NASA Scientists Present Theory About Why We Haven't Met Other Intelligent Life. It's Crushing.

[brush]

I would think the great distances in space would be a prime reason why there's been no contact with other intelligent life. Racism, genocide, inequity and sabotage are mentioned, which of course suppresses development of technology which would include transport methods to conquer the vast distances in space in a short enough human-life time span for back and forth communication.

https://www.huffpost.com/entry/great-filter-theory-intelligent-life-extinction-nasa_n_636fee4ce4b0ca9acf253784

The “Great Filter” theory — as in “filtering out” various forms of life — argues that other civilizations, possibly several, have existed during the life of the universe. But they all destroyed themselves before they could make contact with Earth, noted the paper, “Avoiding the ‘Great Filter’: Extraterrestrial Life and Humanity’s Future in the Universe.”

Whatever seems likely to wipe out humans would conceivably also threaten intelligent life on other planets, the authors argue. The likely culprits — which could be impacted by humans or other intelligent life forms — include nuclear war, pandemic, climate change, and uncontrolled artificial intelligence, the authors note.

The trick, the biggest challenge of all, will be to work together to survive, the researchers said.

“History has shown that intraspecies competition and, more importantly, collaboration, has led us towards the highest peaks of invention. And yet, we prolong notions that seem to be the antithesis of long-term sustainable growth: Racism, genocide, inequity, sabotage,” the writers warn.

[Ray Bruns]

1. Maybe the reason they haven't contacted us is because we have a nasty habit of slaughtering

Each other on a regular basis.

[brush]

5. Yep, we continue to cut our own throats. Look at Putin...

trying eliminated Ukraine's sovereignty and capture it's fertile fields/food production for Russia, which has of course resulted in food export interruption and shortages the world over.

[Irish_Dem]

9. Yes. If humans kill each with such joy and regularity, why would outsiders be safe?

[Ferrets are Cool]

51. Or slaughtering anything we don't understand.

[Cetacea]

101. And slaughtering other intelligent beings

Perhaps dolphins and whales will win the intelligence argument after all.

[Goonch]

2. A few made it...

[Omnipresent]

15. You are mistaken!

They say they’re from France!

[Ray Bruns]

17. Those aren't aliens. I believe they said they were from France

[DenaliDemocrat]

3. In a Kantian sense - we can go not experience the world

As humans. It is totally unreasonable to assume another species evolved in another place and time would face the same things humans do.

[brush]

12. Yeah, the article mentions that...that other civilizations...

may have died off from internal dysfunction just as we probably will.

It's less than 95 years since Dr. Robert Goddard, one of the pioneers in the theoretical exploration of space, successfully began development of solid-state rocketry. That's not that long ago. Just think if development could go on uninterrupted by human dysfunction for another century, where we could be.

[rickford66]

28. Goddard pioneered liquid fueled rocketry

Von Braun used his patents to develop the V1 and V2

[reACTIONary]

70. +10 - The rocket's red glare...

solid fuel rockets (gunpowder ) had been around for some time.

[Beartracks]

59. We Kan't?

Sorry.

==========

[central scrutinizer]

4. Maybe just overpopulation

Organisms in a closed ecosystem eventually use up all the resources and drown in their own waste

[Duppers]

74. Seems as if we're headed in that direction.

We need to realize we cannot continue at this rate. However, most folks don't believe this or care.

[keithbvadu2]

77. "use up all the resources "... Agent Smith from the Matrix

[Takket]

6. These videos are excellent describers of this topic.......

&t=61s

[purr-rat beauty]

76. I love that channel

great science and great illustration

[alterfurz]

7. maybe the most plausible theory...

The cosmological theory most consistent with human conduct -- just take a look at today's headlines -- is that our planet exists as the asylum to which other worlds commit their lunatics. -- Sydney J. Harris (1976)

[brush]

14. Ahhh man, I hope not.

[brush]

27. Thanks for videos.

[Irish_Dem]

8. So Intelligent Live isn't that intelligent, even across the universe.

[Mike Nelson]

10. Well...

... my view is that the time it takes to seek contact + the time it takes to decode the contact = long enough for the original sender to be gone. We should look for, and send, information that will be most likely one way.... and, if we get lucky, great!

