What are the realistic odds that another planet exists in another galaxy with intelligent life?

Answer 1

Well, life has existed on our planet for about 4 billion years. Intelligent life (as defined by us, of course) has been around less than a million. If you want technological life, it has been around only a couple hundred years. There are approximately 200 billion stars in our galaxy, but only about 1/40 are of a type (like our sun) which would both last long enough for life to develop and be hot enough to power the reaction for life. That leaves about 5 billion stars. We don't know what percentage of these have planets, nor what percentage of those that have planets have them the right distance away from the star. An optimistic guess of 1/10 for each of these gives about 50 million stars with planets the right distance from their star.

Now we have to guess how likely it is that life has evolved. Given how fast it happened on arth, this is probably fairly likely, say another 1/10 for 5 million stars with life. Then we have to ask how many of those could evolve intelligent life. This seems to be a hard thing given how long it took on Earth. The ratio on Earth has been less than 1 in 4000. This gives about 1250 planets that could have developed intelligent life. If you require technological life, that 1 in 4000 becomes closer to 1 in 10 million and we get a 50-50 chance of another technological species developing.

Now the kicker. How long does technological life last once it evolves? My (perhaps pessimistic) guess is less than 10,000 years. Now what is the probability that we will overlap in our 10,000 years with another civilization's 10,000 years? Again, this is out of a period of several hundred million years, if not billions of years, so this reduces the chance that another technological civilization exists *right now* in our galaxy to less than 1 in 20,000. If all you require is intelligence, it makes a guess of perhaps 1 or two other intelligent races existing right now.


Of course, ALL of this is simply guesswork. We don't really understand the conditions needed for life, let alone intelligent life or technological life to develop. But it does make it seem unlikely that we will be in contact with other species during our 10,000 years.

Answer 2

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Answer 3

The "realistic odds" are excellent in favor of this. There are several tricky parts to work out in making the estimate, but as the number of planets you allow increases, so do the odds of there being intelligent life. (I didn't say communicating with them, just that they would exist).

We're still grappling with what "intelligence" really is, and this is not so easy to figure. It appears to be what's called an emergent property (something like birds flying in massive, undulating formations, etc) and that cannot be recognized by studying any single member of a group. If that's true, then who says other intelligences have to be like our own? Who says they even WANT to communicate? Also, just to be detected, they have to have mastered enough technology to make radio sets...so we can detect a signal. BUT that signal has to be able to reach us, at the speed of light, within a time frame that makes our communicating with them possible. Someone on a planet a million light years away isn't going to be able to be your new favorite pen pal.

Still, the odds of intelligent life out there are really, really good.

Answer 4

Darrell C.:

When you say, "...another planet exists...with intelligent life" you are making the daring assumption that this one, the planet earth, harbors something near or akin to "intelligent" life. There are, no doubt, many a discipline that might argue this point with you. But that is something for discussion another day.

However, your question, for unknown reasons did not include our own Milky Way Galaxy. Perhaps your intent was to say, another solar system.

Be that as it may, I suggest that you do a Yahoo Search for 'The Drake Equation'. The Drake Equation provides a disciplined mathematical model for such potential estimates as the probability of intelligent as well as technologically developed otherworldly civilizations.

The explanation is far too lengthy to reproduce here, but the following web site may be a fun place for you to begin:

http://www.activemind.com/Mysterious/Topics/SETI/drake_equation.html

Hope this will help you!

Answer 5

"The Drake Equation was developed by Frank Drake in 1961 as a way to focus on the factors which determine how many intelligent, communicating civilizations there are in our galaxy. The Drake Equation is:

N = N* fp ne fl fi fc fL
The equation can really be looked at as a number of questions:

N* represents the number of stars in the Milky Way Galaxy
Question: How many stars are in the Milky Way Galaxy?
Answer: Current estimates are 100 billion.
fp is the fraction of stars that have planets around them
Question: What percentage of stars have planetary systems?
Answer: Current estimates range from 20% to 50%.
ne is the number of planets per star that are capable of sustaining life
Question: For each star that does have a planetary system, how many planets are capable of sustaining life?
Answer: Current estimates range from 1 to 5.
fl is the fraction of planets in ne where life evolves
Question: On what percentage of the planets that are capable of sustaining life does life actually evolve?
Answer: Current estimates range from 100% (where life can evolve it will) down to close to 0%.
fi is the fraction of fl where intelligent life evolves
Question: On the planets where life does evolve, what percentage evolves intelligent life?
Answer: Estimates range from 100% (intelligence is such a survival advantage that it will certainly evolve) down to near 0%.
fc is the fraction of fi that communicate
Question: What percentage of intelligent races have the means and the desire to communicate?
Answer: 10% to 20%
fL is fraction of the planet's life during which the communicating civilizations live
Question: For each civilization that does communicate, for what fraction of the planet's life does the civilization survive?
Answer: This is the toughest of the questions. If we take Earth as an example, the expected lifetime of our Sun and the Earth is roughly 10 billion years. So far we've been communicating with radio waves for less than 100 years. How long will our civilization survive? Will we destroy ourselves in a few years like some predict or will we overcome our problems and survive for millennia? If we were destroyed tomorrow the answer to this question would be 1/100,000,000th. If we survive for 10,000 years the answer will be 1/1,000,000th.
When all of these variables are multiplied together when come up with:
N, the number of communicating civilizations in the galaxy. "
----SETI


Try out the equation yourself at the reference link.

Answer 6

The odds are extremely high given the number of planets/stuff out there and the time for life to develop.

That being said, I'm sure it's very different from what we see here on earth since the conditions would be very different.

Answer 7

There Are Probably enough Planets In Our Galaxy , That possess Intelligent Life

i will ask an alien Next time I See Him / Her

Answer 8

The equation for estimating this this is called Drakes equation.

The real question is what are the odds that we have an intelligent life form on this planet?

Answer 9

I don't think we have enough information even to calculate the odds very accurately, but from the sheer numbers involved I'd bet my dessert that there are LOTS of inhabited planets. Out of those, I'd expect maybe one of every million or so to be inhabited by what we'd call intelligent life. Intelligent meaning no professional wrestling or gangsta rap.

Answer 10

There are 100 thousand million stars in the Milky Way and assuming that, like us, each star has one planet with intelligent life, there should be 100 thousand million planets with intelligent life in the Milky Way alone...