Galactic-Scale Energy (2011)(dothemath.ucsd.edu)
dothemath.ucsd.edu
Galactic-Scale Energy (2011)
https://dothemath.ucsd.edu/2011/07/galactic-scale-energy/
62 comments
Once we get too big for our britches, the ancient aliens in our way will put us in our place.
Filling in the roofs and spending billions amounts to linear growth. (Spend $1, get $1 worth of energy; fill 1 roof, get that area in energy). The argument of the article is that the exponential growth will outshine whatever linear coefficients we throw at it.
Even going interplanetary; that is only linear growth -- go to 1 new sun, get 1 new sun of energy!
Exponential wins in the end no matter what.
Even going interplanetary; that is only linear growth -- go to 1 new sun, get 1 new sun of energy!
Exponential wins in the end no matter what.
Its only linear because the process is linear as you described. There's no reason why we can't have exponential growth - produce a machine which manufactures more of itself. This machine also contains solar panels (and other appendages) to collect resources to replicate itself.
Then very soon, the earth will be overrun with such machines, and we can go interplanetary, then consume the sun to go interstellar. At least, whoever that remains after the grey goo takes everything else would go interstellar...
Then very soon, the earth will be overrun with such machines, and we can go interplanetary, then consume the sun to go interstellar. At least, whoever that remains after the grey goo takes everything else would go interstellar...
Feels like a similar methodology here https://xkcd.com/605/
It does, and you can see at the end of his list a tapering of the growth. US energy consumption has grown 1% in the last 10 years, not 1% per year, 1% in total. Now sure, some of that is offset by some shift to imports (energy is expended in China, for the benefit of the US), but not all of it.
However had energy use increased at 2.9% since 1990 it would be nearly twice as high as it really is (4.2GToe vs 2.3 in 2018)
The Earth as a whole, with rapidly industrialising countries like China and India, global energy use from 1990 to 2018 only increased about 1.5% per year.
The world is becoming more efficient, and ultimately there is a limit to consumerism - I personally use less energy today than I did 20 years ago, and I'm sure that's the same for many people in the west. As transport becomes more efficient, there's only so many times you can go on a plane in a year (144 was my own record, but lets say it's 1000), after that point energy use on airplanes can't increase - there just aren't enough hours in the day.
However had energy use increased at 2.9% since 1990 it would be nearly twice as high as it really is (4.2GToe vs 2.3 in 2018)
The Earth as a whole, with rapidly industrialising countries like China and India, global energy use from 1990 to 2018 only increased about 1.5% per year.
The world is becoming more efficient, and ultimately there is a limit to consumerism - I personally use less energy today than I did 20 years ago, and I'm sure that's the same for many people in the west. As transport becomes more efficient, there's only so many times you can go on a plane in a year (144 was my own record, but lets say it's 1000), after that point energy use on airplanes can't increase - there just aren't enough hours in the day.
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Thankfully, the planet contains abundant stores of Uranium.. and we are nowhere near peak efficiency in commercial and industrial processes. These one dimensional analysis of the problem are particularly useless, especially when their only conclusion is "we must stop growth."
The average power usage may well be 2000W, but how many average consumers are there? If we're facing a multi-mode distribution of those users, then this "stop growth" strategy instantly creates new "castes" from this distribution. As a long term strategy, it seems doomed in one way or another.
The average power usage may well be 2000W, but how many average consumers are there? If we're facing a multi-mode distribution of those users, then this "stop growth" strategy instantly creates new "castes" from this distribution. As a long term strategy, it seems doomed in one way or another.
The article accounts for this in average earth temperature. The earth’s surface would be hotter than the sun in 1000 years, and would generally be uncomfortable after 200. The only way around that would be a substantial change in the thermodynamic efficiency of our energy use and/or a non radiative means of disposing of heat.
Granted, if we did have the equivalent energy of a sun - we are unlikely to be spending it all on earth. Escaping earths gravity would be a trivial expense.
Granted, if we did have the equivalent energy of a sun - we are unlikely to be spending it all on earth. Escaping earths gravity would be a trivial expense.
Large parts of the Earth's surface are going to be generally uncomfortable within 10 years, never mind 200.
Large parts of the Earth's surface are going to be generally uncomfortable now, never mind 10. Of course it'll be worse by then.
Large parts of the Earth surface were generally uncomfortable in 1850, so that's not really a useful statement.
There's no way we achieve the higher powers of ten without a big infrastructure migration to space. Really that's the promise of those higher powers, you move from a terrestrial to a at least a solar civilization.
That thermodynamic argument was the least convincing part. If you wanted to, you could beam your power plant's infrared radiation towards space, or put the plant itself in space and have it beam its waste heat away from the planet. The idea that heat dissipation is limited by the black body radiation of the Earth assumes that your house is part of the power plant's radiator, which itself implies that you will be living in a power plant's radiator. :-)
That's because you don't understand thermodynamics.
You can't just put the power plant in space and keep the heat from generating the power away from the earth, because the heat gets created where the power is used to perform work. You have to avoid consuming any of that power on the earth entirely.
And you can't just beam the waste heat from every process away from the surface of the earth, that violates the second law of thermodynamics. The heat exists because the energy performed work, you are keeping the energy organized by beaming it in any direction, so it is not waste heat, it is direct infrared from the energy you've produced. You can only do this by not actually using the energy for work. This makes the whole exercise of even producing the energy pointless.
