Fermi Paradox

[kerbiloid]

1 hour ago, magnemoe said:

Say you colonized a few planets this is an important achievement

Why to colonize them if your population lives comfortably on their homeworld and doesn't grow?

Say, you live in a comfortable cottage near a wasteland.
Will you build cottages one by one until they cover all wasteland, or 1 or 2 will be enough?

1 hour ago, magnemoe said:

brings lots of prestige to the leadership

Or vice versa — "when will we stop spending our efforts for more and more pyramides?"

1 hour ago, magnemoe said:

This increase the distance to the next planet, 40 light year is far, you will need an fast generation ship. 

And then awake on board of this ship, alone, with a sticker on the freeze chamber glass: "Good luck. Send us a postcard from your new home.".

1 hour ago, magnemoe said:

even if you have an solar system civilization with plenty of resources

Or if you live in a paradize with nearly closed resource loop, which recycles everything unused and requires tiny amounts of resources - to replenish occasional losses.
For example: heat anything up to 20000 K and separate atoms. Any stone, any piece of trash becomes either metallurgical resource, or organical one.

Edited June 2, 2016 by kerbiloid

[magnemoe]

59 minutes ago, kerbiloid said:

Why to colonize them if your population lives comfortably on their homeworld and doesn't grow?

Say, you live in a comfortable cottage near a wasteland.
Will you build cottages one by one until they cover all wasteland, or 1 or 2 will be enough?

Or vice versa — "when will we stop spending our efforts for more and more pyramides?"

And then awake on board of this ship, alone, with a sticker on the freeze chamber glass: "Good luck. Send us a postcard from your new home.".

Or if you live in a paradize with nearly closed resource loop, which recycles everything unused and requires tiny amounts of resources - to replenish occasional losses.
For example: heat anything up to 20000 K and separate atoms. Any stone, any piece of trash becomes either metallurgical resource, or organical one.

Yes, either you dont create interstellar colonies or you stop after some time. 
Most probably don't go interstelar, for one it pretty much require an class 1 civilization. 
An purely planet based civilization will have an higher chance of failing someway as everything tend to become more dependent. 
 

[PB666]

2 hours ago, magnemoe said:

I don't agree that Earth is optimal for life, its however optional for us. This will be important for interstellar colonization. 
Say you colonized a few planets this is an important achievement who brings lots of prestige to the leadership, it also secure the species. 
However will you continue doing it. making more colonies is not the milestone the first was, its also likely that you will raise the bar for how earth like the planets has to be. This increase the distance to the next planet, 40 light year is far, you will need an fast generation ship. 

So its likely to stop, that is even if you have an solar system civilization with plenty of resources, if not you don't go interstellar.

I also agree about radio signals, its an trend to go cell based with higher frequencies. For space lasers will probably take over a lot. 
You can not detect broadcasts from lots of lightyears away no matter the equipment, signal strength will be less than noise level. 
You could detect directed signals from an decent distance however they would be infrequent. 
 

 

Well, before we go claiming how optimal earth is, consider for a moment that all life on earth descended from one type of cell. This is interesting because some posit that after the great bombardment Earth woukd have been cold and the best place for life would have been isolated upwellings and volcanic pools. If this were the case why don't we several versions, each evolved from independent bioneogenesis. The current timing now is between 3.5 and 4.2 billion years ago, which means the interval between the first archae and first complex is on the order 2.5 to 3.6 billion years. What this either tells us is that life did not evolve easily or that most life was low level junk, possibly as life on other planets, and only one life form had the qualities to proceed onward as earths conditions became more favorable. 

And yet as we observe the keplar data we find nothing even close to being as optimal as earth, and primarily planets that orbit non-sun like stars. What is worse, we are not even clearly aware how much atmosphere the inner planets had at formation, or how magnetically active our own sun was. And yet we continue to call planets earth-like when they orbit stars that are nowhere near sunlike.

Here is a metric, most of the stars so far picked as candiates are not visible tonthe naked eye, in fact no red dwarf is visible to the naked eye. The overwhelming majority of stars we see are without telescopes are two shortlived to support complex life. The overwhelming majority of stars we cannot see locally because of faintness are too red to support life. A large hanful  stars within 100 light years of earth fit the longevity and emmisive characteristics of our sun.