[Turbineguy]

11. Maybe other civilizations

don't think of us as intelligent life.

To a being able to travel these distances, we would just be heavily armed idiots. The kind to stay away from.

[brush]

16. Yeah, space magats.

[TomSlick]

55. I think your idea is close to correct.

I suspect that if there are more advanced civilizations out there, they just don't find us all that interesting.

[LeftinOH]

92. Earth may be the North Sentinel Island of the Galaxy..

if not the Universe. As in: Do NOT go there - they'll kill you!

[NCDem47]

13. Perhaps extraterrestials have looked at Earthings...

And took a hard pass. We were never advanced enough to warrant contact.

[hadEnuf]

57. Exactly. They wouldn't need to contact us to learn about us if they are advanced enough.

They may have already figured out how we would react to contact. We are no way mature enough to handle it yet.

[roamer65]

18. They are out there.

I think they regard us as nothing more than a DNA experiment.

Would not surprise me if they have learned to harvest DNA before each species goes extinct.

[enough]

19. Or -- advanced civilizations know how to hide their existence from the rest of the universe

to keep from becoming targets of rapacious violent unintelligent civilizations.

(As played out in The Three Body Problem by Liu Cixen)

[hunter]

47. I figure these civilizations build custom universes more to their liking and move out of this one...

... making them forever beyond our reach.

I also figure the speed of light in this universe is absolute.

The odds of us finding any evidence of civilizations who have moved on or destroyed themselves are negligible.

Science fiction that involves faster-than-light travel is pure fantasy, these futures are not any more likely than the wizardry of Harry Potter. There's nothing wrong with fantasy so long as the magic obeys consistent rules.

On the other hand the universe may be saturated with intelligent life and we're just too stupid to see it.

[electric_blue68]

99. Did you just spoil me? I was planning to read that at some point soonish!...

I recently finished his pretty wild set of short stories. 👍

It's ok.

[enough]

102. No no! No spoiler-- that's just one of uncountable fascinating ideas and plot twists in that book!

Read it— and the rest of the trilogy— you will love it.

[electric_blue68]

103. I was impressed w his short stories so I'll see if it's an e book at my library. 👍

[Otto_Harper]

20. Consider that the two most humbling thoughts on this matter are

1) Humankind might well be the most advanced race to ever have evolved in the Universe.

2) Perhaps we're not.

[MySideOfTown]

26. Consider the most advanced race to ever evolved in this Universe,

created this Universe. There may be other Universes.

[Orrex]

40. A limerick:

When we witness the universe first
And within its expanse are immersed,
We consider its scope
And arrive at the hope
That we're neither its best nor its worst.

[NullTuples]

21. Perhaps the correct question is: Why would other intelligent life want to meet us?

Sure, we have some amusing good traits, but let's face it; we're not ready yet. Not sure we ever will be, even assuming life on our planet survives another few thousand years.

[hatrack]

22. Or, it could be that conditions that have prevailed on Earth are exceedingly unusual . . .

Ward and Brownlee argue that the universe is fundamentally hostile to complex life and that while microbial life may be common in the universe, complex intelligent life (like the evolution of biological complexity from simple life on Earth) required an exceptionally unlikely set of circumstances, and therefore complex life is likely to be extremely rare.

They argue that among the essential criteria for life are a terrestrial planet with plate tectonics and oxygen, a large moon, magnetic field, a gas giant like Jupiter for protection and an orbit in the habitable zone of the right kind of star. Additionally, events during the Earth's geological past such as Snowball Earth, the Cambrian Explosion, and the various mass extinction events that nearly destroyed life on Earth arguably make the existence and survival of complex life rare as well.

They also suggest that animal life, having taken hundreds of millions of years to evolve, unlike bacteria, which were the first life to appear on Earth, is extremely fragile to sudden and severe changes in the environment, and therefore is very prone to becoming extinct very easily and quickly within a short period of geological time, while microbial life is much more resilient to such changes.

