I wonder if its possible to prove we are alone. Or are we going to search forever?

I hope we cannot prove that we are alone. The sky just wouldn’t be as interesting anymore.

this did make me curious if there was some mathematical way to prove an absence of life. not sure how that would be possible tho.

wouldnt that be more interesting if we were alone?

You first have to define "life". There could be forms of life that we'd never consider or think possible and be nothing at all like any life we see on Earth. But if you do develope a working definition, it could be possible to disprove its existence by a form of proof by contradiction by proving the existence of things or conditions that would prevent your "life" from being able to exist.

I think it’s a logical fallacy, you can prove the existence of something, but you cannot prove the non-existence of it.

I think, unless we can literally colonize everything, it'll be sorta like the argument for/against God. Where are they/we can't know they aren't there. Both of which are technically valid.

If we prove we are alone then I'd be far more inclined to believe the more "super natural" theories about the universe.

Why would we assume anyone else would definitely be watching and how would we even be able to tell if they were?

Technically I don't think it's possible to prove we are alone, the universe is just too vast. If we keep searching for centuries and don't see or hear anything, I think we can logically place some constraints on the prevalence of ET across the cosmos ie. rare to the point of one civ per galaxy or local group or something. We are nowhere near that, however.

It's called the anti-life equation

There are some interesting models based on the formation speeds of stars and planets and how long they remain habitable, as to how prevalent life might be at the different stages of the universe.

They suggest that the peak of habitable worlds that have existed long enough for life to exist and evolve to an intelligent stage (given certain assumptions about the difficulty of that) is actually some billion years in the future, and that humanity could be relatively early on the bellcurve of the distribution for life. Not extremely early, but well before the theorized majority of opportunities for intelligent life.

It involves assuming that earth life is typical, or at least no an extreme outlier in terms of requirements and timeline to evolve, because it's the sole datapoint we have, and assuming humanity is special or unique would be a form of anthropocentrism.

Without faster than light travel that would be impossible to prove since the universe is alot bigger than just the observable universe. With the speed of expansion increasing and already expanding faster than the speed of light, it would get harder and harder as our technology improves.

We're not going to exist forever. It's possible that intelligent life is born, looks out into the sky, and fizzles out before finding even the graveyards of other intelligent species who once did the same.

Even if they were watching, wouldn’t the event be visible at a different point in time?

Not really. The universe is just too vast. We don't even know for certain that life HAS to be carbon based. We might see an exoplanet, decide it's not habitable, move on, and all the while a thriving sulfur based life form forms civilizations, learns, grows, puts things in orbit, travels to their moon, then nukes themselves into oblivion for no good reason.

Just need to read the 3 Body Problem series to make it feel better about being alone in the universe.

Civilizations could have already occurred or haven't yet. If we don't settle other worlds, the mantle of earth will eventually gobble up all evidence of our own existence if we aren't around by then. Applying that to a "Past" civilization on Earth is moot as well due to it being impossbile to find the evidence of such an outstanding claim.

I have to disagree. There'd still be so much worth finding, both biological and otherwise. Finding out we're the only conscious beings would instill in all of us a deep purpose to spread consciousness everywhere. We'd be the primordial being, enshrouded in perpetual myth throughout the cosmos. 'The First Ones' .

Also, who knows how violent or immoral some other conscious being may be. We seem to be kind, for the most part. With a little more widespread knowledge and direct democracy, I think we could be very successful in our voyage to the stars.

The timescale is the only thing that really hurts this idea. Frame of reference could be off by millions of years

I agree, we likely have been staring at the skies for millions of years, even before we reached our ‘modern human’ point of evolution I imagine we looked to the skies and wandered what it all was about for a lot longer than we would like to give credit to.

I find it hard to believe we will ever get close to another intelligent life form to the point of a handshake, we might end up picking bio-signatures in the composition of far away planets atmosphere, perhaps even signs of artificial lighting, but that does not mean we will ever actually go there, if science is still lacking we might still not have a effective way to make the distance of space near negligible, then we have problems.

To me, from that point it makes sense that we end up sending some sort of drone technology there, even if it takes 1000 years to get there and Humans are all dead, its still contact in some format.

My point is, even at this current stage of technology we realistically and absolutely could send drones to pretty much every close by potentially habitable planet.

Im in full belief that if we ever do experience ET, it will actually be their technology sent here, nice little care package if you will.

Your yogurt is going to expire in 2 days.

You probably would need to make distance a completely negligible factor in travel for this, you would have to make it so you could travel instantaneously to visit the complete opposite of the universe. The problem is, obviously these galaxies on the other side of the universe probably are moving away from us at a ridiculous velocities, to the point that you could not catch up to them perhaps.

