[lisper]

> humans are a source of boundless novelty and creativity

No, they aren't. It only seems that way to you because you haven't lived very long yet, and what life you've lived has been lived at one of the most propitious times in the history of the universe. You've known nothing but peace and prosperity and discovery of new things, and so it's easy to imagine that this can go on forever. And maybe it can. But it won't.

Just as a purely practical matter, humans are not going to survive beyond the heat death of the universe. They are extremely unlikely to survive when the sun becomes a red giant. So even with arbitrarily advanced technology, the time available is finite. A few billion years may be better than a few dozen, but no matter what it's going to be finite. And a good thing too, because you really don't want to live forever. To paraphrase Douglas Adams, forever is a long time. A really really long time. You just won't believe what a vastly, hugely, mind-bogglingly long time it is. I mean, you may think a few billion years is a long time, but that's just peanuts compared to forever. In an unbounded amount of time you can read every book that has ever been written and every book that could ever be written an arbitrary number of times. You can watch every movie, play every game, write every program, learn every fact that can be expressed in a text shorter than the current size of Wikipedia and you still won't have made a perceptible dent in an unbounded life. Long before you get to the non-existent end you will be bored out of your skull and you will yearn for oblivion.

But all of this is academic because, again, as a practical matter human civilization is unlikely to last this millennium, maybe not even this century. The human species will likely go on, but civilization is probably toast. Unless something really radical changes really soon, we're looking at a climate tipping point happening before the end of this century. Whether that actually ends up destroying civilization before the end of the century is open to debate, but once the permafrost releases its methane there's no coming back from that. We're looking at 5-10 degrees C of warming after that, and no way is this round of civilization going to survive that. If you really want to make a dent in the world, that is the problem you need to be looking at because it is going to dominate everything else in your lifetime, no matter how much you manage to extend it.

[JoshTriplett]

> It only seems that way to you because you haven't lived very long yet

Neither of us have. But nonetheless, humanity continues to get better, and I'm familiar with a great deal of research on the nature of novelty, creativity, and fun, in the face of not only endless life but increasing intelligence. It's one of many, many problems that have solutions.

(And as an aside, anyone who truly decides that life is not worth living can always decide they don't want more of it, but that would be short-sighted and pessimistic.)

> Just as a purely practical matter, humans are not going to survive beyond the heat death of the universe. They are extremely unlikely to survive when the sun becomes a red giant.

We have billions of years to solve both problems. People two hundred years ago could not envision the society of today. It seems the height of both pessimism and hubris to believe that you can accurately predict the limitations of humans billions of years from now. The latter problem we understand now.

And more generally, there are many people working on existential risks to humanity, though more would always be welcome.

> And a good thing too, because you really don't want to live forever.

Do not presume to tell me what I want by projecting your own desire to die someday.

> You can watch every movie, play every game, write every program

And more will be created, because again, humans are a source of boundless novelty and creativity. And new forms of collaborative entertainment and edification and fulfillment will arise, many that we cannot yet envision. New forms of envisioning will arise.

> as a practical matter human civilization is unlikely to last this millennium, maybe not even this century

By all means, please work on solving that problem, rather than spending energy telling other people not to solve other problems in parallel.

> If you really want to make a dent in the world, that is the problem you need to be looking at

A massive number of people are already looking at that problem. And without going into a massive tangent, that problem hardly needs more technical solutions even if I were a climate expert; that problem needs political experts, among other things.

[lisper]

> Neither of us have

I've lived longer than you have.

> We have billions of years to solve both problems

That's true, but we don't have billions of years to solve climate change. But no matter how much time you have, you cannot get around the fact that exponential growth is unsustainable even with arbitrarily advanced technology. Unless you can find a way to exceed the speed of light (and good luck with that) resources can only ever grow quadratically.

> It seems the height of both pessimism and hubris to believe that you can accurately predict the limitations of humans billions of years from now.

No, it is your unbounded optimism which is unjustified, unless you can figure out how to do an end-run around relativity.

> Do not presume to tell me what I want by projecting your own desire to die someday.

First of all, I don't want to die. Dying sucks. But living forever would suck more.

And I didn't intend "you don't want..." to be taken literally. What I meant was something more along the lines of: I know you think you want to live forever, but I claim that's because you have not fully thought through the consequences, and if you were able to live forever you would find that it's not as great as you think. But that just seemed a little too wordy.

> And more will be created

No, this is the thing you have not fully taken on board. Human creativity only seems unbounded because our lives are so short and so we're only able to sample a tiny fraction of what is possible. But with a truly unbounded life span that would no longer be true. You really could experience every possible sensory input an arbitrary number of times, and eventually you would get sick and tired of everything.

