An interesting question to me is - if the Earth was seeded with life, does this mean we will find life elsewhere in the solar system, because they were too, or does it mean we will not find life elsewhere, because a rogue planet collided with proto earth in a very unlikely event, and the rest of the solar system (or at least the potential life supporting objects) came out of a sterile nebula around the sun?
Why are there no other detectable signs of human life, like smoke signals, territory markers, or emissaries from any more but a handful of other tribes? Surely if advanced humans existed, they would have contacted these tribes by now, to share technology, discoveries, and medicine. Yet they haven't.
How can the whole planet be so... silent?
And, won't uncontacted tribes in the amazon have seen airplanes and such?
So, we don't see or hear artificial signs in other galaxies because light is from the times when there was not complex life in the universe.
Now, we only have to solve why we don't see or hear artificial signs in our galaxy. But the problem is not so perplexing because we are talking about one or two million years.
If, for instance, a big part of the galaxy is bad for complex life (after all, we are far away from the center and that could be relevant), Fermi's paradox is solved.
If all the civilizations started more or less at the same time that us, it's not so weird that we have not found anybody else. If you add some other factor (maybe civilizations are only possible far from the center, so there is a big spread between them) the probabilities improve.
It also would mean interesting times ahead for humanity.
Of course, all this is only idle speculation.
To be clear, I'm not saying that's what it is ... the fermi paradox is a great thought experiment. But let's just keep things in perspective. Low odds don't mean something won't happen, just like "true random" doesn't mean the same song can't/won't play 10 times in a row ;)
As in, the universe may be littered with the ruins of single-planet civilizations slightly ahead of our technology level. We may have observed and cataloged many such planets, failing to notice the ruins.
1)
Ordinary Matter ~10^53 kg (4.9%)
Dark Matter ~5*10^53 kg 26.8%
Dark Energy ~1.3*10^54 kg 68.3%
Undiscovered ? ?
Also, people talk a lot about not meeting aliens, but just talking to them. Based on the fact that we have little/no idea how Dark Matter and Energy works, and we only really use radio signals (when funding permits), it may be like trying to whisper at the Queen of England while standing in Norway; a telephone would be much better.
2) Tom Scott on immortality and risk : https://www.youtube.com/watch?v=B5a6wrJpxP4
3) Life may be so abundant in the universe that it's not worth talking or meeting up with. What would you say to a single mayfly if you could talk to one on it's level? No scientist or other person has bothered to try, and I think there's a good reason for that.
http://www.jodrellbank.manchester.ac.uk/media/eps/jodrell-ba...
And just the existence of life doesn't mean there's complex life. We don't have a firm lower bound on how long life took to arise on Earth after we got liquid water on the surface but it can't have been more than 120 million years. Photosynthesis, mitochondria, and other innovations allowing for complex life like you and me took way, way longer. I made a diagram for a blog post here:
http://hopefullyintersting.blogspot.com/2018/03/the-drake-eq...
In the context of this thread, lets say you are a species which stepped out of your planet, there are plenty of asteroids, and even planets lying around you can mine for resources. You settle billions of your kind in space. You are not running out resources and have no motivation beyond research and science to venture out a little far.
Would you, such a race, want to travel interstellar distances? You would travel far distances by organic growth.
Also its likely how old the universe is anybody who didn't kill themselves to extinction, is likely at our phase of development. And is likely asking the same questions as us. Those beyond our phase of development are hiding for a good reason.
It's not a given that alien civilizations "should" have developed this or that technology that we ourselves don't have.
Of those, I find plausible the observation that as we tame the world to suit us, we shrink. Cities, civilization, supermarkets, products, TV, internet. By this trend, we'll live in dream terranes before long. (BTW as people get richer, reproduction gets less).
But we'll need power, and eventually a dyson sphere to capture all the sun's light - perfect for an inward-looking, closed-off people! Then what, I'm not sure. Perhaps long before that, we won't need other suns; we'll have artificial suns (controlled fusion).
That's what happens to everyone else: as they grow in technological sophistication, they get better and better at directly meeting their own (previously evolved) needs.
As a result, intelligent life around the universe only exists as short 'blips', being around for too short a time to ever meet other species.
The history of man suggests otherwise. The more our civilization progresses, and the more the population swells, the broader the array of philosophical positions those within the civilization tend to hold. We have no evidence for everyone eventually coalescing around one 'right' belief set.
