- #36
DaveC426913
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No, that's the probability of you not reading the opening post.Dickfore said:It's 1 ...
...the probability of having life on other planets..
No, that's the probability of you not reading the opening post.Dickfore said:It's 1 ...
...the probability of having life on other planets..
Did you see the reason for deletion? Instead of the op, I saw the first post on the 3rd page.DaveC426913 said:Ahahah. too late. I saw that.
Chronos said:I like the idea of a high probability of life anywhere liquid water is found, and an extreme probability where oxygen exists in the atmosphere of an exoplanet. Both are the subject of study by exobiologists. Evidence of liquid water has already been found on the moons of Jupiter and Saturn. An undersea volcano would provide sufficient energy to fuel carbon based life forms. Current evidence suggests this is how life originated on earth. It is unlikely any element other than carbon would permit the complex molecules necessary for life. Silicon runs a very poor second.
ranrod said:Thinking about this makes my head spin!
From the 200 billion stars in the milky way, how many planets on average for each? From the ones with planets, how many are stable solar systems? From those, how many will remain relatively uninterrupted for billions of years (not only the central star(s) but uninterrupted from outside-the-solar-system influences)? From those how many have a 'free' goldie locks area (no asteroid fields, no collisions for billions of years, no gas giants, no highly elliptical or irregular orbits)? From those how many have giant outside planets, such as Jupiter and Saturn that shield the life-bearing planets from asteroids and other planet killers? From those how many have a lot of water? From those how many have the other ingredients for life?
I can see the 200 billion stars yielding zero or a handful of candidates before we even ask if intelligent life can arise in them.
I'd like to know when do we think scientists will be able to come up with a more accurate estimate? 100 years from now? 50? 25?
baywax said:Like Dr. Stephen Hawking says, intelligence may not be the ultimate result of evolution and may actually be a mutation that hinders the survival of our species. This may not bode well in the search for other intelligent beings. He does hold out hope of finding life on other planets mind you.
ranrod said:That statement may work locally, but bacteria (used in his example) can't see the giant asteroid that will wipe out the planet. Intelligence allows us to protect Earth, as well as make other homes elsewhere in the galaxy (though we may not be doing a good job at either). Besides, on what grounds could we claim there's an ultimate goal to evolution? I can make the converse case - what good are all the amazing wonderments of the universe if there's no one out there to comprehend them?
... The reason is that living systems are so much more complex than any inanimate objects; a potted plant is more complicated than the most splendid galaxy.
Gannet said:Here is another site I found on this subject which I like. http://www.tufts.edu/as/wright_center/cosmic_evolution/docs/fr_1/fr_1_chem.html"
In section Qualities of Life it makes the following profound statement
Dmitry67 said:My view is pessimistic: We exist, and probability of life in INFINITE Universe is 1...
Chronos said:I like the idea of a high probability of life anywhere liquid water is found, and an extreme probability where oxygen exists in the atmosphere of an exoplanet.
DaveC426913 said:Can you clarify? It seems you are saying that life should have a high probability of forming where there is oxygen.
IIRC, oxygen is not a requirement for life; life on Earth started in a CO2 and ammonia atmo.
The reason exobiologists are interested in it is because its presence in an atmo is a sign of life - but it is a waste product.
So the cause-effect relationship is the other way 'round: first life, then oxygen.
phyzguy said:The problem with this figure is that the size of the boxes are complete guesses. We have a pretty good idea of the number of stars with planetary systems, but most of the other probabilities, such as:
(1) the probability that a planet is habitable, or
(2) the probability that if it is habitable that it has life, or
(3) the probability that if it has life that it has intelligent life
are complete guesses. Today we have no idea if these probabilities are 1 in 100 or 1 in 10^100.
DaveC426913 said:Well not quite. We know that the worst the odds can possibly be at the highest level are 1 in 10^11 (one example in 500 billion stars).
Your wording was a bit ambiguous.phyzguy said:How do we know that? Are you basing it on the fact that there is intelligent life on Earth? We cannot draw conclusions of the probability of an event based on one example.
DaveC426913 said:You were suggesting that the chances of any given planet in our galaxy being habitable could be as low as 1 in 10^100. I am simply saying that the odds for life on a a planet in the galaxy cannot be worse than 10^11, because in the sample 500 billion so far, we've found one example.
Dmitry67 said:This is true only if most of galaxies have life at least on one planet!
You are assuming that the choice of our galaxy is random,
DaveC426913 said:I am simply saying that the odds for life on a a planet in the galaxy cannot be worse than 10^11, because in the sample 500 billion so far, we've found one example.
phyzguy said:You simply can't make probability arguments like this based on one data point. What you are saying is equivalent to the following reasoning:
(1) I deal out two poker hands. One is a royal flush.
(2) Therefore the odds of dealing a royal flush are at least 50%.
DaveC426913 said:I am simply saying that the odds for life on a a planet in the galaxy cannot be worse than 10^11, because in the sample 500 billion so far, we've found one example.
But we have only been talking about our galaxy.Dmitry67 said:Our galaxy is SPECIAL because WE are there.
Imagine that probability of life is 10^-200 per planet
So only one of 10^-189 galaxies has life
Observer in that galaxy (based on your logic) would conclude that life is very likely event - because in his sample (one galaxy) there is life.
That is not a flaw.phyzguy said:There are three problems with your argument. First, we have not examined 500 billion star systems and determined that only one has life. We've only examined one star system.
Also not a flaw.phyzguy said:Second, by your argument, why stop with only the galaxy?
Hang on. You've twisted the analogy. You're not comparing apples to apples.phyzguy said:the fact that we only have one example means that the uncertainty in the estimate (which is proportional to the square root of the number of observations) is equal to the estimate itself. Back to my royal flush analogy. If I have two poker hands, and one is a royal flush, I can say that the odds of a royal flush are 50% +/-50% - in other words I know nothing about the odds of a royal flush. That is the situation we are in.
DaveC426913 said:I am simply saying that the odds for life on a a planet in the galaxy cannot be worse than 10^11, because in the sample 500 billion so far, we've found one example.
Dmitry67 said:If we randomly pick any planet in OUR galaxy, the probability that there is life on is >10**-11 - TRUE
If we randomly pick any planet, the probability that there is life on is >10**-11 - FALSE
In general, this number (10^11) is absolutely useless, because it does not give us any estimation about how rare is the life in the Unvierse.
Dmitry67 said:In general, this number (10^11) is absolutely useless, because it does not give us any estimation about how rare is the life in the Unvierse.
phyzguy said:However, this tells us NOTHING about how many OTHER aces are in the deck.