I read somewhere that all of our radio signature would fade away to the point that it's indistinguishable from background noise within five lightyears.
Plus, we've been around for ages and only briefly let out a bunch of radio waves. I image we might not even generate that many anymore.
By that logic, you could easily image that the universe is teeming with intelligent life that happens to not have sent a powerful radio signal out here, or whose tech development timeline never included wide public radio signal broadcasting.
Yep radio waves degradation is due to the inverse square law. The strength of the signal is determined by the inverse of the distance squared. So the drop off is pretty extreme.
I used to be greatly tempted by the fermi paradox, but upon learning about limitations we have observing the skies.... I believe the entire fermi paradox talk, is just steeming from the fact that we think too highly of ourselves as a civilisation and the efford we put into observing the skies.
Most people, including myself until recently, don't realise that most of our astrophysics/space science is very limited to our immediate close promixity in the cosmological scale.
Correct me if I am wrong but we are only able to do science around the other stars in the Milky way (e.g. exoplanet observations)
Beyond Milky way, all the light from the stars are collapsed into a single blob along with the rests of the stars in their home galaxy.
> Correct me if I am wrong but we are only able to do science around the other stars in the Milky way (e.g. exoplanet observations)
Oh yeah and on top of that the way we detect planets around stars creates a extreme bias on dwarf stars since a positive detection needs a few transits before confirmation of a planet can be made. And since dwarf planets transit within days/weeks sun like stars take around a year so it would take 3 years of observation to find an Earth around a sun-like star. But I have heard science communicators imply that what we have detected so far is representative of what is out there which is absurd.
If FTL is impossible(which I doubt since it's only "impossible" in some capacity in Special Relativity. But Special Relativity does not describe our universe, General Relativity does and even that has limits),then not seeing Aliens is not a paradox at all considering radio waves only go out a few light years, and the distances are just too great. And if there are any Alien probes in our solar system sitting on IO or some moon we'd have no idea since we have only done flybys and never truly scanned the surfaces.
I thought on this for a few days. The nature of scientific process, forces us to maintain absolute emphasis on our observation, to an extent which we are willfully ignoring the limitations and scope of our observations.
I wonder who is to blame, is this the current state of scientific studies? or they are actually considering these limitations in the papers, but it is ignored by public? then, is it the science communication to the public that's failing?
I feel shy even bringing up such topics among friends, because it is so far out of the common understanding that it will sound like flat-earth conspiracy to most.
People don't like to hear anything that goes like "we don't know some things at all". There is a comfort in knowing somewhere, some scientist are %100 accurate and know it all.
I wouldn’t go so far as to claim that we have hard evidence of aliens crashing here or visiting our solar system, but you’re going completely the other way and making an extraordinary claim without evidence. Absence of evidence is not evidence of absence.
The Drake equation? We can see the stars, we can see the planets (and there are lots of them). We can infer the number of earth-like planets. So where's all the intelligent life?
If you look at all the crazy coincidences that were required for life to develop on Earth, it starts to make sense that we're alone. Single star in the system, need a big Jupiter to block space rocks, our target is a rocky planet close to star, but needs to be hit by an abnormally large moon right as the lithosphere is cooling, ripping out 1/3rd of it so that the planet can have giant continents barely covered with water part of the time, then submerged the rest of the time to the cadence of this moon, oh and has to be the right star type, and etc etc etc.
If it takes something like all that for life to spontaneously erupt, we're likely alone.
That's one example of how life is formed. By someone's definition on wiki, life could be defined as
> self-sustained chemical system capable of undergoing Darwinian evolution
Meaning in a different environments with different moons, stars, temperatures, as long as the environment could support abiogenesis (could be different from what we currently know), life would be able to be sustained but it might be a hell of a lot different.
I don't really know what I'm talking about but surely a different life form would've existed at some point somewhere... Right?
Jupiter directs more rocks towards earth than deflects. But life on earth appeared immediately after it cooled suggesting that the process to start life is relatively straight forward. And life by default adapts and evolves based on it's environment, so how crucial the moon is for life says more about how life on earth adapted than how it can possibly form.
We don't know that any of those conditions are necessary. Right now what it looks like is certain chemistry, which happens to be pretty common, an energy gradient of sufficient magnitude, and relative stability.
If we look at it as crazy coincidences, we can say that the earth is in a very unique state due to the crazy coincidences such that theres nowhere else just like it, but then, theres nowhere like anywhere else and everything that exists is the result of crazy coincidences. So, combinations of crazy coincidences that create very unique places are pretty common, ubiquitous even. So there's likely a lot of very unique places out there with very interesting processes going on.
I don't know if we will ever discover life. I don't know if we will ever observe another intelligence that spontaneously developed. But one thing I'm certain of, there are things going on out there that are more interesting than dead rocks circling even bigger dead rocks.
My theory on this is that intelligence, language and culture are surrounded by very high local maxima and we only got over the hump and down into our minima by incredibly slim chance.
So our original evolutionary advantages were persistance hunting & rock throwing (ranged weapons). This gave us such a huge advantage that we had enough excess energy we could start to develop bigger brains, language and culture (tools). For it to be possible we needed:
* Huge evolutionary advantages (rock throwing? fire to cook? walking upright? sweating?)
* Vocal chords that would let us develop language
* Hands that would let us make tools
And once we have that we can start to evolve intelligence and shared culture. But for a very very long time this was evolving a trait that is an actual hinderance. So we also need for that to be our 'peacocks tail'. A costly trait that is selected _for high cost and total uselessness_. And that trait could've been practically anything else!
Imaigne all the worlds where ranged weapons are developed by a species which just can't do language. Or where they can't make tools only throw rocks they find with their evolved longbow like limbs. They'd conquer the world but that would be it. And that world is now too well optimised for another animal to develop intelligence, they can't afford it.
If this is the case life could be wildly abundant but 'intelligence' more or less unheard of. This is infact what we see in the historical record on earth, there were many epocs of dinosaurs, as far as we know none of them shaped rocks for throwing, had language or developed cultures. In the time we've been around no indepdent intelligent species have evolved (we only see evidence of ones with a common ancestor.)
I think the drake equation suffers from the same fallacy that seems to beset everyone talking about AI. Intelligence is over-rated, it is not a linear thing or a super power where more of it is always better and can solve any problem. It's incredibly costly and often quite useless. Our actual problem solving is more down to trial and error at the level of culture than we like to admit to ourselves.
While I don't really have an opinion either way on whether we're likely alone or not, I just want to point out that the blindspot in this argument is that all those things are truly necessary for life.
This is like a form of the anthropic principle [1], where we think that just because those conditions appear to have been necessary for our evolution (and since Earth life is the only example of life we know), that exactly those conditions must be necessary for life elsewhere.
We may only think that because we evolved here and thus think you must need all of that as we can't think of it any other way.
On another note, you probably are absolutely right and we do need at least some of that. Not too hot or cold. No massive asteroids to destroy everything...etc. I think some of the rest may be negotiable though. Like do you need water? I think yes, buuut maybe some other liquid could work?
Maybe it's emptier than it should be because that's how the universe is always made to appear to emergent civilisations at the dangerous and volatile point of evolution we presently find ourselves at?
Being very generous, in my opinion, and assuming 1 in 2 systems has a planet/moon that is inhabitable by life as we know it, and that 1 in 2 of those has tool-building life at some point, in our galaxy you get something like 1 tool-building civilization per 600,000 square light-years spread out over 12 billion years.
The truth is more interesting: the galaxy is emptier than it should be.