They also argue that due to the immense size of the universe, even if another habitable planet like Earth does exist elsewhere, and that the Earth is not the only planet in the universe with complex life, such planets would still only appear in relatively small numbers compared to planets that are habitable only to bacteria, and would most likely be too far away for any intelligent lifeforms, if they exist, to make contact with each other as well as with our own planet, as the vast distances between those planets would essentially isolate them, and by the time any signals reach their destination, the planet the signal originated from may no longer be habitable anymore except for at least bacteria, and whatever life that sent said signal may already be extinct, making any form of contact with each other useless.

Finally, they warn about the current degradation of the Earth's biosphere due to human activities, suggesting that if humans destroy a significant portion of animal life on Earth, then they would also destroy that same amount of that kind of life in the entire universe.

EDIT

https://en.wikipedia.org/wiki/Rare_Earth:_Why_Complex_Life_Is_Uncommon_in_the_Universe

[Auggie]

34. +1

Thanks for this.

[jaxexpat]

23. The fundamental requirement for interstellar travel is sentience.

The question is, can the stubborn lethality of sentience permit the species to endure long enough to achieve the requisite technology for that travel?

[A HERETIC I AM]

75. Opposing digits would be another.

If you have paws or hooves, you can’t really build things.

One would think having an opposable thumb TYPE arrangement would be required to manufacture things.

[muriel_volestrangler]

89. Opposing digits are easy to evolve, and there are also tails, trunks and tentacles

Appendages that can coil, or hold things between them (doesn't have to be done by just one appendage, nor are you limited to 4).

For advanced manufacturing needed for extraplanetary rockets, you need an oxidizing atmosphere in which you can harness fire - this is the problem dolphins or octopuses would have in getting beyond the "Homo erectus" stage, I reckon. Do many planets develop an oxygen-rich atmosphere (it took the Earth a bit of time) with organisms that thrive in it, or do they just stay as microbial water-based planet (or does the evolution of oxygen-emitting "algae" poison all the rest of life and kill it off before it can live in it and even make use of it?)

[jaxexpat]

90. Yeah, exactly.

Since the dawn of time horses and cows, when told to "get a grip", just walk away silently and a little ashamed. But on the other hand, they are rarely accused of theft, the infamous "five finger discount". Nor do they appreciate the base 10 numerical system. Decimals? forget it.

[grumpyduck]

24. Why does it always seem to be assumed

that other civilizations are more advanced than ours? There could be lots of them out there that are either at our level or way behind, without the technology to go looking for "aliens."

[patphil]

25. I think it's a poor assumption that other intelligent life is like us.

I think it's just as possible that we have been observed on many occasions and other life forms just don't want to have anything to do with a species that appears to have a death wish.
We've often shown that we are fear based, and can't seem to accept the differences within our own species. How could we possibly have a positive relationship with a completely different life form?
Simply put, we aren't worth the risk.

[brush]

31. You nailed it. "...can't seem to accept the differences within our own species."

With trump and magats constituting the non-loyal opposition, we have little chance to develop the tech needed to even communicate with other civilizations, much less reach them.

And internationally we have monsters like Putin trying to destroy its neighbor...but likely to damage his own country irreparably.

[Kaleva]

35. How would they be able to observe us in real time?

The light reflected from our planet could take thousands, millions or even billions of years to reach an alien civilization. An alien civilization observing the planet may be seeing Earth as it was before the time of the dinosaurs.

[druidity33]

38. jeez, obviously...

they're here among us... RIGHT NOW!

[Kaleva]

43. I've always suspected my neighbor.

[druidity33]

49. I kinda figure...

it's the mushrooms. They can pretty much live in space via spores. And if you connect in the right way with the right kind of mushroom... well, you know. They have been co-opting us humans for a very long time. It's possible they helped us create language. But they're not always benign. Can't eat the wrong kind you know.

[patphil]

66. By using intelligent machines sent out to investigate planets throughout the galaxy.

If faster -than-life travel could be achieved, they could have been here, and observed us for thousands of years. I'm not saying it happened, but any species that could travel between the stars would be many orders of magnitude beyond us in technology.
That said, I seriously doubt they would interfere with us unless we became a threat to them.
Unfortunately, we are more of a threat to ourselves than to any alien species.

[Kaleva]

82. Even with faster then light travel, it could take millions of years

The observable universe is about 92 billion light years in diameter and the Milky Way is just one of the estimated several hundred billion to 2 trillion galaxies in the observable universe. Talk about finding the needle (Earth) in such a huge haystack.