> please work on solving that problem, rather than spending energy telling other people not to solve other problems in parallel

Those are not mutually exclusive. Part of solving climate change is persuading as many people as possible to work on it. Furthermore, one of the principal drivers of climate change is complacency and boundless optimism, the blind faith that some other smart person will figure it out and everything will be OK. It won't.

> that problem needs political experts

That too. But it also needs you. And everyone else.

[tlb]

> resources can only ever grow quadratically.

Growth can be cubic if you're expanding outwards at a constant speed and assuming (on a large enough scale) an even distribution of matter in space.

[lisper]

No. The total amount is cubic over time, but the growth is the derivative of this, hence, quadratic.

But this is irrelevant. The point is, resources are polynomial at best. They can never keep up with exponential growth in the long run, barring new physics.

[JoshTriplett]

> I've lived longer than you have.

Let's not play that game. Neither of our relative ages matter for the purposes of extrapolating to billion-year lifespans, nor do they render you particularly qualified for deciding whether such people will get "bored". Far more qualified people than either of us have done research on the topic, and I have at the very least read many research papers and articles by those who do.

> No, it is your unbounded optimism which is unjustified, unless you can figure out how to do an end-run around relativity.

The sun burning out is a problem we can already hypothesize ways to solve now, given technologies whose development has a scale of "centuries" or "millennia" rather than "billions of years". The most obvious solutions involve leaving the planet, and that doesn't even touch on the possibilities of stellar engineering. That's easily imaginable within the scope of today's science fiction, let alone the unforeseen technology of even thousands of years from now. I feel quite safe making the prediction that, conditional on humanity lasting the billions of years between now and then, the sun's expansion will not destroy civilization, humanity, or any non-trivial number of lives.

Much more critical existential threats, likely to be a problem on much shorter timescales, include nearby celestial events, collisions, or other things we don't have billions of years' to prepare for.

As for longer-term problem of continued existence in the universe, I wouldn't hazard a concrete prediction, but I'm sure we'll learn a great deal more about physics between now and then, not to mention likely existing in a form where thought and subjective perception of time (as well as the ability to solve problems) can occur far faster than "one second per second". In any case, I think it is safe to predict that people will not actually give up on that problem until actual effort is put forth attempting to solve it for a very long period of time.

Besides, my optimism has come up against cynicism and fatalism far worse than yours and survived unscathed, and it continues to serve me well. I don't find that fatalism is conducive to actual solutions. (And when it comes to actual predictions, I aim for accuracy rather than either overestimation or underestimation, but I find that hope tends to help as long as it accompanies actual action.)

> First of all, I don't want to die. Dying sucks. But living forever would suck more.

That's a testable hypothesis. If it turns out to be possible, why not try it and find out, before deciding in advance how you'll feel countless years in the future? Not like you couldn't change your mind later if you still feel the same way.

> You really could experience every possible sensory input an arbitrary number of times, and eventually you would get sick and tired of everything.

There are entire branches of research dedicated to exploring and solving this problem. That research looks at concepts like what we actually find interesting and fun (for one example, problems that are difficult enough to be a challenge but not so difficult that we can't make progress or learn something), the classes of things we can find fun at different intelligence levels, and ways to ensure that the number of interesting things to experience grows faster than the amount of time available to experience them in. In short, no, you will not get bored.

(And that's not even getting into very dangerous failure modes like "oh, what if I just modify myself to not get bored", which is incredibly problematic but still a more interesting hypothetical attempt at actually trying to solve the problem rather than giving up.)

> That too. But it also needs you. And everyone else.

I already have a problem to dedicate my life to. Many others do not, and they would be better people to target with your advocacy. I would suggest that you'd do much better focusing on "this is an important problem to work on" rather than "drop this specific cause and work on this one". Fortunately, humanity is capable of doing more than one thing at once, and in fact should do more than one thing at once. These goals do not conflict with each other, and a much smaller set of people is able to work on one than the other, which strongly suggests a benefit to specialization.

[lisper]

> Let's not play that game.

It's not a game. I know what it's like to be your age. You do not yet know what it is like to be my age (but you will, and when you do, remember this exchange). You're right that the difference doesn't matter on billion-year time scales, but I do know some things that you do not yet know, but which you will come to know. In particular, I know what it is like to have subjective experiences that convince me of the truth of propositions I would not have accepted without having experienced them directly. (Actually, you know what this is like too. You just aren't extrapolating that experience.)