I think the biggest hole in the argument is the jump to 100% efficiency. we don't consume mor energy because we feel like it, we consume it because we need it, and a factor of 5 increase in efficiency would equate to a factor of 5 decrease in production of energy resources.
You can't just put the power plant in space and keep the heat from generating the power away from the earth, because the heat gets created where the power is used to perform work. You have to avoid consuming any of that power on the earth entirely.
And you can't just beam the waste heat from every process away from the surface of the earth, that violates the second law of thermodynamics. The heat exists because the energy performed work, you are keeping the energy organized by beaming it in any direction, so it is not waste heat, it is direct infrared from the energy you've produced. You can only do this by not actually using the energy for work. This makes the whole exercise of even producing the energy pointless.
I think the biggest hole in the argument is the jump to 100% efficiency. we don't consume mor energy because we feel like it, we consume it because we need it, and a factor of 5 increase in efficiency would equate to a factor of 5 decrease in production of energy resources.
> And you can't just beam the waste heat from every process away from the surface of the earth, that violates the second law of thermodynamics.
Surely this can't be right, because if it were, air conditioning (the normal everyday kind) would be impossible, right?
What we're talking about here is loosely analogous to air conditioning the entire Earth (with the heat being sent to space rather than the outside air). Sounds like a hard engineering problem, but not impossible.
Surely this can't be right, because if it were, air conditioning (the normal everyday kind) would be impossible, right?
What we're talking about here is loosely analogous to air conditioning the entire Earth (with the heat being sent to space rather than the outside air). Sounds like a hard engineering problem, but not impossible.
> What we're talking about here is loosely analogous to air conditioning the entire Earth (with the heat being sent to space rather than the outside air). Sounds like a hard engineering problem, but not impossible.
It's possible to make radiative coolers that do exactly this, within limits. It's easy at night; harder in the daytime. Here's an example.
https://www.futurity.org/radiative-cooling-system-2141732/
It's possible to make radiative coolers that do exactly this, within limits. It's easy at night; harder in the daytime. Here's an example.
https://www.futurity.org/radiative-cooling-system-2141732/
That's not a very descriptive or explanatory article, I'd be very interested to learn more technically about this device if you happen to know or have anything.
It's basic thermodynamics; if you leave a tray of water outside at night and you protect it from wind (convection) and insulate it from the ground (conduction) and there are no clouds, it will radiate heat away into the much cooler night sky. You may have ice in the morning, even if the ambient air temperature is above freezing.
(This is also why cloudy nights are warmer than clear nights in winter--clouds prevent some of the ground's heat from radiating away.)
The technique has been used for centuries to make ice in the desert, but it only works at night and it's inefficient.
https://www.fieldstudyoftheworld.com/persian-ice-house-how-m...
With modern technology it's more efficient and it appears it can even be made to work in the daytime:
https://energyindemand.com/2020/10/17/generations-after-peop...
https://onlinelibrary.wiley.com/doi/10.1002/adpr.202000106
(This is also why cloudy nights are warmer than clear nights in winter--clouds prevent some of the ground's heat from radiating away.)
The technique has been used for centuries to make ice in the desert, but it only works at night and it's inefficient.
https://www.fieldstudyoftheworld.com/persian-ice-house-how-m...
With modern technology it's more efficient and it appears it can even be made to work in the daytime:
https://energyindemand.com/2020/10/17/generations-after-peop...
https://onlinelibrary.wiley.com/doi/10.1002/adpr.202000106
> Surely this can't be right, because if it were, air conditioning (the normal everyday kind) would be impossible, right?
Keep in mind that air conditioners are net generators of heat. The work they do moving heat around generates more heat. If you build a sealed sphere 100 feet in diameter around an air conditioner and plug it in, the air inside the sphere will heat up. This is why you cannot just open your refrigerator door to cool your house. Earth's atmosphere is warmer today around cities where a lot of air conditioners are in use. (Although excess CO2 has a much bigger effect of course.)
Keep in mind that air conditioners are net generators of heat. The work they do moving heat around generates more heat. If you build a sealed sphere 100 feet in diameter around an air conditioner and plug it in, the air inside the sphere will heat up. This is why you cannot just open your refrigerator door to cool your house. Earth's atmosphere is warmer today around cities where a lot of air conditioners are in use. (Although excess CO2 has a much bigger effect of course.)
Using power to generate work is not what happens in air conditioning. With air conditioning, you are moving heat from one spot to another (another word for it: "heat pump"). That is why it's over 100% efficient.
Generating economic value from work that the OP describes would not be "air conditioning" it would be converting heat into work -- which cannot be over 100% efficient, and in fact would be significantly less than 100% efficient at the temperatures we know.
Removing that heat using a heat pump would require some off-world reservoir of cold, which doesn't exist. The reservoir of cold that we are using now (and in any conceivable future) is the earth itself, which is what the parent comment means by "you can't use the work."
Generating economic value from work that the OP describes would not be "air conditioning" it would be converting heat into work -- which cannot be over 100% efficient, and in fact would be significantly less than 100% efficient at the temperatures we know.
Removing that heat using a heat pump would require some off-world reservoir of cold, which doesn't exist. The reservoir of cold that we are using now (and in any conceivable future) is the earth itself, which is what the parent comment means by "you can't use the work."
