Ask HN: Why isn't anyone else bothered by the fact that life is only on Earth?

> I am bothered by how improbable it is that even simple life forms have not been discovered anywhere else in the universe.

The obvious reason is that our ability to look is extremely limited.

Could there be subterranean life surviving deep in Martian rock? We don't know, we haven't looked yet there yet.

Could there be life sustained by thermal vents in Europa's subterranean ocean? We don't know, we haven't looked there yet.

We've identified some habitable zone exoplanets. Do any of them have life? We don't know, we don't have the technology to tell. If we are talking about Earth-like multicellular life, you'd expect there would be some atmospheric changes, which we'd eventually be able to detect remotely via space telescopes (even if the current generation of space telescopes can't yet). But if we are talking about subterranean microscopic life – how could we tell without physically sending a probe there? So I don't think we'll know this century.

And surely there's many more habitable zone exoplanets out there we haven't identified yet, because our telescopes aren't good enough. And eventually we'll get better telescopes, and we'll identify more of them. But even then there will be many more that even those telescopes aren't powerful enough to identify.

There is life everywhere in the universe. Just because we haven’t find evidence doesn’t mean there isn’t life elsewhere in the universe. Till recently we didn’t even know that life exists in the depths of oceans near volcanic vents. We can’t even see astronauta footprints on the moon. How can we ‘see’ life on far away planets or astroids or whatever we haven’t discovered yet.

> There is life everywhere in the universe.

How do you know this?

Trillions is an unfathomable number. There are trillions of planets out there. Statically there is life on one of the trillions of planets besides earth.

I get what you're saying, but I'd expect that we'd at least get fossil records on some of our nearby neighbors.

The nearest neighbors are not ‘near’. It is unfathomable for some, like me, to think that there is no life out there - as we know it or something totally different. The number of galaxies, stars, planets are way too many. You don’t have to agree.

You’re wrong, water has always existed on Mars in some form [1], and Mars is older than Earth.

[1] https://en.m.wikipedia.org/wiki/Water_on_Mars

“Nearby neighbors” might be tough if that is your primary concern, especially if you want fossils.

The next closest star is 4.24 light years away. 25 trillion miles.

Although, Venus could have been like Earth at one point.

One theory is that even if life existed, a city like New York would have turned to dust over a billion years due to the conditions Venus has today. There would be no evidence it ever existed.

May I ask why you find it so troubling? I mean, what if we were the only life in the universe? Would that be bothersome? What if we weren't? Is that more bothersome? Or is merely the fact of not knowing bothersome?

Per my understanding of how Mars used to be [1], I don't understand how there aren't even any records of microfossils. I also don't understand why the rest of the universe looks pristine. For example, intelligent life on Earth has created so much space junk in just ~300000 years since the earliest human civilization. It appears that intelligent life, once it forms, doesn't take much to go from pre-civilization to space exploration, at least based on human civilizations.

[1] https://www.livescience.com/space/mars/mars-may-have-been-mo...

I don't understand either. Personally, I believe the rare earth hypothesis is more credible than it seems at first glance. But the matter is warped by our own definition of life, in that we're looking for familiar things (i.e. humanoids or bacteria or radio signals) out there. For me, when looking deeply at viruses, kinesin or even something like fire, the line between living and unliving seems like a pretty arbitrary definition in many ways. Which is fine, but if we decide the definition is something resembling us, or life on earth, then I think the rare earth hypothesis seems as credible as any other theory. Not to mention when you think deeply about physics, or just how inhospitable the vast majority of space seems to us. But on the other hand, I guess finding anything extraordinary or complex is all that we're really looking for.

But, regardless, I guess I am just confused, as bothersome to me sounds a bit like worry. I am not worried (i.e. bothered) about the matter, as it seems irrelevant to my livelihood. I believe I will die without knowing either way and have no qualms about that. But if you are bothered by the matter in the sense that you're just very interested, curious, and desiring to know, that's very understandable. It would be truly awesome if we found concrete evidence of life elsewhere.

