2 ms·

The space of possible future human technologies is effectively infinite, to say nothing of extraplanetary resources.

tzs 3y ago
> The space of possible future human technologies is effectively infinite, to say nothing of extraplanetary resources. You are underestimating how quickly exponential growth gets out of hand. Take population for example. If we wanted to have 1% annual population growth, in ~12 100 years the volume of humans would be 9 x 10^60 m^3. If we started expanding into space right now, and we expanded at the speed of light, in 12 100 years we'd have access to 6 x 10^60 m^3, which is not big enough. Of course by then we may have bioengineered smaller humans. That doesn't help much. It just changes that 12 100 to 12 800. Or how about energy? If human energy use grows by 1% a year in ~9300 years we will be using 5.3 x 10^59 Joules per year. That's about the same as the amount of energy you would get if the entire mass of the Milky Way galaxy were converted to energy (E=mc^2). Forget the Milky Way. Let's think big. What if we converted the entire freaking universe--all the observable mass, and all the dark matter, and all the dark energy--into energy for humanity. At 1% annual growth from now we'd be using that much per year in 12 000 years.
- dublinben 3y ago
  If human civilization has been growing exponentially for a while, how have we not already hit these enormous galaxy-straining limits? The total number of humans still easily fits on just the Earth alone.
  - tzs 3y ago
    We haven't been growing exponentially for very long. Before agriculture was invented there wasn't much growth at all. We were limited by how much hunter-gatherers could hunt and gather. Growth happened when people expanded to some new territory, and that was limited by poor transportation options. When agriculture was invented around 12000 years ago growth picked up, with the population doubling around every 1000 years. That lasted until around 5000 years ago, when the population was around 100 million. There wasn't much grown for the next couple thousand years. Around 3000 years ago growth picked up and the population tripled by 2000 years ago. It slowed again until around the industrial revolution and then picked up quite a bit. The world population growth rate went from around 0.1% per year before the industrial revolution to around 0.6%. The 20th century brought many developments that allowed for even more growth. That allowed the growth rate to hit around 2.24% in 1964. It's been declining since then, dropping to a little below 1% a couple years ago. It's been pretty much the same pattern since we became Homo sapiens. When there is an increase in available resources or we get new technology that lets us better utilize resources we can have a relatively short period of exponential growth until we reach the limits of those resources and then growth slows or stops. With the industrial revolution and then the developments in the 20th century we were able to have about a century of sustained high growth, but we're reaching the end of that expansion and the growth rate is declining. We'll almost surely have more breakthroughs that allow for growth increases, but some people want to plan based on the assumption that we'll have such breakthroughs often enough that we can count on high growth indefinitely. The point of the galaxy-straining limit calculation is that the past pattern of periods of exponential growth being followed by declining growth is something inherent in exponential growth. It's not something that can be escaped by finding new places to settle or more efficient ways to use existing resources. Thus, we should be planning on the recent period of exponential growth ending rather than becoming depending on exponential growth continuing indefinitely.

tzs 3y ago

> The space of possible future human technologies is effectively infinite, to say nothing of extraplanetary resources. You are underestimating how quickly exponential growth gets out of hand. Take population for example. If we wanted to have 1% annual population growth, in ~12 100 years the volume of humans would be 9 x 10^60 m^3. If we started expanding into space right now, and we expanded at the speed of light, in 12 100 years we'd have access to 6 x 10^60 m^3, which is not big enough. Of course by then we may have bioengineered smaller humans. That doesn't help much. It just changes that 12 100 to 12 800. Or how about energy? If human energy use grows by 1% a year in ~9300 years we will be using 5.3 x 10^59 Joules per year. That's about the same as the amount of energy you would get if the entire mass of the Milky Way galaxy were converted to energy (E=mc^2). Forget the Milky Way. Let's think big. What if we converted the entire freaking universe--all the observable mass, and all the dark matter, and all the dark energy--into energy for humanity. At 1% annual growth from now we'd be using that much per year in 12 000 years.

dublinben 3y ago
If human civilization has been growing exponentially for a while, how have we not already hit these enormous galaxy-straining limits? The total number of humans still easily fits on just the Earth alone.
- tzs 3y ago
  We haven't been growing exponentially for very long. Before agriculture was invented there wasn't much growth at all. We were limited by how much hunter-gatherers could hunt and gather. Growth happened when people expanded to some new territory, and that was limited by poor transportation options. When agriculture was invented around 12000 years ago growth picked up, with the population doubling around every 1000 years. That lasted until around 5000 years ago, when the population was around 100 million. There wasn't much grown for the next couple thousand years. Around 3000 years ago growth picked up and the population tripled by 2000 years ago. It slowed again until around the industrial revolution and then picked up quite a bit. The world population growth rate went from around 0.1% per year before the industrial revolution to around 0.6%. The 20th century brought many developments that allowed for even more growth. That allowed the growth rate to hit around 2.24% in 1964. It's been declining since then, dropping to a little below 1% a couple years ago. It's been pretty much the same pattern since we became Homo sapiens. When there is an increase in available resources or we get new technology that lets us better utilize resources we can have a relatively short period of exponential growth until we reach the limits of those resources and then growth slows or stops. With the industrial revolution and then the developments in the 20th century we were able to have about a century of sustained high growth, but we're reaching the end of that expansion and the growth rate is declining. We'll almost surely have more breakthroughs that allow for growth increases, but some people want to plan based on the assumption that we'll have such breakthroughs often enough that we can count on high growth indefinitely. The point of the galaxy-straining limit calculation is that the past pattern of periods of exponential growth being followed by declining growth is something inherent in exponential growth. It's not something that can be escaped by finding new places to settle or more efficient ways to use existing resources. Thus, we should be planning on the recent period of exponential growth ending rather than becoming depending on exponential growth continuing indefinitely.