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

Many believe civilizations which survive the challenges of technology will inevitability build Dyson Spheres encompassing their entire sun. So how do we find these megastructures if they exist?
▬ Dyson Sphere Search Chapters ▬▬▬▬▬▬▬▬▬▬
0:00 Intro
02:11 What is a Dyson Sphere?
08:00 Can we see a Dyson Sphere?
15:19 (TEA) Time Elapse Argument
19:35 Couldn’t such a powerful civilization hide their Dyson Sphere from us?
24:44 Wouldn’t a better power supply than fusion eliminate the need for a Dyson Sphere?
30:41 Where should we be hunting for Dyson Spheres, or groups of them?
34:05 What about all those Voids, Dark Matter, and stuff like that? Couldn’t those be Dyson Spheres?
 
Isaac Arthur often uses one or other of my images, especially when he's talking about Dyson Spheres; this time it's only visible for a second, up in the corner.
freeman1.png

I don't really have the patience to make animations, so he doesn't use my stuff so much these days.
 
Apologies if this has already been posted, but this has the potential to be a game changer as regards Fermi's paradox:

"In simple terms, Grimaldi’s theory is that signals from extraterrestrial intelligence may be out there (contrary to Fermi’s paradox) and we may be looking in the right direction (contrary to Drake) but our problem is that we haven’t waited long enough for them to enter the hole in the cosmic radio signal sponge where we currently reside. Considering his lowest threshold for getting out of the silent bubble or “pore” is 60 years and we’ve only been looking for signals for 60 years, it is entirely possible we just have to wait a little while longer and we’ll get a SETI signal. Then again, it could be a wait of 1800 years."

https://mysteriousuniverse.org/2023/05/Forget-Drake-and-Fermi-Here-s-Why-We-Haven-t-Detected-Aliens/
 
I can sort-of see where this idea is coming from, but it is unlikely to be correct. Grimaldi models each 'technoemission' as a hollow shell, which is only visible for a short period on an expanding wave front. This 'technoemission' could be a radio broadcast or the optical or infrared signature of a megastructure such as a Dyson Sphere or densely populated system.

ajacc327f1_lr.jpg


Trouble is these technoemissions are likely to last much longer in the case of megastructures - who would build a megastructure then dismantle it almost immediately? So the Galaxy would not resemble a sponge so much as a solid mass. We should be able to see megastructures far across the galaxy by now.

And I must say that I doubt that any civilisation would waste energy on an isotropic broadcast in all directions. If you know what you want to say, and who you want to say it to, you would focus the beam (probably as a coherent laser).
 
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What would a derelict Dyson sphere look like? Wouldn't it take quite a degree of input to keep it from tearing itself to bits, overheating, getting bashed by debris, etc.? Even assuming some sort of lattice structure isn't it inherently unstable? Even Niven's ringworld was starting to fall apart. How soon before it looked like a set of junk or started to accrete into planets?
 
Perhaps they don't want to or need to contact us, I have no doubt that other races and civilizations exist out there, but I believe they prefer to observe rather than interact
 
They likely take one look and say sod that let’s be honest a hell of a lot of our time and money is spent on killing each other
 
They likely take one look and say sod that let’s be honest a hell of a lot of our time and money is spent on killing each other
They will observe that we have social media and AI - and will predict that our civilisation will collapse in a very short time.
 
They may have developed the technology to search for extraterrestrial civilisations through examining the biosphere of exoplanets etc. and found evidence of a civilisation relatively close to them and also us on Earth but a long way away. All their effort will then go into the nearer civilisation and we would be put on the back burner.
 
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Absence of evidence ≠ evidence of absence.
For all we know, alien races of all sorts could have visited us, or tried to contact us, and we just haven't noticed.
Do you think ants in our flowerbeds are aware of us as we do the gardening?
 
What would a derelict Dyson sphere look like? Wouldn't it take quite a degree of input to keep it from tearing itself to bits, overheating, getting bashed by debris, etc.? Even assuming some sort of lattice structure isn't it inherently unstable? Even Niven's ringworld was starting to fall apart. How soon before it looked like a set of junk or started to accrete into planets?
This is something I've thought about as well. Dyson spheres come in two main types; the Dyson Shell, which is a complete, solid sphere around the star, and the Dyson Swarm, which is a swarm of separate satellites that each follow their own orbits. The Shell concept would be difficult to achieve in the real world, and would require that the mass of the sphere is supported dynamically using orbital ring technology. An orbital ring uses a stream of massive orbiting particles to support the structure against gravity - these particles have a lot of momentum, and if the mass-stream was interrupted or deflected by accident, then the kinetic energy of the ring particles would severely damage the sphere. Eventually you have a badly damaged sphere that just falls apart into huge chunks and eventually collapses into an accretion disk.