> The most reasonable explanation after you exclude something artificially forcing life to exist on Earth, or preventing it from existing anywhere else, is that we just need to explore the universe more, and grab samples from other planets in habitable zones.

I suppose we would if we could. Distance presents a fairly big problem. With current technology just getting to the nearest known exoplanet would take about 10,000 years, one way.

What more do you think “we” should do about this, so you can sleep at night?

I think the first problem is long-range communication capabilities. I am not in this field, but I think a network of optical communication nodes which span light years is needed. I imagine each node should be small, cheap to manufacture, and self-repairing in some form [1].

The second step is meeting energy requirements for deep space exploration, and I think the answer there is nuclear-powered deep space probes which can use the optical network to relay information back to Earth. But more importantly, there needs to be a self-contained autonomous system which can detect signs of life, ascertain next steps for making a determination, and ask for help when it doesn’t know the right next step, amongst other things [2].

Note that both of the things I am mentioning are half-done.

[1] https://www.nasa.gov/general/spear-probe-an-ultra-lightweigh...

[2] https://spacenews.com/space-force-taps-four-firms-for-laser-...

For me, the incentive for deep space exploration is answering the why question of human loneliness in the universe. But another incentive is deep space mining.

Given the time required for space travel compared to human lifespans this doesn’t get close to the threshold for something I would worry about. Even if we launched a probe to the nearest planet tomorrow neither I nor any of my descendants for hundreds of generations will know what it finds.

I get the impression that you have mixed science fiction, wishful thinking, press releases, and outright grifting together. A species that can’t unite to stop destroying the one planet we know can sustain life seems ill-prepared to unite to explore the universe.

> I get the impression that you have mixed science fiction, wishful thinking, press releases, and outright grifting together.

Oh, don't get me wrong--I am aware of current capabilities, but you're right that I added in a wishlist of sorts. I think humanity is always going to be blowing itself up one way or another, but some of this work might unite people around a greater purpose (settling other planets), and/or be useful for job creation.

We can buy more teslas to support space travel /s

I am of the view that the chance of life in a single universe is vanishingly small. Fortunately, there can be many, many universes, or many, many effective universes. I googled the number of stars in the universe and it said 10^23. I am admitteedly not sure exactly what all this entails, but that is a pretty small number. How many ways are there to arrange a deck of cards? 10^68. That means you would have to put 10^45 decks of cards in each star system just to get a good chance of finding another deck with the same order of cards as one you shuffle yourself. And life it a lot more complex than a deck of cards. The number of stars grows linearly with the volume of space. Probability shrinks much faster. I don't know what the actual probabilty of life evolving is, but I wouldn't expect it to be very easy. And I don't think there is any reason to think the universe we see is the only "try" there has been to create life.

Comparing a physical count to permutation count doesn’t really compute me to. The only correlation that these two concepts have is the fact that they are numbers. One scalar’s magnitude has no bearing on the significance of another’s in an entirely different domain.

How would we discover simple life forms elsewhere in the universe? It's not impossible the Mars rovers could have have found fossils, but it's not like we've been to the 100 million other stars in this galaxy, never mind any other galaxy.

Our radio and other telescopes aren't good enough to detect life on other solar systems unless we get really lucky, though if we manage to get 1000 au out we could use the sun's gravitational lens to magnify other planets enough that would see continents, detect artifical radio sources, etc.

Interstellar travel is hard, maybe not even practical. It's one thing to travel to another star, it's another thing to travel to another star, create an industrial base, then travel to another star. And why would you be motivated? You might be alive, just barely, to get the news from the next star over, but not much longer than that.

