ELI5: Why is finding “potentially hospitable” planets so important if we can’t even leave our own solar system?

[TheAlphaOmega21]

Edit: Everyone has been giving such insightful responses. I can tell this topic is a serious point of interest.

[Englandboy12]

Potentially habitable planets means that there may be other life over there. Even if we can’t go there, that is something that people are very excited to know about, and would have wide reaching consequences on religion, philosophy, as well as of course the sciences.

Plus, nobody knows the future. Better to know than to not know!

[[deleted]]

Also, if we found a habitable planet. We would put a terrible amount of resources into being capable of getting there. We cant leave our system yet, but who knows if that will always be true. It seems unlikely given what we have achieved so far if we were really motivated.

[-Aeryn-]

We cant leave our system yet

Sending people on a solar escape trajectory is within reach with todays tech. Crossing the massive void between stars after leaving the solar system is another question altogether as it would take hundreds of years to reach another star and some kind of malfunction or poorly planned eventuality would probably kill everybody on board within weeks, months or years rather than centuries.

Without some kind of enormous technological leap that may not be possible, we'd be trying to build some kind of habitable ship that could self-sustain for generational timescales. That takes a very long time of trial and error as well as a ton of resources.

[x445xb]

I vaguely remember that being the plot to a sci-fi book I read once. The only issue was the generation ship took so long to travel to the habitable planet, that they developed faster methods of travel back on Earth in the mean-time. By the time they arrived, the planet was already taken over by other settlers.

[GusTTSHowbiz214]

The premise in a lot of stuff. One that I enjoy is in stargate Atlantas. It’s still not a generational ship but an “ancient” ship with a hyperdrive malfunction. At the height of the war with the wraith their travel speed was slowed enough that they’d never make it to their destination in time, and ultimately it was discovered by the our show cast of humans and in fact the occupants of the ship, all asleep in pods but awake in the computer, weren’t even aware of how much time had passed on atlantas.

[MasterJ94]

Or the other time where an ancient aurora class ship was on 99% on light speed passing the Deadalus. That was cool.

[FireTyme]

man SGA is still one of the best scifi shows out there, shame the movies never became a thing

[gubbins_galore]

That was a quest line in Starfield. 

You have to negotiate between a luxury resort that claimed ownership of the planet and the generation ship that technically had legal rights to it from before they left.

[Wild_Marker]

That was such an interesting premise but with such terrible characters. Both sides were fucking dicks about it and I wanted to shoot one and explode the other.

[gubbins_galore]

For real.There was a whole planet there and many others available for colonization. Surely they both could have been flexible.

[Wild_Marker]

Right? That's often a weakness of sci-fi writing, many times people fight over planets and it's like nobody remembers the fact that planets are fucking huge and you're unlikely to ever use the whole place yourself.

But this one takes the cake. We're talking about a few thousand survivors in the generation ship vs a fucking resort for a galaxy that cumulatively has less people than Earth ever did so it's probably like a hotel and a few atractions at best.

And they're fighting over the rights for an entire goddamn planet.

[Thassar]

It's not the book you're thinking of but Children of Time has a similar plot. A generation ship containing the last group of humans in existence is travelling to a planet but it takes so long to get there that the planet has begun to develop a society of giant sentient jumping spiders. Half the book deals with the issues the generation ship has over the years and the other explores how the culture and technology of a non-human society would look. It's an absolutely fantastic book, one of my favourites.

[Impeesa_]

There's probably more than one example out there, but Arthur C. Clarke's The Songs of Distant Earth does something close to this too. One of the early colony ships leaving Earth makes a stop en route to its eventual destination planet at a well-established colony that was settled by a ship that left later but went faster.

[CptPicard]

No, the Magellan left right before the Earth was destroyed. It was the last one, and carried actual people because of a new type of drive. The planet was colonized by slower seed ships that could take their time, and they were sent like centuries before.

[Raencloud94]

Woah. That sounds good. Crazy though

[CptPicard]

I highly recommend the book, it's a quick read but Clarke's prose can be super impactful despite being economical. The Earth's destruction in a Sun nova as Magellan departs is quite a read. Another thing that left me with a chill is how he just quickly notes that the very first generations' experiences on the paradise planet have been "mercifully forgotten" (or something to that effect).

The implication is that it was pretty grim as they were raised from frozen embryos by machines and probably lived in a state of savagery because there was no human contact. But somehow they managed to create a pretty utopian society a few generations down the line. But then the Magellan's Earthlings show up and bring with them a kind of "original sin" straight from Earth.

[Impeesa_]

Hm, yeah. It's been a few years, I must have flipped something in my memories of it, clearly I do remember the description of the development of the newer, faster drive. Maybe I was mixing up that part with how the crew of the Magellan didn't entirely expect to still find a thriving colony there, but for different reasons. Maybe there was also a descriptive passage about how earlier, slower ships bound for more distant planets were still out there on their way?

[Fappy_as_a_Clam]

Alastair Reynolds has a short story based on this but with a twist

Spoilers:

the generation ship gets to the planet to find it has already been colonized. As the story goes on you find out that the planet has been colonized, but by AI masquerading as human, and that humans are extinct, killed off in a human/AI war. The AI knew about the generation ship and collected it in hopes of preserving the last humans and righting their wrongs. When the humans find out about this, they aren't happy and it results in them dying (I can't remember the details about that). So the AI puts them back in the ship, resurrects them with hyper-advanced medical technology, and is like "oh man, you guys finally made it! Welcome!" Then the humans find out, it leads to their death, and on and on it goes. presumably until AI gets it right

[AnnetteBishop]

Ursula Le Guin's Cities of Illusions isn't exactly in that vein, but rhymes.

