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It's worth bringing up The Most Important Video You'll Ever Watch [1], which the lecturer characterizes as humanity's biggest problem is our inability to unders

by cletus 15y ago

It's worth bringing up The Most Important Video You'll Ever Watch [1], which the lecturer characterizes as humanity's biggest problem is our inability to understand the exponential function. Watch all 8 parts. I have come to the conclusion that there simply are too many of us. We can probably sustain our current levels for a century, maybe two, but at some point scarce resources (and their subsequent cost) will have a devastating effect. Basically, we need to correct our population before nature does. As much as people point to space being our future, I simply (sadly) do not agree. While there might be plentiful resources in the asteroid belt (and on other bodies) nothing compares to how cheaply we can pull things out of the ground here on Earth. Our society is predicated on cheap, plentiful resources such that it can't survive them being several (or even one?) order of magnitude more expensive. As far as interstellar space goes, even if we solve the reaction mass problem and have perfect (100% efficient) conversion of matter to energy, it will still be prohibitive to go to even the nearest stars. Perhaps the simplest explanation of the Fermi Paradox is that potential growth for a starfaring civilization is geometric (being a sphere ultimately limited by the speed of light) while growth rates are exponential. And exponential will ultimately "win". [1]: http://www.youtube.com/watch?v=F-QA2rkpBSY http://www.youtube.com/watch?v=F-QA2rkpBSY

astrofinch 15y ago
That video is a joke for anyone who has more than a superficial understanding of math. Just because a process has fit an exponential curve does not mean exponential growth is going to continue forever. Past growth patterns are fairly weak evidence of future growth patterns. ("Housing prices always go up!") That's not to say we shouldn't fear a process that is inherently exponential in nature, like the reproduction of bacteria or a nuclear reaction going supercritical. But if the process only appears from the outside to have been growing exponentially, that's only a weak indicator that it will start behaving in an insane fashion. In any case, it seems that as nations become more developed people stop having kids: http://www.overcomingbias.com/2010/11/fertility-the-big-problem.html http://www.overcomingbias.com/2010/11/fertility-the-big-prob...
- pbhjpbhj 15y ago
  The demographic transition might slow population growth, but for how long? http://www.nature.com/nature/journal/v460/n7256/abs/nature08230.html http://www.nature.com/nature/journal/v460/n7256/abs/nature08... suggests that populations passing through the DT eventually recover and begin to grow again. There's not a clear causality either.
  - astrofinch 15y ago
    It says their fertility rate goes up; there is no mention made of it surpassing the replacement rate.
    - pbhjpbhj 15y ago
      Suggests. From the full paper: >"* Morespecifically,ourfindingsreduce,if notyetcompletelyreject,fearsofpopulationdeclinethathavebeenincorporated inmanynationalpopulationforecastsforhighlyadvancedcountries.Nevertheless,weexpectcountrieslaggingbehindintermsofdevelopmenttocontinuetheir fertilitydecline,consistentlywithcurrentscientificknowledge.Moreover,some countriesatintermediatedevelopmentlevelsarelikelytofaceadeclineinpopulationsizebecausethesecountriesdonotyet—andmaynotintheforeseeable future—benefitfromthereversalofthedevelopment–fertilityrelationshipthathas occurredatadvancedHDIlevels*" http://ccpr.ucla.edu:8080/CCPRWebsite/events/ccpr-previous-seminars/ccpr-seminars-previous-years/Kohler-advances%20in%20development.pdf http://ccpr.ucla.edu:8080/CCPRWebsite/events/ccpr-previous-s...
- wazoox 15y ago
  > Just because a process has fit an exponential curve does not mean exponential growth is going to continue forever. Did you watch the video? This is precisely what it's talking about. Though the economy and energy usage have grown up exponentially for the past two centuries, we cannot hope that it will go on forever. Population growth isn't a concern per se, resource overconsumption and the impossibility of future economic growth are.
  - crististm 15y ago
snowwrestler 15y ago
The world population growth rate is not exponential; in fact it has been declining for decades. It seems increasingly possible that the human population will stabilize or even decline in this century.
- im3w1l 15y ago
  The strongest selection pressure in the western world is for people to spend every waking hour making babies. It sounds very likely that population growth will pick up its pace this century unless it is actively prevented.
  - tsotha 15y ago
    And yet all indications are that's not what happens. The most likely scenario is by mid century the world population will be in decline and continue to do so at an accelerated pace until at least 2100. Medicine has given us control over our fertility, and the way modern societies are structured children are a financial liability.
  - Dove 15y ago
    The strongest selection pressure in the western world is for people to spend every waking hour making babies. True as that may be, people are not acting the way that would lead you to expect. World population appears to be on a logistic curve -- http://en.wikipedia.org/wiki/Logistic_function http://en.wikipedia.org/wiki/Logistic_function http://en.wikipedia.org/wiki/File:World-Population-1800-2100.png http://en.wikipedia.org/wiki/File:World-Population-1800-2100... -- and birth rates for a lot of the world are close to or below replacement. http://en.wikipedia.org/wiki/Fertility_rate http://en.wikipedia.org/wiki/Fertility_rate The selection pressure is real, but it is not the only force in play. Economic pressure is acting too, and it is against raising children; they are expensive to raise to adulthood, and you cannot derive any material benefit from them. It seems to me that, in this case, the economics have much greater force than the genetics. Whatever disposition toward childbearing you inherit from your parents, whether genetic or ideological, is a small thing compared to whether circumstances make providing for them practical. In general, when dealing with a complex system, it is not enough to know that a single force is acting on it. You need to understand all the forces, and how strong they are and how they behave. All too often, this is the case with selection pressure arguments -- supposing that the force in question is the only one in play, without any regard for whether it has the power to do the job expected of it. I find that the best course of action is usually to look at the actual data, and see how the system really is behaving, apart from theory. Nontrivial systems very rarely meet naive expectations.
huherto 15y ago
Is it an exponential function or a simoid?
InclinedPlane 15y ago
Psssst. Want to know a secret? More humans doesn't equal less resources, it equals more resources. The Earth isn't "running out" of anything, the idea of a carrying capacity for a technological species is ridiculous.
- wazoox 15y ago
  You're exemplar of this video subject: exponential growth can't go on forever, and you obviously didn't understand that. That's quite sad. Another article for reference: http://physics.ucsd.edu/do-the-math/2011/07/galactic-scale-energy/ http://physics.ucsd.edu/do-the-math/2011/07/galactic-scale-e...
  - InclinedPlane 15y ago
    I have a degree in Mathematics, TYVM. Human population isn't growing exponentially, only pseudo-exponentially.
    - wazoox 15y ago
      Resource consumption is growing exponentially. That is the real problem.
      - Game_Ender 15y ago
        Energy is the only resource that matters. With enough energy and technology we can recycle and transform whatever current raw physical materials we have available, no matter how inefficient it is. With the population leveling off, I think the amount of physical materials needed at any one time will stop growing exponentially. Consumption will rates will still be increasing, but we can recycle the raw materials to keep the absolute amount needed within physical limits.
      - csomar 15y ago
        Sorry, I'm not an expert in that kind of stuff. But since resources don't get out of Earth, then the total loss of resources is 0. Resource consumption is growing exponentially Hmm, really? My computer is thinner, so is my TV (and probably my future car), I don't purchase paper any more (or almost don't purchase/use it) and I consume more digital products than physical ones. Yet, even if I purchase double of what I have the next year, I can't keep in that pace for too long.
zmj 15y ago
> Perhaps the simplest explanation of the Fermi Paradox is that potential growth for a starfaring civilization is geometric (being a sphere ultimately limited by the speed of light) while growth rates are exponential. And exponential will ultimately "win". I read a paper within the last few months that used simulated expansion into a galaxy to debunk that idea. The fallacy is that growth is continuous and ceases simultaneously across a civilization. The (simulated) reality is that only a tiny percentage of frontier colonies need to survive to prevent extinction and eventually resume growth. I wish I could find the paper. Anyone know the one I'm talking about?
radu_floricica 15y ago
Don't remember if the video addresses this (saw it years ago), but aren't most exponentials just part of the ever-present logistic curve? ( http://en.wikipedia.org/wiki/Logistic_function http://en.wikipedia.org/wiki/Logistic_function )