At what point does searching for ETs become futile, 1000 ly? This is not to argue that we could not travel to other stars, but in the end it might require a very tenacious and conservative population that waits 100s of thousands of years for a star to come close enough we can jump to it, and then establish colonies or do terriforming,  so that we are expanding say a light year outward every 500,000. How long would it take us to create a SOI of 2000 light years in radius? A billion years, but the galaxy is 100 light years across, and we could fit hundreds of these bubbles into it and still never encounter another alien species. 

 And so sun like stars have a certain metal content thus a certain age bracket in our galaxy, there are not alot of time in the milky way for Earth like planets around sun-like stars to have enough time to spread. I don't think you are going to find gnat-like sentients that have 'brine shrimp egg'-like cysts. Something that could be placed on a hawkings flyer and lasered to the next world as a seed ship. Given IS travel appears to be a hinge point in the mobility of humans, its probably an equal hinge point for other species as well. When we factor in that all of the more curious and inventive animals on earth tend to have EQs on the high side, its going to be some species with both mass and higher EQ needing a ship at least the size of a space capsule just to survive in IS space, not to mention accelerate or decelerate. 

its not surprising at all that as more data cimes in why we we have not been visited, what is increadingly surprising to me is people are hyping up the earth-like world and Fermi paradox explanations 'proper' when the observation and need for explanations doesn't seem to exist.. Where is the life? Show me something even remotely capable of supporting life, not some hype -piece that is pulled off of MSNBC.  Sunlike stars are not hard to see in any good telescope. If not, the bubble is moved so far away from earth the paradox inevitably voids itself. It is of no importance, and we would be left looking for traces of pre-archae like cells in the atmospheres of very far off worlds, shaking our heads and pondering whether the world would be worth colonizing or just use the star as a way point. 

[magnemoe]

1 hour ago, Green Baron said:

Yep :-). Earth is not "optimal" for us, organisms have adapted in a proper way to to the conditions. Not "optimal", because then a small change would result in a distinction, just "sufficient". And with the freedom of changing "little things" every now and then so that changes in the conditions don't effect everyone. If we want to go interstellar (or even interplanetary) we have to take "our" conditions with us, with the help of technology. In my opinion that step does not secure the species, when cut off of technological supply that technology will sooner or later fail, killing the travelers. I assume there are no "replicators" that fabricate worn out hightec things and that the travelers cannot take the earths raw materials and fabrication chains with them).

Let us assume that are not that many possibilities to create sentient/intelligent/mobile beings as a result of an evolution because the available elements are the same (i know life forms based on different bases are imaginable but not as effective as what earths evolution has breeded out, but i'm prepared for being corrected). Let us further assume that any travel faster than light is pure fiction.

In this case i don't see any paradoxon: others, civilized or not, may exist (i think they do) but the distances between "neighbors" are too far and too long. Technology will fail, radiation will kill the travelers or sterilize them.

Maybe newly planned telescopes will tell us more in the next decades.

We have only had sentinel life on earth once, make it probably that its uncommon. 
Even if you have an intelligent species its no guarantee that it will create an technological civilization capable of going interstellar. 
For one you have to be able to organize in large communities, humans are good at this first cities even predates farming, now if an alien species are not they will not notice this before they try to make city states and none will notice before this. 

You are unlikely to detect hunter gatherers without an landing, see my avatar
Her species has problems, first its the problem with large organizations however they have not noticed as an predator with no prey species who are suitable for domestication,

[Scotius]

Read any old (written some 50 years ago or more) astronomy book. Inside them you will find theories about how our Solar system formed, how could other systems form and how many of them could be out there. Some writers - astronomers and astrophysicists, staying firmly inside boundaries of science of the period went so far as to predict the number of existing planetary systems as...50. Fifty. In our entire Galaxy. Half a century later we discovered hundreds of planetary systems in the little bubble of space we can cover with our instruments - and every year we find more. This changed just because we've built better telescopes, and developed scientific methods of finding the signs of existing planets and interpreting the data in right way.