> some off-world reservoir of cold, which doesn't exist
Space has an average temperature of 2.7K, and there's a lot of it. Can interplanetary space be an off-world reservoir of cold?
Space has an average temperature of 2.7K, and there's a lot of it. Can interplanetary space be an off-world reservoir of cold?
It is. We receive light from the sun in the visible light range. Earth emits something like 20 photons in the infrared for each incoming visible light photon. The reason is that the sun’s surface temperature is ~20x higher than Earth’s.
So now we are getting into albedo and black body radiation, but the short answer is that you cannot radiate heat out from earth (or any body) into the vacuum faster than it radiates out by itself.
An air conditioner performs the work of moving heat from one place into another. There's a reason your compressor is outside, that's because if it were inside the heat pump wouldn't work. You're expending energy to move heat generating more heat, you'd just heat up your house. The compressor wouldn't work outside if the heat wasn't convected or conducted off the radiator into the air, there has to be a temperature differential between the ambient environment and the radiator.
With the earth, there's nowhere to pump the heat to, there's only vacuum. You'd have to convert the heat to something else like light, radiate it out, expend energy to do it, and in the process generate more waste what from that energy that will then radiate out at the natural pace. At best in this process, you'd break even and just be really expending energy beaming light out into space and accomplish nothing with regard to the heat you're trying to move.
An air conditioner performs the work of moving heat from one place into another. There's a reason your compressor is outside, that's because if it were inside the heat pump wouldn't work. You're expending energy to move heat generating more heat, you'd just heat up your house. The compressor wouldn't work outside if the heat wasn't convected or conducted off the radiator into the air, there has to be a temperature differential between the ambient environment and the radiator.
With the earth, there's nowhere to pump the heat to, there's only vacuum. You'd have to convert the heat to something else like light, radiate it out, expend energy to do it, and in the process generate more waste what from that energy that will then radiate out at the natural pace. At best in this process, you'd break even and just be really expending energy beaming light out into space and accomplish nothing with regard to the heat you're trying to move.
>you are keeping the energy organized by beaming it in any direction
I am afraid it is you who misunderstand thermodynamics, my friend. :-) Entropy is a matter of degree, and as long as the beam leaving the Earth is less ordered than the beam coming down, it can work. For example, imagine a hot nail on the moon suspended a few inches above a mirror. The heat will radiate into space and the moon won't get hotter.
I am afraid it is you who misunderstand thermodynamics, my friend. :-) Entropy is a matter of degree, and as long as the beam leaving the Earth is less ordered than the beam coming down, it can work. For example, imagine a hot nail on the moon suspended a few inches above a mirror. The heat will radiate into space and the moon won't get hotter.
Yes, but that energy cannot be used for work on the moon...
Presumably the work is what heated the nail up in the first place…
Yes, and if that work was done on the moon, the nail wouldn't be the only thing that was hot.
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But the energy transported to Earth from your space power plant still creates waste heat when it is used to do work (and also when it is transported to earth). You cannot beat the second law.
Let us, per the article's title, do the math...
* Total energy consumption = 10^26 watts (hope the caret comes through HN formatting)
* Assume some magical generation and transport mechanisms which don't involve energy gradiants (avoiding pesky thermodynamic realities), and are 99.9% efficient.
* Total waste energy is 10^23 watts.
* Radiators are on Earth, and we dedicate 1/2 of the entire surface area (not just land) to radiators. Earth has about 5.1 x 10^8 km^2, so say 2.5 x 10^14 sq. meters.
* Radiators for the waste heat would be dumping 10^23 W / 2.5 x 10^14 m^2 = 4 x 10^8 watts per square meter. That's 400 megawatts. Per square meter.
* That's a black-body temperature of 9,165 K (the Sun's surface is 5,772 K). Peak wavelength is 316 nm. So half the Earth's surface is a glowing UV light pointed at the sky. I don't think we'd have to worry about the ozone layer disappearing. (A very bright, inefficient UV lamp--plenty of infrared, hard UV, and soft X-rays to go around!)
* OK, so put the power plants in geostationary orbit. Say 1 million power stations, each with radiators 1 square kilometer.
* 1e6 stations * 1e9 square meters = 1e15 sq meters.
* So, that's only 1e8 watts/meter! Hmm. Still 6,480 K, but peak is blue-violet rather than UV. Still lots of UV and infrared, but it's space, who cares. Just don't cross the beams (ha ha, meaning no deep-space traffic). And mind the Moon! (Wouldn't want to give anbody on earth a reflected sunburn).
* The radiation pressure from the waste engery for one power stations would be about 730 kN (160,000 pounds). Would need counter-balanced beams.
* Geostationary orbit is about 26,000 miles. The surface area of a sphere that big is 2e16 square meters. So about 1/20th of the sky would be covered with powerplant radiators.
And this is just for the hypothetical 0.1% waste energy. Multiply all of the above by 1,000 for the actual used energy. So you'd have half the Earth's surface as power receivers slurping up 400 gigawatts/square meter of X-rays and hard UV. Each power station would see a force of 739 mega-newtons; you'd have to have a counter-balancing beam pointing away from Earth. And then you'd need to radiate away all that energy after it was used.