[patphil]

87. How many countless trillion of civilizations could be looking?

There could be millions just in our galaxy; no need to travel between galaxies if that were the case.
This is all speculation, but we should look at the possibility that we are an aberration in our inability to rise above fear, anger, hatred, and violence.
Self limiting species may be in a distinct minority, and, since we fall into that category, we may not be able to see a true picture of galactic life.
Our fundamental view of the cosmos is more than likely terribly flawed, and totally unsupported by realities we can't, or simply don't want to, see.

[Major Nikon]

69. Humans have an inquisitive nature

Other intelligent species may not. So even if they had the ability to contact us, they may have no desire to do so.

[TreasonousBastard]

29. Years ago there was aTwilight Zone type tv episode that had...

the space wanderer visit us saying our peacemaking methods were useless and we had a week to get our shit toge
We did, somehow and when the week was up, we showed him our plans.

He sneered and stifled a laugh, saying he was misunderstood, and that his was race of warriors. Our feeble attempts at war were not good enough fo alliance.

The book with the m best answer was the one where
God looked over His creation on the 7rh day and said "fuck it" and walked off. No one's seen him since.

[Kaleva]

30. A majority of the universe is outside the observable boundry

The observable universe is about 92 billion light years in diameter.

The entire universe is thought to be several times that in diameter.


The first radio waves transmitted from earth have traveled about 100 light years . The diameter of the Milky Way is close to 106,000 lights years. It's 2.5 million light years to the Andromeda Galaxy.

The universe is expanding faster then the speed of light. We will never, ever see or detect anything in the vast majority of the Universe. From the universe within our ability to see, it could take millions or billions of years before we detect signals from alien civilizations from the time they were first transmitted.

[Evolve Dammit]

32. Any truly intelligent life would determine us to be a violent species, shithole planet and move on?

[modrepub]

33. Most life on This Planet

Has never been capable of long distance communications. To me it seems an organism’s primary focus is to reproduce itself before it dies. All the special stuff humans do to actually be capable of long distance communications is just an unimportant side trick.

To think we are the pinnacle of evolution and all other life forms aspire to do the thing humans do seems like the big fallacy (mistake) here. The average lifespan of a given species on earth is maybe 100k years. To have another form of life manage to pull the same feats as us at the same time seems remote. In other words, we may exist in our current abilities but other worlds may have dinosaurs who while successful don’t play with radios.

[Kaleva]

45. +1

[Marcuse]

36. What could go wrong?

[Takket]

64. hey hey, that was in the MIRROR Universe lol

[Richard D]

37. Most logical explanation is . . .

. . . “Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space.”

Not to mention that radio and television signals have only been going out for not very long. Even then the inverse square means that any signals a hundred light years out from us would be very weak and whoever was looking would have to have their huge antennae pointed directly at us and be listening on the very bands that we broadcast on.

The other option is that they are here and are keeping very very secret.

[multigraincracker]

39. If time and space are boundless or endless.

everything has to be possible sometime or someplace.

[Mr.Bill]

41. Distance is always mentioned as an impediment to meeting alien life, and it is.

But there is another impediment that is rarely mentioned and that is time. The amount of time we humans have existed here is a blink of an eye on the spectrum of time the universe has existed.

The chance of it happening somewhere else at the same time as us has to be billions to one, if not more, even if we survive for hundreds of thousands of years into the future.

[WestMichRad]

58. This!

And other galaxies are so mind-bogglingly far away, the energy needed to send communicative transmissions is huge (think: that of stars). And the time window would have to align perfectly.

So while the probability of intelligent life out there is very small, the huge number of galaxies there are makes it likely, IMHO, that it has evolved somewhere. Aligning that with the tiny window of time that we’ve been able to detect transmissions from them is highly improbable.

Or they’ve observed us and written us off.

If you found a civilization with a leader like tRump, wouldn’t you run away??

[Mr.Bill]

60. Send more Chuck Berry!

Early SNL fans will get this.

[Kaleva]

63. Time and distance go together

We measure distance in light years.