Other civilisations? We still don't know where to look, and what to look for. Maybe radio waves. Maybe flashes of coherent light. Or coherent X-rays. Or maybe gravitational impulses? Or maybe our nearest neighbour already moved past that, and uses only quantum entanglement communications - which we have no way of detecting now. And the next closest neighbour, some 400 lightyears away is building its first telegraph line right now?

Galaxy is vast. And 100 + years of existence of technological civilisation on Earth is a minuscule blip on the astronomical scale. Our entire endeavour of finding aliens so far can be summed up as: "Hmm, let's take a look at the sky...Meh, empty. Nothing's there. We're alone."

[kerbiloid]

1 hour ago, magnemoe said:

An purely planet based civilization will have an higher chance of failing someway as everything tend to become more dependent. 

While a civilization needs a planet to live, the easiest place to be fortified is its homeworld.
So, to prevent its extinction it's much easier to build an underworld of vaults on the Earth than to build similar cities on Mars (also mostly underground).
The recycling technologies and artificial food production are more relevant things to survive than additional planets.

If a supernova bursts near the Earth, the Martian colony will also be gone.

Once a civilization achieves an ability to build kilometer-sized spaceships (as in "Visitors" series or as hollow ex-asteroids), it has no more vital need in planets.
You can spend decades on board of a cruise liner if it is recycling all what you need.

Even more: since that point there is no difference between  ship and a city.
When a saucer is orbiting it's a space colony, when it lands - it's a town. A dozen of saucers parked aside are a city.

Once a civilization achieves an ability to terraform planets in reasonable time limits, or to sculpture planets as a clay in another way, it can just create planets at her wish.
So, it loses the last reason to fly somewhere to find the same pieces of Si/Fe/Al/O mix.

Also unlikely "an ancient civilization under a dying star looking for a new home" can appear.
Just because a civilization unlikely had a time to appear under an unstable star.

Edited June 2, 2016 by kerbiloid

[PB666]

32 minutes ago, magnemoe said:

You are unlikely to detect hunter gatherers without an landing, see my avatar
Her species has problems, first its the problem with large organizations however they have not noticed as an predator with no prey species who are suitable for domestication,

Her species? parthenogenic? thats the problem, recombination breeds diversity, without 3-letter word you don't get oddballs or Einsteins. 

[KerikBalm]

A paradox is when two seemingly true things cannot be true at the same time.. or at least two things derived from assumptions believed to be true.

The paradox is between one obvservational fact, and one extrapolation from observational facts *and* assumptions believed to be true.

It is most easily resolved by discarding the idea that the assumptions are true. Most debate focuses on which assumptions to disgard.

Fact #1) A complete lack of evidence of any extraterrestrial civlization/life

Facts #2+) An observation of the extreme scale of the universe, observing numerous structures (ie galaxies and stars) that are similar two what we can observe in our system, known to hold life

Assumptions... numerous:

* __% of stars have planets

* __% of planets are Habitable

* __% of habitable planets are develop life

* __% of planets with life develop a civilization

* __% of civilizations are capable of interstellar communication/visitation/we would be capable of detecting

* __ % of the above civilization that exist at this moment(given that they may go extinct/change to non-communicative, etc), and not say 1 billion years ago, or 1 billion years from now

* Civilization communicates/visits/exists in a way that we would recognize

Statement derived from facts 2+ and assumptions: We should be able to detect an extraterrestrial civilization ... contradicting Fact #1... a Paradox is claimed

many like to question the assumptions about the amount of communication/visitation... saying they communicate in ways that are as unrecognizable to use as radiowaves would be to cavemen... or the "zoo hypothesis", or they aren't interested in contact enough to put the resources into it.

Lets say one resolution is:

They are there, but we can't see them

- ie, the last assumption I listed is wrong

another resolution is:

There aren't many there at all, perhaps 10 or less per galaxy

- ie, some of the earlier assumptions are vast overestimates

So far, based on our planet hunting so far, the earlier estimates of how many of the planets might have life already appear to be significant over-estimates... but we can't say by how much.

There are a few *maybes* for the capability of having life... but until we get direct spectrometry of their atmospheres, its impossible to say if they have some life (and even then, we can't say they have no life)...

The old absence of evidence is not evidence of absence.

