Author Topic: The Fermi Paradox  (Read 8588 times)

rkbabang

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Re: The Fermi Paradox
« Reply #20 on: July 28, 2015, 09:26:27 AM »
Maybe that is the great filter.

Anybody who posits a "Great Filter" has to remember that it has to be very very good filter. There are billions of stars/planets. There's also billions of years in development. So "Great Filter" has to be something on the order of 1B:1 if not stronger.

Most of the filters proposed here and elsewhere are much more leaky IMO.


There could be multiple filters.  What if only 1 in a billion planets which can support life ever develop it.  What if 1 in a billion planets which have life ever develop multicelled organisms.  What if 1 in a billion planets with multicelled organisms ever develop a species with a large brain.  What if 1 in a billion species with large brains have appendages able to grasp tools.  What if 1 in a billion of those species has the right combination of smarts/crazy/rebelliousness to build a technological civilization.  What if only 1 in a billion technological civilizations fail to destroy themselves before discovering faster than light travel, .... and on and on.

There could be a great number of filters all put together comprising a Great Filter.


yadayada

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Re: The Fermi Paradox
« Reply #21 on: July 28, 2015, 09:36:10 AM »
Yeah from watching cosmos I got that there were early human like creatures that would make tools and would be more advanced then chimps. But they were very focused and specialized in certain things and could not adapt quickly. They had an edge on early humans that were like us (that were not very specialized).  Then conditions on earth became more harsh (or just harsh enough?) and only the creatures that would constantly adapt to new climates and environments could survive (us). And the very fixed creatures who specialized but could not change their ways quickly did not survive.

So you have to wonder how much more harsh could things have been before we would have died out? What does that bell curve look like? Where a certain type of harshness produces us? A bit less harsh and you get bad adjusters that take way too long to change their ways and a bit too harsh and you get more extreme humans that are more violent (because of the lack of resources + hostile nature), or a quick extinction altogether?

So you might need a white star like us (only 10-20% in the universe?). You need a planet circling it in stable orbit for at least 1-2  billion years or so. It would have to be in a relative quiet area in the universe without gamma rays (that would rule out a lot of sun like stars).

And then you would need all kinds of  natural selection filters that last just long enough and are just extreme enough to produce the kind of intelligence that can figure out how to cross to other star systems.

Finally you would need a certain amount of resources like metals and fossil fuels. What if there are too many fossil fuels? There might not be enough pressure to find alternatives. Too little and you might run out too soon and it could destroy civilization.

It would have to have the right amount of gravity. Who says that you could get enough info to advance tech without the info our hubble telescope provided about the universe?

Or how about this, without satellites the cold war might have went different? As that provided a big break through in intelligence for the allies. So you would have to avoid an extinction event there.

And we are scared of nukes now, but what if we invent a new energy source that is even more powerful and can use anything as fuel? It might become suddenly much easier to build powerful bombs.

And finally you would have to assume faster then light travel is possible in theory. Our galaxy is about 100k light years across. So 50k light years from us there might exist a massive advanced multiplanetary civilization that possibly knows of our existence (that would be very hard though, since they cannot see us yet)? But they think we are too far away to bother visiting if they would have powerful enough telescopes.

So if there are a 100 billion habitable planets with intelligent life in our universe that is only one planet per galaxy on average. So odds are very low of meeting in that case, despite having a 100 billion planets with inteligent life!

Even if there were 10 or 20 in our galaxy, on average they could be too far away to practically meet.
« Last Edit: July 28, 2015, 09:39:53 AM by yadayada »

Jurgis

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Re: The Fermi Paradox
« Reply #22 on: July 28, 2015, 10:14:04 AM »
There could be multiple filters.  What if only 1 in a billion planets which can support life ever develop it.  What if 1 in a billion planets which have life ever develop multicelled organisms.  What if 1 in a billion planets with multicelled organisms ever develop a species with a large brain.  What if 1 in a billion species with large brains have appendages able to grasp tools.  What if 1 in a billion of those species has the right combination of smarts/crazy/rebelliousness to build a technological civilization.  What if only 1 in a billion technological civilizations fail to destroy themselves before discovering faster than light travel, .... and on and on.

There could be a great number of filters all put together comprising a Great Filter.

There could be.

Just to note that so far some filters are shown to be more leaky than expected before. E.g. the number of planets is much higher than expected before. The number of planets in "life zone" is much higher than expected before.

Some of the filters you mention are addressed in the studies and are much leakier than you suggest.

But for some probabilities are not known and cannot be easily known until we find life/etc. in other planets/stars. So you might be right about them.
"Before you can be rich, you must be poor." - Nef Anyo

boilermaker75

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Re: The Fermi Paradox
« Reply #23 on: July 28, 2015, 10:54:18 AM »

So you have to wonder how much more harsh could things have been before we would have died out? What does that bell curve look like? Where a certain type of harshness produces us? A bit less harsh and you get bad adjusters that take way too long to change their ways and a bit too harsh and you get more extreme humans that are more violent (because of the lack of resources + hostile nature), or a quick extinction altogether?


Any harsher and it would have been over. From our DNA it has been determined that the human population was once reduced to less than 1,000 reproductive adults. This near extinction event was the eruption of the volcano Toba on Sumatra.

