Fermi paradox assumes that advanced aliens use technologies detectable by current human technologies. It might be the case that human technology-detectable civilizations cover maybe a few hundred years before switching to advanced non-radio tech, so essentially they have "shells" of detectable broadcast expanding out from their locations, making it even more unlikely for us to be lucky enough to catch them.

Having read this fascinating thread with such deep and thought provoking questions, I've come to what I believe is the only reasonable conclusion...

I think we can safely assume that the dinosaurs were never as technologically advanced as we are now--there'd be something, somewhere, however miniscule, but we'd have found some evidence now that they did possess technology--something not iron based that would rust away. I say this because the opposite is frightening to consider, lest our lizard overlords are looking down upon us now, mockingly.

Can you imagine a flying T-Rex on a Back to the Future hoverboard? That's scary as hell. Forget sharks with laser beams. Scaly, giant dinos surfing Manhattan, mouths agape devouring brains for sport. Should they ever return from their lair in the core or their outpost on Phobos, we're doomed. Godzilla might seem like a paradise fantasy.

Our sun is due to become a Red Giant and will thus expand and consume the Earth and destroy it in about 5 billion years.

Imagine the disappointment if we haven't made any contact with aliens by then.

The Fermi paradox makes no assumptions at all.
It just looks at the Drake formula, and (almost) no matter how pessimistic you are about the various factors and the speed with which an interstellar civilization would colonize the galaxy, the sheer number of stars and the billions of years since which our galaxy exists, the Drake fomula more or less predicts that our galaxy should be teeming with life (and thus with communication signals (if we could read those signals)). So, "where are they?"

• Maybe we just can't detect their signals (for a few decades Earth was brighter in the radio spectrum than the sun, until we largely switched to digital transmission, so our very own history might already provide an explanation why we can't find them - weak digital signals would simply disappear in the background noise)
• Maybe, and that is the scary explanation, there's the Big Filter. Either technological civilizations usually kill themselves before they reach the interstellar stage due to unforeseen technological risks (such as nano machines, nuclear warfare, ecosystem collapse, artificial intelligence, ...) which suggests that, in all likelihood, this is the fate that awaits us. Or the galaxy is dominated by a sinister predatorial race that kills all competition in its infancy, whenever they detect them - the one race that developed interstellar colonization first and/or which won the first interstellar war, and all the other ones ever since.
• ...and about 18 other major explanations

There was no civilisation of any sort in the Mesozoic. There are simply too many predators running loose. Virtually 60% of animals on land and more in the sea were very fierce predators. Any civilisation would have found that situation untenable, just imagine creatures like T rex and the allosaurs being tolerated wandering about, not to mention the hundreds of species of smaller predators. It is almost a hallmark of any civilisation, even Bronze Age examples, that predators are quickly eliminated and the herbivores domesticated.

Well, Allosaurs and T-Rexes certainly didn't live during the same time period. If you count Australopithecus, the human race is five million years old and developed the current technological civilization, if you're generous and count the Pyramids, within the last 5,000 years (and 99% of that progress was made in the last 500 years). Humanity eliminated most megafauna and competing predators about 10,000 years ago (or turned them into dogs).
If that acceleration of the cultural evolution is typical for sentient beings, our ability to separate the time of the petrification of fossils simply doesn't have the resolution to even identify a five thousand year period. All that we know is that most dinosaurs disappeared some time about 65 million years ago, +/- 1 million years. IF one dinosaur species developed intelligence AND a technological civilization, it could very well be responsible for their own extinction due to some self-inflicted ecosphere collapse that merely coincided with a comet's impact, and we simply wouldn't know it. What we do know is that over the last 10,000 years the overall biodiversity on our planet has plummeted in an unprecedented manner as a result of our shaping of the environment - whether it's the turning of forest into arable land, or just polluting the air, the water, and the ground with toxic byproducts of our industrial activities, or by eliminating certain species that were of vital importance to other species. Like, the biomass of insects in Germany going down by 80% over the past 40 years, and with it the bird population.