 

I think it is proper to exclude earth from out datasets. The probability of having at least 1 life bearing planet in your dataset does not change no matter how many planets you sample, and it does not change even if the rate is 1 out of 10, or 1 out of a trillion. making the observation requires and observed and thus 1 planet that bears life. The datapoint for the observer tells us nothing about the true rate, as that datapoint is in there regardless of the rate.

So we must exclude earth, and look at all other sampled planets... there are only a handful that might have liquid surface water, and that is highly speculative...

So we need to look at the probability of getting null detections for all the sampled planets if the true rate were X.... then take the highest X that gives us a 5% chance or less of all sampled planets not having /being suitable for life (ie 95% chance that if that was the true rate, we would have detected another haitable planet by now)

But of course, we need to consider the probability of a sampled planet having life/being suitable for life without us noticing.

And were' left again arguing over assumptions with no data to back any of them up.

Personally, I'm of the opinion that civilizations are very rare in the galaxy.

[lugge]

Well, we don't know if life is rare. Maybe it is, maybe it is not.
At the moment, we think its rare.

Now imagine, we would detect some kind of life on Mars (maybe gone long ago). Some simple stupid cells. Would we still think life is rare?
No. We would think "hey, 2 planets with life in our own solar system, life cannot be as rare as we thought".

Now imagine we would detect life in Jupiter's atmosphere or in Europa's ice ocean.
We would think "wow, seems that life forms nearly everywhere."
If this would be the case we would assume life everytime we discover a new exoplanet.

At the moment, no one can say if life is rare or not.
But the question can be answered by discovering our own solar system instead of some rocks many lightyears away. If we find life in only one more world in our system, we can assume life is not as rare as we thought and if we find it on two or more worlds we can assume life is pretty common.

However, sentient life is another story...

[PB666]

1 hour ago, lugge said:

Well, we don't know if life is rare. Maybe it is, maybe it is not.
At the moment, we think its rare.

Now imagine, we would detect some kind of life on Mars (maybe gone long ago). Some simple stupid cells. Would we still think life is rare?
No. We would think "hey, 2 planets with life in our own solar system, life cannot be as rare as we thought".

Now imagine we would detect life in Jupiter's atmosphere or in Europa's ice ocean.
We would think "wow, seems that life forms nearly everywhere."
If this would be the case we would assume life everytime we discover a new exoplanet.

At the moment, no one can say if life is rare or not.
But the question can be answered by discovering our own solar system instead of some rocks many lightyears away. If we find life in only one more world in our system, we can assume life is not as rare as we thought and if we find it on two or more worlds we can assume life is pretty common.

However, sentient life is another story...

But what if life on mars was the lowest level, less advanced than anything on Earth, what if it was a few steps above a sterike lab experiment. 

Even if we find life on mars it still could be excessively rare. Note that rare has a real time meaning, so that if ot only existed for 500 million years the p of life on mars is 0.1 at any guven instance. I suspect that with enough digging we will find self-catalytic organic reactions on Mars that could be considered catabolic in the sense of earth life, but the next step to find communities of lineages feeding metabolites into each outher, this i have deep suspicions will not be found. 

Again one has to caution against making educated guesses otherwise we fall into the pitfalls of past thinkers, until we have the technology to test fir the presence of living cells on Mars we should assume that Mars is sterile as the default argument thst needs to be disproven. Otherwise we allow assumptions intonthe arguments that create a bias against using facts versus speculation. 

[magnemoe]

1 hour ago, KerikBalm said:

A paradox is when two seemingly true things cannot be true at the same time.. or at least two things derived from assumptions believed to be true.

The paradox is between one obvservational fact, and one extrapolation from observational facts *and* assumptions believed to be true.

It is most easily resolved by discarding the idea that the assumptions are true. Most debate focuses on which assumptions to disgard.

Fact #1) A complete lack of evidence of any extraterrestrial civlization/life

Facts #2+) An observation of the extreme scale of the universe, observing numerous structures (ie galaxies and stars) that are similar two what we can observe in our system, known to hold life

First issue with Fermi paradox is that we will receive radio signals from them, its an load of reasons why we dont. 
mostly as signal strength goes down for random transmisjons for ourselves. Doing regular broadcasts to planets who might have life have low chance for success and might be dangerous its also pretty expensive and boring over millions of years. 
In short nobody is sending out signals in any volume we will pick up.