A Dyson swarm, on the other hand is more stable, unless the swarm elements collide with each other, in which case a massive Kessler Syndrome event would result; this too, would gradually collapse down into an accretion disk. I suspect that even a well-designed Dyson Sphere would collapse within a few million years, if the maintenance systems failed to operate.

After a few tens or hundreds of million years, the resulting debris disks would start to form new planets - probably dry and volatile poor planets, since most of the volatiles would be lost in the collisions. In the meantime a smashed-up Dyson sphere would probably look a lot like any other debris disk - perhaps drier than a natural disk, and with larger chunks (at least at first).
 
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Has anybody read the latest Stephen Baxter novel “ Galaxias” yet?
Fermi is certainly something He has been intrigued by...

Without ( hopefully giving away spoilers) it seems an decent stab at explaining Fermi to a degree, at least in our little ‘ol Galaxy....
 
Thanks! I'll take a look. I love Stephen Baxter - even though the last one I read (Xeelee Redemption) contained a glaring maths error.
 
Perhaps they don't want to or need to contact us, I have no doubt that other races and civilizations exist out there, but I believe they prefer to observe rather than interact
The Prime Directive prohibits them from interfering with our natural development.
 
Perhaps they don't want to or need to contact us, I have no doubt that other races and civilizations exist out there, but I believe they prefer to observe rather than interact

I rather suspect that our best hope is that aliens would value knowledge enough to remain hands-off and simply observe us without interfering.

After all, what can we predict about alien psychology? Movies tend to depict aliens as either mindlessly hostile, and intent on wiping the human race out, or wise benevolent God-like creatures who have evolved past hostility and simply want to share their wisdom. What's more likely to be true? One answer is that 'they're aliens so we can never understand their motives'.

But I don't think that's altogether true. We can predict a few things about aliens. There will, for examples, be constraints on the behaviour of biological aliens (ignoring for the moment the suggestions that we might encounter mechanical AI aliens created by long dead species).

Biological aliens will have evolved in an ecosystem that must, by definition, be controlled by the principles of natural selection. Humans exist today because our ancestors were good at surviving. Natural selection favours survival traits. If you're good at passing your genes along, the next generation will have more of your genes. Aliens will have been shaped by the same processes. They will have been selected over millions of years as competent survivors.

So the real question is - what sort of behavioural traits favour survival? Answer that and you can predict some things about aliens.

One thing that recurs frequently is in-group co-operation. Huge numbers of species develop as social animals, and social species tend to co-operate. That sounds encouraging, but the other side of the coin is that social species rarely co-operate outside the group.

Ants have wonderful complex societies. Inside the nest every individual has a role. - And ant nests frequently go to war with other ant nests. You co-operate with your kin, not 'those other buggers'.

Another thing that helps survival is exploiting available resources. If it's there - take it.

Luckily, mindless hostility is not a survival trait. Killing for killing's sake is a waste of energy and potential resources.

So, in summary, aliens are more likely to adopt a 'what's in it for me' approach to other species. Aliens visiting Earth would probably not go out of their way to eradicate humans unless there was some advantage to be gained from doing that, which of course is possible.

And unconditional benevolence is equally unlikely. Benevolence is reserved for the in-group.

Our best hope, as I said, is that they would consider the knowledge to be gained from studying us is valuable enough for them to remain hands-off.
 
I rather suspect that our best hope is that aliens would value knowledge enough to remain hands-off and simply observe us without interfering.

After all, what can we predict about alien psychology? Movies tend to depict aliens as either mindlessly hostile, and intent on wiping the human race out, or wise benevolent God-like creatures who have evolved past hostility and simply want to share their wisdom. What's more likely to be true? One answer is that 'they're aliens so we can never understand their motives'.

But I don't think that's altogether true. We can predict a few things about aliens. There will, for examples, be constraints on the behaviour of biological aliens (ignoring for the moment the suggestions that we might encounter mechanical AI aliens created by long dead species).