> The most obvious solutions involve leaving the planet

To realize your ambitions it is not enough for some humans to leave the planet. They all have to go. And not just the seven billion of us that are here right now, but the quadrillions or more that will exist after millions of years of exponential growth with no death.

But all this is irrelevant. The details of how the sun ends or how to deal with that don't matter. The point is that no matter how it all plays out, you will eventually hit the fundamental limits imposed on growth by physics, so if you're really serious about producing unbounded life spans you have to have a plan for that. Sooner or later, the second law of thermodynamic is going to come for you. In fact, if you think about it, the goal of producing even a single unbounded life span is quite literally the the same goal as producing a perpetual motion machine, one that just happens to be implemented in human biology.

> why not try it and find out

I've already told you: because it is possible to know now that it will necessarily end badly. Exponential growth is unsustainable, not because of technological limits, but because of limits imposed by fundamental physics. If we don't limit our growth by choice, the laws of physics will do it for us sooner or later, and that will not be pleasant.

So in the long run we have to either die or stop having children. There is no other option.

> problems that are difficult enough to be a challenge but not so difficult that we can't make progress or learn something

You have clearly not come to grips with what an unbounded life span actually looks like. Unbounded is fundamentally different from finite-but-really-really-long-compared-to-what-we-have-now. In an unbounded time you can hit all kinds of limits on novelty that you will not hit in a long-but-finite time.

> you'd do much better focusing on...

Perhaps, but I find it valuable to engage with smart people I don't agree with to test my positions against the strongest opposing arguments. Every now and then I discover that I'm wrong about something that I was very sure about going in. I'm actually kind of sad that didn't happen this time. I would love for someone to convince me that I'm wrong about this.

[JoshTriplett]

I'm going to pull the most important part of my response up to the top, because I think there's an important difference in your last comment that changes the fundamental nature of this argument. Which is to say, you've moved away from trying to argue a point that I will never agree with, to making an argument that is much closer to true, and to which I have more hope that you will agree with my response below.

> So in the long run we have to either die or stop having children. There is no other option.

This is a very different statement from your previous assertions that we have to die, period. You're now allowing for at least one other alternative; there are many more alternatives, many of which would be more palatable (to people today or more importantly to people millions of years from now), but now that you've allowed for at least one alternative, that substantially changes the nature of the "resource constraints" argument, and it's no longer framed as a unsolvable problem. That seems like progress.

If your argument had started out as "we need to avoid growing our resource usage exponentially for an unbounded amount of time", then I would have mostly agreed with you on that. (I would add caveats like "assuming nothing improves in our fundamental knowledge of physics that allows for more alternatives", but that does not invalidate the point.)

As a side note, having the resources to sustain biological reproduction is the least of the potentially exponential resource concerns that would apply in the kinds of hypothetical future worlds I'm talking about; another would be the expansion of resources used by individual people as part of their own subjective thoughts and perceptions, becoming more intelligent by having a literally more powerful brain.

(Please note that objections about why the specific alternative you raised seems unpalatable aren't needed here; the point was that you are now observing there's at least one alternative, and I'd be quite happy with the resulting reframing of the problem as one of not having exponential growth in an assumed-finite universe. There are many, many ways to address "don't grow exponentially without bound".)

To quickly outline other options, barely scratching the surface but making it clear there's depth here: once we start talking about the primary resource being some form of computation, other possibilities include sharing computational cycles and affecting subjective perception of time or speed of thought; think "time multiplexing" rather than "space multiplexing. (That's also making some assumptions about how time, physics, and computation will work, and I think it's reasonable to assume we still have a lot to learn about all of those things. Leaving aside the open question of whether the multiverse is finite.) I would also observe that the form and perception we will have millions or billions of years from now is likely to nearly incomprehensible and unrecognizable to us today.

> To realize your ambitions it is not enough for some humans to leave the planet. They all have to go. And not just the seven billion of us that are here right now, but the quadrillions or more that will exist after millions of years of exponential growth with no death.

Yes, that was the point: if the planet were no longer habitable and we could not fix that, the remaining people who had not already left for other planets or parts of space would have to do so at that point. (That is, again, assuming that in five billion years we still think that's the most reasonable way to solve the problem, as opposed to any of the other myriad options we may have at that time.)

"quadrillions" seem highly unlikely to be on this planet to begin with, even if we've built both up and down to its limits; long before we could be anywhere near that point, many will have already left the planet, if not the solar system.

Populations grow more slowly or not at all when people feel substantially safer. Also, see above.

> Actually, you know what this is like too. You just aren't extrapolating that experience

I have in fact done such reasoning, based on different premises and additional information you aren't including, and have thus come to different conclusions.

