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Why Haven't Aliens Contacted Us Yet? (Fermi Paradox)

Four dimensions seem to be the absolute minimum requirement, assuming you want time to pass within your cosmos.

Current string theory posits eleven, but I wouldn't be surprised to find out that that turns out to be bullshit.
A very serious mathematician once assured me that nine was the minimum number of dimensions, any less wouldn't work. He did try to explain it to me, but although I do have a good grounding in everyday maths - after all statistical / data analysis was the bedrock of my career - I was unable to follow his reasoning.

Maybe because the explanation involved him drawing diagrams in beer on the bar. I don't say that to denigrate his opinion, I do it to partially explain why I couldn't follow him.
 
The Great Filter hypothesis is back in the news. A team including two researchers at NASA's JPL has posted an online essay (not yet peer-reviewed or formally published) updating and expanding upon the earlier writings about the Great Filter.

Their online essay can be accessed at: https://arxiv.org/ftp/arxiv/papers/2210/2210.10582.pdf

The Daily Beast notes the essay and provides more news about it and reactions to it at:

NASA Has a Theory for Why We Might Be Alone in the Universe
https://www.thedailybeast.com/nasa-...-life-in-the-universe?source=articles&via=rss

If you're interested in the history of this hypothesis, the revised 1998 edition of Robin Hanson's seminal 1996 paper can be accessed at:

https://web.archive.org/web/20100507074729/http://hanson.gmu.edu/greatfilter.html
Personally, I would rather visit a civilisation in which intrepid explorers are setting sail in galleons to dark and distant continents than one in which everyone is glued to the internet, but the problem with the former is that we have to do all the legwork to make contact (even if contact were advisable).

The following article is worth a visit for the image of myriad galaxies alone:

https://www.popularmechanics.com/sc...t-discovery-of-2022-neil-degrasse-tyson-says/

Surely no-one can seriously argue that there isn't an advanced alien species in just one of those galaxies...?

Also, what evidence of ET might we detect first?

"Though humans don’t transmit many intentional signals out to the cosmos, many technologies people use today produce a lot of radio transmissions that leak into space. Some of these signals would be detectable if they came from a nearby star."

https://bigthink.com/hard-science/lasers-radio-waves-aliens/
 
To be fair, we have trouble communicating with others of the same species, here on earth.
I even have difficulty communicating with people in my own street sometimes.
 
Surely no-one can seriously argue that there isn't an advanced alien species in just one of those galaxies...?


all-galaxies-1668098573.png

Well, there is a good argument to be made that none of the galaxies in that image were inhabited when the light left them 13 billion years ago. Those galaxies at that time were very young, and probably very metal-poor. There were almost certainly few planets around the stars in that image, and the planets that did exist were almost completely made from hydrogen and helium.

On the other hand all of those galaxies are now thirteen billion years older, and probably do contain trillions of metal-rich planets and millions of civilisations, but we will never meet them because we could never get there (and they would never reach us) due to the expansion of the universe.

Expansion is a bastard.
 
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The PEW Research Group that studies human behavior found the more a person is religious the less likely this type of person would accept the idea of an extraterrestrial being.

I not into organized religion and maybe that is why I have seen and accepted that we are not alone.

There maybe life in other parts of the universe, but everyone is looking in the wrong place.

The answer is multiple dimensions.
 
all-galaxies-1668098573.png

Well, there is a good argument to be made that none of the galaxies in that image were inhabited when the light left them 13 billion years ago. Those galaxies at that time were very young, and probably very metal-poor. There were almost certainly few planets around the stars in that image, and the planets that did exist were almost completely made from hydrogen and helium.

On the other hand all of those galaxies are now thirteen billion years older, and probably do contain trillions of metal-rich planets and millions of civilisations, but we will never meet them because we could never get there (and they would never reach us) due to the expansion of the universe.

Expansion is a bastard.
I wonder if any of them still exist in that 13 million year plus darkness, or could they just eventually just fizzle out maybe because of some unknown factors of which we have no knowledge?
 
True Sid,

The outer reaches of the universe could be burnt out, eternal darkness, cold, nothingness of past galaxies and planets.

Thirteen billion plus years is a long time !
 
True Sid,

The outer reaches of the universe could be burnt out, eternal darkness, cold, nothingness of past galaxies and planets.