Pelagic

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Re: The Fermi Paradox
« Reply #24 on: July 28, 2015, 11:30:40 AM »
Multiple filters combined with the vastness of space is in my opinion why we haven't found anything, yet. I'd also wager that our first contact with an intelligent civilization goes something like when European explorers encountered Native Americans, with humans playing the role of the Europeans.

I saw this about an asteroid with more than $5 trillion of platinum making a pass near Earth. Once space starts to become profitable I think we'll see a tech boom that leads us to at the very least operating throughout our solar system. This leads to another possible filter, space is likely filled with numerous uninhabited solar systems, a space-faring race would have to pass up 100s of resource rich systems on its way to us. Even if they knew of us, why make the trip, our solar system probably isn't all that special, if you're capable of getting here there are likely many others closer.

http://www.forbes.com/sites/ericmack/2015/07/19/trillion-dollar-baby-asteroid-has-wannabe-space-miners-salivating/

rkbabang

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Re: The Fermi Paradox
« Reply #25 on: July 28, 2015, 11:45:17 AM »
Multiple filters combined with the vastness of space is in my opinion why we haven't found anything, yet. I'd also wager that our first contact with an intelligent civilization goes something like when European explorers encountered Native Americans, with humans playing the role of the Europeans.

I saw this about an asteroid with more than $5 trillion of platinum making a pass near Earth. Once space starts to become profitable I think we'll see a tech boom that leads us to at the very least operating throughout our solar system. This leads to another possible filter, space is likely filled with numerous uninhabited solar systems, a space-faring race would have to pass up 100s of resource rich systems on its way to us. Even if they knew of us, why make the trip, our solar system probably isn't all that special, if you're capable of getting here there are likely many others closer.

http://www.forbes.com/sites/ericmack/2015/07/19/trillion-dollar-baby-asteroid-has-wannabe-space-miners-salivating/

We could also play the role of the Europeans.  Even if there are many millions of advanced civilizations we may be the most advanced in our galaxy, so we may make first contact when we visit a less advanced species on their home planet.  There is a huge leap from travel within your solar system to travel between solar systems, there is another huge leap from there to travel between galaxies.   It is plausible that we will find less advanced life in our solar system long before an intergalactic species finds us.

Jurgis

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Re: The Fermi Paradox
« Reply #26 on: July 04, 2018, 09:14:40 PM »
Dissolving the Fermi Paradox: https://arxiv.org/abs/1806.02404

An interesting stats based paper on why there is no Fermi paradox and why we may the only civilization in our galaxy or even observable universe.

Actually authors' conclusions are pretty much based on broadness of uncertainty in one of the parameters in Drake equation. But I won't spoil it fully... you have to read the paper.  8)

Conclusions are a bit depressing. Especially if we manage to blow ourselves up.  ::)

It's a bit surprising that no one until now approached this question in the way authors did. Maybe it shows how tough it is to think differently.

Should we evaluate our investments the way the authors evaluated Drake equation? I think this is somewhat related to what racemize tried to do in one of his articles and to what Damodaran does. 8)
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Cevian

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Re: The Fermi Paradox
« Reply #27 on: July 04, 2018, 09:37:17 PM »
Thanks for sharing this Jurgis. I look forward to reading the article with interest.

I just finished a very depressing book, "Straw Dogs" by the philosopher John Gray. Not for the faint-hearted.

He had a sentence in there I highlighted which seems appropriate here: "Scientists searching for extra-terrestrial life ponder anxiously whether mankind is alone in the universe. They would be better occupied trying to communicate with the dwindling numbers of their animal kin."

The way we treat other life on earth is appalling, not sure why we continue to look for life elsewhere.

Spekulatius

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Re: The Fermi Paradox
« Reply #28 on: July 05, 2018, 01:41:16 PM »
Isnít it far more likely that other civilizations find us  than the other way around?

It vote for staying low as Stephen Hawkins recommended as no news is good news.
To be a realist, one has to believe in miracles.

Jurgis

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Re: The Fermi Paradox
« Reply #29 on: July 05, 2018, 01:51:45 PM »
Isnít it far more likely that other civilizations find us  than the other way around?

It vote for staying low as Stephen Hawkins recommended as no news is good news.

There is no "staying low" and I hope Stephen Hawking understood that.

A civilization advanced enough for interstellar travel is very very very likely advanced enough to detect us.

If you want to avoid being steamrolled by advanced civ, the good news is that we don't see any Kardashev scale III civs ( https://en.wikipedia.org/wiki/Kardashev_scale ) in our galaxy or other galaxies. We could still be steamrolled by Kardashev scale II (or scale 2.5) civ, but we don't see any of them nearby either. A scale II+ civ would very likely detect life and possibly radio signals from our planet within the radio/light/etc sphere that goes let's say from 1950s or so. So within 50-70 light years right now.

Even if we don't stay low and tight beam info out, this is still limited by speed of light and very likely would only increase the chance of detection by civs that don't have interstellar travel (since civs with interstellar travel would detect us tight-beam-or-no-tight beam).
« Last Edit: July 05, 2018, 01:58:06 PM by Jurgis »
"Before you can be rich, you must be poor." - Nef Anyo