceptable is still up in the air in my views
Civilizations that manage to survive reach technological singularity, and simply hole up.
Ephemeral civilizations have only a short time to detect each other; I doubt that happens often.
Then you start relying on deliberate lighthouse efforts.
There is also a small matter of the inverse square-law.
They can be as precise as they like, and revise their estimates to 361.055371 (or 31573.22 or 37964.0000) if they want. Precision without accuracy is worthless.
At least they estimated distributions for some of the parameters. My favourite part was the honest phrase "the model now enters the realm of essentially pure conjecture" when they moved to considering the life parameters. Probabilities and uncertainty estimates here should have been of the NaN sort.
Alas, they then proceeded to assign finite uncertainties to unestimable quantities. The standard deviations they actually gave are merely parametric, with the assumption that the underlying model structure is valid. Given that they obtained very different values from three different models (all of which may be wrong), the true uncertainty is far higher. An estimate of a value accompanied by an estimate of its uncertainty - with the estimates depending on pure conjecture - does not convey anything approaching accuracy.
Of course, if the numbers are just for fun, or for dinner conversation, that's fine. As scientific estimates, they should be discarded.
Those who can make you believe absurdities can make you commit atrocities. - Voltaire
Happens when you play Pan's flute too long.
It's now 37,962. The Qnak'k'z of Kuberon II just set off a prototype nanoplasmic bomb that wiped out the whole planet. The timid and peaceful Fnumri of Kuberon VI's third moon were not directly affected, but the flash gave them such a fright they all died of double heart attacks. Sad indeed.
At the bottom of the
Indeed. Succinctly: http://xkcd.com/384/
God: Bender, being God isn't easy. If you do too much, people get dependent on you; and if you do nothing, they lose hope. You have to use a light touch, like a safecracker or a pickpocket.
Bender: Or a guy who burns down a bar for the insurance money!
God: Yes, if you make it look like an electrical thing. When you do things right, people won't be sure you've done anything at all.
A fool throws a stone into a well and a thousand sages can not remove it.
It is entirely plausible that a civilization could be a billion years ahead of us.
Nerd rage is the funniest rage.
If the number came out to 32,768 I'd be a little suspicious being that it's 2^15.
Up until the last year or so ago all they could detect was gas giants orbiting distant stars. Now the technology has advanced to the point that they can now detect smaller rocky planets too.
I look at the plethora of life on Terra and it's hard not jump to the conclusion that if there's liquid water, there's life of some sort. Doesn't even have to necessarily be liquid water too. Hydrocarbons would work.
but the real question is how many are registered to vote in Chicago?
You're missing an entire aspect to the Fermi paradox.
The universe is old. VERY old. About 14 billion years. Earth is fairly young, about 4.5 billion years.
Assuming intelligent alien life take about as long as intelligent Earth life to evolve (give or take a billion years), these other civilizations would have billions and billions of years ahead of us.
Or 4352342. "Calculating" any such number is not in hardly more scientific than throwing dice to figure it out. Sometimes I wish scientists wouldn't have this urge to make the impression of having a clue, when, quite obviously, the don't have a clue. Or, as in this case, provably cannot have a clue.
Now one knows yet how life came into being. Stop making calculations that require knowing that to even get close to meaningful numbers.
Take the Voyager data as a nice proxy measure of long-distance communications. With our best RTs looking in exactly the right spot, its 3W of power and moderately directional antenna could barely send 110 baud from the orbit of Pluto. Crunch, crunch ... that means that an ET lighthouse at 1000ly needs to be transmitting 75 GW (or have equivalent antenna improvements). How likely?
You don't need FTL for star travel, even travel on the scale of current human lifetimes. You just need to accept that you can't go home. Relativity is a blessing, not a curse. Do the math and you will see that with 1G of acceleration you can reach any part of the universe in a reasonable amount of your time.
Warning: this article may contain humor, sarcasm, parody, and perhaps even irony. Read at your own risk.
Where did you find the figure of 1000 ly? I was wondering about this myself and if you have someone who put that together I would be interested in seeing their numbers and logic.
In any case, it would need to be 75 GW of power using the same receiver as was originally used with Voyager. Is it better today? My guess is that it is. We keep getting better responses out of the same bandwidth because our sensitivity to the signal increases. I bet you that NASA engineer looks back at the 3W/110 baud numbers with nostalgia and laughs on the same level many of us do about the 640k of RAM claim.