Edit: Oh, and while 1/2 of the Earth is receiving 400 GW/m^2, the other half is using that amount. Which would be the real limit. I don't think anybody would carry around a 10 GW iPhone 237+.
* Total energy consumption = 10^26 watts (hope the caret comes through HN formatting)
* Assume some magical generation and transport mechanisms which don't involve energy gradiants (avoiding pesky thermodynamic realities), and are 99.9% efficient.
* Total waste energy is 10^23 watts.
* Radiators are on Earth, and we dedicate 1/2 of the entire surface area (not just land) to radiators. Earth has about 5.1 x 10^8 km^2, so say 2.5 x 10^14 sq. meters.
* Radiators for the waste heat would be dumping 10^23 W / 2.5 x 10^14 m^2 = 4 x 10^8 watts per square meter. That's 400 megawatts. Per square meter.
* That's a black-body temperature of 9,165 K (the Sun's surface is 5,772 K). Peak wavelength is 316 nm. So half the Earth's surface is a glowing UV light pointed at the sky. I don't think we'd have to worry about the ozone layer disappearing. (A very bright, inefficient UV lamp--plenty of infrared, hard UV, and soft X-rays to go around!)
* OK, so put the power plants in geostationary orbit. Say 1 million power stations, each with radiators 1 square kilometer.
* 1e6 stations * 1e9 square meters = 1e15 sq meters.
* So, that's only 1e8 watts/meter! Hmm. Still 6,480 K, but peak is blue-violet rather than UV. Still lots of UV and infrared, but it's space, who cares. Just don't cross the beams (ha ha, meaning no deep-space traffic). And mind the Moon! (Wouldn't want to give anbody on earth a reflected sunburn).
* The radiation pressure from the waste engery for one power stations would be about 730 kN (160,000 pounds). Would need counter-balanced beams.
* Geostationary orbit is about 26,000 miles. The surface area of a sphere that big is 2e16 square meters. So about 1/20th of the sky would be covered with powerplant radiators.
And this is just for the hypothetical 0.1% waste energy. Multiply all of the above by 1,000 for the actual used energy. So you'd have half the Earth's surface as power receivers slurping up 400 gigawatts/square meter of X-rays and hard UV. Each power station would see a force of 739 mega-newtons; you'd have to have a counter-balancing beam pointing away from Earth. And then you'd need to radiate away all that energy after it was used.
Edit: Oh, and while 1/2 of the Earth is receiving 400 GW/m^2, the other half is using that amount. Which would be the real limit. I don't think anybody would carry around a 10 GW iPhone 237+.
Why not have one square meter of radiators that emits gamma rays?
As I recall, gamma rays cannot be generated by thermal processes such as electron orbit decay - so we would need a nuclear radiator which converted waste heat into atoms which would rapidly decay into gamma rays.
Assuming we’ve done all of that… you would still need to deal with the rocket engine you’ve created. Sending out a tight beam of a suns worth of energy is equivalent to a rocket engine with 1x10^18 newtons, creating challenges of its own - including an appreciable acceleration of the planet earth.
A more plausible escape hatch for the energy may be a black hole heat sink. In theory, such a device could perfectly “recycle” waste heat into usable energy.
Assuming we’ve done all of that… you would still need to deal with the rocket engine you’ve created. Sending out a tight beam of a suns worth of energy is equivalent to a rocket engine with 1x10^18 newtons, creating challenges of its own - including an appreciable acceleration of the planet earth.
A more plausible escape hatch for the energy may be a black hole heat sink. In theory, such a device could perfectly “recycle” waste heat into usable energy.
Oops, I miscalculated the total satellite area; (meant 1e6 x 1e6 = 1e12). To keep everything else the same, replace "each with radiators 1 square kilometer" with "each with radiators of 1,000 square km."
Only a small fraction of Uranium is usable for fission without breeding. There is (IIRC from a LFTR youtube) 4-10x as much thorium as uranium.
The other issue is most designs are solid fuel rod, and they waste a huge percentage of the fuel once "spent".
Nuclear isn't price competitive with existing wind/solar, and any new nuclear project is 10-20 years away, and with wind/solar in substantial/active cost improvement and economies of scale, nuclear may never be competitive.
I loved those LFTR presentations, and I would like to think a scalable LFTR solution could be made price competitive with wind/solar once it stabilizes, but right now probably not.
LFTR can use thorium (still needs a fissile uranium starter plug), and can probably breed non-fissile uranium, I've heard it can breed existing nuclear waste into usable fuel as well. It uses 99% of the fuel according to the sales brochure, which I view as a massive huge advantage: it takes all the handwringing and NIMBY about waste storage out of the equation. IMO that should be a table stakes for any "new nuclear" design.
It's basically meltdown proof with the plug, isn't pressurized, and somewaht self-regulating in temperature if I understand the neutron economy and expansion/contraction of salts. Also a "table stakes" aspect of any new nuclear project IMO.
Scalability is probably the biggest path forward to competitive fission as well, the original MSR at ORNL was allegedly closet-sized. Massive concrete dome designs lend too much to boondoggle management and cost overruns. Scalability would enable nuclear to compete with the current kings of scalable power generation: wind and especially solar.
Maybe pebble bed can get a lot of the same table stakes as LFTR. Maybe a LFTR could serve as an onsite fuel reprocessor for a more economical design if LFTR isn't broad market feasible. I'm not a nuclear engineer, I'm just a fan of the ultracool engineering and science.