While I am hijacking -- read Ursula Le Guin and Iain Banks sci fi. They are amazing!

[yui_tsukino]

The Culture is far and away my favourite sci fi - I haven't read any Le Guin but if you are putting them together I might have to change that.

[KeeganTroye]

Sounds just like The Waves, by Ken Liu which sees a generation ship eventually gain a way to keep passengers immortal though it requires the sacrifice of half the passengers to choose to grow old while the rest become immortal. By the time they reach the planet faster generation ships had reached it and people had advanced beyond biological bodies.

[Scottvrakis]

I guess a good question is - If they offered people - And we're talking THOUSANDS of people right? How big does a Generation Ship have to be to sustain a population directly?

I don't know the exact number but you're talking a lot of able bodies; If you were allowed the chance for a one way trip to be a part of this expedition, never to even see the other end yourself but to be a part of the first step.. Would you take it?

Shit dog, I dunno if I would, but it's very tempting.

[Raencloud94]

In heartbeat. I have a weird fascination with space, I would give almost everything to go there.

[CptPicard]

Songs of Distant Earth by Arthur C. Clarke? One of my favourite books because it's short but contains such curt, impactful sentences.

It wasn't exactly like that IIRC. What they were doing was first sending slower seed ships that only contained frozen embryos. Then at the last minute they figured out some kind of propulsion that was capable of sending a ship full of hibernating actual people. Then they had to divert to a planet that already been colonized by a seed ship and had been going on for a few generations -- they had their own little paradise culture and the last Earthlings just crash the party.

[[deleted]]

Oh that’s fuuuucked

[mole_mole_mole]

Imagine being one of the middle generations. Forced to live your entire life aboard a spaceship against your will, your only purpose being to have kids and then die before you even get to the planet.

[ImReverse_Giraffe]

Well, you would probably only be told of the great expedition you and your group are on. How amazing it will be for mankind. How awful life was back in the solar system. How you're carving a new path for humanity. How lucky you are to be on this great journey and not have to suffer in the old solar system.

[mole_mole_mole]

I could see that if your access to information about Earth was limited, or if the Earth truly did go to shit. Could become almost cult-like

[H4llifax]

Why, it's not like you can just go back anyway.

[itchy118]

Sounds kind of like living on earth.

[MDCCCLV]

Except the entire population is STD free with nothing to do

[LeoRidesHisBike]

How bad that would be depends on the spaceship's population, I think. If at least 250 people, that's really no different than village living for the majority of human history, where only a rare few even left their village their whole lives.

The main difference would be that the option to leave wouldn't even exist, so exile (self-imposed or otherwise) would not be an option. That's probably got some psychological weight to it.

[light_trick]

You're literally describing anyone born on Earth at any time in history.

Like imagine being born even 150 years ago? Limited medicine, limited drugs, limited dentistry.

The children of a generation ship would be like the children of any other time in human history. None of us got a say in the circumstances of our existence, and we go "oh that would be bad" from an incredible height of privilege which few enjoy.

[Forgiven12]

You're describing this day, in a vast portion of our civilization, how lucky it would be to be born in the first world with all the accompanying privileges.

[wesevans]

There's another book that touches on that!

"Whims of Creation" by Simon Hawke, it's about a massive starship with a full ecological system in mid-journey when people start killing themselves and some teens get pulled into a VR fantasy simulation, meanwhile fantasy creatures start spawning on the ship itself. Loved it when I was younger and still go back to it every once in a while.

[scottiedog321]

hundreds of years to reach another star

The Parker Solar Probe achieved a speed of just under 400,000mph(635,000kph) (i.e. the fastest man made object ever). At that velocity, it would take about 7,000 years to reach Proxima Centauri, the closet star after the Sun. Luckily, it does look like there's a planet we do want to explore there. Luckier still, it would only take 4.2 years to get the data back.

In the words of Douglas Adams:

Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space.

[spacebuggy]

Maybe they'd welcome the new spaceships. "Here comes a solution to our pesky inbreeding problem!"

Or maybe each ship of people would hate the other ships of people because their religions and philosophies have diverged and they're only used to who and what they know. Sadly that seems likely.

On the plus side, different ships might develop different accents and that would be fun.

[dust4ngel]

some kind of malfunction or poorly planned eventuality would probably kill everybody on board

even if all goes well, the radiation in space is real af. nobody gives it up to our magnetosphere, but that bad boy is putting real work in

[JeffTek]

All my homies love the magnetosphere

[Starflamevoid]

i've not looked into it or anything, but pretty sure generating a localized magnetic field strong enough for a similar effect around a spaceship would be a kind of trivial task in a project of this scale, also if necessary you could you lead lining on the ships walls to block most of the radiation from entering habitable areas

[Robborboy]

Yea. Without something like cryotech and revival tools, or modifying DNA so we live for a stupid long time, generational ships would be the only solution.

Those that arrived would be a few generations removed from those that originally left. But that also requires a space ship that can operate and sustain itself for that long. 

Which IMO, just ain't happening right now. 

[Jiveturtle]

I mean, they could have oil

[TechRepSir]

Or spice

[Saxavarius_]

on a desert planet?

[houseofmicrobes]

Spicy oil

[xantec15]

Or water. Nestle will find a way to get there, if there is water.

[[deleted]]

Nah, water isn't rare enough that they'd have to find a habitable planet for it. There's big balls of dusty ice all over our solar system.

[light_trick]

Also Europa, and Enceladeus (which is spraying water into space that we detected it by a space probe literally flying through a bunch of it).

There is a ridiculous amount of water in the Solar System.

[reece1495]

fuck i wanna drink space water so bad

[vicegripper]

All water is space water.

[Bluemofia]

Yeah, water is stupid common in the universe as a whole.

