It would be nice if there was a benevolent afterlife where you could explore the universe/multiverse (among other things) and interact with dead aliens and their media. Imagine alien games, alien films, alien music, etc. I highly doubt any diety would make a universe and only have a single intelligent species in it that can’t even feasibly access the rest of said universe while they’re alive.
I don’t think it’s a matter of belief. It’s probability.
It all comes down to the Drake equation. We do have some better information about some of the terms of this than we did a few decades ago.
We now know that extrasolar planets are common. But on the other hand, earthlike planets seems to be quite rare. This might change a bit as observational techniques improve, but it seems that a lot of the systems so far examined have characteristics which rule out earthlike planets.
It could be argued that earthlike planets are not necessarily the only ones which could develop life, of course. But non-water-based life remains speculative.
The basic answer, I think, is: we still don’t know.
This is a particularly good video about the Fermi paradox. There’s too much there to quickly summarize, but the part that I found compelling was speculation about the “Great Filter” hypothesis – that perhaps there exists a point in the evolution of life and intelligence that either stops evolution or destroys what is already there and that is virtually impossible to get past. The crucial question is if the Great Filter exists, is it behind us – have we already won an incredibly improbable lottery – or is it still ahead of us, dooming us to destruction?
If it’s behind us, it could something as basic as abiogenesis itself or the improbable evolution of mitochondria. If so, the galaxy could be full of habitable but lifeless planets, or teaming with life, none of which has evolved beyond bacteria. If it’s ahead of us, it could be the inevitability of nuclear destruction, or some new technology yet unknown, or known but considered benign, like artificial intelligence.
It’s a thoughtful video that’s worth your time. I don’t think it was previously posted:
It’s kind of silly to point to “A” Great Filter, when instead there are likely hundreds (+) of Small Filters, and to think that just one of them makes up more than (say) half of the chances of life (or not) is pretty simplistic and unrealistic.
I’m not sure if I’ve posted this before but I’ll throw it out again here. I have an idea for a future Great Filter that afaik no one has previously mentioned. It falls into the category of civilization destroys itself; not by nuclear war or an AI apocalypse or grey goo or ecological degradation, but by something more insidious. My candidate for the Great Filter is that technological species in the end essentially deconstruct themselves.
What I mean by that is that as science advances it ends up undermining the foundations of that civilization or even that species’ biological basis. Geology, astronomy and physics destroy whatever initial beliefs that civilization began with about the nature of the universe. Paleontology scotches their creation myths, and archeology and textual analysis put paid to whatever comforting lies they might have told themselves about their history. Psychology (both individual and mass) and neurology destroy the very idea of “free will”, of individuals as prime movers. Many believe that our current state of affairs is already the result of Western civilization having lost the belief that Christianity is literally true back in the 19th century. Having cast aside all illusions, the species “steps outside of themselves” and outside finds an empty void.
The breaking point comes when thought itself becomes something open to manipulation, and it becomes possible for that species to engineer what they think, feel or believe. Readers of Philip K. Dick’s science fiction about the consequences of psychoactive drugs will be familiar with the idea; C.S. Lewis’s The Abolition of Man is another look at the subject. The probable result is a period of highly unstable destructive feedback. Multiple incompatible and rival systems of thought might achieve local minima and form closed belief systems. Perhaps the rise of totalitarianism in the 1930s was a weak preview of this; now imagine Nazism, Stalinism or Maoism only with effective mind control at their disposal. Either the rival systems destroy each other or are prevented from doing so by social and/or technological collapse. If the species doesn’t become altogether extinct, it devolves essentially into hive creatures mostly devoid of independent thought.
Future great filters are a lot more difficult than past ones to conceive of.
Because, as mentioned, humans are not far off being “noisy” / detectable and we’ve spent almost all our history killing each other and destroying natural resources*
And let’s not lose sight of what a singular great filter would need to do. There are hundreds of billions of star systems in our galaxy alone. As Epic Spaceman brilliantly illustrates, there are rather a lot of galaxies. If the main filter is ahead of us, it likely needs to cull at least billions of species.
* Not all humans have been violent, or have used natural resources in an unsustainable way.