Dedicated Cthulhu Cultist since 4523 BC.
... our 37,964 overlords.
now we need to go OSS in diesel cars
With NTSC analog TV going away next year, one of our big identifiable sources dies
True, but any alien civilization that has been viewing our broadcasts has been given fair warning of the switch and have been told where they can obtain a digital receiver box with a government coupon.
The Internet is generally stupid
Correct me if I'm wrong here, but an Earth-like planet couldn't have come about much sooner, since we need so many elements that we can only get from old burned-out stars. There's gotta be a lot of cycles before there's enough material further up the atomic chart to make an interesting planet.
But, the diameter of the milky way is about 100,000 light years - so, if we assume that pre-Galileo civilization was oblivious to ET, we as a species are only aware of civilization signs within 400 light years or so.
Not true. It's quite possible to observe signals from much farther away; it's only a question of sorting through them to see if any of them look like evidence of intelligent life. There's no particular reason to think that they must have started transmitting at the exact moment that Galileo did his experiments.
Where the relationship between time and distance matters is when you want to communicate with those civilizations, or determine whether they are close enough to detect our signals.
There is another issue about distance that is completely independent of how long our civilization has been capable of detecting evidence of extraterrestrial life, and that is how much power such a signal would require in order to be detected. It is probably impractical for any civilization to produce an omnidirectional signal (unless, possibly, they were only interested in their immediate galactic neighborhood), so we'd have to assume that they take turns beaming the signal to a large number of "promising" stars. The exact number depends on their resources and level of technology, but again there's no reason to think that it has any relationship to pre-Galileo civilization.
The only area where the length of time we've been able to detect such signals is relevant is that that time tends to limit the window of time that such civilizations might have been sending signals that we can detect. We've only been able to detect very weak radio signals for around 60-75 years or so, so if nobody in our light cone has been on the phone to us in that time period, we couldn't have heard them - to say nothing of the fact that given our current level of technology we'd probably also need to have our equipment pointed right at them in order to be able to hear them.
I'm afraid that all that doesn't really tell us very much, except that signals from ET civilizations must be very rare - and given the continued failure to find anything, it tends to cast doubt on whether there are such signals to detect. Either they aren't there (within a detectable distance, anyway) or they're not interested in chatting.
Every time this thought comes up, my brain falls back to musing that the Universe's dark matter is made up of Dyson spheres, and that the stars we can see are a "nature preserve".
Totally frivolous, I know. And probably easy to test false.
It's the most trivial equation I've ever seen. It ranks up there with embarassing things like the Hardy-Weinberg equation and the Fick equation.
Maybe exp(pi*sqrt(163))'s equation ought to become famous. The probability of getting to work is the probability of me being alive in the morning times the probability of me getting up times the probability of it being a work day times the probability of me being bothered with going in times the probability of me surviving the journey.
Doesn't it make you feel good to know that our freedoms are protected by politicans, lawyers and journalists.
Comment removed based on user account deletion
It's not an equivocation per se. I would presume that what you assert to be at issue (you don't specify) is the dilution of the term "belief" to cover subjects ranging from that with little empirical corroboration (religion) to that with significant empirical corroboration (accepted science).
As you see, though, these are shades of gray -- theory requires a greater leap of belief than that which is proven before one's eyes, just as logical philosophies of religion require less of a leap than do their core theistic entities.
Even across the smallest gap, though, to accept things as seemingly married to reality as the Pythagorean theorem, requires belief. It is a very small quantity of belief required for this -- but to assume you use none at all is to expend a great deal more.
Your mind is clear / The things that you fear / Will fade with how much you / Believe what you hear
Assuming intelligent alien life take about as long as intelligent Earth life to evolve (give or take a billion years), these other civilizations would have billions and billions of years ahead of us.
Um, depends on the civ/species. Some species might take a half billion year to come up with a new thought or depend on environmental conditions to drive their species's evolution. Others could learn/advance faster than we do and only take 100 years to get 5000 years farther ahead than us.