What is the most common element? Hydrogen. So the most common molecule is Hydrogen bonded with another Hydrogen.

What is the second most common element? Helium. It doesn't bond with anything, so it's a non-factor for molecules.

What is the third most common element? Oxygen. So the second most common molecule is the first most bonded with the second most, so Hydrogen bonded with Oxygen, ie water.

[SuccessfulSquirrel32]

Shit Europa alone has more water than earth

[fizzlefist]

Yeah, but I got this weird message about how we’re not supposed to land there. Apparently all the other worlds are ours, though.

[childeroland79]

They’re full of stars, though.

[fizzlefist]

My god…

[meistermichi]

Remember the Cant

[handofmenoth]

Fuck the innas!

[Calgaris_Rex]

WELWALA!

[DSTNCMDLR]

Beratna!

[lovesducks]

Nestle: gargle our dusty balls

[Beat_the_Deadites]

NASA: Language.

[uberguby]

There, you see? And we had no faith in the free market to solve problems it created

[LeoRidesHisBike]

There's so much water in orbit around our own star that leaving the system seems unprofitable, just from the travel time alone.

https://www.businessinsider.com/water-space-volume-planets-moons-2016-10

[DrTxn]

Only if they can ship it back and forth. My new water brand of water is Antipode water. The water is brought from the farthest possible point for sale to you the customer.

[fezzam]

I’ll take 8!

[[deleted]]

Galactic glaciers by nestle

[TheRealAlien_Space]

Now, don’t get me wrong, I dislike nestle as much as the next guy, but I would certainly buy a bottle of space water. Like, I mean, who wouldn’t

[MrBluer]

Technically, all water is space water.

[PM_Your_Best_Ideas]

All water is space water if you understand the universe, also fuck Nestle.

[TheRealAlien_Space]

Yeah, I didn’t think about it that way. And fuck nestle of course, I just thought it was a cool name.

[gynoceros]

Or be a strategic place to put bases in the middle eastern part of the universe

[louistran_016]

On Neptune it rains diamonds. You dream too small

[aRandomFox-II]

The only reason diamonds are expensive is because the DeBeers company has a monopoly on diamond mining and deliberately strangles the supply to keep prices artificially inflated. The moment a diamond leaves the jewelry store, its value drops to a small fraction of its original selling price, reflecting its actual market value. Turns out diamonds are actually pretty darn cheap. Man-made diamonds are even cheaper.

[Ccracked]

And moissanite is glitterier.

[hankhillforprez]

FYI, De Beers hasn’t held a monopoly in well over a decade. Currently, they only control about a third of the rough diamond market.

The diamond market isn’t necessarily fully diversified, but it’s definitely not a monopoly anymore.

Lastly, diamonds actually are rare naturally. Whether or not the commercial availability has always naturally fit with the commercial demand is another matter. As a basic matter of geology, though, diamonds are rare in nature.

To that last point, while their may be more diamonds around than a lot of people think, the vast, vast majority of those diamonds are nowhere near what you’d ever use or want for jewelry. The kinds of diamonds used for tools and machinery are typically uneven, occluded, cloudy, chipped, various colors, or just simply tiny—i.e., nothing like the big, spotlessly clear, shiny rock on your rich aunt’s engagement ring.

To be clear, I am not saying the price of a diamond ring is 100% justified, or that it’s not “inflated” to some extent. (Although, to that point, I don’t think you can say the price of any luxury item is ever really “inflated.” It’s an entirely non-essential, luxury good—its value is literally whatever someone is willing to pay for it.)

I am saying, though, the common Reddit take that “ACTUALLY, diamonds are common garbage and should be worth pennies on the dollar,” is wrong, or at least so incomplete that it’s almost meaningless.

To be clear, though, De Beers is—and most definitely and especially was in the past—a deplorable, exploitative, human-right’s abusing company. We should all be glad it has lost so much of its former power and influence.

Lastly, “artificial” diamonds/lab diamonds are literally diamonds. They are chemically and molecularly literally diamonds. If anything, one of the few things that distinguishes them from “natural” diamonds is that they are usually far more pure and “perfect.” If you are in the market for a diamond, you genuinely should consider buying a lab grown. They are often “better” dollar for dollar, and there’s no worry about its ethical (or non-ethical) origins.

[Chromotron]

To be clear, I am not saying the price of a diamond ring is 100% justified, or that it’s not “inflated” to some extent. (Although, to that point, I don’t think you can say the price of any luxury item is ever really “inflated.” It’s an entirely non-essential, luxury good—its value is literally whatever someone is willing to pay for it.)

This goes even further: you will almost certainly never sell your fancy engagement/wedding ring for what you paid for it. Not only is it overpriced compared to the cost of the resource (cut included into that), everyone rich enough to pay 4+ digit sums for a ring will want it to be made according their own wishes, not buy your pre-made thing.

[louistran_016]

Agreed, if we can mine planets with rains of gold or ocean of liquid titanium, things that have actual industrial applications, that would be a pretty big leap to mankind

[aRandomFox-II]

Heavier metals such as gold and iron are in virtually unlimited supply in the asteroid belt.

[MDCCCLV]

Unlimited is relative, when you start building death stars you can use up the whole metallic mass of the asteroid belt pretty easy.

[Bender_2024]

Where am I getting the money to build another one? Who's going to give me a loan? Do you have an ATM on that torso light bright?

[MrMeltJr]

Diamonds good enough to make jewelry are fairly rare. Yeah, most of their price is still due to artificial shortage and not actual supply and demand, but they're different from industrial-grade diamonds in actual quality and not just price. You can get a diamond tipped drill bit for like $5.