The second argument is that some civilization will colonize the entire galaxy. Its unlikely described some of it earlier, 
You don't solve your population problems or get resources with interstellar colonization, you do it for honor and that fades as the number of colonies increase 
 

[tater]

The idea of finding broadcasts is pretty far-fetched, IMHO. Any such signal would need to be beamed to get the S/N ratio up, and then we'd have to happen to look at the right target star as the transmission came during whatever time interval they sent it. The chances seem vanishingly small that we'd happen to look at the time a signal happened to arrive. Targeting via something like Keplar is sort of pointless, as we're looking at the small subset of stars where a transit is possible from out POV. Then of course there are the usual Drake equation sort of variables like do our civilizations even overlap, etc.

The chance of contact, ever, seems unlikely, IMO.

Note that the above statement says nothing at all about the existence of other civilizations, it only addresses the likelihood of making contact with them.

[PB666]

50 minutes ago, tater said:

The idea of finding broadcasts is pretty far-fetched, IMHO. Any such signal would need to be beamed to get the S/N ratio up, and then we'd have to happen to look at the right target star as the transmission came during whatever time interval they sent it. The chances seem vanishingly small that we'd happen to look at the time a signal happened to arrive. Targeting via something like Keplar is sort of pointless, as we're looking at the small subset of stars where a transit is possible from out POV. Then of course there are the usual Drake equation sort of variables like do our civilizations even overlap, etc.

The chance of contact, ever, seems unlikely, IMO.

Note that the above statement says nothing at all about the existence of other civilizations, it only addresses the likelihood of making contact with them.

If you place radio telescopes at some distace from the sun and could peer at the ring just beyond the corona the circle, not the sun or corona you could pick up radiotelemtry from distant communications between a planet and its deep space spacecraft. A good place to do this is in the kuiper belt. So if we were actually searching and had some suspect stars (we dont, at least not locally) you could selectively dispatch space craft and simply place the in stationary positions , maintaing position with ion drives and nuclear power. 

Step one. find suspect local candidates stars. 

Edited June 2, 2016 by PB666

[tater]

Think of the geometry required. We look at a candidate, and then we will need to be on a line between their craft using a DSN and their world as the communications both directions will be directional. There is beam slop, and of course the spacecraft moves (sweeping the beam over a wider area), but the transmissions are not constant... Seems considerably worse that a needle in a haystack. 

It's not impossible, I'm just thinking it's really, really unlikely.

[PB666]

We if we could find planet nine, at least in part of its orbit its moving slow enough, you could station satellites at P9 sun L2 and use planet nines very cold and low frequency surface as a focusing body, Although a very dense body is preferred.

 

[tater]

Seems like the best geometry would have to put the alien craft between us and their homeworld. The signal strength would otherwise be terrible... all that is aside from the usual Drake issues (that we happen to be looking at a time period when a signal could possibly arrive.

It's so much harder than even paleontology, where taphonomy can tell us at least where to look to get that tiny window into the past (places where critters happened to die that also happened to be just right for fossilization).

[PB666]

You definitely have to hold your position for a while. This is not a cheap occupation, eve-dropping on the mob-boss is not easy, eve-dropping on a boss 200 light years away is not expected to be easy either. There is a base assumption that they use radiotelescopes, but if laser projectivity can be refined in the very low wavelength, it might be even cheaper to communicate with lasers in which case you have to really be focused in front of the target to detect. I can see the electronics evolving quickly toward this.

And, what if we can tweek the entanglement's no-communication rule such that it allows communication under limited circumstances, if that were the case, at some point all space communications would go silent, forever. As such, we would need to look for passive evidence of sentient life, such as trails of ion-drives, or chemical ejecta, etc. I think this is going to happen, under stringent causality rules its not possible, but it may be possible to do without breaking causality.

In addition to that, as computers increase, we may have very little to say to spacecraft, they may be intelligent enough to perform all their standard missions without interference up to the point mission is complete and new parameters need to be submitted.