by cletus 15y ago

astrofinch 15y ago

That video is a joke for anyone who has more than a superficial understanding of math. Just because a process has fit an exponential curve does not mean exponential growth is going to continue forever. Past growth patterns are fairly weak evidence of future growth patterns. ("Housing prices always go up!") That's not to say we shouldn't fear a process that is inherently exponential in nature, like the reproduction of bacteria or a nuclear reaction going supercritical. But if the process only appears from the outside to have been growing exponentially, that's only a weak indicator that it will start behaving in an insane fashion. In any case, it seems that as nations become more developed people stop having kids: http://www.overcomingbias.com/2010/11/fertility-the-big-problem.html http://www.overcomingbias.com/2010/11/fertility-the-big-prob...

pbhjpbhj 15y ago
The demographic transition might slow population growth, but for how long? http://www.nature.com/nature/journal/v460/n7256/abs/nature08230.html http://www.nature.com/nature/journal/v460/n7256/abs/nature08... suggests that populations passing through the DT eventually recover and begin to grow again. There's not a clear causality either.
- astrofinch 15y ago
  It says their fertility rate goes up; there is no mention made of it surpassing the replacement rate.
  - pbhjpbhj 15y ago
    Suggests. From the full paper: >"* Morespecifically,ourfindingsreduce,if notyetcompletelyreject,fearsofpopulationdeclinethathavebeenincorporated inmanynationalpopulationforecastsforhighlyadvancedcountries.Nevertheless,weexpectcountrieslaggingbehindintermsofdevelopmenttocontinuetheir fertilitydecline,consistentlywithcurrentscientificknowledge.Moreover,some countriesatintermediatedevelopmentlevelsarelikelytofaceadeclineinpopulationsizebecausethesecountriesdonotyet—andmaynotintheforeseeable future—benefitfromthereversalofthedevelopment–fertilityrelationshipthathas occurredatadvancedHDIlevels*" http://ccpr.ucla.edu:8080/CCPRWebsite/events/ccpr-previous-seminars/ccpr-seminars-previous-years/Kohler-advances%20in%20development.pdf http://ccpr.ucla.edu:8080/CCPRWebsite/events/ccpr-previous-s...
wazoox 15y ago
> Just because a process has fit an exponential curve does not mean exponential growth is going to continue forever. Did you watch the video? This is precisely what it's talking about. Though the economy and energy usage have grown up exponentially for the past two centuries, we cannot hope that it will go on forever. Population growth isn't a concern per se, resource overconsumption and the impossibility of future economic growth are.
- crististm 15y ago