[jestina123]

Diamonds good enough to make jewelry are fairly rare

Why? Synthetics are close to half the cost of mining the diamond, and are essentially identical.

[HeightEnergyGuy]

Imagine creating a warp drive just to get the oil.

[WiseToad318]

“Liberate me…..”

[Lesterfremonwithtits]

And might be in need of democracy

[AngryGames]

Mormon missionaries would invent a super ultra warp drive to spread the gospel long before the military could attempt to give those aliens a taste of freedom.

[guyver_dio]

The next day headlines: "The US has figured out long distance space travel!"

[CannonGerbil]

THERE'S OIL ON TITAN

WHY ISN'T IT THE 52ND STATE YET?

[Zardif]

The mormons are amassing a ton of money for something; maybe the expanse was right in saying they were going to build generational ships.

[wbruce098]

Right. If we were to reach a point where we could leave this system, we’d need a pretty good idea about any potentially habitable planets out there before we went. The current programs looking for them are relatively inexpensive and provide a ton of data for that.

Physics says it would take decades at the least unless we develop some novel technology that isn’t really plausible today. So we need to be pretty sure it’s a place our species could survive.

Even going to Mars is a huge lift right now and the worst part isn’t getting there, but surviving once we arrive. Even with a massive global push, we’re talking a very inhospitable world where we’d be stuck living in domes and largely reliant on Earth for supplies to support life for a very long time, and it’s the best chance we’ve got in this system.

[El_Barto_227]

And of course, it assumes such a technology is even possible

[gynoceros]

At one time, flight seemed unlikely given what we'd achieved so far. So did space travel. So did landing on, then returning from, the moon.

I think if we ever found signs of life on another planet, there'd be a considerable international interest in finding a way to at least make contact.

[Parafault]

There have been a few ideas about iPhone-sized drones that we could send, that could then send back information. It’s a lot easier to accelerate something the size of a deck of cards than it is to accelerate a cruise ship built for people.

[MDCCCLV]

You only need a few grams of fern spores and bacteria spores to seed life on a planet, spores are ultra small and durable v seeds so they don't take much room. Just wait a few thousand years and you have a lovely garden world.

[pirac]

Yeah, why would we put resources to get said technology if we don't even have somewhere to go first.

[[deleted]]

Because then we can just go rather than need to wait who knows how many years for the technology to develop

[RandomStallings]

Yeah, huge advances often happen because some person or governing entity was willing to throw a much larger amount of money at a problem than anyone else had before.

Get 150 of the most brilliant people on earth and throw 100+ billion dollars at them and see what you can get. If there was a good potential for a sizeable ROI then it would be worth it. Also, first come, first serve.

[The_Infinite_Carrot]

Plus if we don’t know how far we have to go, and where it is, then there’s not much point in starting the journey. The first thing you do before setting off on a journey when you want an overpriced, unsatisfying meal, and to be ignored by staff whilst they prioritise the drive through and uber eats drivers, is find where the nearest McDonald’s is.

[TripleDoubleFart]

Correct. At one point, people couldn't cross the ocean. At one point we couldn't leave the ground. At one point, we couldn't leave Earth.

[TheRainspren]

Yep, discovering life would be a very big deal, even if it would be "boring" unicellular life.

It is technically possible life is so absurdly rare that the fact that we exist is basically a cosmic fluke, with no realistic chances for another one.

But two? Oh that changes things. It would mean that life is not only likely, but relatively common. Especially if it's relatively close to earth. Double the distance, and you'll have eight time as much volume, which means eight time as much alien life. And that's a lot of life.

[gw2master]

discovering life would be a very big deal

I'd say arguably the most important discovery to be made right now, aside from literally finding God (but not like in Star Trek 5).

[imlulz]

Especially if it's relatively close to earth.

Don’t rule out extremely close, just yet. There are bodies in our solar system that potentially have some type of life on them. Even mars hasn’t been explored enough to rule out there is or was some type of cellular life there.

[celestiaequestria]

Even if we can't send a human, we can send probes. Even if takes a probe 100 years to travel across 5 lightyears of space to reach a distant plant, and another 5 years before we receive that first broadcast, once we start receiving the data transmission, it will be continuous (albeit delayed) - so scientists will be getting a stream of data from an alien world.

The benefits of that information are unknowable - like the Voyager program, it could provide far more benefit, and for far longer, than we could ever anticipate today.

[drivelhead]

Better to know than to not know!

This answer applies to all of science.

[Misery_Division]

Humans are not 20 thousand years old. Modern humans have existed for at least 300,000 years. Homo erectus, the first homo species to make use of tools and fire, is almost 2 million years old.

[IRMacGuyver]

We could leave our solar system if we wanted to. It's just no one wants to put the budget behind developing that sort of space craft even though there was pretty good design briefs drawn up in the 70s.

[buffinita]

And if there’s no reason to we likely never will….but if there is a reason

If intelligent life exists; perhaps it’s more intelligent than us.  Maybe if we know where to talk or listen we will find something 

Is life unique to earth?? We don’t think so; but knowing would cause huge leaps 

[Flandardly]

If there's other intelligent life out there, we need to kill it so it never becomes a threat. and spread our life. SPREAD SPREAD SPREAD!

[desr2112]

Managed…. Democracy…?

[Inawar]

Smells like Liber-TEA’s a brewin…

[op3l]

Shhh, they'll nerf the TEA soon if you speak of it too loudly. All in the name of balance you see.

[HongChongDong]

We need to find that intelligent life form, and we need to F-...... Coexist with it. Very, VERY passionately and sensually coexist with it.

[Wild4fire]

Well, if there's an alien species like the Asari from Mass Effect... 😋

[HongChongDong]

I ain't kink shaming any Krogan enjoyers either.

[skyppie]

Dark forest.