History is also littered with non-reproductive sects, like the Essenes, aesthetics, or, today's answer to these, anti-natalists and child-free individuals. These groups don't tend to be very good at passing their belief systems on to new generations however, as one might expect, and they don't tend to last particularly long once they've emerged on the civilization scene.
Seeing the wide spectrum of intelligence and education that humans manage it's hard for me to believe we'll ever reach a point of uniformity as a species were something like self-imposed extinction would be plausible.
There's always a risk of that, unless you can 100% guarantee this won't happen you're basically gambling with another person's life. I don't think you have the right to do that.
I don't get this. What use are ethics when everyones dead and gone?
From looking at the graph, and the 300 milion year doubling, they seem to put life complexity at about 256 base-pairs at the origin of the earth.
There should be a link to the actual paper in the article.
...today. Life was simpler back in the day. For example, RNA world. This more primitive life might not survive more sophisticated life. (thougn it's also possible it's still around, but we haven't noticed it; or haven't recognized it as life).
IDK if small enough, but viruses are simpler.
If it can reproduce - e.g. a short strand of DNA or RNA or even something simpler - it could form the beginnings of "life" as a precursor, even though it wouldn't meet our current definitions of "alive".
There's theories of fatty spheres being the first "cells" (really, "kinda sorta cells").
How life began is obviously still an unanswered question, but if the conditions for self replicating molecules were sufficient early on for Earth, I'm not sure why billions of years would be needed for life to form versus several hundred million years.
Planets that exist without a solar system, but do retain sufficient heat, might have been out of solar winds harm ?
https://en.wikipedia.org/wiki/Abiogenesis#Earliest_biologica...
Further questioning I have though is, does solar radiation penetrate through ocean water?
What radiation is between solar systems or what rogue planets would likely encounter, and how that effects single cell life, amino acids, organic compounds, and any other building blocks to life?
Barely. 10km of water will shield you from almost any amount of radiation, and we know of life forms which live at those depths, so they could have developed even when Earth was completely bathed in radiation.
If this happened it did so at the microbe level. Physical evidence would be extraordinarily difficult. If we did find evidence of another tree it would be so 'alien' to our tree that might mistakenly call it extraterrestrial.
It took hundreds of millions of years, possibly up to a billion years, for basic life to form on Earth. I would say that is not "soon"; it's a really long time.
The obvious response to that is, yes it seems like a long time, but it's not much on geological time scales. But it feels to me that there's an implicit circular argument here: the whole reason that geological time is measured in terms of such huge spans is because it took life such a vast amount of time to get to the point where humans exist to discuss it (understandably).
The first billions years on earth mostly involved the planet getting hit by large things and the surface melting. Repeat every millennium.
Ocean floor is continuously destroyed as it's subducted, and continents won't have fossils if they are under frequent bombardment.
Right, but if giant bombardments completely boil away the oceans and atmosphere to rain liquid rocks back down on the surface, there very very likely won't be life, either. So the claim is not just that "fossils only go back to X" but that X is so close to the end of the giant bombardments that there's almost no time left (geologically speaking - maybe 10-20MY) for "life but no fossils yet".
This is a common popular misconception. See something like Simon Conway Morris's book Life's Solution. There is evidence that life existed on earth almost as soon (geologically speaking) as the early bombardment stopped repeatedly boiling away the entire oceans and atmosphere, within something like 10-20 million years. Thus, all the interpretation about the implications of that.
If current knowledge is remotely correct, heat death will happen, no matter how immortal Homo deus will become. The quarks are against us.
And if complex systems theory teaches us anything then it would be preposterous to assume any ultimate superiority in understanding the universe on our part.
Who knows who wrote crazy alien versions of Hacker News posts 2 billion years ago in one of the other couple of thousands of galaxies seen in Hubble Deep Field alone...
In fact, dolphins. Octopi. Yeah, pretty much a given I'd imagine, in the right complex ecosystem, that intelligence is a thing.
It seems like there is an obvious further inference to make - people have debated whether life originated on earth or not. Given that the vast majority of planets do not have a star, and given that we know there are chemotrophs even on Earth that prove it is possible to live without a sun, it seems overwhelmingly likely that life came from one of these rogue planets that was large enough to retain enough heat underground for the evolution of life over the first few billion years of the universe. That would also neatly explain why evidence of life appeared so soon after the Earth became solid.