Our galaxy has about three hundred billion stars, and Earth today has about seven billion people. Assuming only half as many useable planets as stars, we could combine these two numbers into an initial crude guess for the size of a galactic civilization, and define a “galaxy of people” to be a thousand billion billion (or 1021) people. Now consider some famous galactic civilizations in science fiction.
Perhaps hydroponics would be a viable solution for food supply? Though requiring more energy intensive methods, it would dramatically reduce the square meters of space needed. This would be especially effective if the hydroponic systems were multi-storied structures, either set below the other builds, or perhaps between them. Of course, more efficient recycling of water resources would be necessary to allow the increased human population to be sustained.
Urban sprawl is a product of our present economics system more then anything else. As it becomes economically viable for taller buildings to be constructed, with a sufficient apartment size catering to human needs, there will be considerably less sprawl. A city with an average height of a thousand meters should be possible with our current materials, but simply isn't possible due to economics..
Perhaps, though I think it more likely that humanity will advance it's technology to the point where our cities meet the requirements of our present psychology.
Maybe the population estimates are within reality who knows the Galaxy is a huge entity. But travel will be an interesting problem unless you can have instantaneous transfer but then energy becomes the limiting factor for population, food and transportation. Older civilisations if they exist are most likely wiser and more cautious and not prone to long distant commutes.
Why not have planets with 40 billion people on them?
Well how about this: nobody wants to live on such a planet (no fresh air, no peace and quiet, no privacy, no space, no natural beauty) and since few people actually want to raise 10 kids, we won't create 40 billion people worlds unintentionally either. Oh yeah, a world of 40 billion people will burn through resources very quickly, that's why a 40 billion people world doesn't make economic sense either, when you also consider the long term.
Interesting explanation for dark matter. ETs capturing and using all the energy within a volume and radiating the waste heat at the ambient temperature so they are invisible against that background.
When we look at the apparent distribution of galaxies, we see large voids where the suns don't shine. Obviously, ETs are intercepting the light. We don't see them around here because the nearest void is a few hundred million light years away.
Not necessarily. What about using fusion, running on ice "comets" between the stars, as part of a gradually extending sphere. That is, many small, dense communities rather than just one super-mega "community" around the sun.
This immediately suggests another Fermi-paradox-relevant argument. If as Robin calculates here, the energy and material from our solar system can support so many more cells (be they human or otherwise), and if we think there are aliens elsewhere that got a head start, shouldn't some of them have expanded to fill at least their own solar system much more effectively, and more efficiently use the matter and energy available? So assuming the calculation is correct the question again becomes, where are they? Shouldn't we see the effects? Either the dust we see around so many other close stars IS them (which begs the question of why they're not here) or I've just given Robin more ammo for his Great-Filter-is-Ahead argument.
Most science fiction seems to vastly underestimate the population that a single planet or star can hold, and the strength of the economic pressures to keep an economy close together, rather than spread across vast distances. <3I am long-term pessimistic on space exploration for exactly this reason, but most of my friends were raised on science fiction and don&#039t seem to fully realise that without FTL everything collapses.
"Now do ems require less power than current meat-people? A current laptop runs about 5-10 W when running. A smartphone ~0.2W. Neither of these is even vaguely close to running an Em at this time. Presumably, when and if ems are runnable, it won’t be too long until they are runnable on laptopt/smartphone form factors. If this is true then ems will enjoy a significant power advantage over meat-humans."
Not a chance, EM's will need thousands of petaflops, with any accurate biophysical model under the hood (which will be needed, if you are going to "upload" any human brain). You may have some intelligence at teraflop ranges (your future smartphone) but it won't be an EM.
In terms of both meat-based humans and sims it seems the energy available would speak more to the limits of population than the volume.
The U.S. in 2008 ran on 10 KW power per person of generated power. Another 100 W per person of food can be ignored for the purposes of this calculation.
The total solar energy hitting the earth is 2e17 W (200 Million Billion W). At 10 KW each, earth could support 2e13 people (20,000 Billion). If Earth were populated as densely as Manhattan, Robin says 14000 Billion people. That is close to the limit if we continue to need 10 KW each.
What if we increase our solar collecting area? Dyson sphere is the limit, a sphere at the radius of earth surrounding the sun getting the Sun's total power output available for use. That ups the ante by a factor of 0.5 Billion.
The total energy output of the Sun could support 500 Billion Billion people at 10 KW each, the current American usage rate.