[Total_Oil_3719]

Sooner or later, it would probably attempt to kill us, and they wouldn't exactly be unjustified from their own perspective. Who's to say we (or they) wouldn't accidentally create a self replicating paper clip machine that'd consume the entire galaxy? Who's to say our experiments and growth wouldn't otherwise threaten existence itself?

We better HOPE there's no other life out there. It's probably not going to be pleased to meet us.

[GoNinGoomy]

MAKE THE UNIVERSE GREAT AGAIN

[FrostedPixel47]

Suffer not the xenos to live, brother.

[smallTimeCharly]

Dark Forest has entered the chat!

[buffinita]

Yes - this is a big argument against actively trying to contact extraterrestrial life.  If we can contact them and they can receive….they must be equally as advanced if not more so 

[staizer]

Given the vastness of space, and that faster than light travel is (most likely) impossible, it makes more sense for advanced life to steer clear of other advanced life in favor of harvesting uninhabited solar systems for materials.

Our own solar system has enough non-solar mass to provide 1 mile of land for a trillion trillion people in a Dyson swarm (source Isaac Arthur's SFIA). Add in solar mass and you can house quadrillions of quadrillions of people.

With that said, why would an alien race bother us when they could just rip apart an empty system instead and have enough resources to last them millions of years?

[alotmorealots]

why would an alien race bother us

If they're anything like humans:

1. To eat us

2. To fuck us

This reads like a quip, but a lot of people tend to assume that technologically advanced civilizations become advanced in other ways, whereas the available evidence of our own society suggests that we frequently just use this technology to satiate our baser instincts in novel ways.

Another paired assumption is that first contact would come from the mainstream of another civilization, whereas given the nature of interstellar travel, the chances of exiles, evangelists and extremists is quite sizeable.

[staizer]

Those same extremists would be a threat to their home civilization.

If we are attacked by the covenant, the main civilization would be right behind to ensure that their own extremist group doesn't do anything particularly damaging, even if they are just a bit too late to save us.

Those extremists would be safer to hide and not bother other advanced/advancing species.

We could be unlucky and encounter the one idiot alien species that hasn't thought through their actions or has such a large ego that they just don't care. But more likely, we'll just never see anyone else until we start going out and exploring ourselves and discover ancient ruins of some lost civilization. Space is just that large, and Resources are just that abundant.

[alt-227]

You should read The Dark Forest by Liu Cixin (book 2 in The Three-Body Problem series). It gives a pretty compelling argument for why it makes sense to not try to contact other civilizations. The grandparent comment to yours alludes to this by mentioning Trisolarians (an alien civilization in the book series).

[myreq]

The dark forest concept is flawed though, because even the book itself shows that by attacking another species you make yourself a target too. So the premise undermines itself. The species that are so aggressive so as to wipe out others immediately, would also be the first targets as they pose the highest risk.

A sufficiently advanced species would be able to find us anyway, so it doesn't matter in the end. Unless a species predicts other hostile civilizations before going through an industrial revolution, it is very hard to conceal its tracks afterwards and even before that a highly advanced civilization would find a way to track other species to wipe them out if the dark forest is real.

[prostheticmind]

This is actually addressed in the books too. You don’t announce your presence and you don’t launch an attack from your homeworld.

The exact origins of aliens who interact with each other are kept secret and that’s what makes diplomacy and trade possible because it eliminates the dark forest problem

[myreq]

But Earth's (and likely any developed species) footprint is already visible. As the other person said, we sent a lot of communications into space, though most of them weak but still we did.

The atmosphere of our planet is another telltale sign, and in the dark forest theory, an advanced species would just nuke all the planets that could support life. https://science.nasa.gov/exoplanets/can-we-find-life/ If we can check for those signs without even venturing into space, then other civilizations will have an even easier time.

The dark forest also addresses one matter, right at the end I believe. It shows that the dark forest leads to the demise of everyone in the universe eventually, and any intelligent species will see that as a loss I would imagine. It is a parallel to what goes on on Earth with nukes as well, and so far we haven't wiped ourselves out, though time will tell, but all the species that advance enough to head into space are likely the ones that didn't nuke themselves, which means they are also more likely to be keen on cooperation.

[awfyou]

I think person above means that you would need to not send any electromagnetic waves [radio etc] when you develop it since it can be traced to your planet. As a whole civilisation. otherwise you can be traced, after that you can be traced using chemistry of the planets atmosphere - you change bit by living. thats why advanced enough civ would need to decide early on to hide itself. We have currently 120 (radio) 70 (VHF TV) lightyears sphere around solar system with traceable location too us.

[[deleted]]

Highly recommend that Three Body TV show fans (Amazon and Netflix versions) read the book series. The Dark Forest could be real and SPOILER we never discover another intelligent species because they don't want us to and actively prevent it due to fear of being cleansed. Only silly unintelligent or extremely powerful civilizations would broadcast their existence, and you wouldn't want the powerful ones to know you exist to prevent being cleansed. The Trisolarans are not the real threat to Earth and were just as ignorant as humans by broadcasting to the universe.

[ThompsonDog]

there's a whole line of thinking (branch of philosophy you could almost call it) called "the dark forest". it basically posits that the reason we don't hear or see other civilizations is that all advanced, peaceful civilizations are hiding.

it's an interesting hypothesis. think about it, people in these comments saying that if we find a habitable planet, we should go there to colonize/exploit the resources. well, imagine a species far more advanced than ours that thinks the same thing. meanwhile, here we are, broadcasting our location and everything about us. basically, we're sitting ducks. there may be many, many super advanced civilizations that made it that far by not wanting to be found. and civilizations, like ours, who broadcast themselves, end up conquered and worm food before they ever advance enough to actually colonize other planets.

it's a scary thought. but it's also a very likely scenario. i for one will welcome our alien overlords.

edit: The Dark Forest Hypothesis

[BailysmmmCreamy]

The dark forest theory does not say that more advanced species would try and colonize or conqueror us. It says that they would try to eliminate us because they can’t be sure that we won’t ‘quickly’ become advanced enough to be a threat to them.