But the economics don't line up for nuclear currently.
The other issue is most designs are solid fuel rod, and they waste a huge percentage of the fuel once "spent".
Nuclear isn't price competitive with existing wind/solar, and any new nuclear project is 10-20 years away, and with wind/solar in substantial/active cost improvement and economies of scale, nuclear may never be competitive.
I loved those LFTR presentations, and I would like to think a scalable LFTR solution could be made price competitive with wind/solar once it stabilizes, but right now probably not.
LFTR can use thorium (still needs a fissile uranium starter plug), and can probably breed non-fissile uranium, I've heard it can breed existing nuclear waste into usable fuel as well. It uses 99% of the fuel according to the sales brochure, which I view as a massive huge advantage: it takes all the handwringing and NIMBY about waste storage out of the equation. IMO that should be a table stakes for any "new nuclear" design.
It's basically meltdown proof with the plug, isn't pressurized, and somewaht self-regulating in temperature if I understand the neutron economy and expansion/contraction of salts. Also a "table stakes" aspect of any new nuclear project IMO.
Scalability is probably the biggest path forward to competitive fission as well, the original MSR at ORNL was allegedly closet-sized. Massive concrete dome designs lend too much to boondoggle management and cost overruns. Scalability would enable nuclear to compete with the current kings of scalable power generation: wind and especially solar.
Maybe pebble bed can get a lot of the same table stakes as LFTR. Maybe a LFTR could serve as an onsite fuel reprocessor for a more economical design if LFTR isn't broad market feasible. I'm not a nuclear engineer, I'm just a fan of the ultracool engineering and science.
But the economics don't line up for nuclear currently.
These analyses have been predicting doom for decades. They just keep moving the goal post.
Huh, I had to re-read the article.
"But let’s not overlook the key point: continued growth in energy use becomes physically impossible within conceivable timeframes." (conceivable timeframes ~ few 100 years)
As far as I understood, the argument is not "we are doomed" but that there is a natural limit to the growth of energy consumption in the not too distant future using some naive assumptions. In any case, it is implying that 2.9% growth per year is a lot! if it is extrapolated by just a few 100 years. Do I misunderstand something? Why is this controversial?
But I did not yet read all the linked later posts.
"But let’s not overlook the key point: continued growth in energy use becomes physically impossible within conceivable timeframes." (conceivable timeframes ~ few 100 years)
As far as I understood, the argument is not "we are doomed" but that there is a natural limit to the growth of energy consumption in the not too distant future using some naive assumptions. In any case, it is implying that 2.9% growth per year is a lot! if it is extrapolated by just a few 100 years. Do I misunderstand something? Why is this controversial?
But I did not yet read all the linked later posts.
It's not profound to say that sustained (infinite) growth is unsustainable, but it is of interest when it's within a conceivable timeframe.
It's not worth reading however, because the author whimsically extrapolates energy usage starting from 230 years before the invention of the lightbulb to get their exponential growth argument which doesn't hold at all for modern data.
https://data.worldbank.org/indicator/EG.USE.ELEC.KH.PC?end=2...
It's not worth reading however, because the author whimsically extrapolates energy usage starting from 230 years before the invention of the lightbulb to get their exponential growth argument which doesn't hold at all for modern data.
https://data.worldbank.org/indicator/EG.USE.ELEC.KH.PC?end=2...
You are correct.
I don’t think most people advocate for indefinite growth of energy usage; when people talk about sustainability of growth they are typically referring to economic growth. This has often been correlated with energy usage in the past but there’s nothing that says it has to be that way, and indeed there are a number of countries that have shown that decoupling the two is possible: https://ourworldindata.org/energy-gdp-decoupling
It tends to be tightly correlated to energy use up to a certain material standard of living. At that point they start to decouple.
They don't even decouple at high material standards of living. Recent increases to GDP produced emissions too but those new emissions were offset by reductions in emissions of existing industries.
This "decoupling" gets us basically nothing because it's not like we can just stop emissions tomorrow since GDP and emissions are "decoupled".
This "decoupling" gets us basically nothing because it's not like we can just stop emissions tomorrow since GDP and emissions are "decoupled".
Counter example: if we can make computation 1000x more efficient per teraflop, we could use computers to trivially design drugs to cure cancer etc (just a random example) and yet our energy consumption would not change. GDP may be the wrong measure, but there would be economic growth or standard of living growth for no change in energy consumption.
This has already happened at a higher multiplier.
An Apple Watch has more processing power than a Cray 2, but it uses a rechargeable battery instead of a 150kW power supply.
The problem is that cycles expand to fill the space available, so another 1000X drop in efficiency would mean new kinds of applications rather than being limited to affordable super computing.
While individual computers are far more powerful and use far less energy, the power consumed by computing on Earth as a whole is far higher than it was. (Not even counting energy vampires like crypto.)
There's no reason to assume that trend would stop. Displays could easily have much higher resolutions (possibly holographic), IOT could be truly ubiquitous, AI could be in everything, entertainment could be social, interactive, and immersive, and so on.
An Apple Watch has more processing power than a Cray 2, but it uses a rechargeable battery instead of a 150kW power supply.
The problem is that cycles expand to fill the space available, so another 1000X drop in efficiency would mean new kinds of applications rather than being limited to affordable super computing.