There could be thousands or even millions of alien advanced lifeforms living on other planets in the estimated several hundred billion to 2 trillion galaxies within the observable universe.

However, it could take many thousands or millions or even billions of years before we detect signals from any of them.

[robbob]

106. Thank you for a common sense reply!

Last edited Mon Nov 21, 2022, 02:49 PM - Edit history (1)

This isn’t a sci-fi movie folks. Unless some species out there has invented faster than light travel our next closest neighbours might be hundreds or even thousands of light years away. Now, Einstein proposed that faster then light travel is literally impossible according to the laws of physics, so we certainly aren’t going anywhere far unless we discover the loophole in natural law that would allow it.

[Javaman]

42. well, if we stop promoting sociopaths and psychopaths as leaders...

that would solve much of the problem.

[brush]

46. Agreed. With the trumps, Putins and maga-republicans...

we'll keep cutting humankind's own throat.

[republianmushroom]

44. if you are intelligent would you wants to me humans ??

[kairos12]

48. They were interested until Carl Sagan died.

Then, they asked, why bother?

[BaronChocula]

50. Stephen Hawking cited

our history of genocide as a reason we may not want to contact other intelligent life. Other intelligent life may be as greedy, exploitive, and more powerful than we imagined.

[Meowmee]

52. A bunch of rubbish

There has been no evidence of capacity for that anywhere else.

[Mr.Mystery]

86. I agree. This article is massively human-centric.

It assumes (makes an ass of u and me) that other intelligent life would be like us, would have the same motivations, physical abilities.

Maybe they’re intelligent trees and can’t move. Maybe they have no desire to find other life off their planet. Maybe intelligent life is extremely rare in the universe.

As for what killed them off, an asteroid, volcano, lack of magnetic field causing the atmosphere to float away etc. are better explanations than genocide.

[Meowmee]

88. What I meant was there is no evidence

Intelligent life ever existed at all beyond here.

[hatrack]

93. Shorter version: no one is coming to save us from ourselves

.

[Meowmee]

98. Yes that is one way of looking at it 😀

[Mr.Mystery]

95. Also very true . . . and if it were, there's no reason it would be like life on earth. nt

[Meowmee]

97. Yep 😀

[Uncle Joe]

105. If the universe were a hologram, it could be, we're all essentially part of the same thing. n/t

[mainer]

53. The Fermi Paradox

Fermi said the same thing decades ago. With technological advancement comes the ability to destroy yourselves.

[PoindexterOglethorpe]

54. You can't think of this in terms of the entire Universe.

Just our own galaxy. Interstellar distances are bad enough. Inter-galactic? Forget about it. Also, something like three quarters of all the galaxies out there are already so far away that there is simply no chance we could reach them ever.

So, several things. My Son The Astronomer has told me that in his field there's a strong feeling that we may well be the first intelligent life in our galaxy so far. Yeah, 14 billion years seems like a long time, but it's not that long on a cosmological scale.

As Hatrack, post 22, points out, the conditions that allowed life to develop here are highly unusual.

" ... planet with plate tectonics and oxygen, a large moon, magnetic field, a gas giant like Jupiter for protection and an orbit in the habitable zone of the right kind of star. "

Another thing to consider is that something like three-quarters of all the stars in our galaxy are red dwarfs. So any kind of life that would develop on a planet near a red dwarf is going to be vastly different from what we're familiar with. In addition, the closer to the center of the galaxy you get, the higher the radiation of all kinds, which would also mitigate against life evolving. Which means, only a relatively small percentage of stars are going to be similar to ours and far enough away from the center to have any hope of evolving life. And that is ignoring the plate tectonics, etc that are needed.

Plus, any species only lasts for so long. A million years would be a phenomenal run. And don't invoke long-lived species like jelly-fish as a counter, because none of those species are creating culture or civilization. So the glib assumption that there must be intelligent species millions of years more advanced than we are is ludicrous.

And then there's the speed of light problem. Really, nothing can go faster. Black holes/wormholes aren't a good alternative, because you'll be killed going into one of those. Even travelling a meaningful percentage of c (the speed of light) isn't a solution because, again according to My Son The Astronomer, the problem with travelling all that faster is that you'll be exposed to a greater concentration of the many kinds of deadly radiation the galaxy has to offer. I strongly suggest reading How To Die In Space by Paul M. Sutter, a real life astrophysicist. He explains all this far better than I can.