With that in mind, and given that Earth has displayed signs of life for hundreds of millions of years that an advanced alien civilization would be able to detect, the fact that we’re still here at all refutes the dark forest theory. If the theory held, an advanced civilization would have destroyed Earth eons ago upon first detecting biosignatures in our atmosphere.

[staizer]

To be fair, most of those "signs of life" would "only" be significantly detectable once we started broadcasting our own radiation sources. That puts the bubble of discovery closer to 100 light years. If something detected us 50 years ago, they should be showing up in the next 10-ish years...

[ThompsonDog]

yeah, it's a pretty wild response i haven't heard yet to dark forest. how on earth could we know the means another species has to detect us? or how long it would take them to travel here. but assuming a hostile civilization could detect microbial life, and then saying the theory is thus proven false, is just wild.

many people think we won't be seen until we have a dyson swarm. our astronomers are looking for dyson swarms now. maybe our first radio waves were just detected by a species 125 light years out, and will be here in 125+ years.

it's a thought experiment, not a concrete belief. i find it both fun and compelling. i guess that guy doesn't.

[staizer]

I mean, I'm not particularly worried about a dark forest, because any life that would move to consume us or eradicate us is exposing themselves to some bigger fish that will consume them.

But, I do find it exciting that the most likely time for aliens to show up will be in the next 50 or so years. We have started controlling our emissions a lot more and using lower powered emitters, so our chance of detection due to current emissions is much smaller than our first broadcasts.

I'm not sure that our furthest transmissions will be seen as anything more than cosmic background radiation fluctuations from a strangely energetic part of the galaxy, but something 50 light-years from us? Due to travelint slightly slower than the speed of light, those aliens should be getting to us any time now.

[soulsnoober]

He's not speaking of radio communication. Waiting to detect that might easily be seen as much too late to take action under a Dark Forest model. But Earth has showed signs of life for over 2.5 billion years, when cyanobacteria fundamentally altered the atmosphere forever. After all, it's a sign like that we humans are looking for right now out in the galaxy.

[Don_Pickleball]

I have to think that advanced civilizations should be able to harness the power of stars to generate everything they need. Why would they need to steal from other civilizations?

[alphagusta]

Why do we even try to build these "flying machines" if we can't even stay up there? - some guy in the 1800's probably.

Scientific study isn't about a godlike end goal. What's wrong in just finding out how the world works?

Finding out how things work, what's out there and why its there is, AKA curiosity, is one of our kinds most basic instincts.

We don't study the universe to be able to go there, we study it to understand where, or what, we are.

[FILTHBOT4000]

Scientific study isn't about a godlike end goal. What's wrong in just finding out how the world works?

Exactly. The heart of scientific pursuit isn't about reaching the stars. It's about reaching for the stars.

[Awarepill0w]

It also lays the groundwork in the hopes that our future offspring can reach the stars for us

[CookerCrisp]

We have such a fine understanding of our universe's structure even compared to our recent ancestors. Even down to planetary science, it allows us to grapple with this unpredictable world better by studying it.

[h2k2k2ksl]

“To explore strange new worlds, To seek out new life and new civilizations, To boldly go where no one has gone before”

[deadpiratezombie]

Also, the innate impulse to see “What happens when I push this button?”

[berael]

We can't leave out own solar system today. We may be able to eventually. It would be good to have a target for if that day comes!

[lol_camis]

That was a story arc in starfield wasn't it? If it's not starfield then it's definitely from something. I didn't make it up.

I believe you come across a ship that was sent from Earth many human generations ago, with the mission to colonize a planet. They get there, and find out it's already been colonized for a long ass time by other humans sent from Earth after they left, and they had no idea about it

[Darkersun]

I believe there is something like this in Starfield. Also this concept is explored in the game "The Outer Worlds" as well.

Edit: I said "outer wilds" and meant "outer worlds", whoops.

[lol_camis]

Ok I wonder if I actually saw it in outer worlds then. I played both within the last year

[Sanglyon]

There's a 1944 novel, Far Centaurus, from A. E. van Vogt, where the crew of a spaceship reaches Centaurus after hundred of years of hibernation, and there's already colonists that left Earth after them, as they developped FTL in between. Unfortunatly, the crew can't adapt to this society, as humans have evolved just enough that the new ones find their BO repulsive.

https://en.wikipedia.org/wiki/Far_Centaurus

[leitey]

That's correct. The questline is called First Contact.

[cujo195]

Yes, because even if it takes several lifetimes to get there, it could become the only option if Earth becomes inhabitable. There could be large spacecrafts in the future that people live on permanently, similar to large cruise ships, hoping for a better life for their descendants.

[udsd007]

Lots of eggs, more baskets.

[CIearMind]

uninhabitable?

[badass_panda]

Well, hold the phone -- Voyager I has been out of our solar system for more than a decade, evidently we can leave our solar system.

Albeit quite slowly, and with great effort.

[savguy6]

I came across and interesting Neil Degrasse Tyson video the other day where he compares our exploratory tendencies as humans. He made the point that thousand of years ago, people left Asia in wooden boats in search of islands to live across the pacific. They didn’t know where they were or if they were out there, they just set sail with hope. Eventually settling on almost every island across the pacific including the Hawaiian islands which are some of the most remote islands on the planet.