There is also the thing that a civ that far ahead could just be classified godlike and though they have limits, their kids could seed the entire rest of galaxy with random life, probes to monitor it all, and do it cheaply for an elementary school project on budget of what we'd see as what any parent would waste on any given class room project... say less than about $20 worth of effort. Now what could we do to them? Nothing. We should just be happy to be their classroom project and hope that they don't sterilize the planet when they don't need us anymore.
Unfortunately, Fermi's Paradox is based on postulating certain axioms which aren't that self-evident at all. So at best it's not a "paradox", but rather proof that you can reach a false conclusion if you start from a false hypothesis.
E.g., that if a sentient civilization exists, it will necessarily colonize every rock and planet in sight. I'm sorry, but while that's the bread and butter of SF, it's not self-obvious at all in the real world. Colonizing is a matter of too many factors which may, or may not, add up that way. E.g.,
1. Colonization happened on Earth only when overpopulation pressures made it happen. Prior to that, most "colonies" were merely trading posts. We were merely interested in buying cheap stuff there and selling it expensively over here, and viceversa.
But here's the fun stuff about over-population: on Earth it seems to have stopped and actually reversed in every country which has access to good medical care and sanitation. People make lots of kids when survival is a crapshot, and they have to beat the odds. If only 1 in 3 of your kids will likely survive, you make 6 to try to beat the odds and occasional flukes. But as soon as survival becomes just short of guaranteed, people first go through a population boom for about a generation, then it sinks in that they really don't need more than 1 child. They might make a second as a sort of a backup, but that's really it then. Most western countries either _are_ currently going down in numbers, or are only saved by immigration from the poorer ones.
So given an Earth where the vast majority of people can get medical care for their child, the population of the whole Earth would actually decline. It's not that far fetched, as possible futures go. Give it a billion years or so, and Earth will probably be no more than a few thousand people in a few quaint towns, surrounded by square miles of woods and nature preserves.
So there you go: that's one example of a civilization which might never have the pressure to offload its population to other planets.
2. Let's go back to those trading posts I mentioned. They happened because there was an economic incentive to. The same incentive doesn't exist yet even for importing anything from the moon.
Basically the hypothesis that we'll start colonizing all around, _depends_ on discovering some miracle engines and/or some miracle sources of energy, so hauling a thounsand tons of steel from Alpha Centauri is cheaper than making it at home. What if the physics we know now _is_ mostly correct, and that economics never works out that way? Who's going to pay for some trillions of dollars worth of a colony ship, if they don't ever expect a return on that investment?
3. (Or 2.a.) To further nail that coffin, what if FTL is really impossible? How's interstellar trade even going to happen without that? (To pay for that colony, you know.) No, please don't jump to a half-baked answer yet.
Let's say we build a mining colony only 5 light years away from Earth. Now let's say we have some damn good engines, that can accelerate to nearly the speed of light by the middle of that distance, then decelerate for the other half of that trip. (And I mean really _awesome_ SF engines there. Nuclear or even fusion don't come even close.) So it takes 10 years for a ship from there to come to Earth. It takes another 5 years for signals from Earth to get there. So from the moment you sent a "yes, I want to buy 1000 tons of steel" order, to the moment you get that steel, it'll be 15 years.
But let's say we build that colony on the idea that it will continuously send stuff, so Earth gets a continuous stream of shipments. Ok. So it takes 10 years for the colony ship to get there, let's say a year to really get the colony going, then 10 years back with the ore. That's 21 years from the moment you bought the ship, to when you get your first shipment. Are you willing to bet a trillion dollars on the idea that you'll still need that ore in 21 years?
Remember that on Earth some resources went
A polar bear is a cartesian bear after a coordinate transform.
In contrast to micro-electronics and receivers, I do not believe transmitter efficiency has improved much. The example of Voyager is as transmitter. I don't believe it can receive anything and is running on pgming.
If the purpose of the Drake Equation is to stimulate conversation, I wish more people would pay attention to the middle factor, fl, because it's the most significant one. The reason is that the value of the middle factor is the biggest unknown, by far.