 

 

[Aethon]

10 hours ago, Shpaget said:

I have a question

"We don't put much power into our TV or radio transmissions because their intended audience is not very far away. Our defense radars are much stronger and the current Phoenix search could detect that kind of signal out to the limit of our current search which is 155 light years. The strongest signal generated by our technology is the planetary radar on the Arecibo radio telescope and we could detect its signal half way to the center of the galaxy."  Jill Tarter.  SETI Institute.

http://www.jb.man.ac.uk/research/seti/questions.html

10 hours ago, 11of10 said:

A question:

Unknown.  How do you look for something you don't know the nature of.

I have ants in my driveway.  They see me go by everyday, but I doubt  they have any idea they are surrounded by a technologically advanced space-faring civilization, or even what those concepts mean. 

 

[magnemoe]

57 minutes ago, PB666 said:

You definitely have to hold your position for a while. This is not a cheap occupation, eve-dropping on the mob-boss is not easy, eve-dropping on a boss 200 light years away is not expected to be easy either. There is a base assumption that they use radiotelescopes, but if laser projectivity can be refined in the very low wavelength, it might be even cheaper to communicate with lasers in which case you have to really be focused in front of the target to detect. I can see the electronics evolving quickly toward this.

And, what if we can tweek the entanglement's no-communication rule such that it allows communication under limited circumstances, if that were the case, at some point all space communications would go silent, forever. As such, we would need to look for passive evidence of sentient life, such as trails of ion-drives, or chemical ejecta, etc. I think this is going to happen, under stringent causality rules its not possible, but it may be possible to do without breaking causality.

In addition to that, as computers increase, we may have very little to say to spacecraft, they may be intelligent enough to perform all their standard missions without interference up to the point mission is complete and new parameters need to be submitted.

Lasers are better in space, it require that the base station is in space too. Upcoming clouds of satellites in low orbit will use lasers to speak to each others 
Not done for deep space as you would need telescopes in orbit to recessive the signal 

You should be able to pick up beamed power who miss, rare event but would be an distinct and strong signal 
Else only then their structures block out the sun,
In system it should be no issue getting various signals, one nice thing for an tiny flyby craft
 

[Superfluous J]

6 hours ago, magnemoe said:

You are unlikely to detect hunter gatherers without an landing, see my avatar

Actually now that you brought it up, what IS your avatar? I always thought it was an anthropomorphized camel with a green hat, blue shirt, and pink pants. Made out of yarn.

No seriously that's what I thought it was.

EDIT: Nevermind. That's @PB666's avatar. He quoted you. Though that just pushes the question...

Edited June 2, 2016 by 5thHorseman

[Green Baron]

Well, up to now nobody can really tell wether life is unique, rare or common. The basic molecules might as well be a common thing, as is water and oxygen, and maybe as are planets in the habitable zone(tm).

Maybe there is a window for possible communication between civilizations of let's say 200 years from the invention of radio-coms to the self destruction in war or pollution on the one side or becoming so self confident and satisfied that they simply don't care about others on the other side. But this concept would mean that civilizations have to be very close to each other in a galactic scale, just to get aware of the other before one side leaves the window.

Ok, this is not 100% serious and not my idea, it's (science)fiction (Stanislaw Lem), and it reeks of the 80s ...

:-)

Edited June 2, 2016 by Green Baron

[PB666]

Its is an illustration of the most dangerous entity in the known universe. If you know what it is the you might also know why the pot of petunias said 'oh, not again'. Thats a view of his good side, to view all of his sides you need CN3D 

 

[Green Baron]

6 minutes ago, PB666 said:

Its is an illustration of the most dangerous entity in the known universe. If you know what it is the you might also know why the pot of petunias said 'oh, not again'. Thats a view of his good side, to view all of his sides you need CN3D 

 

Omega ?

:-))

Edit: nevermind, i got it ...

Edited June 2, 2016 by Green Baron

[PB666]

12 minutes ago, Green Baron said:

Omega ?

:-))

alpha, commonly known as A. Enemy of infants, friend of the vain. Enemy of romans, friend of wallstreet. Answer to the question hon' why are you cooked. 

I should point out that its the most dangerous non-living entity, explaining its ghostly appearance. 

Edited June 2, 2016 by PB666

[Green Baron]

It's not a map of galactic civilizations :-)