I actually discuss things like this all the time with MSTA.

[William Seger]

61. I agree, we could be the first

I think it's possible that life arising from a chemical soup is so extraordinarily improbable that it might have taken billions of years on billions of planets before it happened for the first time. And I also believe that there are physical limitations to interstellar travel that can't be overcome by technology -- it would take actual magic.

[PoindexterOglethorpe]

78. Exactly. And I get very frustrated at those who

think advanced life must be everywhere, and glibly assume that an advanced civilization could easily over come the speed of light limitation and therefore have probably already visited us. They need to learn some physics.

I mean, I'm as much a fan of science fiction as anyone here, and I love s-f that requires ftl travel so there can be some kind of galactic empire.

At this point, our very fastest rockets can travel all of 0.001% c. The only way we will ever colonize planets around other stars is if we can build generation ships and take hundreds, more likely thousands of years to get there. This is why we should be taking much better care of this planet.

People often say, Well, we can just terraform Mars, or build habitable stations on the Moon. Terraforming Mars would probably take tens of thousands of years, maybe a lot longer. And even if it could be magically transformed overnight, the much lower gravity is bound to cause huge problems, especially with human reproduction. It would be even worse on the Moon. As for Venus, it is at least almost exactly the same size as Earth, but its day is even longer than its year, so that's a problem. And it is so close to the Sun, that even a magical terraforming would probably only be good for a few hundred years before it starts to get too hot again.

Again, I discuss these things all the time with My Son The Astronomer.

[brush]

85. Look at the video in Post 6. More likely than not that there are...

other civilizations out. Reaching them is another matter.

[PoindexterOglethorpe]

91. Yes, I'm familiar with those videos.

They do overlook the issue of just how long any given advanced technological civilization might last.

People not only don't understand how vast interstellar distances are, how confining the speed of light (c) is, but how long time is. Even a few thousand years is a long time to humans. Millions? Billions? Those time frames are essentially unfathomable. The odds of even two technological civilizations existing at the same time in the galaxy is pretty small. And the odds that we can actually pick up their electronic signals, or that they could pick up ours, in the brief time either one is transmitting, is smaller yet. But again, it does not actually seem possible to pick up such signals, let alone decipher them.

People who seem to know this better than I do, have said more than once that if an advanced civilization had existed on this planet even as recently (!) as one million years ago, probably zero traces of it would remain. For all the concern about plastics filling up the landscape and oceans -- which is a valid concern -- all that plastic will eventually be gone, probably in less than a thousand years after we humans are gone. Some things do last longer, but allow a million or more years, and zip, nada.

Meanwhile, suggesting that a civilization might last even a million years, completely overlooks evolution. Evolution happens. Things change over time. Even now, humans are actually evolving faster than ever.

[brush]

94. They don't, and neither did the OP neglect to mention that...

other civilizations may have come and gone, as we may, without any contact BECAUSE OF THE VASTNESS OF SPACE. Those things are well understood.

Also both point out the human arrogance and hubris in thinking that of the trillions...trillions... of galaxies and even more quintillions of stars and planets out there in the universe, that there is no chance that conditions for intelligent life developed anywhere else.

[PoindexterOglethorpe]

96. Other galaxies don't matter.

They are so far away that inter-galactic travel will simply never happen. Oh, and some 90% of all galaxies that we can see are already so far away that even at light-speed we could never possibly visit them. But you know that.

I honestly think that one important limitation on the development of multiple civilizations out there is that fully three quarters of all stars in Milky Way are red dwarfs. Whatever life might evolve on a planet around one of them will surely be unknowably different from what we have here. Even if it does result in a technological civilization. And that doesn't take into account the fact that once you get towards the center of the galaxy, cosmic radiation will probably prevent any life from evolving. Not to mention the specific conditions we have here that may be truly unique: planet within the Goldilocks Zone, a large moon which gives us tides, plate tectonics which shake up things on a regular basis.

Honestly, no one would be more thrilled than I if we actually discovered even a proto-life form on Mars. Or elsewhere in our Solar System.