Thirteen billion plus years is a long time !
In fact. . . come to think of it, maybe that's why UFO's are showing up more and more now, because they've had to keep leapfrogging in order to avoid being destroyed before their existence gets completely wiped out completely if they reach an eternal void? :thought:
 
This is possible, but there is no significant difference between the galaxies we see on one side of the universe compared to those we can see on the other side.

That suggests very strongly that the entire Hubble Volume has more-or-less the same physical characteristics, and that every galaxy we can see will follow a similar evolutionary path to the ones nearer to us. In short, there will be mature stars, and mature planets, and galaxies, everywhere we can see, right to the edge of the universe.
 
Maybe aliens haven't contacted us because (a) ftl travel is simply impossible and (b) no civilisation has yet cracked fusion power as it's fundamentally a question of large masses, so such aliens all die out once their local resources have been consumed.

...and now, the weather... :)
 
I imagine that however life started initially it didn't depend on the death of any other life to sustain it. However most life on Earth at the moment does, directly or indirectly. Although some plants seem to be able to survive rooting into rock rather than soil.

Could most life elsewhere have evolved to take nutrients directly from minerals and energy without the stage where some organism somewhere "decided" on the shortcut of consuming something else or feeding off of its corpse?

If such alien life found us what would its reaction be? Obviously impossible to guess at what alien reaction/emotion/whatever would be but we could guess at some sort of fascinated horror. Would this be enough for them to quarantine us? Perhaps monitor this dangerous evolutionary aberration but keep well out of our way?

No real scientific basis for this, just idly wondering!
 
My own opinion is that intelligent life is just so hard to get established that for all practical purposes we are alone. Like Brian Cox thinks, there may only be 1 or 2 human level.intellgient species in any given galaxy, so the chances of them overlapping and communicating is very slim.
 
Could most life elsewhere have evolved to take nutrients directly from minerals and energy without the stage where some organism somewhere "decided" on the shortcut of consuming something else or feeding off of its corpse?
You are describing 'intelligent autotrophs', organisms which use environmental sources of energy to drive their metabolism. Intelligent plants would be an example of this, but I think intelligent autotrophs would need to follow a significantly different evolutionary path. The late Greg Bear described a planet where the entire ecology was sentient, from the plantlife and soil organisms to mobile animal-like morphotypes which trimmed and managed the forests.

I don't think that intelligent, mobile autotrophs are impossible, per se, but there needs to be some mechanism that allows the metabolic energy of the organism to become concentrated enough to allow mobility. Plants are wonderful organisms, and we all rely on them to gather energy for our needs, but they are very slow movers as a rule.
 
You are describing 'intelligent autotrophs', organisms which use environmental sources of energy to drive their metabolism. Intelligent plants would be an example of this, but I think intelligent autotrophs would need to follow a significantly different evolutionary path. The late Greg Bear described a planet where the entire ecology was sentient, from the plantlife and soil organisms to mobile animal-like morphotypes which trimmed and managed the forests.

I don't think that intelligent, mobile autotrophs are impossible, per se, but there needs to be some mechanism that allows the metabolic energy of the organism to become concentrated enough to allow mobility. Plants are wonderful organisms, and we all rely on them to gather energy for our needs, but they are very slow movers as a rule.
Well, we as humans seem to be doing a pretty good job of moving them about, distributing them all over the world as well as nature having the greatest hand in everything - even trying to repair that which we mess up.
 
Plants are wonderful organisms, and we all rely on them to gather energy for our needs, but they are very slow movers as a rule.
Photosynthetic organisms (plants and bacteria) utilising inorganic carbon are fantastically successful on land and sea on this planet and possibly others. Comparison of intelligence and mobility to humans is a difficult and not particularly useful exercise, as they operate in a completely different time-frame to us.
 
Yes. There may be innumerable planets with sentient plant-like autotrophs (or lichen-like autotrophs, which are a different type of autotroph altogether). But if they are immobile, they are unlikely to build interstellar spacecraft and come to visit us, so we will have to go out there and find them ourselves.
 
Photosynthetic organisms (plants and bacteria) utilising inorganic carbon are fantastically successful on land and sea on this planet and possibly others. Comparison of intelligence and mobility to humans is a difficult and not particularly useful exercise, as they operate in a completely different time-frame to us.
Are we displaying metabolic rate chauvinism here? Beings that live for very long periods or are even to all intents immortal may see us as moving very swiftly and not, as individuals lasting long enough to be able to contact. Starting a fire to them may be the equivalent of a nuclear explosion to us but does that prevent them from developing a technology that may be capable of space travel? The lightspeed limit would mean little to them.
 