While individual computers are far more powerful and use far less energy, the power consumed by computing on Earth as a whole is far higher than it was. (Not even counting energy vampires like crypto.)
There's no reason to assume that trend would stop. Displays could easily have much higher resolutions (possibly holographic), IOT could be truly ubiquitous, AI could be in everything, entertainment could be social, interactive, and immersive, and so on.
> if we can make computation 1000x more efficient per teraflop, we could use computers yo trivially design new drugs to cure cancer etc
You're assuming two things: that cancer and disease can be cured by any feasible increase in computing power (not that outrageous an assumption), and that the energy savings won't be offset by keeping an even older population of disease survivors comfortable and alive. Reality is not as simple as "cure all our ailments and we're good to go".
You're assuming two things: that cancer and disease can be cured by any feasible increase in computing power (not that outrageous an assumption), and that the energy savings won't be offset by keeping an even older population of disease survivors comfortable and alive. Reality is not as simple as "cure all our ailments and we're good to go".
There's nothing wrong with energy. It's just that certain ways of producing energy are destroying our planet. Now that we have better and cleaner ways of generating energy, we can resume coming up with creative ways to convert energy into useful things like food, transport, computing power, clean water, etc. There is no shortage of ideas on that front. But we've kind of been sitting on our hands here because energy is an expensive bottleneck.
Transitioning all of that to sustainable processes, is the game changing transition that is defining this century. It's happening very rapidly now. And yes, I do believe we are going to see an unprecedented economic boom as well. Last century was nice. This one is going to be better.
Transitioning all of that to sustainable processes, is the game changing transition that is defining this century. It's happening very rapidly now. And yes, I do believe we are going to see an unprecedented economic boom as well. Last century was nice. This one is going to be better.
This is just a bad analysis. You have to go to the comments to find relevant terms like "Dyson swarm" and "Kardashev scale". The worst mistake is limiting energy collection to what hits the Earth.
Here is (IMHO) the likely course of humanity, assuming we don't descend into fascism with the upcoming climate-change caused mass migration and starvation or otherwise wipe ourselves out.
We will build Dyson swarms. What are Dyson swarms? They are nothing more than a collection of orbitals that orbit the Sun. The most basic form of these is an O'Neil Cylinder, which is about 3 miles in diameter and 10-20 miles long. You put solar power collectors on these things and they're pretty much self-sufficient.
Why this size? Because you can build that with a material no stroner than stainless steel. Any larger and the centrifugal force will of rotating for spin gravity will tear it apart. If mass production with graphene ever goes anywhere, it opens the door to building McKendree Cylinder, which could get to ~300 miles in diameter and thousands of miles long.
So the question is why. Several reasons:
1. You can effectively collect all the energy the Sun outputs;
2. This is only predicated on solar power, something we can already build. It isn't predicated on nuclear fusion power generation, for example. I'm personaly not convinced fusion will ever be commercially viable. It might and that'd be great but it's not a pre-requisitie for that and that's what's important;
3. It requires no new physics or no magical new materials; and
4. Here's the big one: it's super-efficient in creating living area per unit mass. I think I saw an estimate that you could build a complete Dyson swarm around the Sun with ~1% of the mass of Mercury. Such a Dyson swarm could comfortably house more than 10^15 people with an energy budget per person orders of magnitude than what we have now.
So a brief note about the Kardashev scale. This is an approximation but a Kardashev-1 ("K1") civilization is defined as using the entire energy output of a planet. This is estimated as 10^16 Watts. A K2 civilization uses the entire energy output of a star, estimated at 10^26 Watts. A k3 civilization is the entire galaxy at about 10^36 Watts.
Humans use about 10^11 Watts (IIRC) of energy. So a K2 civilization might have 10^15 people but have access to 10^26 Watts of power. That's 10^11 Watts of power per person.
The scale of a K2 civilization is almost beyond comprehension.
Here is (IMHO) the likely course of humanity, assuming we don't descend into fascism with the upcoming climate-change caused mass migration and starvation or otherwise wipe ourselves out.
We will build Dyson swarms. What are Dyson swarms? They are nothing more than a collection of orbitals that orbit the Sun. The most basic form of these is an O'Neil Cylinder, which is about 3 miles in diameter and 10-20 miles long. You put solar power collectors on these things and they're pretty much self-sufficient.
Why this size? Because you can build that with a material no stroner than stainless steel. Any larger and the centrifugal force will of rotating for spin gravity will tear it apart. If mass production with graphene ever goes anywhere, it opens the door to building McKendree Cylinder, which could get to ~300 miles in diameter and thousands of miles long.
So the question is why. Several reasons:
1. You can effectively collect all the energy the Sun outputs;
2. This is only predicated on solar power, something we can already build. It isn't predicated on nuclear fusion power generation, for example. I'm personaly not convinced fusion will ever be commercially viable. It might and that'd be great but it's not a pre-requisitie for that and that's what's important;
3. It requires no new physics or no magical new materials; and
4. Here's the big one: it's super-efficient in creating living area per unit mass. I think I saw an estimate that you could build a complete Dyson swarm around the Sun with ~1% of the mass of Mercury. Such a Dyson swarm could comfortably house more than 10^15 people with an energy budget per person orders of magnitude than what we have now.
