More than 4.500 extraterrestrial civilizations in the Milky Way?

At Last, How Many Alien Civilizations are There?

This is the title of a new paper published few days ago on astrobio.net

New data from the Statistical Drake Equation (SDE - which is an alteration by an Italian astronomer, Claudio Maccone, of the famous Drake Equation) suggest that thousands of advanced technological societies could exist in our Galaxy.



Here's what Drake's equation said, back in 1961:

N = Ns x fp x ne x fl x fi x fc x fL

N = number of alien civilizations in the Milky Way
Ns = estimated number of stars in the Milky Way;
fp = fraction or percentage of these stars with planets on its orbits;
ne = average number of these planets with potential to host life as we know it;
fl = percentage of these planets that actually develop life;
fi = percentage of these planets that actually develop intelligence on human level;
fc = percentage of these civilizations that actually develop electromagnetic radiation emitting technologies;
fL = percentage of these civilizations that keep emitting electromagnetic signals to space. This factor is extremely dependent on the lifetime a civilization remains electromagnetic communicative.



The new Statistical Drake Equation (SDE) of Maccone, is mathematically more complex and robust than the Classical Drake Equation (CDE):

The SDE is based on the Central Limit Theorem, which states that given the enough number of independent random variables with finite mean and variance, those variables will be normally distributed as represented by a Gaussian or bell curve in a plot. In this way, each of the seven factors of the Drake Equation become independent positive random variables. In his paper, Maccone tested his SDE using values usually accepted by the SETI community, and the results may be good news for the “alien hunters”.

Although the numerical results were not his objective, Maccone estimated with his SDE that our galaxy may harbor 4,590 extraterrestrial civilizations. Assuming the same values for each term the Classical Drake Equation estimates only 3,500. So the SDE adds more than 1,000 civilizations to the previous estimate.

Another SDE advantage is to incorporate the standard variation concept, which shows how much variation exists from the average value. In this case the standard variation concept is pretty high: 11,195. In other words, besides human society, zero to 15,785 advanced technological societies could exist in the Milky Way.

The whole paper explain as well, with one of the consequence of the SDE use, why the “Great Silence” detected by our radio telescopes is not discouraging at all.

This is interesting, but proves nothing... yet?

Thanks for the read.

Because we dont know how easy it is for life to spontaneously start in the first place many of the values for the variables of the drake are just guesses based on nothing solid.

All the life on earth we have ever observed came from a single common ancestor. The birds , fish, humans, plants and viruses all are related. Until we can find a form of life on this planet that doesnt fit in the family tree we can even begin to guess the values for the last 4 variables in the drake equation , fl, fi , fc & fL.

fl = the fraction of the above that actually go on to develop life

all terrestrial life stems from a common origin. If abiogenesis were more common it would be speculated to have occurred more than once on the Earth. Scientists have searched for this by looking for bacteria that are unrelated to other life on Earth, but none have been found yet. It is also possible that life arose more than once, but that other branches were out-competed, or died in mass extinctions, or were lost in other ways. Biochemists Francis Crick and Leslie Orgel laid special emphasis on this uncertainty: "At the moment we have no means at all of knowing" whether we are "likely to be alone in the galaxy (Universe)" or whether "the galaxy may be pullulating with life of many different forms.".

So the old and the revised formula is saying there could be n amount of alien civilizations out there IF a bunch of numbers are correct but in all honesty we have not got a clue if they are correct and have no evidence to even point to them being correct. So it really proves nothing, its a fun but pointless formula.

I have to agree with Pheonix - these are scientific guesses - we know nothing of extraterrestrial civilizations in the Milky Way.. yet.

Interesting and fun, but, we've still yet to hear anything from anyone else, or see any indication that there's an anyone else out there to hear anything from.

Earth is lonely.
We want friends.

reply to post by Philosophile

Of course you're right, it doesn't prove anything, and it can never prove anything. Allow me to quote from the white paper linked in the OP:

Looking to the Drake equation factors, it is obvious that none can be precisely determined by modern science. More than that, as we move from the left to right in the equation, estimating each factor becomes more controversial. The later terms are highly speculative, and the values one may attribute to each of them might tell more about a person’s beliefs than about scientific facts.

The article goes on to say that even accepting Drake's numbers, the huge standard deviation means that the correct answer is between 0 and 15,000+.

It's a fun idea used to think about the factors involved in finding an alien civilization, but it's certainly not proof of anything.

Originally posted by charles1952
reply to post by Philosophile

 

Of course you're right, it doesn't prove anything, and it can never prove anything. Allow me to quote from the white paper linked in the OP:

Looking to the Drake equation factors, it is obvious that none can be precisely determined by modern science. More than that, as we move from the left to right in the equation, estimating each factor becomes more controversial. The later terms are highly speculative, and the values one may attribute to each of them might tell more about a person’s beliefs than about scientific facts.

The article goes on to say that even accepting Drake's numbers, the huge standard deviation means that the correct answer is between 0 and 15,000+.

It's a fun idea used to think about the factors involved in finding an alien civilization, but it's certainly not proof of anything.

Ah, okay. Thank you for that clarification. I suppose the only way we'll ever really know is when we're able to observe them. I wonder if the world really is prepared enough though to have factual evidence to the existence of extraterrestrials.

I actually dislike this equation because it has too many unknown variables which put it squarely in the pure speculation category. Then it's used as some kind of "proof" when it is anything but.