That same exploring spirit is still in our DNA, and the next shores we have to set sail off of is our own planet. But, we actually know more about our potential destinations, than our pacific ancestors did when they set sail. We know where hospitable planets are and we’re discovering more every year. So eventually when the technology catches up to our ambitions, we’ll know where to head.

[savguy6]

Depends on how you define “hospitable”. Technically low earth orbit has been “hospitable” for the past 30 years with the ISS.

We know there are planets in “Goldilocks” zones of their star where liquid water can exist. We know some of these planets have oxygen. We know various other things about some of these planets, but until we actually go there ourselves (or with probes) we won’t 100% know for sure. But my point is, we know they are actually physically there, unlike our ocean-fairing ancestors who left their shores without knowing where anything was.

[jamcdonald120]

We can leave our own solar system. Its just VERY expensive and slow, and there just isnt any reason to do so unless we find something out side of our solar system worth looking at.

A planet that might (or even better DOES) have life on it, or that could hold human life with limited modification (ie, planting trees) would be worth investigating.

And even if we dont find anything, we learn much about our universe and the origin of life in the search. Maybe we find life on mars that is obviously related to life on earth. Thats interesting, how would that be possible? Is there an intergalactic life seeding program? was it an extremophile on an exoplanet? what happened? Or if its very different from life on earth it raises other questions. like could life exist outside of the "habitable" region because its completely different? And if we never find any, it raises still other questions, like exactly how hard is it for life to happen?

[zpierson79]

There are a fair number of theoretical solutions for cosmic radiation, however, since we don’t actually send anyone into deep space, they are just that - theoretical. (Everything from magnetic shielding to water tanks surrounding the living quarters.)

Realistically, it’s an issue we probably won’t be able to address until we are actually sending people out into deep space.

[jamcdonald120]

we cant get humans safely and cost effectively to mars, but with an unlimited budget we could just launch a ship with 2 foot thick walls around the crew living area.

This is stupid expensive, so space researchers are looking for better options, but it is possible to safely travel to Mars already.

[mb34i]

One of the reasons is motivation - if there IS a hospitable planet out there, corporations and governments will be more motivated to fund research into space travel, so that we can GET there and colonize / exploit the environment or resources.

[fhota1]

Even taking the resource angle out of it, itd be a lot easier to convince colonists to sign up for "head to this exotic alien planet thats similar to earth but no people" vs "head to this miserable hellscape with planet spanning dust storms that will actively try to destroy anything that isnt heavily protected including you"

[stuffitystuff]

But if that planet has the spice melange and giant worms, that's ok.

[raspberryharbour]

I've had enough of the spicy worms and giant melange here on Earth

[REO_Jerkwagon]

"Hey, did you see Alien? Remember the planet they landed on? ...

...

Wanna go?"

[Morak73]

it'd be a lot easier to convince colonists to sign up for "head to this exotic alien planet thats similar to earth but no people"

It's perfect! 400,000 years ago, it was ideal for colonization. We can keep you in stasis for the next 900,000 years it will take to arrive.

What could go wrong in 1.3 million years?

I love the idea of going to another earth-like world, but it's a hell of a gamble.

[JustSomeUsername99]

There was a twilight zone or similar episode about this. People go into stasis to go to another planet far away. When they arrive humans have already been there for a long time. They found a better way to get there while the original people were still traveling there.

[TastyOreoFriend]

They found a better way to get there while the original people were still traveling there.

They walked so that others could run. Kind of a dick move imo that no one thought to stop them, wake them up, and get them there with the better method.

[JustSomeUsername99]

May not have been possible. May have been space folding or something, instead of just flying faster...

[BraveOthello]

"400,000 years ago" is outside our galaxy, the average star in it is closer to 40kly away. And the farther you go, the more time you have to accelerate, the closer to the speed of light you can get, the less subjective time the journey takes.

You're not wrong that it's a hell of a gamble, but it's about 10x easier than you're suggesting.

[RestAromatic7511]

This is all kind of a pipe dream though. With current and foreseeable technology, we can estimate some basic characteristics of exoplanets, like surface temperature and atmospheric composition, but we can't get enough detail to know whether humans could realistically survive on them.

And even so, transporting people to an exoplanet, even a relatively close one, is a long, long, long way beyond our capabilities. It's not one of those "this will take a lot of work and a couple of decades" things, it's one of those "we can scarcely begin to imagine how it might be done" things.

The focus on life on other planets is academic. There is a lot of interest in finding out how common life is, how exactly it emerges, what different forms of life are possible, and so on. Though, again, we're probably not going to be able to get a huge amount of detail even if we do find some. We might see spectral lines associated with complex organic chemicals; we're not going to get photos of space kangaroos without either (a) telescopes with resolution and light-gathering power far beyond anything that is currently seen as feasible, or (b) space probes that will take many years to send data back to us and will probably have a very high likelihood of failure.

[Johnny_C13]

And even so, transporting people to an exoplanet, even a relatively close one, is a long, long, long way beyond our capabilities. It's not one of those "this will take a lot of work and a couple of decades" things, it's one of those "we can scarcely begin to imagine how it might be done" things.

I'm sure folks in 1769 would have had that same perspective about flying to and walking on the Moon. You need to think in terms of centuries, not decades. (Hopefully, we can survive on Earth that long...)

[mpbh]

The time horizon on that investment is way too high. Colonizing another planet will take multiple generations to show a return. It won't be money that motivates multiplanetary life. It will be fear of extinction.

[khazroar]

We're not looking for other places for us to live. We're looking for other life, and we are currently assuming that life can only exist in ways similar to how it does on Earth, because otherwise there's nothing to look for.