So a brief note about the Kardashev scale. This is an approximation but a Kardashev-1 ("K1") civilization is defined as using the entire energy output of a planet. This is estimated as 10^16 Watts. A K2 civilization uses the entire energy output of a star, estimated at 10^26 Watts. A k3 civilization is the entire galaxy at about 10^36 Watts.
Humans use about 10^11 Watts (IIRC) of energy. So a K2 civilization might have 10^15 people but have access to 10^26 Watts of power. That's 10^11 Watts of power per person.
The scale of a K2 civilization is almost beyond comprehension.
I'm glad that a few of the influential billionaires out there nowadays calling the shots think along the same lines as you. I grew up under this dark cloud of thinking there's no future for humanity, we all have to tighten our belts and cut way back to survive at all, blah blah blah.
Yet here we are, right on the cusp of realistically exploiting the ridiculously vast resources of the solar system! I'll bet that 50 years from now, humanity will be so rich that even stingy red state welfare will pay for a lifestyle I can barely afford nowadays on my fat tech salary.
Yet here we are, right on the cusp of realistically exploiting the ridiculously vast resources of the solar system! I'll bet that 50 years from now, humanity will be so rich that even stingy red state welfare will pay for a lifestyle I can barely afford nowadays on my fat tech salary.
See also: "Exponential Economist Meets Finite Physicist" which covers the same material in the context of economic growth.
> Some while back, I found myself sitting next to an accomplished economics professor at a dinner event. Shortly after pleasantries, I said to him, “economic growth cannot continue indefinitely,” just to see where things would go. It was a lively and informative conversation.
https://dothemath.ucsd.edu/2012/04/economist-meets-physicist...
> Some while back, I found myself sitting next to an accomplished economics professor at a dinner event. Shortly after pleasantries, I said to him, “economic growth cannot continue indefinitely,” just to see where things would go. It was a lively and informative conversation.
https://dothemath.ucsd.edu/2012/04/economist-meets-physicist...
This article (and site) are pretty great, and helped shape a lot of my worldview. It tends to throw a bucket of cold water on a lot of the arguments regularly made on this website, though, so I'm surprised to see it here.
What sort of arguments do you see made on this website that this would refute?
Presumably that much of the tech industry and the way it’s funded is built on the assumption of boundless growth.
I don't think any tech funding is premised on boundless growth. It's usually a 20x-1000x factor of growth for a tiny part of the existing economy.
This is important because the difference between boundless growth and a certain factor of growth is literally infinite, and has huge implications for reasoning about the future
This is important because the difference between boundless growth and a certain factor of growth is literally infinite, and has huge implications for reasoning about the future
Forgive me, for I am doing an end-run around a HN rule (replying to a reply to a reply). But it seems an entertaining question...
> What if you radiated a Sun's worth of energy (10^26 Watts) out of 1 square meter?
* Blackbody temperature: 2 x 10^8 K.
Peak blackbody wavelength: Wolfram didn't like that question. However, it did helpfully note that it was twice the temperature needed for controlled nuclear fusion, and 5e7 K above the temperature at which the triple alpha process occurs inside stars.
It also noted that it was equivalent to 17 keV. This would, suprisingly to me, be X-rays and not gamma; the cut-off is 100 keV. 17 keV is a photon wavelength of 73 picometers (7.3e-11 m); a helium atom's diameter is about 62 pm.
* Luminosity would be about 4e15 lux. It would, of course, be twice as bright as the sun (equivalent to seeing both solar hemispeheres at the same time.) You would be able to see the Earth from lightyears away.
* Radiation pressure would be 730 x 10^12 newtons (80 gigatons).
* This would accelerate the Earth by 1.2e-10 m/s^2. Even if sited at one of the poles, that's only 4 millimeters/sec over one year. Not useful for jaunting around the Solar System except on geologic timescales.
* Asteroid Apophis is a whole 'nother matter. It's estimated to be 6 x 10^10 kg. Assuming we left its destruction to THE VERY LAST SECOND (i.e., distance 0), the radiation pressure would accelerate it at 36 km/s^2. (Yep. You try it: [0]; it's x 2 because it is reflecting) Of course, it would melt it in about half a nanosecond (literaly).
* Mars' moon Phobos would fare better. Assuming the radiator is a 73 picometer X-ray laser with 1.1 m diameter (1 m^2 area), beam divergence (based on no-doubt-poorly-applicable-in-reality formulas) would be about 2e-11 radians. At conjunction, the Earth and Mars are a maximum of 400 million km apart. Wolfram thinks (it ain't easy calculating the sine of 2e-11) the beam would diverge to about 8 meters wide at that distance. Phobos masses about 1e16 kg. It would only accelerate at 0.14 m/s^2, or 12 km/s/day. And it wouldn't melt for at least 80 milliseconds.
[0] https://www.wolframalpha.com/input?i=730e12+newtons+*+2+%2F+...
> What if you radiated a Sun's worth of energy (10^26 Watts) out of 1 square meter?
* Blackbody temperature: 2 x 10^8 K.
Peak blackbody wavelength: Wolfram didn't like that question. However, it did helpfully note that it was twice the temperature needed for controlled nuclear fusion, and 5e7 K above the temperature at which the triple alpha process occurs inside stars.
It also noted that it was equivalent to 17 keV. This would, suprisingly to me, be X-rays and not gamma; the cut-off is 100 keV. 17 keV is a photon wavelength of 73 picometers (7.3e-11 m); a helium atom's diameter is about 62 pm.