N = Ns x fp x ne x fl x fi x fc x fL

N = number of alien civilizations in the Milky Way

Ns = estimated number of stars in the Milky Way; (we kinda know but still estimated)

fp = fraction or percentage of these stars with planets on its orbits; (estimated, we haven't surveyed every single square inch of the universe)

ne = average number of these planets with potential to host life as we know it; (unknown)

fl = percentage of these planets that actually develop life; (completely unknown, could be none, could be all)

fi = percentage of these planets that actually develop intelligence on human level; (completely unknown, could be none, could be all)

fc = percentage of these civilizations that actually develop electromagnetic radiation emitting technologies;(unknown)

fL = percentage of these civilizations that keep emitting electromagnetic signals to space. This factor is extremely dependent on the lifetime a civilization remains electromagnetic communicative. (unknown)

And I see others have the same thoughts as me...

They have folks looking here Project Argus: What We've Heard So Far with some "weird hits" I went over there and checked out a few (because of your thread) and found that we may being getting "hits" alot! Heres
one:last updated 22 September 2012 -I bet that some things are going on behind the scenes but, these folks...take forever ha ha ha ..to let us know..if they will let us know

Peter Cheasley, VE2TPR, detected this narrow-band signal component, standing out clearly against the background noise, on 3500 MHz, from RA 23:58:46, Dec 44d 05m N, at 0113 UTC on 8 November 2003. The spectral display is exactly what we would expect from an unmodulated carrier such as might be emitted by an interstellar beacon. Unfortunately, without independent corroboration or a repeat of the signal, further analysis is not possible, and we can only speculate as to the signal's true origin.

more here www.setileague.org... and here www.setileague.org...

Originally posted by Druscilla

Interesting and fun, but, we've still yet to hear anything from anyone else, or see any indication that there's an anyone else out there to hear anything from.

Earth is lonely.
We want friends.

Sure, but the SDE equation provides an interesting insight about this "Great Silence", using a Gaussian (that derives from this equation) showing that the probability of finding the nearest extra terrestrial civilization from Earth is close to zero up to 500 light-years away from Earth:

500 light-years away, the chance of detecting any signal from an advanced civilization approaches zero. And that is exactly the range in which our present technology is searching for extraterrestrial radio signals. So, the “Great Silence” detected by our radio telescopes is not discouraging at all. Our signals just need to travel a little farther – at least 900 light years more – before they have a high chance of coming across an advanced alien civilization.

Originally posted by PhoenixOD

All the life on earth we have ever observed came from a single common ancestor.

now you're making stuff up. what is this mysterious beast that turned into 8.7 million different species that live on earth.

and this scientist just made up a formula and randomly guessed every number in his equation. its impossible to know without go out there.

by out there i mean space.

This proves nothing. However, I think it’s very naive and a bit self absorbed to believe that there’s nothing else out there. Considering the sheer size and age of the universe, there just has to be other intelligent life out there somewhere. Surely we are not it.

Seti is the BIGGEST joke out in the UFO field.. They keep putting up Satellite Dish's listening for Frequencies.. When alien messages are sent through beams of light.. something the NSA has known for over 40 Years.. I always thought that douch who talks for seti is a paid Govt. disinformation officer..

reply to post by randomname

now you're making stuff up. what is this mysterious beast that turned into 8.7 million different species that live on earth.

Its called DNA , look it up

reply to post by elevenaugust


What I'm getting from your reply is that we need to wait almost a whole millenium for our light-speed slow radio bubble to propagate out into a larger expanse with a higher probability of detection from other civilizations.

That's 'them' detecting us though, isn't it?

Certainly were there a culture broadcasting EM/RF while we were still smearing ourselves with mud before the invention of pants, those signals would be in the higher probability range you speak of and boinking into our receivers by now, no?

Certainly it's no recipe for two-way Howdy Neighbor contact, but, some stray bit of what would now be thousands of years retro from the origin point would at least give us a nice bit of Olympic level eyebrow raising.

It's pretty simple.



If they are out there then we will eventually find them or they find us. Until then though, we wait.

Great read to by the way. S/F

-SAP-

The fraction of planets that develop life is the key factor for me in the continuing exploration of Mars and other planets in our solar system. If life is found on another body in the solar system that I would suggest that means that pretty much every star system will be teeming with life, and that will increase the chances of a handful of those planets where something more interesting than a slime mould on a rock, not that there is any wrong with that, develops that creates it's own civilisation.

What happened to the big announcement from NASA and Curiousity? I saw the hoax about plastic, but has there been any other development or news I may have missed in the last couple of days?

I thought this was an interesting estimate of alien civilizations for the Milky Way. I also noted the comment about an estimated "40 billion habitable worlds" in the galaxy as well, but that differs from the estimate I have heard some scientists say of around 100 million habitable planets estimated in our galaxy. Its just a guess though, there may be way more or way less. I think personally there are more.

a reply to: data5091


This is a two year old thread, in the meantime (yes, in only two years!) we made a lot more,astonishing discoveries such as exoplanets and that basically EVERY star has planet systems. Our knowledge there changes incredibly fast.

It was by coincidence just a day or so ago I read some article and as far as I remember, they mentioned BILLIONS (!) of potential earth-like planets in our galaxy alone. Of course we don't know how many of them will have life and how many of them will have "civilizations". That 4.500 number may just be well off.

At this point in time, our knowledge status quo is really that if you look up to the sky, pick ANY random star, chances are you DO in fact also look at some planets and many of them may well be "earth-like". Just a few years ago we didn't even know that.

a reply to: elevenaugust

fl = percentage of these planets that actually develop life;
fi = percentage of these planets that actually develop intelligence on human level;

How do you even come up with a number to insert here?

We can "predict" all we want or come up with equations or whatever....Until we find something this is all nonsense..IMO of course