Becoming older will not change my goals, just my experience and relative capabilities. And I've already made advance commitments to consciously avoid letting myself become more cynical or jaded with age and experience. On the contrary, I find that my sources of novelty and happiness and hope tend to grow over time.

Also, lest you feel that I don't have any caution or acknowledgement of concern in the reasoning I'm doing: The scale of problems I'm talking about wanting to solve here do, in fact, require an abundance of caution and concern to reason about and solve. That caution goes into things like "how do we avoid horrible failure modes like 'just modify yourself to not get bored' and other paths that effectively lead to wireheading", and "will we get the logic right on a computer that ends up running a universe-scale simulation", and "how do we make sure the systems we build prevent any possibility of cascading failures, at least on par with the level of redundance and resilience demonstrated by biological systems", and "how do we prevent either the physical or digital equivalent of grey goo". See "Security Mindset" ( https://www.schneier.com/blog/archives/2008/03/the_security_... ) and extrapolate to universe-scale problems; the security mindset is a great place to feed in caution, cynicism, and pessimism, and that's where much of mine goes.

> You have clearly not come to grips with what an unbounded life span actually looks like.

I have, in fact. I understand exactly what you're alluding to when you suggest that there are a finite combination of possible inputs. That's also assuming that the state of the person processing those inputs is the same and has not changed. And that in turn gets into questions about memory and recall and integration of our experiences. (We do not, today, remember literally everything we've ever perceived, and our memories are effectively selective, subjective self-stories of our experiences and perceptions. We should exercise great caution before making modifications to how we handle memory and experiences.) The bigger concern will not be the combinatorial limits on possible inputs; the bigger concern will be the number of combinations of brain configurations; you didn't even make the argument about how in a finite space there may be a limited number of total brain configurations you can have. All of those, however, are limits far far far more distant than the age of the universe.

To get past roughly 120, we need to solve aging and degeneration. To get past thousands of years, we need to solve accidental death, and ultimately move past biology. To get our species safely past millions of years and myriad existential threats, we'll need to distribute ourselves around the universe and otherwise have more redundancy, as well as having much more capability to predict and respond to those existential threats. To get past billions of years, we need a lot more understanding about the fundamental nature of the multiverse. "Number of unique brain configurations" is a problem we may have to deal with even further in the future than that. I don't think it makes sense to avoid solving the first problem because we don't yet know how to solve some of the later ones.

In case it isn't abundantly clear, I am well aware that the probability of personally making it through all of those, given that the first hasn't even happened yet, is not great. There's a difference between hope (which I have in abundance) and naivety (which I avoid). And I make a conscious effort to not fall into the "not thinking about it" trap that most people have about death. But I'm still going to do everything I can to work on the first few problems (in order of priority), and from my perspective, non-zero is always better than zero. As long as I'm alive I'll continue to have hope.

> I'm actually kind of sad that didn't happen this time. I would love for someone to convince me that I'm wrong about this.

I'm hoping that the observations above help in that regard. Beyond that, I hope that time will help. Perhaps when humanity survives climate change you will have more hope, since that seems to be your foremost concern; if it does not, and saying "I told you so" brings you solace, feel free. I wish you the best of success in taking concrete actions to make humanity more likely to survive.

(This will be my last comment on this thread.)

[lisper]

> > So in the long run we have to either die or stop having children. There is no other option.

> This is a very different statement from your previous assertions that we have to die, period.

Actually, it's not. I would have thought it was self-evident that ceasing to have children was not a viable option, but apparently you don't see that, so I will explain: the desire to have children is woven deeply into the human psyche, indeed, into the psyche of every living thing that has a psyche, for a very simple reason: genes that build brains that want children reproduce better than genes that build brains that don't.

The only way to achieve immortality without unsustainable exponential growth is to asymptotically reduce the reproduction rate to 0. The more immortals you have, the fewer of them will be able to have children without exhausting the resources of the universe. And if you think this is a small price to pay for immortality you really don't understand human nature, or even life itself.

> Populations grow more slowly or not at all when people feel substantially safer.

That's true, but you will never reduce the growth rate to zero organically. You will always have some people who want a child. Among mortals this is not a problem. As long as the reproduction rate is <= 1 this is sustainable. But the sustainable reproduction rate in a population of immortals is zero, and you will never achieve that absent draconian enforcement because Darwin.

> I'm hoping that the observations above help in that regard.

Not at all. All you've done is provide evidence for my initial hypothesis, that you are hopelessly naive.

> (This will be my last comment on this thread.)

That's fine. Check back in 20-30 years.