The space colonization project that makes the most sense in this solar system (read it carefully to see why it strictly dominates everything that's been proposed) is

https://arxiv.org/pdf/2011.07487

I'd assume anyone who develops interstellar travel would develop that first, it would be suicide to plan to colonize an Earth-like world on the other end (might face severe biological incompatibility) but it seems a realistic plan to build something like that Ceres megastructure on the far side. In fact, if somebody developed D-D fusion they could exploit similar objects that are scattered throughout interstellar space which makes the hops between stars shorter but might mean they'd be indifferent to stars and dry Earth-like planets completely when they could, instead, gravitationally disrupt generic outer solar system/interstellar bodies (like Pluto) and make a number of small ringworlds or other megastructures.

If there's any evidence they haven't been here it's that Ceres is still there.

There are more solar systems in the universe than there are GRAINS OF SAND on our planet. We have explored such a ridiculously small amount of the universe that your assertion doesn't make much sense.

A lot of people are bothered by it. There's not much we can do about it yet - we've done what we can with the crude methods we have available to look around, but we're severely knowledge-and-tech limited in ways of checking.

It leads to a lot of philosophical hypothesis though, including the idea of a "great filter", which makes a lot of people extremely worried. Hell, the richest man in the world, and one of the most powerful, is supposedly motivated by a desire to get off-world to avoid a future disaster. I haven't heard him speak specifically about lack-of-aliens as a reason for worry, but I'm sure he's come across that argument before.

This cannot be stressed enough:

Space is big. Whatever you think big is, it’s so much bigger, that even thinking about it is mind bending and could induce vertigo.

The nearest star, our Sun, could hold 1.3 million Earths. It only looks the size it does because it’s far away. How far? At the speed of causality (the universal speed limit), which is the speed at which light travels in a vacuum, of 3.0 x 10^8 m/s or 670.6 million miles per hour (pretty fast), light from the Sun takes 7 minutes to reach Earth. For a comparison on the scale of just the planets in our solar system, that same light takes 5.5 hours to reach Pluto.

You might think that’s not so big.

As a point of reference, Voyager, which has been traveling since 1977 (~47 years) at around 38,000 mph, is around 23.5 light hours away.

Now, our closest star, Proxima Centauri, is 4.2 light years from Earth. Voyager hasn’t even gone a light day in nearly 50 years. At currently attainable speeds, it would take over 50,000 years to get there.

That’s just the closest star. Just one potential solar system.

Our galaxy, the Milky Way, is thought to have 1-400 BILLION stars (hard to tell from the inside). Our observations indicate that it is 100,000 light years across.

Now if that wasn’t bad enough, for intergalactic travel, the closest galaxy, Andromeda, is 2.5 million light years away. It is estimated to have up to a trillion stars.

After that, it gets even more stupefying. We can see hundreds of billions (with a b) of galaxies as far away as GN-z11, which is estimated to be 32 BILLION light years away.

We’ve made it less than a light day.

We have no idea if we can even approach even a substantial fraction of the speed of light, and even if we could, there’s time dilation and the issue of slowing dowm. Communication would be anywhere from difficult to inconvenient to practically impossible.

Anything beyond that is either science fiction or a very well kept secret.

So that’s the reason we don’t have alien fossils or microbes.

It can take 18 months just to get to the next closest planet, and 8-10 yesrs to get to the farthest. never mind anywhere else.

And we are so far away from everything (as is everything else), even if there were radio or tv broadcasts, they would be far too weak for us to detect.

There probably is life out there, but maybe the great filter is that stars have a fixed lifespan and the distances are just too great to overcome.

First of all: ASAP? You're talking about a trillion dollar program that would take centuries. We can't even feed the people on this planet or stop murdering each other for 5 minutes. Why is it of such utmost important to detect something vaguely out there?

Second: I'm not sure why you're asking about fossils and debris? The size of space is so big that the most advanced state of the art is to detect atmospheric compositions as a whole. How would we possibly be testing for microfossils"?

If you mean on more local places like Mars, there's pretty good evidence Mars has/had a microbiome. But without better proof, it's not like they're going to make announcements. The rovers make deliberate choices on what experiments it carries and those devices need to withstand the trip and justify the shipping/opportunity cost. They don't have an electron microscope, but they have tried other methods of identifying life. A small ETM is planned for a future mission, though.