You would some how have to have the energy to accelerate to FTL and likely not stop accelerating at any given point for x amount of time to outpace the movement of the galaxies.

I feel like some manipulation of quantum physics or dimensional science could be the real route for space travel, i don’t believe physically travelling point A to B is our real end goal.

[removed]

unless the govt is lying and aliens are here already, I doubt we will have the answers before the of the century so after I am dead.

That is also a good point, didn't think of that part

[removed]

Watch out for Pizza The Hut

Intelligent life probably, but we may find microbial life in our own solar system in places like Mars or Saturn's moon Enceladus before the end of the century.

Okay, but to what end?

When humans watch cosmic events, the best we can do for active imaging (illuminating the event in some spectrum rather than just passively receiving the light/radio/neutrinos/whatever) is to shine a laser at the moon or use radio to get a pitiful handful of bits out to probes at the edge of the solar system. If an alien intelligence wanted to observe us observing something, they would have to be able to pick up those reflected non-natural signals to see that there was another intelligence at work.

Conversely, for us to observe aliens observing something, they would have to be lighting it up with enough signal for us to see the reflection/spillover. In our own cosmic neighborhood, we've just started being able to detect entire planets bathed in the light of entire stars. In other galaxies we can't even detect individual stars, we can pretty much only resolve supernovae. Even if aliens could generate an energy beam strong enough for us to detect from another galaxy, why use it to illuminate a stellar curiosity? It would be so energetic that it would likely destroy the object that it was focused on.

Not to be too much of a downer, because what you say is possible, but odds are overwhelming that extraterrestrial life will be carbon based. Carbon is just so flexible, there's a good reason why organic (carbon-based) chemistry, as a discipline, is larger than inorganic chemistry (everything not involving carbon).

It's also very likely that it will exist along with liquid water. At lower temperatures there just isn't enough energy to lead to complex life in reasonable time frames; at significantly higher temperatures you start bumping into other issues even before you reach plasma (which will probably make life development impossible to bootstrap).

Oh sure. But when we're talking about even just our galaxy, there are so many planets that we just can't say anything for certain. We have life evolved to live and even thrive at hydrothermal vents in the deep ocean. And our planet is pretty young. 1 in a billion odds mean very little when you get over 100 billion chances. We'll never be able to prove or disprove. That's what's so exciting about the universe. Anything is possible.

Even with only 100 year offset

1. Advanced civilizations probably don't use omnidirectional signals because it's a massive waste of energy. Their transmitters and receivers are probably set up for signals to be sent in one direction like a laser. You could even transmit power like this.
2. You could detect such a tightbeam signal from very far away. There is even a theory referenced here that the famous WOW! signal was a tiny bit of leakage from a power transmission.
3. If alien civilizations do want to be found, one way they could make it easier to find them would be to beam a signal at a cosmic event which they are certain any civ with telescopes will look at. That way, any civilizations on the other side of the event from your beam will open up their data and say "huh, that shouldn't be there."
4. (It's also possible that they would send a signal to that event for reasons other than communication, I guess like a very patient version of radar? but anyway)
5. In other words: I, an advanced alien, have spotted a binary neutron star pair in the next galaxy over. I know it will take my signal 250k light years to get there, but that happens to be exactly when these two stars will end their dance in a kilonova. However, I know any fresh young civs will definitely be awed by the big explosion it makes, so they will all turn their telescopes at it. Being ancient and alien and inscrutable, I send this signal even though I will likely be long dead before it's even partway there. 250k years later, the signal arrives at the massive explosion.
6. Another half million years later, someone on Earth---which happens to be more or less exactly on the other side of that binary star pair from our old alien friend---records this explosion, and then notices there's an artificial signal buried in there on top of the stuff that looks like every other explosion. If they talk to aliens anything like we do, we're left very disappointed by some mathematical universal constants and a picture of what they looked like naked. (We could probably actually learn some tech by figuring out how they made such a powerful signal but I like my version better)

anyway this was my best tl;dr

Voyager 1 and 2 is the drone technology you speak of. Too bad we wont be around to see what finds them…

Outer Wilds and Project Hail Mary touch on this idea very well.

[removed]

How would passive observation help us find other passive observers?

No.

You'd have to exhaustively rule out all life.

In your trek to do so you would seed the universe with microbes or heck even those who just split off and settle down, and new forms of life would develop.

[removed]

Are either of them aimed at anything in particular though?

Or even only one month. That’s quite depressing.

[removed]

We'll not be able to "prove" anything of that sort anytime soon. We're not entirely sure how our own brain works, let alone the Universe.