So, if overburdening the capacity of ecospheres to compensate for environmental changes is a hallmark of technological civilizations it is entirely possible that our planet may have had up to four intelligent species so far, three of which may have killed themselves and disappeared without a trace (except, mass extinction events). I'm not saying that THIS is THE explanation. There is no indicator other than the mass extinction events themselves to support that thesis, and natural causes such as giant rift volcanos as a result of Pangaea and other megacontinents breaking up are a far more likely explanation of these ecological catastrophes. All I'm saying is, there's evidence that technological civilizations develop very fast in geological terms (=our own history), and there's an almost negligible likelihood that we would find any trace of civilizations from millions of years ago, unless they were space-faring and left their vehicle parked on the lunar surface. In that case there's excellent chances that we may eventually find them, unless we're killing ourselves first.

If all humans would die today, geologically there would be very few traces of our existence in a million years from now; the radioactive glass spheres under the Nevada desert (but they are few, and must be found), and probably an unusual carbon-rich 1mm global layer of sediment where all of our plastic ended. The Pioneer and Voyager space probes. And the lunar landers, and possibly the satellites in geostationary orbit.
That'd be it.

Exactly what can end a tech civilisation? Even nuclear war has winners and losers. AFAIK and the historical record bears witness even massive disasters like the epidemics of the past have failed to even slow down human progress. It would take something like a Permian or Cretaceous extinction event to do the trick, and even there I believe we could preserve a nucleus of civilisation given some sort of pre-knowledge of the events not available to the dinosaurs or other ancient animal types. I am sceptical of past civilisations rising and falling, once progress starts it seems that nothing can stop it. Naturally when we begin to establish self-supporting communities on other planets we are unstoppable, it would take the Sun going nova to do that.

Look around. Geologically speaking, we are in the middle of an extinction event, the most severe one since the Permian, as far as the velocity of the extinction is concerned. A geological extinction event does not necessarily mean that all life gets exterminated, just that the ecosystem that supports a certain species collapses (and with it, the species disappears). Sabertooth cats for example were so successful, they hunted their prey to their own extinction. The rest of the planet shrugged their shoulders, and went on.

We don't have to kill everything in a technological civilization induced extinction event, just ourselves. That could be genetic modifications with unforeseen long-term consequences, nano machines, AI, or an unlucky combination of several factors - just like there's not one singular factor for the current decline in biodiversity (which, again, is geologically unprecedented ... maybe a fact worth contemplating real hard). As a species, mankind just happens to remodel the planetary ecosphere with pollutants, general deforestation, or hunting multiple species to extinction. There's no big plan behind this, just the individual desire to live prosperous, and the elimination of leading causes of death which means that an increasing number of humans only die of old age (and we're working on that, too). Now, don't get me wrong. In the short run and at the individual level that's great news. As a species and as a technological civilization we have never done better than today. It's just not sustainable. We're using up the planetary ecosphere - which you can do for a while, but not forever.

As it can happen to us, it could have happened to others as well. I'm not saying that this was "it" in the past. I'm just saying that if it was, it's not in contradiction to the (very few) traces that we found. We're making up the early history of mankind and the human evolution from maybe 30, 40 (partial) skeletons that we found over the last 200 years. That's not really much, and these are finds for the very recent past. With dinosaurs, it's proportionally much worse. It's just because they ruled the planet for such long periods that so many fossils can be found, and our means to date fossils is rather coarse.

You see, Ssnake, I just don't go with your arguments on this. I don't think that barring a nova, mankind can be exterminated. The genie is out of the jar. Sure our civilisation can be trashed, we can have new dark ages, but will always recover. Check out the Toba volcanic event or bottleneck 75,000 years ago. We were down to approx. 10,000 individuals globally but still came back. Our technology is our salvation as a species.

Here is an interesting look into evolution and the likelihood of intelligent life.


https://www.realclearscience.com/ar..._might_be_the_only_intelligent_life.html

So now the debate has gone from debating whether or not intelligent life exists outside of Earth to debating about climate change and the possible extinction of humans?


Gotta love the idiosyncrasies of SimHQ.