Biological aliens will have evolved in an ecosystem that must, by definition, be controlled by the principles of natural selection. Humans exist today because our ancestors were good at surviving. Natural selection favours survival traits. If you're good at passing your genes along, the next generation will have more of your genes. Aliens will have been shaped by the same processes. They will have been selected over millions of years as competent survivors.

So the real question is - what sort of behavioural traits favour survival? Answer that and you can predict some things about aliens.

One thing that recurs frequently is in-group co-operation. Huge numbers of species develop as social animals, and social species tend to co-operate. That sounds encouraging, but the other side of the coin is that social species rarely co-operate outside the group.

Ants have wonderful complex societies. Inside the nest every individual has a role. - And ant nests frequently go to war with other ant nests. You co-operate with your kin, not 'those other buggers'.

Another thing that helps survival is exploiting available resources. If it's there - take it.

Luckily, mindless hostility is not a survival trait. Killing for killing's sake is a waste of energy and potential resources.

So, in summary, aliens are more likely to adopt a 'what's in it for me' approach to other species. Aliens visiting Earth would probably not go out of their way to eradicate humans unless there was some advantage to be gained from doing that, which of course is possible.

And unconditional benevolence is equally unlikely. Benevolence is reserved for the in-group.

Our best hope, as I said, is that they would consider the knowledge to be gained from studying us is valuable enough for them to remain hands-off.
The thought sometimes appears that one day we might be come like big game to some breed of Aliens hunted down for fun like we have done
 
If the current thinking that there is a large number of inhabited planets beside our own is true, then any alien races which have the disposable resources or the drive and impetus to leave their own planets are probably all visiting each other.

Why go to Cleethorpes when you could go to Paris?
 
I rather suspect that our best hope is that aliens would value knowledge enough to remain hands-off and simply observe us without interfering.

After all, what can we predict about alien psychology? Movies tend to depict aliens as either mindlessly hostile, and intent on wiping the human race out, or wise benevolent God-like creatures who have evolved past hostility and simply want to share their wisdom. What's more likely to be true? One answer is that 'they're aliens so we can never understand their motives'.

But I don't think that's altogether true. We can predict a few things about aliens. There will, for examples, be constraints on the behaviour of biological aliens (ignoring for the moment the suggestions that we might encounter mechanical AI aliens created by long dead species).

Biological aliens will have evolved in an ecosystem that must, by definition, be controlled by the principles of natural selection. Humans exist today because our ancestors were good at surviving. Natural selection favours survival traits. If you're good at passing your genes along, the next generation will have more of your genes. Aliens will have been shaped by the same processes. They will have been selected over millions of years as competent survivors.

So the real question is - what sort of behavioural traits favour survival? Answer that and you can predict some things about aliens.

One thing that recurs frequently is in-group co-operation. Huge numbers of species develop as social animals, and social species tend to co-operate. That sounds encouraging, but the other side of the coin is that social species rarely co-operate outside the group.

Ants have wonderful complex societies. Inside the nest every individual has a role. - And ant nests frequently go to war with other ant nests. You co-operate with your kin, not 'those other buggers'.

Another thing that helps survival is exploiting available resources. If it's there - take it.

Luckily, mindless hostility is not a survival trait. Killing for killing's sake is a waste of energy and potential resources.

So, in summary, aliens are more likely to adopt a 'what's in it for me' approach to other species. Aliens visiting Earth would probably not go out of their way to eradicate humans unless there was some advantage to be gained from doing that, which of course is possible.

And unconditional benevolence is equally unlikely. Benevolence is reserved for the in-group.

Our best hope, as I said, is that they would consider the knowledge to be gained from studying us is valuable enough for them to remain hands-off.
While that is a well observed and impeccably reasoned stance, I would argue one or two points.

Firstly, from an evolutionary perspective, the human race has not long got beyond what could be seen, as you observed, as the natural selection period of our existence. Modern medicine and healthcare have only been around a couple of hundred years, and even then, unevenly distributed. As such, in the longer term, as in thousands of generations, effects of same are as yet unknown. There are hints though.

Even in the natural world, there are signs that natural selection can be derailed somewhat by sexual selection without other pressures. For example, there are already birds of paradise species that have become so selective in terms of mate choice that the natural adaptions in terms of plummage are actually proving a liability to the males. They develop the most striking plummage that is favoured by the females, but as soon as they have passed on their genes, they are then less able to escape predators. However, this has only happened in the context of a natural environment where survival is not a challenge at all.