Are we displaying metabolic rate chauvinism here? Beings that live for very long periods or are even to all intents immortal may see us as moving very swiftly and not, as individuals lasting long enough to be able to contact. Starting a fire to them may be the equivalent of a nuclear explosion to us but does that prevent them from developing a technology that may be capable of space travel? The lightspeed limit would mean little to them.
Presumably at the speed they would have to attain for escape velocity it would feel like instantaneous transport off planet. And we're talking Ents with space capabilites to give a visual image to this life form.
 
Maybe there are civilizations in our planet’s oceans and that produces USOs ?

I was surprised that when a few years ago they were looking for a missing airplane in the Indian Ocean, it was said very little was known about this part of the world.

The Indian Ocean was the ocean explorers seemed to have ignored.

More is known about our Moon than the Indian Ocean.
 
Yes. There may be innumerable planets with sentient plant-like autotrophs (or lichen-like autotrophs, which are a different type of autotroph altogether). But if they are immobile, they are unlikely to build interstellar spacecraft and come to visit us, so we will have to go out there and find them ourselves.
What makes us think we humans are so intelligent...? We are at present destroying our own biosphere through our own growth - and frankly it's probably too late to stop it - whilst also causing a mass extinction of creatures unfortunate enough to be sharing this biosphere with us...
 
My own opinion is that intelligent life is just so hard to get established that for all practical purposes we are alone. Like Brian Cox thinks, there may only be 1 or 2 human level.intellgient species in any given galaxy, so the chances of them overlapping and communicating is very slim.
There are an estimated 40 billion habitable planets in our own galaxy.

Perhaps at this moment in time there are handful of species like us spread out across the light years, however there could be ruins of ancient intelligent life scattered across the galaxy (frankly I would rather explore an extinct civilisation than die of space pox from meeting a living one). Then there would be planets with lush, verdant rainforests and dinosaurs and others with primates in ascendancy... All this fascinates me as much if not more than meeting another race glued to the internet whilst their polar ice caps melt...
 
There are an estimated 40 billion habitable planets in our own galaxy.

Perhaps at this moment in time there are handful of species like us spread out across the light years, however there could be ruins of ancient intelligent life scattered across the galaxy (frankly I would rather explore an extinct civilisation than die of space pox from meeting a living one). Then there would be planets with lush, verdant rainforests and dinosaurs and others with primates in ascendancy... All this fascinates me as much if not more than meeting another race glued to the internet whilst their polar ice caps melt...
40 billion isn't apparently very many it seems, given we don't know how hard it is for life to get started, how hard it is more multicellular life to evolve (an apparently hard great filter), how hard/lucky it is for intelligent life to evolve and not go extinct. Conway Morris, for example argues that the evolution of ntelligent life requires more than a habitable planet, it needs something like a gas giant like Jupiter (to absorb those extinction meteors) and something like a moon. Gould believed that luck and randomness is such a factor that rewind the evolutionary tape and there's no guarantee intelligent life would have arisen on earth even under the exact dame conditions. And Cox argues that the great filters are such that it's unlikely more than 1 or 2 I telling species would exist in any given Galaxy.

Of course, this is all based on a set of one and therefore we really don't know anything, lol

For me, I just take the simple argument that if intelligent life was easy then it would be abundant. But there's no sign of anything whatsoever except us. The simplest explanation for the silence, than, is that we are alone. I may, of course, be very, very wrong. Eitherway its fascinating and terrifying.
 
40 billion isn't apparently very many it seems, given we don't know how hard it is for life to get started, how hard it is more multicellular life to evolve (an apparently hard great filter), how hard/lucky it is for intelligent life to evolve and not go extinct. Conway Morris, for example argues that the evolution of ntelligent life requires more than a habitable planet, it needs something like a gas giant like Jupiter (to absorb those extinction meteors) and something like a moon. Gould believed that luck and randomness is such a factor that rewind the evolutionary tape and there's no guarantee intelligent life would have arisen on earth even under the exact dame conditions. And Cox argues that the great filters are such that it's unlikely more than 1 or 2 I telling species would exist in any given Galaxy.