I say this, because I don’t like the cynicism where people claim that all humans are always violent and selfish – it often goes side by side with handwaving our worst atrocities.
Humans can do better; it’s not hopeless IMO.
There are many possible manifestations of “the Great Filter” including the possibility that multiple filters may be operating concurrently. I don’t think anyone has said that there’s necessarily just one, just multiple hypotheses for what they might be, and perhaps a predominant one.
I dunno, intergalactic travel is as far as we know VASTLY more demanding than interstellar travel within a galaxy. Unless warp travel or wormholes really are possible, civilizations in galaxies hundreds or thousands of millions of light-years away might as well be in another dimension as far as we could ever have knowledge of.
Has physics ever established a theoretical maximum space travel speed?
As far as we currently know traveling faster than light would require traveling backwards in time, which is speculative at best. Thanks to time dilation shipboard time could be arbitrarily low* but that raises a slew of other problems.
*Or could it? I don’t know if at some point within a ridiculously high fraction of the speed of light like 99. (45 nines)% contradictions from quantum mechanics arise.
No, not necessarily. Remember we’re only talking about detection, not them visiting for tea and crumpets.
Granted, the bar for being detectable in another galaxy is much higher than for being detectable in the same galaxy. But it looks possible with physics as we know it, so it’s relevant for the Fermi paradox.
Indeed I believe I saw something about an extragalactic survey that looked for any glaringly obvious signs of Kardashev Level-3 civilizations, and didn’t notice any.
You mean like the speed of light? Which has been established as the maximum possible speed, period.
Now that absolute upper bound is a fairly loose upper bound for any sort of machine we can yet imagine. The problem of dust & gas being in the way even out in interstellar space gets significant as you get up anywhere near c.
If you’re trying to ask something else, I’m struggling to understand what it might be. Which may be a failure of my reading comprehension or imagination.
Exactly. The problem is we have no idea what the odds are. Saying there are x amount of exoplanets out there sounds like a big number but until you know what the odds are of life spontaneously arising from inorganic matter (Abiogenesis), that large x number is meaningless.
Prof David Kipping on the subject (within the first few minutes of the video).
Not to be pedantic, but HBDC seems to be asking about ‘traveling’, in which case that would be something with mass. As such, we would never be able to travel at the speed of light, we might be able to get very close, but never attain it.
But I get what you are saying…
I see your point too. Still wondering what HBDC was thinking.
There is still no real evidence of any kind for alien life. Not even slime mold under a rock.
Eyewitness reports are known to be unreliable, ask a detective investigating a crime. Obscure pictures of something are not evidence.
Show me a real life alien we can interview. It is all smoke, mirrors, inuendo, rumors, someone KNOWS. Bullcrap.
Aliens have probably never been to Earth at any time, they aren’t here now, they aren’t watching us, they cannot travel the incredible distances involved anymore than we can or ever will be able to. There is probably life out there, but other galaxies don’t matter because of time, speed, and distance. So the number of probabilities goes way down.
We are thinking of a technological, intelligent, space travelling race within our own Milky Way, and there are probably not ANY. Likely very, very rare. That is the answer nobody wants to accept.
Star Trek, Star Wars, has so polluted the public thought that people cannot think clearly. Billions, trillions, of possiblities don’t mean crap. All of the aliens I see depicted look like little, hairless, wrinkled old ladies with big black plastic eyes. They don’t even put much effort into imagining.
Real evidence remains to be zero, as is in nothing. Keep dreaming of billions, but show me the Real McCoy and you can’t. It remains Kooky to belive in alien space travellers.
Yeah, one would think that if UFO/UAPs were real we would have at least ONE photograph that isn’t either an obvious fake, a point of light in the night sky or a blurred black smudge in the daytime sky. Someone on the board in some thread said something like the distinguishing factor of dubious claims is that despite decades of searching the evidence never gets any better. Contrast rare but real transient phenomena like ball lightning or sprites or bolides that were confirmed once surveillance became more ubiquitous.
Huge difference between the OP’s question “Are they out there”, and these last two posts answering “Are they here now-ish?”
The answers can simultaneously be “Almost certainly” and “No way in heck”.
And IMO those are the most likely correct answers. Both of them.