* Luminosity would be about 4e15 lux. It would, of course, be twice as bright as the sun (equivalent to seeing both solar hemispeheres at the same time.) You would be able to see the Earth from lightyears away.
* Radiation pressure would be 730 x 10^12 newtons (80 gigatons).
* This would accelerate the Earth by 1.2e-10 m/s^2. Even if sited at one of the poles, that's only 4 millimeters/sec over one year. Not useful for jaunting around the Solar System except on geologic timescales.
* Asteroid Apophis is a whole 'nother matter. It's estimated to be 6 x 10^10 kg. Assuming we left its destruction to THE VERY LAST SECOND (i.e., distance 0), the radiation pressure would accelerate it at 36 km/s^2. (Yep. You try it: [0]; it's x 2 because it is reflecting) Of course, it would melt it in about half a nanosecond (literaly).
* Mars' moon Phobos would fare better. Assuming the radiator is a 73 picometer X-ray laser with 1.1 m diameter (1 m^2 area), beam divergence (based on no-doubt-poorly-applicable-in-reality formulas) would be about 2e-11 radians. At conjunction, the Earth and Mars are a maximum of 400 million km apart. Wolfram thinks (it ain't easy calculating the sine of 2e-11) the beam would diverge to about 8 meters wide at that distance. Phobos masses about 1e16 kg. It would only accelerate at 0.14 m/s^2, or 12 km/s/day. And it wouldn't melt for at least 80 milliseconds.
[0] https://www.wolframalpha.com/input?i=730e12+newtons+*+2+%2F+...
sin(2e-11) is almost exactly 2e-11 since sin(x) ~= x for small x. :)
The article leaves out a crucial point: the main driver of growth in energy usage is growth in human population. The human population of Earth is expected to level off this century. So any projection beyond that that assumes continued energy growth at the same rate is not realistic.
The article does mention this:
> Chiefly, continued energy growth will likely be unnecessary if the human population stabilizes.
> Chiefly, continued energy growth will likely be unnecessary if the human population stabilizes.
This analysis excludes geothermal and nuclear, which have massive energy potential. Yet even limited as it is, based on its assumptions, we could grow at these rates for centuries, at least, before having to worry about physical limits even within the solar system, so why fret about it now.
Focusing on realizing that growth now would save monumental amounts of energy from being wasted, as the sun radiates it into space, and allow trillions to live who otherwise wouldn't have.
Focusing on realizing that growth now would save monumental amounts of energy from being wasted, as the sun radiates it into space, and allow trillions to live who otherwise wouldn't have.
Yes, growth is logically not going to continue forever. But we are nowhere close to the point that growth will inevitably have to stop.
There's a moral undertone here of course that that growth is coming at a price and that therefore we need to show some restraint. It's a very elaborate argument against energy gluttony. That's a particular world view that seems to never really catch on with the wider public. At least judging from their waste lines.
What does seem to happen is that we are rapidly transitioning to more guilt free forms of energy generation. For example, put solar panels on your roof and you get free kwh for your Tesla and you can turn your AC on as long as you want. Problem solved. That's a consumerist version of reality that is a bit more real in the sense that that is actually something that a lot of people aspire to do at a scale that matters.
Not all energy usage is bad. Energy production growth is fine as long as we do it sustainably. And now that that seems to become the default, the next interesting thing for humanity is to figure out what to do with all that clean, plentiful energy.
There's a moral undertone here of course that that growth is coming at a price and that therefore we need to show some restraint. It's a very elaborate argument against energy gluttony. That's a particular world view that seems to never really catch on with the wider public. At least judging from their waste lines.
What does seem to happen is that we are rapidly transitioning to more guilt free forms of energy generation. For example, put solar panels on your roof and you get free kwh for your Tesla and you can turn your AC on as long as you want. Problem solved. That's a consumerist version of reality that is a bit more real in the sense that that is actually something that a lot of people aspire to do at a scale that matters.
Not all energy usage is bad. Energy production growth is fine as long as we do it sustainably. And now that that seems to become the default, the next interesting thing for humanity is to figure out what to do with all that clean, plentiful energy.
In other words: the exponential function grows very fast.
> The abundance of deuterium in ordinary water would allow us to have a seemingly
I mean isn't it obvious that we are missing opportunities here? Are we really that complacent that we can't achieve anything on a grand scale anymore? Plant solar panels everywhere that there is not agricultural land and meets the criteria for energy efficiency. Fill in the all the roofs. It's vacant space. Spend billions more on fusion research.
> The merciless growth illustrated above means that in 1400 years from now, any source of energy we harness would have to outshine the sun.
Hopefully by that time we'd be an interplanetary species. Unless we imagine we can keep digging all the way to the core to extract resources down here. When all the good stuff is literally sitting out there waiting for us to plunder.
> Chiefly, continued energy growth will likely be unnecessary if the human population stabilizes.
I doubt our insatiable hunger for more, more, and more will stop anytime soon - even if the numbers stagnate, our egos will grow bigger and bigger and we'll want more and more. It's in our nature. So why not go beyond our planet for that never-ending "want"? Consumer everything that's out there and turn into shiny new crap for down here. Once we are done, eject it into the sun and keep the earth tidy.