snowwrestler 15y ago

The world population growth rate is not exponential; in fact it has been declining for decades. It seems increasingly possible that the human population will stabilize or even decline in this century.

im3w1l 15y ago
The strongest selection pressure in the western world is for people to spend every waking hour making babies. It sounds very likely that population growth will pick up its pace this century unless it is actively prevented.
- tsotha 15y ago
  And yet all indications are that's not what happens. The most likely scenario is by mid century the world population will be in decline and continue to do so at an accelerated pace until at least 2100. Medicine has given us control over our fertility, and the way modern societies are structured children are a financial liability.
- Dove 15y ago
  The strongest selection pressure in the western world is for people to spend every waking hour making babies. True as that may be, people are not acting the way that would lead you to expect. World population appears to be on a logistic curve -- http://en.wikipedia.org/wiki/Logistic_function http://en.wikipedia.org/wiki/Logistic_function http://en.wikipedia.org/wiki/File:World-Population-1800-2100.png http://en.wikipedia.org/wiki/File:World-Population-1800-2100... -- and birth rates for a lot of the world are close to or below replacement. http://en.wikipedia.org/wiki/Fertility_rate http://en.wikipedia.org/wiki/Fertility_rate The selection pressure is real, but it is not the only force in play. Economic pressure is acting too, and it is against raising children; they are expensive to raise to adulthood, and you cannot derive any material benefit from them. It seems to me that, in this case, the economics have much greater force than the genetics. Whatever disposition toward childbearing you inherit from your parents, whether genetic or ideological, is a small thing compared to whether circumstances make providing for them practical. In general, when dealing with a complex system, it is not enough to know that a single force is acting on it. You need to understand all the forces, and how strong they are and how they behave. All too often, this is the case with selection pressure arguments -- supposing that the force in question is the only one in play, without any regard for whether it has the power to do the job expected of it. I find that the best course of action is usually to look at the actual data, and see how the system really is behaving, apart from theory. Nontrivial systems very rarely meet naive expectations.

huherto 15y ago

Is it an exponential function or a simoid?

InclinedPlane 15y ago

Psssst. Want to know a secret? More humans doesn't equal less resources, it equals more resources. The Earth isn't "running out" of anything, the idea of a carrying capacity for a technological species is ridiculous.

wazoox 15y ago
You're exemplar of this video subject: exponential growth can't go on forever, and you obviously didn't understand that. That's quite sad. Another article for reference: http://physics.ucsd.edu/do-the-math/2011/07/galactic-scale-energy/ http://physics.ucsd.edu/do-the-math/2011/07/galactic-scale-e...
- InclinedPlane 15y ago
  I have a degree in Mathematics, TYVM. Human population isn't growing exponentially, only pseudo-exponentially.
  - wazoox 15y ago
    Resource consumption is growing exponentially. That is the real problem.
    - Game_Ender 15y ago
      Energy is the only resource that matters. With enough energy and technology we can recycle and transform whatever current raw physical materials we have available, no matter how inefficient it is. With the population leveling off, I think the amount of physical materials needed at any one time will stop growing exponentially. Consumption will rates will still be increasing, but we can recycle the raw materials to keep the absolute amount needed within physical limits.
    - csomar 15y ago
      Sorry, I'm not an expert in that kind of stuff. But since resources don't get out of Earth, then the total loss of resources is 0. Resource consumption is growing exponentially Hmm, really? My computer is thinner, so is my TV (and probably my future car), I don't purchase paper any more (or almost don't purchase/use it) and I consume more digital products than physical ones. Yet, even if I purchase double of what I have the next year, I can't keep in that pace for too long.

zmj 15y ago

> Perhaps the simplest explanation of the Fermi Paradox is that potential growth for a starfaring civilization is geometric (being a sphere ultimately limited by the speed of light) while growth rates are exponential. And exponential will ultimately "win". I read a paper within the last few months that used simulated expansion into a galaxy to debunk that idea. The fallacy is that growth is continuous and ceases simultaneously across a civilization. The (simulated) reality is that only a tiny percentage of frontier colonies need to survive to prevent extinction and eventually resume growth. I wish I could find the paper. Anyone know the one I'm talking about?

radu_floricica 15y ago

Don't remember if the video addresses this (saw it years ago), but aren't most exponentials just part of the ever-present logistic curve? ( http://en.wikipedia.org/wiki/Logistic_function http://en.wikipedia.org/wiki/Logistic_function )