And to wrap it up: you're assuming life would want to be found. Space is unfathomably big, but it's also unfathomably old*. Humans won't be recognizable if we survive a few million years. How about a billion? What results may not even seem like life as we know it all. Their home may not even exist anymore, and they move through the interstellar medium. We can only look for known signs of bioactivity right now... not, say, crystalline beings in stasis ships traveling the void with virtually 0 energy emissions.

Or maybe they just realized it's a waste of resources - what would one even have to gain compared to lose? They may have made horrifying weapons that have no countermeasures and hide, knowing any first contact could kill their entire people.

And if they're sufficiently advanced, why not just create digital heavens and live in bliss and excitement for, essentially, eternity with their families and friends? Why look out into a void for aliens they probably could never understand when they can have cool space adventures with sci fi technology in their Matryoshka Brain?

All this is, is a neat thought. You're letting it get to you, but it's genuinely not important. Smart folk are trying, but it takes a long time and the odds aren't in favor of your life changing in even the smallest way from the endeavor.

How many other planets do we have the capacity to examine microfossils from? Being able to check out asteroids (qua bits of fragmented planets) for a very short time.

In my opinion, the greatest achievement of ASI will be when it concludes, after careful and thorough consideration of all the evidence and laws of nature from the quantum up, that it is impossible that random evolution could be responsible for the quantity and variety of life forms in the amount of time the universe has existed. It won't know where life came from, but it'll know it wasn't natural.

We haven't detected life yet, but there could be plenty of planets out there where it began to evolve around the same time it did here. Let's say many began broadcasting centuries ago, the signals could still take millions of years to reach us.

The further away from Earth, the further back in time, the smaller the chance of highly evolved life.

I’m not really bothered at all. Something like us may exist many times over in the vast universe. We may never know. And that’s what is exciting, IMO. The idea of dying with all the answers is not that exciting to me. But to die with some of the answers, knowing there is the excitement of discovery, for future generations, is precious.

> The idea of dying with all the answers is not that exciting to me. But to die with some of the answers, knowing there is the excitement of discovery, for future generations, is precious.

The "why" of existence is part of the human condition, and it's a big reason for the development of individual and societal artistic and intellectual endeavors, including work that happened in pre-civilization by cave dwellers. I'd like to know what I can.

Exactly!

Pascal was bothered by it. In the Pensees he said “The eternal silence of these infinite spaces fills me with dread.” Maybe you’d enjoy this blog post about it: https://www.steelsnowflake.org/post/pascals-terror

I'm a proponent of the "firstborn" hypothesis — we don't see any other signs of life yet because the universe is still in its relative infancy and we're among the first sentient species to pop up out of the primordial muck.

It's anthrocentric, but humans are the smartest people I know so I cut them some slack ;)

Even if we knew there's life on some other planet... what would we do with that information? If you wanted to send a message there, you wouldn't live long enough to get the response anymore. So at this point the discovery would be meaningful for the civiliasation (maybe), but meaningless for us personally.

I think what is potentially even sadder is the idea that there might be life but we're all on islands and can't get off / communicate.

As far as discovering life elsewhere, our vision / reach is so small that I'm not bothered by it at this point.

How about:

* No life on Mars, because it didn't have the luck, even despite having water.

* No microfossils from anywhere else we've looked because that's zero places.

* No other intelligent life because we're freakishly unlikely even relative to space being enormous.

My personal belief is that there are aliens out there but they aren't as advanced as us so no electricity to send signals or maybe they are too far away to send a signal yet?

It takes a lot more than electricity to send a detectable signal multiple light years. And unless we're lucky, the minimum is likely to be tens of light years.

Assuming we even found a likely star system, built some huge focused transmitter, we'd still need to broadcast for probably hundreds of years for it to have a chance of being received. And that's hoping the other side are in exactly the right stage of their development, have built a big receiver and happen to be pointing at us.

Which is to say that the risk of finding life via radio, is, well, pretty small.

