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Let's set aside the part that making a planet where we could live is hard. Just presume we did that, to start. Let's talk Logistics. Presume there are only 1

• kneebonian 4y ago
  Wonderful article about overcoming Earth's gravity well available here https://what-if.xkcd.com/7/ https://what-if.xkcd.com/7/
• ben_w 4y ago
  If you really want to get a billion off earth quickly, you'd use a non-rocket system like a launch loop ($3/kg) or an orbital loop ($0.05/kg). I kinda agree that most humans won't leave Earth, at least for the foreseeable future, even if those things were magically built this year: even in 2019, international tourism was only 1.466 billion people, less than 20%.
  • m4rtink 4y ago
    While I don't see that mentioned very often I do think off-Earth settlements could have many benefits even for the Earth population - say research commoning from experience of living in space environments could have application on Earth. Also many asteroid strikes could be much more likely to be detected and averted using in-space instruments and infrastructure. Even more exotic stuff like dropping first responders from orbit to disaster areas might be useful, but would not ever be doable without infrastructure in place for supporting space operations.
• roryisok 4y ago
  The idea of finding another Earth is not so much about moving everyone from Earth to somewhere else, but rather about "backing up" our species and civilisation in additional places. If an asteroid is going to wipe out Earth, we can't evacuate 8 billion people, or even 8 million people. but if we had a few generations of colonists in domes on Mars, or floating in the clouds on Venus, or somewhere else, the species itself would hopefully survive. We only have one Earth, and its the best home we could hope for. But we're crazy to keep all of our existential eggs in a single basket and hope it all works out. > If we can make Mars habitable, we can make Earth habitable for far less cost. That said, I absolutely love this sentence. Although I would say, the technology we ultimately have to develop to survive on Mars or the moon will certainly help us keep Earth habitable.
  • TomSwirly 4y ago
    > rather about "backing up" our species First we need to stabilize the Earth, dealing with the threat coming in decades, before we deal with threats that come millions of years apart.
    • ben_w 4y ago
      They say that necessity is the mother of invention. I think the best way to learn how to stabilise the Earth is for some of us to have to cope with stabilising something much worse, something unforgiving on a timescale where there are personal consequences to getting it wrong. Not like here, where the consequences are separated by decades or continents, or where a big pile of money can make up for any personal pain.
  • alienalp 4y ago
    In reality this is just a fantasy. It is not possible for a healthy human to really care about survival of human race in case of something catastrophic happening and wiping out humanity.
    • roryisok 4y ago
      Why? Healthy people care about having descendants they'll never meet.
• adrianN 4y ago
  > Even the most optimistic generation ships would be taking 10s of thousands of years to get there https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion) https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propuls... Nuclear bombs make for pretty good propulsion systems and can propel incredible mass at a decent speed. In a "the planet needs evacuation" type of scenario you don't worry about the fallout either.
• Cthulhu_ 4y ago
  > If we can make Mars habitable, we can make Earth habitable for far less cost. I think the main thing there is that Mars is a blank slate, unclaimed and fairly uniform. We can't terraform Earth because we can't get everyone aligned with the same goals. Moving away from fossil fuels means that a lot of individuals, corporations and countries have to make investments and sacrifices, or lose their grounds for existence entirely. I mean this was only achieved once, when banning CFCs. There's been other agreements - like let's not use cluster bombs or chemical weapons - but those have been ignored without major consequences.
  • hiptobecubic 4y ago
    Why would you not expect these exact same challenges to develop almost immediately on Mars? It's not like one country will own Mars and even if it did, one country generally cannot agree on environmental policy even internally. I fully expect Mars, at best, to be a terrible version of Earth with all the same problems and way fewer benefits. When has "This is too hard, let's do a full rewrite" ever worked?
  • cherrycherry98 4y ago
    Economics is how we align goals. When using clean energy is better and cheaper than fossil fuels then people don't need to be coerced into adopting it. It's rapidly reaching that state and already is there for many.