Now do ems require less power than current meat-people? A current laptop runs about 5-10 W when running. A smartphone ~0.2W. Neither of these is even vaguely close to running an Em at this time. Presumably, when and if ems are runnable, it won't be too long until they are runnable on laptopt/smartphone form factors. If this is true then ems will enjoy a significant power advantage over meat-humans.
No, that doesn't work. You end up with second law of thermodynamics problems. The only way to get rid of heat is to dissipate it to a sink at a lower temperature.
Thermocouples only generate electricity from a temperature difference, and there is heat flow from the hot source to the cold sink and only a fraction can be converted to electricity.
Lasers are not emitting heat, they are emitting work.
In principle you could pump the heat to a higher temperature to emit it with a lower area surface, but that takes work and that work also has to be dissipated at heat at the higher temperature. If you double the temperature (to 2800 K), you only need 1/16 the area. But pumping that heat from 1400 K to 2800 K would take work equivalent to the heat you are pumping, so you would have to dissipate twice as much so you would need 1/8 the area.
You would have to pump the metabolic heat from 300 K to 1400 K in the first place. I neglected that but it would be more than the metabolic heat (~5x more) to do so.
It's possible to turn heat back into work - thermocouples spring to mind - and it's then possible to remove that energy from the Earth without boiling the crust (safety concerns aside, petawatt lasers aimed at the asteroid belt, anyone?)
I've seen it mentioned in Charles Stross's Accelerando - the solution to the Fermi paradox is given by the speed of light.
Not his argument, but: all things being otherwise equal, miniaturization is preferred over expansion - you want to be as close as possible to anything you're interested in, to minimise lightspeed delay. This is a concern for humans even now; ask any gamer whether they like playing first-person shooters on an overseas server.
Our effort goes into getting smaller rather than securing new planets. As I currently understand it, we might be able to spot a planet developed like ours. Drop our size by one order of magnitude and it's harder. Drop it by two or more and I'm pretty confident we wouldn't be able to tell Earth from any other planet.
To paraphrase Hugo deGaris from last year's Australian Singularity Summit, we take this to the extreme - civilisations keep shrinking, first through nanotech, then femtotech, and so on - and the Fermi paradox might have a surprising answer: we DO see intelligent civilisations, whole galaxies of them! We just call them quarks and haven't been able to look inside yet.
Perhaps hydroponics would be a viable solution for food supply? Though requiring more energy intensive methods, it would dramatically reduce the square meters of space needed. This would be especially effective if the hydroponic systems were multi-storied structures, either set below the other builds, or perhaps between them. Of course, more efficient recycling of water resources would be necessary to allow the increased human population to be sustained.
Urban sprawl is a product of our present economics system more then anything else. As it becomes economically viable for taller buildings to be constructed, with a sufficient apartment size catering to human needs, there will be considerably less sprawl. A city with an average height of a thousand meters should be possible with our current materials, but simply isn't possible due to economics..
Isn't the present birth rate in developed countries, and especially urban environments simply a product of the economics of this system?
Perhaps, though I think it more likely that humanity will advance it's technology to the point where our cities meet the requirements of our present psychology.
Maybe the population estimates are within reality who knows the Galaxy is a huge entity. But travel will be an interesting problem unless you can have instantaneous transfer but then energy becomes the limiting factor for population, food and transportation. Older civilisations if they exist are most likely wiser and more cautious and not prone to long distant commutes.
Why not have planets with 40 billion people on them?
Well how about this: nobody wants to live on such a planet (no fresh air, no peace and quiet, no privacy, no space, no natural beauty) and since few people actually want to raise 10 kids, we won't create 40 billion people worlds unintentionally either. Oh yeah, a world of 40 billion people will burn through resources very quickly, that's why a 40 billion people world doesn't make economic sense either, when you also consider the long term.
Interesting explanation for dark matter. ETs capturing and using all the energy within a volume and radiating the waste heat at the ambient temperature so they are invisible against that background.
When we look at the apparent distribution of galaxies, we see large voids where the suns don't shine. Obviously, ETs are intercepting the light. We don't see them around here because the nearest void is a few hundred million light years away.
They'll get here eventually. Just be patient.
>without FTL everything collapses.
Not necessarily. What about using fusion, running on ice "comets" between the stars, as part of a gradually extending sphere. That is, many small, dense communities rather than just one super-mega "community" around the sun.