I believe this is where I come in

What is this game theory? I've never heard that in the context of space stuff.

Or there is a civilisation out there that just roams around looking for this extraordinary and rare events, and sends out information just enough to make nearby civilisations aware and respond. Then bam, feeding frenzy.

How do you beam data at a cosmic event so that it passes the cosmic event right as it happens? Or are we talking a continuous beam here?

I mean I guess continuous on a short time scale, but not continuous like "for 1000" years. Maybe a decade? I don't know how long binary neutron star explosions last

[deleted]

Youtube channel I follow (Professor David Kipping) addresses these topics in a few videos.

Shelling Points for Alien Contact:
https://www.youtube.com/watch?v=3lwlNWMl86M

Is Messaging Aliens a Bad Idea?:
https://www.youtube.com/watch?v=7TAOMvW5LaQ
Revisiting the Wow! Signal:
https://www.youtube.com/watch?v=r6rPNPVQp0Y

Upvoted for the disappointment in point 6, but I have a question - does their laser have to be coming from the opposite direction? Or would we be able to pick up a laser coming through what we’re looking at from the side? And would it hypothetically be traceable back to its point of origin by ‘tracking’ it back along the beam?

… without the half a millions years of delay being anything to worry about, of course.

This is one of the reasons why the fermi paradox has always befuddled me. The central question of the fermi paradox is “if the universe is full of life then why haven’t we heard anything“. And it always seemed obvious to me that the reason why we haven’t heard anything is because we’ve been listening for less than a fraction of a fraction of a fraction of a second on the full year calendar of the universe‘s existence, and we expect to have just heard alien civilizations that could be millions of light years away.

Like, an entire interstellar empire could exist on the other side of the galaxy right now, literally strip mining entire stars for energy consumption, that has existed for 10,000 years, and we wouldn’t know about it for tens of thousands of years more at the bare minimum simply because of the speed of light. An alien civilization that just invented the radio yesterday that exists 100 light years away would be completely undetectable for at least another 100 years, and that’s assuming that they continue to use Omni directional radio transmissions; already on earth those are being phased out.

It’s just odd to me that the fermi paradox has such an iron grip on the discourse around the search for extraterrestrial intelligence; like, space is really freaking big, and that fact alone is the biggest limiting factor on why we probably haven’t heard anything.

When you look at the sheer scale of the universe in both size and time, its near impossible we will ever have contact with another civilization

>And it always seemed obvious to me that the reason why we haven’t heard anything is because we’ve been listening for less than a fraction of a fraction of a fraction of a second on the full year calendar of the universe‘s existence, and we expect to have just heard alien civilizations that could be millions of light years away.

>Like, an entire interstellar empire could exist on the other side of the galaxy right now, literally strip mining entire stars for energy consumption, that has existed for 10,000 years, and we wouldn’t know about it for tens of thousands of years more at the bare minimum simply because of the speed of light.

10,000 years is also a fraction of a fraction of the time the universe has been in existence. If the universe is full of life, then you'd expect civilizations to exist and show their mark on the environment at some point over the past 14 billion years. A human-like civilization could colonize every star in the galaxy within just a few million years even at sub-light speeds, and even if you assume it takes a colonization mission 10,000 years after arrival until it's built up to the point that it can send out a colonization mission of its own.

We didn't exist at the same time as the vast majority of life on this planet, but we can see the remnants and learn a great deal of those past ages. Yet out of the 200 billion stars in the Milky Way alone, we only see life on one single, solitary planet.

>A type I Kardashev civilization is able to harness and consume all the energy available to it on a single planet, approximately 1016 watts

Is this supposed to be 10^16? 1kw seems laughable in this context

See you in Spaceballs 2: The Search for More Money.

I always wonder about some of the assumptions built in to this. Like the idea that we'll just continue to grow in numbers forever. I mean human history shows a decrease in birth rates as living standards improve; maybe most species just find a stasis point of how many of them exist and it's less than "the whole galaxy". If that's true, then it's really not surprising we don't see any. If there were 100 individual stars with civilization around them in our galaxy, even if they'd been there a billion years there's basically zero chance we'd have seen them

In my opinion I’ve always viewed the Fermi Paradox as a qualitative thought experiment, not hard and fast rule.

Thank you! You're the first person other than me who I've seen express this opinion. What's the paradox here? It's an interesting question with interesting possible answers, but I don't think it's a paradox

[removed]

Depending on where these theoretical civilizations are in the universe, would they even be able to see it? It might not be in their sky yet or it might be gone already, because of how long it takes for the light to get there. Whatever civs looking at it would have to be more or less equidistant to it, right?