I also think another answer to the Fermi Paradox could be something like this: life evolves more or less readily, given even faintly favorable conditions. And that life might often go on to develop intelligent life, a kind of civilization. But, what if intelligent life evolves on a planet like Venus, covered with clouds? And here I'm assuming a more hospitable environment, just permanent cloud cover. They might never get beyond those clouds, but think the entire universe is that planet. Or within the gas of a Jupiter or Saturn, and again, never make it far enough up to see the stars? Or a Europa, under a thick ice crust? Or even on a planet somewhat more Earth-like, but have vision that doesn't allow them to see the stars? Or, perhaps worst of all, evolve on a planet around one of the stars that are out there between galaxies, and never quite figure out what the Universe really is?

For what my opinion is worth (and I know you're thinking right now, not much) I do think it's the vastness of time, more than the vastness of space for why we haven't met other intelligent species so far.

[intelpug]

104. unfathomable time

'millions,billions of years unfathomable to most. This is like when they talk about national debt in the trillions. I mean like the average person can conceptualize a million dollars or so and equate it with a yacht , a mansion, land ect. But even 1 trillion ? what can you compare that even to ? It get's to where these number's seem to be just an abstract and not even real anymore.

[dcmfox]

56. Crushing? Nah...

If such a thing exists with much more intelligent beings than us that is a good thing. I look at like college you need to pass this bar or its just worth our time to contact you,

PS thanks for playing would not be part of this, lol

[AllyCat]

62. Because most humans are f'in idiots?

[grantcart]

65. This was the theme of "Arrival"

Alien species that could transcend linear time.

They came to warm/beg humanity to join collectively to work together.

The reason they wanted us to survive is because they saw in the future that humanity was instrumental in saving them.

[BlueJac]

67. We are too violent for them!

Smart civilizations want nothing to-do with us animals on earth!

[Ka-Dinh Oy]

68. Are humans intelligent enough to recognize actual intelligence?

[sakabatou]

71. In essence, we've been blacklisted?

[Crowman2009]

72. They're probably are receiving our wireless telegraph, radio and tv broadcast.

To which they are passing on visiting us for now. Especially when they interpret all the First World War communications and find out our use of poison gas.

[PoindexterOglethorpe]

80. Even those are at best a bit over 100 years travelling.

If it would even be possible to capture those signals. Let alone decipher and translate them.

I keep on asking people who ought to know, and I tend to get vague answers, but I'm not so sure that even on the Moon you could pick up broadcast signals from Earth. Light years out? Get serious! And even if you could, the Earth is rotating 24 hours a day, so any signal you'd receive will within at best a few hours, not be received.

So the very fragmentary nature of signals that might be picked up on some distant planet would not even remotely lend itself to being coherently understood.

I know, I know, it's a common theme that aliens watch our TV, but it's not going to happen.

[HardPort]

73. If they do show up, why should we not expect something like columbus in Hispaniola?

[keithbvadu2]

79. They watched our historical documents on Galaxy Quest and decided we were not worth contacting.

They watched our historical documents on Galaxy Quest and decided we were not worth contacting.
.
.
2 space aliens looking down on earth.
I see the dominant life form has developed space weapons.
Does this mean they are an emerging intelligence?
I don't think so. They have them aimed at themselves.

[JHB]

81. These things always leave out one possibility: Somebody has to be first.

[Swede]

83. It's the prime directive.

As the right of each sentient species to live in accordance with its normal cultural evolution is considered sacred, no Starfleet personnel may interfere with the normal and healthy development of alien life and culture. Such interference includes introducing superior knowledge, strength, or technology to a world whose society is incapable of handling such advantages wisely. Starfleet personnel may not violate this Prime Directive, even to save their lives and/or their ship, unless they are acting to right an earlier violation or an accidental contamination of said culture. This directive takes precedence over any and all other considerations, and carries with it the highest moral obligation.

[VGNonly]

84. Monsters on Maple St.

[link:

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[electric_blue68]

100. If you want to read another interesting, wild take on this I suggest David Brin's - Existence...

It's partly a set of non fiction chapters of the perils we face interspersed with a wild take on this subject that partly reflects some of what's being said here.
Fascinating stuff!