This immediately suggests another Fermi-paradox-relevant argument. If as Robin calculates here, the energy and material from our solar system can support so many more cells (be they human or otherwise), and if we think there are aliens elsewhere that got a head start, shouldn't some of them have expanded to fill at least their own solar system much more effectively, and more efficiently use the matter and energy available? So assuming the calculation is correct the question again becomes, where are they? Shouldn't we see the effects? Either the dust we see around so many other close stars IS them (which begs the question of why they're not here) or I've just given Robin more ammo for his Great-Filter-is-Ahead argument.
Most science fiction seems to vastly underestimate the population that a single planet or star can hold, and the strength of the economic pressures to keep an economy close together, rather than spread across vast distances. <3I am long-term pessimistic on space exploration for exactly this reason, but most of my friends were raised on science fiction and don&#039t seem to fully realise that without FTL everything collapses.
"Now do ems require less power than current meat-people? A current laptop runs about 5-10 W when running. A smartphone ~0.2W. Neither of these is even vaguely close to running an Em at this time. Presumably, when and if ems are runnable, it won’t be too long until they are runnable on laptopt/smartphone form factors. If this is true then ems will enjoy a significant power advantage over meat-humans."
Not a chance, EM's will need thousands of petaflops, with any accurate biophysical model under the hood (which will be needed, if you are going to "upload" any human brain). You may have some intelligence at teraflop ranges (your future smartphone) but it won't be an EM.
In terms of both meat-based humans and sims it seems the energy available would speak more to the limits of population than the volume.
The U.S. in 2008 ran on 10 KW power per person of generated power. Another 100 W per person of food can be ignored for the purposes of this calculation.
The total solar energy hitting the earth is 2e17 W (200 Million Billion W). At 10 KW each, earth could support 2e13 people (20,000 Billion). If Earth were populated as densely as Manhattan, Robin says 14000 Billion people. That is close to the limit if we continue to need 10 KW each.
What if we increase our solar collecting area? Dyson sphere is the limit, a sphere at the radius of earth surrounding the sun getting the Sun's total power output available for use. That ups the ante by a factor of 0.5 Billion.
The total energy output of the Sun could support 500 Billion Billion people at 10 KW each, the current American usage rate.
Now do ems require less power than current meat-people? A current laptop runs about 5-10 W when running. A smartphone ~0.2W. Neither of these is even vaguely close to running an Em at this time. Presumably, when and if ems are runnable, it won't be too long until they are runnable on laptopt/smartphone form factors. If this is true then ems will enjoy a significant power advantage over meat-humans.
No, that doesn't work. You end up with second law of thermodynamics problems. The only way to get rid of heat is to dissipate it to a sink at a lower temperature.
Thermocouples only generate electricity from a temperature difference, and there is heat flow from the hot source to the cold sink and only a fraction can be converted to electricity.
Lasers are not emitting heat, they are emitting work.
In principle you could pump the heat to a higher temperature to emit it with a lower area surface, but that takes work and that work also has to be dissipated at heat at the higher temperature. If you double the temperature (to 2800 K), you only need 1/16 the area. But pumping that heat from 1400 K to 2800 K would take work equivalent to the heat you are pumping, so you would have to dissipate twice as much so you would need 1/8 the area.
You would have to pump the metabolic heat from 300 K to 1400 K in the first place. I neglected that but it would be more than the metabolic heat (~5x more) to do so.
It's possible to turn heat back into work - thermocouples spring to mind - and it's then possible to remove that energy from the Earth without boiling the crust (safety concerns aside, petawatt lasers aimed at the asteroid belt, anyone?)
I've seen it mentioned in Charles Stross's Accelerando - the solution to the Fermi paradox is given by the speed of light.
Not his argument, but: all things being otherwise equal, miniaturization is preferred over expansion - you want to be as close as possible to anything you're interested in, to minimise lightspeed delay. This is a concern for humans even now; ask any gamer whether they like playing first-person shooters on an overseas server.
Our effort goes into getting smaller rather than securing new planets. As I currently understand it, we might be able to spot a planet developed like ours. Drop our size by one order of magnitude and it's harder. Drop it by two or more and I'm pretty confident we wouldn't be able to tell Earth from any other planet.
To paraphrase Hugo deGaris from last year's Australian Singularity Summit, we take this to the extreme - civilisations keep shrinking, first through nanotech, then femtotech, and so on - and the Fermi paradox might have a surprising answer: we DO see intelligent civilisations, whole galaxies of them! We just call them quarks and haven't been able to look inside yet.