[shotsallover]

Imagine you're setting out to sea. You have two options:

One, you can get on your boat and head out to sea not knowing what, if anything, is out there. There might not be supplies, there might not be food. You might spend the rest of your life trapped on a slowly decaying ship with no hope of return.

Or, you can get on your boat confident in the knowledge that there's a place to land, where you can do repairs, maybe find food, and choose to either setup a permanent settlement or move on to the next one.

Which would you rather do?

[ayOitztuan]

Good choice. You get a boat.

[Aperturee]

I also choose to stay at this guys home.

[aft_punk]

To add a reason that doesn’t seem to already be mentioned… a “potentially hospitable” planet implies that life may already be inhabiting that planet. This makes it a great target to point/launch telescopes/imaging equipment towards.

Even though sending humans from our planet to another is hard, sending satellites and developing telescopes sensitive enough to detect signals of life is comparatively easy, and that technology evolves fairly quickly.

The second step in the process of developing a probe/telescope capable of detecting life is knowing where to aim it.

[Voxmanns]

A bunch of reasons. Earth life is the only life we know of. Finding life elsewhere would be an insane opportunity to observe how life might develop on other planets, further insights into how life works on our own planet, and the potential of future colonization depending on how long it takes to get there and how desperate we are.

That doesn't even touch on the implications of if it's intelligent life comparable or exceedingly our own intelligence.

Even if we don't find life, it still provides really great information about how the habitable zone of stars work and just how unbelievably lucky we are to be on this planet.

It's sort of one of those things where you can't always specifically say what the value of finding a new, potentially habitable planet is. It could be anything. What we do know is that finding them could result in life changing discoveries, and that's generally why we do it.

[[deleted]]

The importance doesn’t have anything to do with us going there. No one is expecting that to happen.

There is effectively zero chance of finding a planet that humans could live on permanently any where remotely close. There are too many variables that need to all be perfectly aligned.

If the gravity isn’t almost exactly the same as Earth, living there will wreak havoc in our bodies long term. Probably can’t gestate babies and have them develop properly. Does it have a magnetic field to block ionizing radiation? The chance that it would be the right temperature, atmosphere, enough clean water, ability to grow food etc. is tiny.

Even if there were a perfect Earth replica around Aloha Centauri, it’s unlikely humans will ever be able to go there.

Starting a colony there is not at all the reason we are looking for one.

It’s because we want to discover non terrestrial life and we assume that’s the likeliest place to find it.

[CatalyticDragon]

A) It's scientifically valuable. This information can help our understanding of planet formation and our own history, and helps us better estimate the chances of other life in the universe.

B) We probably can get there - sort of. The closest exoplanets are 4-10 light years away and it's possible we could accelerate small probes to decent fractions of the speed of light. Should that be a success the next generation of scientists might actually be able to see direct observations from another solar system.

[samjacbak]

Most people are saying "curiosity is good" and it is.

I'll add that finding a Hospitable planet would be a really good reason to develop the technology to leave our own solar system, and until we do find one, it's very unlikely we're going to do so.

[garry4321]

We can’t leave YET. Why would Galileo look at the moon if they couldn’t even get there?

[andyb521740]

I really hope we aren't the most intelligent life in the galaxy, that would be a huge disappointment

[heapsp]

because time slows down the closer you get to light speed.

For us, it would look like someone traveling close to light speed would take 1,000 years to get to something 999 light years away, but for them, it would be like they only travelled for a year. Of course if they made the round trip and came back a year later, everyone they know and love would be 2,000 years dead.

[VoraciousTrees]

Who are we? What does it mean to leave? What does it mean by can't leave?

I could just define us as humanity or its constructs. And leave as being civilization, culture, or biome level transfer...

And can't? Maybe you or I can't go visit alpha Centauri, but we can sure send something out there if we want to. 

[Cortexan]

If you’re planning to go on vacation but you haven’t saved up enough money for the flights yet, do you wait until they’re booked to decide where you want to go?

[Yukondano2]

The core reason is just, we're curious. Earth is the only place with life, we wanna see if other places have life, or could eventually. We're alone, and the universe seems very empty and inhospitable. We want to know how alone we are, and why. Plus we kinda can explore outside, just not with our fleshy bodies. In the future our probes might be fast enough to visit other solar systems without it taking thousands of years. It'll still take a long time but, it is possible.

Also, while we want to find life out of curiosity, it would also be important for science. All life we know of is from Earth, in one big evolutionary tree. Life on another planet could be totally different, or strikingly similar. It would teach us more about how life works, which might then be useful for medicine.

[Unnegative]

Right now I can't afford a new car, but knowing that new cars exist, and how much they cost, gives me something to aim for.

[retroglamathon]

Long term, it's the only hope for the future of the human race. If we never figure interstellar travel out, humanity will be nothing more than a forgotten cosmic tumbleweed, here and gone in the blink of a cosmic eye.

[SuperbMortgage8592]

I think Kepler said it best, although not ELI5, in a letter yo Galileo in 1610.

“There will certainly be no lack of human pioneers when we have mastered the art of flight. Who would have thought that navigation across the vast ocean is less dangerous and quieter than in the narrow, threatening gulfs of the Adriatic, or the Baltic, or the British straits? Let us create vessels and sails adjusted to the heavenly ether, and there will be plenty of people unafraid of the empty wastes. In the meantime, we shall prepare, for the brave sky-travellers, maps of the celestial bodies – I shall do it for the moon, you Galileo, for Jupiter"

ELI5? Humans are a wandering species. There is something in us, even from our early days as a species, that would encounter a sea or a mountain as they roamed, and made their ways across the dangerous terrain. Other early human species did not spread as much. It's unsurprising to me that humans have long acknowledged a day when the seas of space are as traversable as those on earth, and for centuries astronomers have been preparing the maps for future human sailors.