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Fermi paradox solutions

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Posted (edited)

When Fermi said that he wasn't in his finest hour, I think. It would be sad that he were remembered mostly by that.

It's very easy to rebut:

Stay in the North Pole for 10.000 years looking for camels. After that time, you haven't seen camel number one. Conclusion: Camels don't exist, because otherwise they would have reached the North Pole by then.

When you're heavily constrained in your observation, it's easy sometimes to forget that there are correlations in your observation methods, accessible places to look, etc.

Fermi's argument is called argument from silence, and it's very well known to archaeologists and historians to be seriously flawed. It is very likely that someone caught something informally muttered by Fermi and poorly thought out, IMO, and then went nuts with it.

The argument from silence can sometimes be used --with extreme care-- if you are reasonably sure that your observation method is not biased.

Another example: Marco Polo didn't mention the Great Wall of China. That doesn't mean it didn't exist back then.

Edit. Another example: Aliens in the opposite spiral arm of the Milky Way could think, "I'm sure there's no life in the Milky Way besides us, because otherwise they would be here by now." But, wait, there's us, isn't there?

You can think of tens more examples like these...

Edited by joigus
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Though I am not sure we can conclude that aliens do not exist, you're right in that the fermi's paradox alone suspects that aliens do exist without any evidence and heavy claims must be supported by the one making it not the one disproving it.  This is why things like the drake equation just seem  like the product of a lot of assumptions. I see what you are saying and appreciate your input. 

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2 minutes ago, compute said:

Though I am not sure we can conclude that aliens do not exist, you're right in that the fermi's paradox alone suspects that aliens do exist without any evidence and heavy claims must be supported by the one making it not the one disproving it.  This is why things like the drake equation just seem  like the product of a lot of assumptions. I see what you are saying and appreciate your input. 

No, sorry. I wasn't clear. Fermi was skeptical of the possibility of intelligent life in the universe that would be in principle technologically capable of interstellar travel. So in that sense, Fermi's comment must have been critical or skeptical of that possibility.

While we were talking, I've searched for references to the origin of Fermi's mutterings, and it seems to have been an informal conversation of which it is by no means totally clear what he meant: https://en.wikipedia.org/wiki/Fermi_paradox#Original_conversation(s)

Then it seems that he got involved in somewhat more serious calculations and estimated the probability of interstellar travelers to be negligible. One of his arguments apparently was that the Earth is a typical planet, which we know for sure not to be true, for example.

 

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Posted (edited)
20 minutes ago, joigus said:

No, sorry. I wasn't clear. Fermi was skeptical of the possibility of intelligent life in the universe that would be in principle technologically capable of interstellar travel. So in that sense, Fermi's comment must have been critical or skeptical of that possibility.

While we were talking, I've searched for references to the origin of Fermi's mutterings, and it seems to have been an informal conversation of which it is by no means totally clear what he meant: https://en.wikipedia.org/wiki/Fermi_paradox#Original_conversation(s)

Then it seems that he got involved in somewhat more serious calculations and estimated the probability of interstellar travelers to be negligible. One of his arguments apparently was that the Earth is a typical planet, which we know for sure not to be true, for example.

 

 

I see thank you. 

Edited by compute

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You're both welcome. A couple of things more.

First, I just wanted to add that Fermi was no idiot, of course. But the assumptions he made date back to 1950. We know much more about planets now. Something we know now, for example, is that the Earth-Moon system is far from typical. The Moon is an unusually large satellite and has a rather bigger than normal stabilizing effect on the Earth's tilt. To the point that astronomers are starting to look upon the Earth-Moon system as a binary planetary system, rather than a standard planet and its small satellite or group of satellites. The huge tidal effect that the Moon has on the Earth is believed to have played a major part in the origin of life at least during the first billion years, stirring the chemicals dissolved in water and thus triggering volume reactions (much quicker and efficient) rather than surface effects.

https://www.space.com/12464-earth-moon-unique-solar-system-universe.html

Another factor is the presence of outer giants like Jupiter and Saturn, for billions of years playing the role of shuttles for asteroids from the Kuiper belt, etc. Water and amino acids in the asteroids are also thought to have been very important. In case any of these factors were found to be essential to the appearance of life, it could be a basis to estimate the number of solar systems in the Milky Way that satisfy similar conditions. Would other different sets of conditions be just as good, or maybe even better? I don't know. I don't know if anybody knows.

Drake's equation came later than Fermi's argument (in 1961). Actually, I think Drake's equation is a more promising ground for estimating the chance of there being intelligent life forms, among other things, precisely because, although ambitious, it's a much less assuming parametrization of the probability, rather than an equation or a "closed" calculation. There is room for re-estimating the factors as we learn more about the phenomenology of galactic (or extra-galactic) solar systems. Plus the last factor is, if I'm not mistaken, the probability that a civilization will be able to send signals, rather than travel to Earth, which significantly increases the odds. Fermi was concerned with interstellar travel, AFAIK.

The detection of signals with a message in them will probably be the first evidence, if there ever is one, of some form of intelligent life besides us in the universe, rather than the flight of UFOs.

But here's the bad news, IMO:

Take a look at this table with time gaps separating the appearance of new levels of organization:

First prokaryotes (from Earth's formation): 1 billion years

First eukaryotes (from prokaryotes): 800 million years

First multicellular eukaryotic organisms (from single-celled eukaryotes): 2 billion years

First intelligent life (from multicellular eukaryotes): 700 million years  

Average for the appearance of a new level of organization: 1.125 billion years

Now suppose there's a planet out there with something like eukaryotes (cells with a nucleus). You're going to have to sit there waiting for 1.1 billion years for you to see anything interesting to happen if the above table is anything to go by. That's the problem.

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Very interesting joigus, welcome aboard.

We don't know anything about interstellar travel.  Maybe it is far more difficult than we imagine.  Maybe intelligence is much scarcer than we can imagine.  Suppose there was an ET that was so advanced that they could travel here.  They would more likely send robotic probes.  Why would they want us to know about them?  With their advanced technology, they could easily conceal themselves from us.  Why would any ET civilization advertise their position in space or allow themselves to be seen?

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1 hour ago, Airbrush said:

Very interesting joigus, welcome aboard.

We don't know anything about interstellar travel.  Maybe it is far more difficult than we imagine.  Maybe intelligence is much scarcer than we can imagine.  Suppose there was an ET that was so advanced that they could travel here.  They would more likely send robotic probes.  Why would they want us to know about them?  With their advanced technology, they could easily conceal themselves from us.  Why would any ET civilization advertise their position in space or allow themselves to be seen?

Thank you. Yes, exactly. Yesterday night, while I was watching a documentary on the topic, I started thinking about something very similar, to what you're saying, although with respect to the signal sending/detecting problem, instead of the interstellar travel.

It doesn't seem to occur to anyone to invest effort and resources to send signals around in all directions in order to increase the chances for possible ET civilizations to detect us. Would we want to do that? My instinct is that life anywhere is bound to be very cautious and tend to listen, probe and grope in the dark rather than be loud and proclaim "Hey, we're here!" My best guess is that there are probably some other ears in the universe listening in the silence and eyes watching in the dark. Maybe not many, but none very interested in being detected themselves.

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