The Fermi Paradox: Where are all the aliens? by Kurzgesagt
Adam Rifkin stashed this in SETI
Hijacking the top comment here, but I find the Fermi Paradox leaves out a very important factor which must be considered. The speed of light. (This might alleviate some of that existential crisis)
Consider that SETI has only been functional since 1960. We have been broadcasting radio waves into space since almost exactly 100 years ago. Do you know how far those radio waves have reached till now?
Seriously. We have announced our capabilities as a technological and sentient species to such a tiny tiny fragment of a fraction of the galaxy (let alone the universe as a whole). Also consider that we no longer broadcast as much as we used to into space. Using the ionosphere to bounce off radio waves is OLD tech. Almost nobody uses that anymore.
So essentially, we spent about 50-60 years being a radio-noisy planet (in a fairly limited frequency range) and we expect advanced civilizations to rush to us and roll out a red carpet? It's the equivalent of a teenager on youtube uploading five videos about how terrible her day at school was, stopping uploading for a month, and then wondering why she isn't getting thousands of likes and turning into the next Beiber.
To be noticed, we would need alien life forms to be looking in the right direction, in the right frequency range, and be well within range of that 200 light-year bubble. Either that, or we would need to be patient and stop giving up before we've barely started.
The light-year problem extends the other way too. Alien civilizations may be swarming over vast tracts of our milky way for far longer than ten thousand years, and we might not be aware of it because the milky way itself is over one hundred thousand light-years in diameter. So the further we see into space, the further back we are seeing into time as well. The images we get from the opposite side of the galaxy are 100,000 years old. To give you some sense of time, 100,000 years ago, humans as a species was just beginning to crawl out of Africa. We had no concept of agriculture or anything of the sort. Proper agriculture was 90,000 years AFTER that. Look at all we've achieved in 10,000 years, and that is despite stuff like the dark ages setting us back 2000 yearsmysticism and superstition and other stupid hurdles. In the time that light takes to travel to us from just outside our local neighborhood, entire alien civilizations could rise up, die, and rise anew. But the Fermi-Paradox writes all of this off so easily.
Looking at our 200 light-year bubble again. There are only about 500 G-type stars in this bubble. As of 2005, we had only found planets around 28 of them. I'm sure we have found a whole bunch more since then, but even then, we are just BEGINNING to probe at space.
It is far too early to feel despair. It is far too early to let defeatist concepts like the Fermi Paradox guide our understanding of our universe.
EDIT: copypasting an additional bit I wrote in response to a comment in this thread:
What we see is an ever-receding 50 year time-slice of the universe (receding with distance). It is hardly what I would call a 'complete picture'. The further the target, the more of their progress would be invisible to us. So if there were a gigantic mirror (pointed at us) in space halfway across our galaxy, we would peek at the earth in the mirror and see... nothing. We might detect organic molecules in the spectrum. But dead silence otherwise. And that would remain the case until about 50,000 years from today.
Thank fucking God for that.
What's all this rush for an unqualified inviting here of alien life from any and all other parts of the multiverse?
Given our history, and even casual observation of other species throughout every realm of nature, the mingling together of species of great differences rarely ever results in musings about existential life and cafe style conviviality...
And we humans are simply fucking dipshits of such narrow intelligence and grave incompetencies given our technological reach that we rarely even contemplate consequences of our actions in terms of probabilities of negative outcomes. And the probabilities of any alien interaction will be that the lesser intelligent and competent beings will be either eaten, studied on a lab table or enslaved by a more competent species... and perhaps all three... just look at what we STILL do every day to our own earthly rabbits, monkeys, dogs and rats simply to make sure organic lipstick doesn't cause a rash.
And if aliens do come visit us in our lifetimes, they most certainly will be the more intelligent and competent...
I hope it will be 500,000 years, or if sooner that we get really, really lucky.
Now you're using known human science and perceptions ... what if unknown alien science makes such space/time distance irrelevant ...?
And of course we too could reach an understanding of wormholes, warp drives, or other dimensions that would change the math. That's certainly possible in the next few hundred years given the pace of breakthroughs humanity has been on.
That's all true... but I've still a sneaking suspicion humanity is not the big man on campus anywhere else in the multiverse but in our own minds – our greatest imaginings are likely poorly formed child's toys in any alien beings' experience that might visit us first.
Well we really have only existed for a very short while. Give us time and we'll develop understanding.
Sounds like our best plea once the aliens land... or come back again:
We're not fully baked yet!
Perhaps that's just how they like us... medium rare.
Haha. Perhaps that's why we're made of meat.
I wish humans would get focused on building our 1000 year sustainable spaceships, and quit focusing on greed, wars, and religion. We're losing precious time.
How long does a 1000 year sustainable spaceship take to build?
A great unknown, but definitely gets delayed every time we waste our time/money on other things. My guess would be we could have it in 50-150 years, maybe not a 1000 year spaceship, but a 50+ year one at least ;)