We're more likely to find life by visiting other planets. To do that you only need to solve 5 (mildly hard) problems. A) you need a multi-generational ship B) a power source that can last at least 1000 years C) a self-sustaining human population - probably between 200 to 600 individuals. Likely spread over 3 generations in terms of age. D) an in-board biome capable of supplying food an oxygen to sustain the population. E) pick a good direction to go in.

Given that pretty much any, and every, thing that can go wrong will kill the crew pretty quick, chances are the ship won't last a decade.

Of course even if the descendants of the crew actually find something, they won't have any way to tell us.

I think we need to develop faster travel [1].

[1] https://www.inverse.com/science/ny-to-la-in-one-second

That's 1% of the speed of light. So a trip to the nearest star would take 400 years. Practically we need to go at least 10% of light speed to get much further than our closest neighbors.

This is more of a philosophical/spiritual question than a scientific/technological one.

Why?

I wouldn't be able to elaborate well so I asked ChatGPT and here's some pointers.

1. Familiarity Breeds Apathy – Most people grow up with the assumption that life exists only on Earth, so they don’t question it deeply. It’s just "the way things are."

2. Existential Avoidance – The idea that we might be utterly alone in the universe is terrifying. Conversely, the idea that intelligent extraterrestrial life exists but remains silent is equally unsettling. Many people avoid thinking about it altogether.

3. Spiritual and Religious Views – Some believe life’s uniqueness is evidence of divine intent, making it feel less like an anomaly and more like a purposeful design. Others believe that even if life exists elsewhere, our existence here is still sacred and meaningful.

4. Cognitive Limitation – The vastness of the universe and the complexity of abiogenesis (life’s origin) are difficult to grasp. People struggle to comprehend distances measured in light-years or probabilities that span billions of years.

5. Anthropic Principle – We exist to ask the question precisely because conditions allowed for life to emerge here. If life were common, we might not find it remarkable.

6. Lack of Direct Impact – Whether life exists elsewhere or not doesn’t change most people’s day-to-day experiences. They’re more concerned with immediate human concerns than cosmic loneliness.

I’ll just counter that there is one very serious and practical reason to have a better understanding of life in the universe—if a spacefaring civilization develops fast travel and reaches Earth first, then humanity will be enslaved and subjugated.

Aren't we already enslaved and subjugated by the ruling class? (Again, a philosophical one)

There hasn’t been a singular ruling class throughout human history. But if another organism competes with us for apex status and wins, then that will change the nature of the ruling class. The ruling class, thus far, in different societies over time has consisted of people of different cultures.

You mean those lights you can see when it's dark outside? Don't let them bother you.

I think your worry comes from a materialist viewpoint. You perceive the universe as only being material, and then, looking out at the infinite material expanse, you are rendered distraught by the seeming lack of life 'out there'.

My view is that the material universe is only an illusion, that Earth is the centre of 'the universe' (it's immaterial that we orbit around the sun) and that life and consciousness only 'exist' on this planet. It's the 'stage' where we play out our lives; from whence we come and to whence we go is the bigger 'mystery' and one more rewarding to ponder on, then wonder about life 'out there'.

Infinite Earths in the multiverse.

Where does the rush come from? From within yourself and wanting discoveries to be made in your lifetime?

The way humanity approaches and organizes things, where everything and everyone is owned and just a tool to increase profit to repeat the same process, spells doom for what we touch. We may feel the need to discover other life to maybe fix us, but other life doesn't need to be discovered by us. Not with the state we're in.

And when it comes to intelligent, advanced life, we might just be drunk assholes running through a forest, screaming, then concluding squirrels don't exist. I mean, that's how I'd react to humanity if I didn't need them. I'd observe them and make 100% sure they never see me. If I couldn't observe them without seeing me, I wouldn't observe them. I might even try to forget them ^^

> Where does the rush come from? From within yourself and wanting discoveries to be made in your lifetime?

Yeah, I know that answering some of these questions in my lifetime is improbable, but I'd like to help the effort.