I think the best course to follow is..if some life form is different from us, they should be considered a threat and be annihilated at once. If in the course of our hostility towards them, we find out they are not a threat then we can find a way to enslave them for our benefit. The minute they become unable to perform that function or decide on a way of fighting back/defending themselves, they should then be annihilated.

I look at the human race from day one. We have been doing that with people of different religions, customs, color and opinions on earth since time has been recorded......so it must be the right thing to do.

Unfortunately people of science and those with compassion try and stop this path,,,..but thankfully we only listen for a few years before we get back on track.

Our propensity for greed.



If man does not evolve philosophically, it is inevitable that we die by our own fire.


And it is this required philosophical evolution that relies on an interstellar species to relinquish their primitive instincts and nature as to why I believe the odds are reasonably high that any intelligent alien species we encounter will not be warmongers, but benevolent and value life. They may also deem us a risk to the galaxy and slap a slave shield around our planet to trap us in, but I doubt they'll fly from star system to star system leaving a trail of bodies and bones in their wake as they fuel their blood lust.

Mad Max ......"Our technology is our salvation as a species"

Not ready to agree to that given the fact that humanity is greatly burdened by greed, destructive wars and persistent stupidity

I'm not sure why you are banging this 'Dinosaurs could have been intelligent' drum of an argument. You are partially right that most of what would indicate that dinosaurs were intelligent would have disappeared but not every trace. If fossils can show imprints of leaves and feathers of dinosaurs from the period then it would have left some kind of imprint of items that would have at least indicated some sort of tool use by dinosaurs. Some part might have been found in tar pits and anything showing primitive knowledge of tools, especially the use of stone tools would have been found. If the dinosaurs did have an advanced species there would have been some traces of it, any traces of it. And intelligence would have been a biological advantage to dinosaurs and would have transferred to birds, which are the descendants of those dinosaurs.

As for our extinction. It will take a little more than a 1-2 degree change on our planet to do that.

Population degredation? Possible. Famine and drought could cause a loss of many lives in places that are currently on the cusp of population oversaturation.

Extinction? Very difficult.

Even in an event like the eruption of Yellowstone I honestly doubt the whole human race would die out. Maybe 90% of it but there has been no creature that has been as adaptable as human beings. As a species we not only survive but thrive on the plains of Africa, in areas like Saudi Arabia. We've sailed across the Pacific in primitive rafts and colonized every habitable island from the Philippines to Hawaii. We have civilizations in the Amazon and near the Arctic Circle. Short of something that completely destroys the planet and ALL life on it we will survive as a race. Our intelligence and our ability to adapt and use what is around us to survive is what will lead to our survival as a species.

In some respects something like massive climate change might have some beneficial evolutionary effects for our race. I'm talking strictly evolutionary, I'm not referring to the loss of humanity, which would be horrible, but the idea that as a race it might make us stronger. Lets face it, from a strictly evolutionary standpoint we have a lot of traits finding their way into our race that aren't particularly advantageous. The blind (which I count my myopic self in), the physically and mentally handicapped, the less intelligent and the older people would all die out in a climate catastrophe. For the most part these folks wouldn't make it. One problem with being as far up on the food change is we have no real reason to weed out the weaker of our species. A catastrophe wouldn't give us this option. Lets face it. Most of us wouldn't make it. Civilization as we know it probably would collapse. But Homo Sapiens would survive.

Not every human being is technically advanced. There are still societies that aren't burdened with technological dependence like ours is. Even in the US there are places and people that know how to survive with minimal tech. It isn't like the knowledge of the 19th Century and before is gone. Even with the collapse of the Western Roman Empire there were still traces of that knowledge available that allowed Europe to survive during the Dark Ages. After the first 10 years, when the vast majority of those that couldn't adapt have died off are gone, then those that remain will probably be able to deal with what is left.

Kind of hard to deal with nuclear winter with Medieval level knowledge. Everything dies when the ICBMs launch. Radiation does not discriminate.


And after a few years pass, the giant cockroaches and scorpions take care of the rest.

Charlton Heston will blame us.