Of course, this is all based on a set of one and therefore we really don't know anything, lol

For me, I just take the simple argument that if intelligent life was easy then it would be abundant. But there's no sign of anything whatsoever except us. The simplest explanation for the silence, than, is that we are alone. I may, of course, be very, very wrong. Eitherway its fascinating and terrifying.
I understand this argument but I struggle with it.

For one, despite the human ego we actually know very little about our universe:

“The universe is not constrained by what some blobs of protoplasm on a tiny little planet can figure out, or test,” Siegfried says. “We can say, This is not testable, therefore it can’t be real—but that just means we don’t know how to test it. And maybe someday we’ll figure out how to test it, and maybe we won’t. But the universe can do whatever it wants.”

https://www.nationalgeographic.com/science/article/what-is-the-multiverse

... and that includes Brian Cox, one of my least favourite blobs of protoplasm

But we are able to look at other solar systems are there appear to be no shortage of both rocky exoplanets like Earth and gas giants like Jupiter:

"Already, too, we have a wealth of exoplanet data from observatories such as NASA's Transiting Exoplanet Survey Satellite (TESS), the agency's retired Kepler space telescope and the High-Accuracy Radial velocity Planet Searcher on the European Southern Observatory's 3.6-meter telescope at La Silla Observatory in Chile. NASA says more than 4,000 exoplanets have been found by early 2022, a large proportion of them gas giants."

https://www.space.com/30372-gas-giants.html

So it does seem that the requirement for an outer gas giant is likely to have been met in a great many of the 40 billion solar systems in our galaxy, which somewhat undermines what Morris is arguing.

But I feel my hesitancy also arises from the 'unique Earth' hypothesis being used within the climate change debate. I am not a climate change denier, but for those scientists and presenters who make their living from being in the public eye it is a gold mine. Brian Cox, for example, is able to garner headlines from stating he believes we are the only intelligent life in our galaxy, therefore it is an absolute tragedy if we allow ourselves to destroy our biosphere through man-made climate change because then the universe is losing something unique. This raise this profile, but him at the forefront of the climate change debate and more work will follow...
 
I understand this argument but I struggle with it.

For one, despite the human ego we actually know very little about our universe:

“The universe is not constrained by what some blobs of protoplasm on a tiny little planet can figure out, or test,” Siegfried says. “We can say, This is not testable, therefore it can’t be real—but that just means we don’t know how to test it. And maybe someday we’ll figure out how to test it, and maybe we won’t. But the universe can do whatever it wants.”

https://www.nationalgeographic.com/science/article/what-is-the-multiverse

... and that includes Brian Cox, one of my least favourite blobs of protoplasm

But we are able to look at other solar systems are there appear to be no shortage of both rocky exoplanets like Earth and gas giants like Jupiter:

"Already, too, we have a wealth of exoplanet data from observatories such as NASA's Transiting Exoplanet Survey Satellite (TESS), the agency's retired Kepler space telescope and the High-Accuracy Radial velocity Planet Searcher on the European Southern Observatory's 3.6-meter telescope at La Silla Observatory in Chile. NASA says more than 4,000 exoplanets have been found by early 2022, a large proportion of them gas giants."

https://www.space.com/30372-gas-giants.html

So it does seem that the requirement for an outer gas giant is likely to have been met in a great many of the 40 billion solar systems in our galaxy, which somewhat undermines what Morris is arguing.

But I feel my hesitancy also arises from the 'unique Earth' hypothesis being used within the climate change debate. I am not a climate change denier, but for those scientists and presenters who make their living from being in the public eye it is a gold mine. Brian Cox, for example, is able to garner headlines from stating he believes we are the only intelligent life in our galaxy, therefore it is an absolute tragedy if we allow ourselves to destroy our biosphere through man-made climate change because then the universe is losing something unique. This raise this profile, but him at the forefront of the climate change debate and more work will follow...
Well then issue seems to be that 40 billion is still too far small a number to make intelligent life likely. I mean, what are the odds of life starting? What are the odds of multicellular life forming? What are the odds that intelligence evolves? What are the odds this all happens without extinction?

I guess with a set of one we don't know. Maybe it is so vastly unlikely that even 100 billion is far too small. Maybe its trillions to one. Who knows.

But since there is no clear evidence of any intelligent life anywhere at anytime, it seems more likely that its exceptional than common.

Edit: on a side note, regarding Morris argument, approx how many earth like planets are out there with both a gas giant nearby and an earth sized moon in their orbit? Both are necessary for him to have intelligent life.
 
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