Life in adjacent otherworlds.

Where DMT/LSD etc is a mandatory requirement to graduate high school.

Are you saying you think Earth is the only planet to contain life?

Looking out there while there's an "invisible" world here they don't see.

+. If it's on "tv" it's fake.

False dichotomy.

https://cliffberg.medium.com/the-false-dichotomy-of-space-ex...

https://www.universetoday.com/131376/shouldnt-fix-earth-firs...

https://www.marssociety.ca/the-fix-our-planet-first-fallacy/

Not sure what you mean by "tv" being fake.

Mars Society founder Zubrin heads an aerospace R&D company....was formerly at Lockheed Martin Astronautics.

Cosmic Serpent. A young anthropologist takes ayhuasca and realises there's non-"academic" ways to ask questions and get answers. About reality.

https://archive.org/details/CosmicSerpent

Yes, but the arguments remain the same, that there is a false dichotomy between spending here versus there, whereas the advances from fundamental research for there benefit us for here.

Agree. Roadsters in space is fund a mental.

Indeed, otherwise we wouldn't have gotten self landing rockets.

it'd be funny in a movie.

in real life it's dead. serious.

The easier explanation is a higher power seeded life here. If you find a functioning phone on a beach, you don't just think a bunch of silicon molecules just evolved into a phone over millions of years. Someone is manipulating those molecules via complex processes.

Most of the universe is entirely predictable. Planets and stars go in predictable orbits for billions of years. Climates are fairly predictable. But as soon as there's a tiny bit of life, the behavior of a planet becomes unpredictable.

We already have space travel. We have artificial satellites. We have radio signals. In a century, we'll have colonized other planets. In a millenia, we would be changing climates on planets or polluting the universe with more satellites. Nukes are supposedly visible from space. So it's surprising we haven't seen this behavior in the rest of the universe. But an advanced enough civilization may have learned how to clean up after themselves and hide all traces.

As far as life goes, we've been around for 5 billion years. There's enough space out there for life to have emerged 8 billion years ago. Even with just a billion or so years of tech head start elsewhere, they should be far ahead of us. Arguably they'd be so far ahead of us that they'd be godlike in comparison.

Where does this higher power come from? There's a lot of answers, but it's sensible seeing that there are other hierarchies. We are a higher power. Higher than cells, molecules, electrons, quarks. Earth may well be some kind of chip or an egg farm. Maybe our purpose as a species is heating up the planet for some kind of galactic yeast.

Or you believe we are not a higher power, and are equally relevant permutations of the reality of the universe.

I think the bigger the claim, the bigger the evidence should be which supports it.

> The easier explanation is a higher power seeded life here. If you find a functioning phone on a beach, you don't just think a bunch of silicon molecules just evolved into a phone over millions of years. Someone is manipulating those molecules via complex processes.

You should read The Blind Watchmaker by Richard Dawkins as it directly refutes your claims. This is not a new debate in the field of theology.

There might be a misunderstanding here, as it seems similar to other arguments. I'm not saying evolution cannot create eyes or intelligent life. I'm saying evolution cannot create mobile phones.

I'm not saying evolution does not exist. It is a self-organizing system. But it's the weakest and slowest one of all. It is nature for systems to self-organize, and create increasingly complex self-organizing systems. A mobile phone is proof that self-organizing systems can be much more powerful than evolution.

I am arguing that the billion year head start is long enough for some other lifeform to create a godlike lifeform, which is capable of manipulating us. Dawkins himself literally supports this view in The Blind Watchmaker, "If we want to postulate a deity capable of engineering all the organized complexity in the world, either instantaneously or by guiding evolution, that deity must have been vastly complex in the first place."

This is not even capital-G God. It's simply a higher power. Capitalism makes humans need money. Someone farms chickens for eggs. Eggs are eaten by some humans for protein. But the protein creates the eggs, chicken, human, capitalism. Systems evolve from the bottom up. The protein is unaware of their role in capitalism.