Here is why: each of the other factors, even those that are based on singular events like the origin of life, are conceptually more extrapolatable (if that is a word):
1) Rate of star creation - multiple events
2) Stars with planets - multiple
3) Number of Earth-like planets - inferred from just a few factors (size, distance, temp, composition, etc)
5) Fraction of life that is intelligent - extrapolate from multiple events (humans, chimps, dolphins, elephants, etc)
6) Fraction able and willing to communicate - this seems almost to follow naturally from 5)
7) Persist long enough for long transmissions through space - trickier, but not too hard to imagine emergence of mature, stable societies.
4) is the big unknown. Really big. TOTALLY unknown at this point. Because once you dig a little into the chemistry and molecular biology, you realize that currently we do not have ANY comprehensive, detailed hypotheses to estimate how non-living molecular systems made the transition to self-replicating living ones.
Note the emphasis is on comprehensive AND detailed, because there are many very interesting and detailed speculations on parts of the process, such as Wachtershauser's Iron-Sulfur theories, and Szostak's ideas about the emergence of RNA replicators.
However, the huge number of parts and complex interactions involved in creating the simplest living organisms places the estimation of probability of origin of life in a whole other category of difficult, compared to the other factors.
At this time, fl is TOTALLY unknown, and so any use of the Drake Equation for computing a final result is likewise totally unknown.
mhack
Building a better ribosome since 1997
I'm not saying it because I'm a optimist. But I think life is highly abundant wherever it can exist it will exist. I'd like to point out that for billions of years there was no multi-cellular life on earth, and once a few cells got stuck together it's only been a few hundred million to get to here. We could have, infact been here 3-3.1 billion years ago if conditions were right. So I'd place money on the upper bound, but it depends if we're talking sentient intelligence species you could have a philosophical conversation with or a genuine technological civilization such as our own.
So if there are between 5x10-7 and 10,000 civilizations in our galaxy, where are they? The answer I think will be interesting - we simply do not know what happens to intelligent species after they evolve. The problem is with the fallacy known as the fermi paradox is that there are far to many plausible reasons why intellegent species may rise and fall, or simply decide not to show up despite having plenty of time to do it.
I consider it vastly more likely that the majority of sentient creatures in the universe have no hands or similar useful appendages and therefore never acquire technology. I reason that planets with oceans (like our own right up to mega planets with water oceans 100s of km deep)would be vastly more abundant platforms for evolution of life in the universe than land area on earthlike planets.
If we could go out in a billion star ships and turn over every rock in the galaxy maybe we'd find most sentient life will be something like a whale or dolphin.
We seem to forget what wanders about on land contemplating financial markets and marvelling at smart phones, is only a vunerably small portion of the bio mass on this rock, and here the oceans are ruled by Cetaceans who in our own example have been here longer than us, and have had some of the highly developed brain structures they share with us millions of years longer, they used to populate hundreds of millions.. but we've eaten most of them). They'd probably persist after cataclysms that would wipe us out. (Octopii and squid are also relatively intellegent too, there's a hint that the format of a ET might be)
So with the majority of ET life being underwater there's little opportunity for tool making by hypothetical aquatic beings, let alone harnessing technologies we have done - which all largely stem from the ability to make fire and bootstrap from there. Consider that the majority of these oceans would be lidded by ice (like Europa) and these types of environments will vastly outnumber earth-like planets in that perfect habitable zone around the right kind of stable star.
So considering planets with habitable land area, in a stable orbit around a stable star, avoiding bombardment or supernova sterilization long enough for life to make the leap to multicellular and upwards, are a rarity - it becomes worse, there are still reasons why ETs may not show up.
Life could evolve at the bottom of a big gravity well -- a much larger planet with such an escape velocity that makes space travel difficult. The planet could have permanent cloud cover, thus the beings inhabiting it never see the sky and never wonder what's out there. They could also be very large like elephants, and therefore won't be inclined to be building flying machines. They could also have a geology absent of fossil fuels, no easy fuel for an industrial revolution. They may just refine a peaceful culture that's stable over longer periods of time and not particularly adventurous.
They may also not develop the right kind of intelligence. Or they may be pathologically self destructive. Our desire to explore and exploit is derived from our ancestors nomadic lifestyle. Without this background we may never have dreamed up the idea of exploring beyond our own world. So who's to stay an intelligent species would inevitably bother beaming signals out to space let alone traveling?
On earth, every single rock we look under, every tiny
After logging in slashdot still does not take you back to the page you were on. It's been that way for 20 years.