Transposing to human experience, where survival, even with severe medical or congential conditions is not an issue, culture, it is expected, takes over. Well, what would be the effects over 100,000 years? Or even a million? An alien species that has cracked both basic health and clean, limitless energy would evolve over a long period in ways we can but imagine. Their values may evolve in similarly unfathomable directions.

It is entirely conceivable that a society that has not had to fight for anything for 4 or 5,000 generations might develop affectations that are little to do with survival of the species in any way that we understand.
 
I sort of hope they are keeping watch over us and will stop us wiping our selves
out, I am likely to be disappointed though.
Odd init how I have more confidence in aliens that may not exist than our own politicians.
:dunno:
 
If the current thinking that there is a large number of inhabited planets beside our own is true, then any alien races which have the disposable resources or the drive and impetus to leave their own planets are probably all visiting each other.

Why go to Cleethorpes when you could go to Paris?
Less looting and fewer cars, shops and schools being burned?
 
If the current thinking that there is a large number of inhabited planets beside our own is true, then any alien races which have the disposable resources or the drive and impetus to leave their own planets are probably all visiting each other.

Why go to Cleethorpes when you could go to Paris?
Cos we speak English here? Well, most of us do.
 
I sort of hope they are keeping watch over us and will stop us wiping our selves
out, I am likely to be disappointed though.
Odd init how I have more confidence in aliens that may not exist than our own politicians.
:dunno:
Yes, they seem to have the collective ability, after a while, of alienating themselves.
 
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I tend to get stuck on the eukaryotic cell development.

Across our galaxy, there are probably hundreds millions of planets that already have simple life. Single cell organisms that thrive. In our own evolution, that was the state of life on this planet for a very long time before the development of eukaryotic cells that had organelles such as mitochondria that allowed them to develop greater complexity by having more efficient and effective means of deriving energy from their environment.

No one knows what precipitated or prompted that development.

It is theorised that life may be near ubiquitous where conditions allow, but that complex life might be very rare indeed, due to that developmental stage.

When that is combined with distance and time, and complex life, and thus a civilisation that could communicate, let alone get here, might be vanishingly rare. Time is an important factor here. In our own history, we have come close to extinction a few times in prehistory. Mega eruptions on the Indian subcontinent some 74,000 years ago may have had us tetering on the very brink. In many other instances, things may not have gone so well.

Therefore, time in terms of species development, as well as incidence, figures higly. For example, a civilisation may have grown, developed and thrived for a million years and then had some harsh fate befall it, and all have happened half a billion years before we came out of the trees.

So, there are many good reasons why, before we ever get into the nature or dispostion of a pontential alient civilisation, why such a civilisation may not have made contact, or even their presence known.
 
Single cell organisms that thrive. In our own evolution, that was the state of life on this planet for a very long time before the development of eukaryotic cells that had organelles such as mitochondria that allowed them to develop greater complexity by having more efficient and effective means of deriving energy from their environment.
No one knows what precipitated or prompted that development.
This is a puzzle, and a very interesting one, too. One should be aware that it appears to have happened twice, once with mitochondria and once with chloroplasts, so it does seem to be something that is both advantageous and possible.

In fact it may have happened three times; the small organelle called the peroxisome may also have been engulfed billions of years ago as an endosymbiont. If it has happened three times that means either we are exceedingly lucky and vanishingly rare, or that endosymbiosis happens on multiple occasions during the evolution of a biosphere.

My suspicion is that endosymbiosis is reasonably commonplace, but it leads to a wide range of different results on different worlds.
 
We seem to be edging closer to definitive evidence of some form of extraterrestrial life:

"Nasa's James Webb Space Telescope may have discovered tentative evidence of a sign of life on a faraway planet.
It may have detected a molecule called dimethyl sulphide (DMS). On Earth, at least, this is only produced by life."

https://www.bbc.co.uk/news/science-environment-66786611
 
We seem to be edging closer to definitive evidence of some form of extraterrestrial life:

"Nasa's James Webb Space Telescope may have discovered tentative evidence of a sign of life on a faraway planet.
It may have detected a molecule called dimethyl sulphide (DMS). On Earth, at least, this is only produced by life."

https://www.bbc.co.uk/news/science-environment-66786611
Do you think there is a drip drip scenario going on?

A few years ago when they found some microbes (they may not have been) but the world went crazy could you imagine the reaction is we found intelligent life? Or if intelligent life found us?

I think it would actually lead to the collapse of the materialistic world, just like if reincarnation or the afterlife was 100% proved. people would just give up on the rat race
 
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