  • poulpy123 4y ago
    We can't terraform earth because we don't know how to terraform, and foe the same reason we can't terraform mars
• charles_f 4y ago
  > Presume there are only 1 billion people left on Earth when we decide it's time to go The scenario that leads to have only 1B left from where we're at would entail such a catastrophic meltdown of society that even building a rocket would likely not be feasible, let alone anything significant for a human exode. Think about it, you're fighting against something that killed 7B people, be it the end of fossil fuels, climate change, a massive and deadly pandemic, a war or another type of catastrophe. There are probably global food shortage, areas that can't be lived in anymore. The global supply chain doesn't exist anymore, and government is much more localized, very different. Being down to 1B is probably not the bottom line of your decline, 1B people is still a lot. Your priorities are based on survival, you're trying to figure out how to grow enough food, gather enough water. You don't have enough reserve capacity that you can spare it on projects like building a lot of rockets and colonizing another planet. Rockets are a thing of complex societies with abondant energy ; not a last minute effort to preserve the human race.
  • mac01021 4y ago
    The GP was just setting a lower bound of 1B to establish a basis for calculating the cost to move humanity offworld. The cost for 5B people or 7B people would be even more cost prohibitive. But also the shrinkage would not have to happen abruptly. In theory you might be able to get to a population of 1B over the course of 200 years without the kind of catastrophic meltdown you're describing.
    • charles_f 4y ago
      I completely agree this would happen over a long time, barring a disaster like nukes or asteroids, which does not seem like the most credible scenario (I dont think I said anything to the contrary)- and I'll confess to a pessimistic vision of the future, when our demise is self inflicted. But look at Covid for a reference point. I mean all things considered this was still too mild to reduce humanity to 1B. This almost immediately (in the span of a year) led to big issues with the supply chain. Products removed from the shelves, years long backlogs on cars. People getting sick all around you and hospitalized, and yet there were societal debates on whether the disease actually existed, whether we should wear masks, or take the vaccine. Climate change is in the same line, people denying change with snarky remarks every time we receive a snowflake, and any step forward being accompanied by two steps backwards (look at the Paris accords). What I mean there is that there is no change witnessed without actual pain, and the change required for something truly threatening for humankind (e.g climate) won't see any actual action till we're already greatly suffering, and probably beyond the point of repair. Now imagine a large chunk of the population disappearing, even over the course of decades, and whether that would leave society in a state where it can afford a significant "gtfo of here" space program. My personal opinion, and that is only an opinion, is that this is not systemically possible ; and therefore I don't believe in GP's base assumption, even if that's departing from the motivation of simplifying that they made :) In any case, beyond cost, short of inventing completely new physics, I doubt earth even has enough resources to catapult us all into and then out of orbit. The most likely scenario to me is a handful of elites (which fortunately for them are fewer and fewer) embarking on rockets, accompanied with scientists and engineers to give them a fighting chance, plus a bunch of slaves to do the grunt work and die, because surviving ain't worth it if you can't enjoy life. (once again, I confess is a pessimistic vision, and is also departing a bit from the initial statement from GP)
• Maursault 4y ago
  I agree with everything you said and everything in the article, except for the number of people. There are 8B people now, and, if nothing changes, by 2100 there will be 16B people. But I would not be surprised if this thing with the mice getting younger is developed rapidly for people in the next 20 years or less, and 20 years after that it's a staple of comprehensive health care, and by 2100 there's instead 32B people. My thing is, whomever wants to colonize space and Mars and distant exoplanets around other stars... let them go. Let whomever wants to go, go. Encourage them to go. The rest of us can clean up the Earth and work to create a future society that doesn't use 175% of the available resources every damn year, work to find a balance that preserves diversity and honest to goodness Nature, stop expanding development and deforestation, finds some equitable solution to birth control, prevent stupid people from constantly breeding, support and encourage LGBQ and celibate priests, solve crime, and stop polluting the air, water, land and the food everything eats. Colonizing space and other worlds only helps Earth and everything living or that will live on it, because while there are very smart people, humanity as a whole is a complete idiot, so the best thing we can do is reduce and limit the number of people here without cruelty or genocide. Think of space as a suicide booth, and let people be free. We shouldn't let insurmountable odds deter them. People will lotteries. Throw enough spaghetti at a wall and sooner or layer, it will stick.
