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."

Comments

What a great example!

[Frequency Domain]

...of spurious precision.

Re:What a great example!

[Sockatume]

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.

Re:What a great example!

[JasterBobaMereel]

This is the problem with the Drake equation

    Most of the factors are not known to any great precision

    Most of the last factors are not known at all ...since we only have one example, us.

With it you can prove that there are a vast number of civilisations or none just as easily

    There are currently 53.4565452112323(56) civilisations in our galaxy ....

 

Re:What a great example!

[ciderVisor]

Base 13 ?

My estimate

[MyLongNickName]

1.

And it is as valid as this astronomer's estimation.

Re:My estimate

[elrous0]

I wish I had mod points. There is simply no way to arrive at any meaningful number based on what we know right now (which is very little). Until we can accurately understand how life even began HERE, there is no way to know how common or uncommon this occurrence is across the galaxy.

The real answer

[SmallFurryCreature]

We just don't have a clue.

The number of things we don't have a clue about is staggering.

• The number of planets that can support life. We just don't know, we presume we have observed some planets but they might be failed stars and have no direct observations for far.
• We don't know exactly where life can and cannot occur. For that matter, we only have our own planet to judge what is alive and what isn't. There is no prove one way or another that oxygen is needed for instance to create life.
• We don't know if space travel between stars is possible. Faster then light travel would change the rules as any species with such tech could settle countless planets and perhaps wipe out other civilizations OR seed them (Star Trek).
• We don't know how life starts. Was life started on earth or did it arrive from somewhere else? Huge difference between life starting on its own on every planet OR there being some galaxy wide single seed.

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+.

Re:The real answer

[mcgrew]

There is no prove one way or another that oxygen is needed for instance to create life

Incorrect. Life caused the Earth's atmosphere to have oxygen. There are still life forms here that oxygen is a deadly poison to.

Advanced?

[i_ate_god]

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.

Re:Advanced?

[AdmiralXyz]

I think there's also the possibility that there HAVE BEEN more advanced civilizations in the past, but they're gone now. Think about it: the Milky Way is what, nine billion years old? Humans have only existed for a minuscule fraction of that time, and humans capable of detecting advanced civilizations for a smaller fraction still. Perhaps many such civilizations have existed throughout the history of our galaxy, but we keep "missing each other on the timeline."

As always, no.

[khasim]

And yes, in this case, absence of evidence *IS* evidence of absence.

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.

My assessment

[MyLongNickName]

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.

Re:My assessment

[MyLongNickName]

And since you miss the big point, I will spell it out.

A polar bear is using the limits of his logic to speculate on the world as a whole. Had an intelligent bear been allowed to travel the world, he would see where his equation breaks down.

An intelligent human attempts to speculate about the universe as a whole. He is smart enough to realize that he has no clue about how often intelligent life occurs on "habitable" worlds, so he plugs in a variable, then proceeds to put in numbers for something he has no clue about. Since it is unknown, his number is bullshit. Drake realized this, but countless amateurs have treated these numbers as the gospel and wildly speculated about the unknown. this in and of itself isn't bad. However when folks put weight on these numbers, it is bad.

Just as the polar bear has no real clue about the planet it lives on, we have no clue about the universe we live in. I hope that as a civilization that we go out and really begin to explore this place. But as long as we are sitting here on earth, killing each other, and wasting resources on there here and now, we cannot jope to fathom the way the universe truly is.

Close neighbors?

[JoeMerchant]

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...

Aliens Cause Global Warming

[ciderVisor]

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.

Re:Aliens Cause Global Warming

[ciderVisor]

His criticism of the Drake equation is even less well informed, in that he's criticising the equation itself, not the parameters that go into it. But the equation is trivially true; it's nearly a tautology. If the correct statement is "we don't know", it's not because the equations wrong, it's because we don't know what values go on the right side.

From Crichton's piece:

"The problem, of course, is that none of the terms can be known, and most cannot even be estimated. The only way to work the equation is to fill in with guesses."

He IS talking about the parameters (on the right side). Your criticism is meaningless.

In short, Crichton should stick with novels, which he's good at, and not critiquing SETI, something he seems to know little about.

Hehehe. Marvelous. Keep it up.

Re:Aliens Cause Global Warming

[Kjella]

"The problem, of course, is that none of the terms can be known, and most cannot even be estimated. The only way to work the equation is to fill in with guesses."

He IS talking about the parameters (on the right side). Your criticism is meaningless.

No, he also says "Speaking precisely, the Drake equation is literally meaningless, and has nothing to do with science." and that I disagree with. Let's say you want to find the population development, and find the formula: population[n+1] = population[n]*(1+birth rate-death rate)+immigration-emigration. Then we investigate these factors and realize that we don't have enough data to tell us anything useful. Is it then unscientific because we never actually got an answer? No, we took a complex question and decomposed it into simpler questions that can be investigated individually in a very scientific way. We are probably a lot more certain we can't answer the question than before. That kind of meta-knowledge is very important and useful as building blocks to make new experiments to find out. Of course, wild ass guesses and saying there's 37,964 ET civs is unscientific, but he's throwing the baby out with the bathwater.

Re:Fermi paradox

[scribblej]

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.

Re:Only 37,964?

[Kjella]

Because if our little planet is anything to go by, a single species can have multiple civilizations, concurrently.

Based on how alien alien civilizations probably are, I imagine everything from Wall Street to bush men will fall under "human civilization" and the point you're trying to make would look as meaningless as saying you and the guys on the other side of town live in different civilizations.