  • chitowneats 4y ago
    > so the best thing we can do is reduce and limit the number of people here without cruelty or genocide. Think of space as a suicide booth, and let people be free. Unrealistic and honestly pretty cruel sounding despite your caveat. If space is a death trap, you will never get more than a few small caravans to give it a shot. No way that would put a dent in your 32B, a number you pulled from nowhere, loosely based on one recent study about improving longevity in mice.
    • Maursault 4y ago
      140M people are born every year, but only 60M people die every year. We'll need to do something if the birth rate keeps increasing or even stays steady, or even slows down, but the death rate stops.
• lucideer 4y ago
  > Just presume we did that, to start. While I'm fully on board with the thrust of your post, I think skipping this obvious first question is kind of missing the point. Terraforming Mars would be such an enormous, slow, expensive, intensive process that any other problems with "logistics" would be long solved before we ever got past that initial challenge. > If we can make Mars habitable, we can make Earth habitable for far less cost. Ultimately this summarises it best: I don't really think logistics would be a problem if we solved making Mars habitable - I just don't think doing that is worthwhile to begin with.
• marcosdumay 4y ago
  > And what power source would you use to move that massive ship, and keep the light and heat on between stars? (Antimatter, I guess?) Fusion. If nobody made it obvious until now, well, fusion is the ultimate interstellar power source. Fuel is everywhere, the ISP is huge (a few orders of magnitude smaller than antimatter, but well, antimatter doesn't exist everywhere), and it's far from the hardest thing to build for a ship like that. Anyway, there is still space to cut orders of magnitude on the cost-to-orbit. But you are correct in that none of that will solve any of our current problems.
• yellowapple 4y ago
  > I weigh a bit less than 100kg, so that's $10,000 just for my mass- not including the life support system I need. That doesn't seem all that unreachable, honestly. The average middle-class income could swing that with a payment plan (said incomes commonly cover car payments already), and even for those who can't afford it, an enterprise seeking workers could surely cover that as part of an employment contract. We could also probably slash the costs - and multiply the scale - even further with non-rocket launch systems like skyhooks or launch loops.
  • aeternum 4y ago
    Yes, people don't realize how expensive transatlantic travel was even as recently as the steam age (1850). A steerage (lowest class ticket) was £3.50 while avg. annual wages were something like £17. It's crazy to think that going to Mars will soon be about the same relative cost as a trip across the Atlantic.
• raffraffraff 4y ago
  > If we can make Mars habitable, we can make Earth habitable for far less cost. I'd put it slightly differently. If we can't keep earth habitable, when we're standing right here on it, what hope do we have of making Mars habitable? Never mind logistics, look at the billions of years of evolution that led to billions of interdependent organisms. We are one of those organisms, but in our guts alone live countless more. As a tech person, have you ever built system A, then built system B which depends on system A. And then, when the both up and running, accidentally modified A to depend on B? And that's just 2 systems. Scale to billions. How the hell do you cold-boot that?
• yarg 4y ago
  Well the first thing that we'll need to do is compute this in terms of actual resources, rather than money - which is a tokenised abstraction from value, and arguably an inflated one. So the raw material and energy requirements to leave the planet carrying people and everything they'll need on the other side. Things will be different once there's been a reasonable build up, but if it's an evacuation we won't have time for that. And things on Earth will be falling apart evironmentally, politically and geopolitically. And what of the political systems on the other side? Work 80 hours or get out of my bubble?