Kardashev Scale | Hacker News Reader

Kardashev Scale

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34 pointssimonpure28 comments

Any papers or books (or thoughts) on why humans developed IC engines before solar powered engines? At first glance solar power seems more accessible than digging for petroleum / natural resources + the sun held an important place in various early religions as well

>why humans developed IC engines before solar powered engines?

IC engines are relatively cheap compared to other ways of transporting people and things, and society lacked a compelling motive to question the IC engine or to try to replace it till a scientific consensus formed (after computer modelling of the climate had become sufficiently cheap) that greenhouse gases were deeply involved in most climate changes and human-caused emissions were bringing discernible global warming -- in the 1990s.

Many engines, especially early on, can accept any external heat source as power. The most currently popular version of this is a Stirling engine, where you can find many toy engines of this type, like the wide bodies ones you can put on top of a hot drink.

Internal combustion was not actually popular for quite some time in early engines, I assume because it has more advanced requirements for fuel and ignition control, so if solar were a convenient enough power source it would have been used.

Yes, you can use the sun to heat up some water or some other fluid and in an abstract theoretical sense you can use the heat in the fluid to produce mechanical energy, but any engine small enough to go into a car or truck capable of providing enough energy to reliably overcoming rolling resistance or to make the car go up a hill is going to need a much denser power source than that.

Well yeah, as I mentioned if it were convenient to use solar for engines people would have done so. My whole point is that we had the technology and didn't do it because it's fundamentally not viable, not because of semiconductor technology.

Edit: oh, it looks like your radically edited both of your comments

Solar is weak. <1kW/m2. A small gasoline engine provides ~100kW of mechanical energy. That mismatch is what requires some magical conversion and storage to connect. Also, the semi-conductor used in photovoltaic solar cells required quantum theory to invent. The IC was “inventable” based on thermodynamics cycles etc. known in the late nineteenth century

The first big investments in petroleum were for lighting via relatively clean-burning kerosene. Petroleum as a fuel came later, when they had a lot kerosene byproduct lying around. There's a obvious problem with solar as a lighting solution: you also need good batteries.

> There's a obvious problem with solar as a lighting solution: you also need good batteries.

Or networks of mirrors.

My thinking gets stuck on the observation that before petrol, literacy after dusk was powered by the wax of bees and the blubber of whales.

Mirrors used to be difficult and expensive. There's no practical way (pre-semiconductor-era) to make thermodynamic engines on sunlight without a method to concentrate it, to achieve high temperatures.

At any rate, the areal power density is really low and wouldn't have been a good engineering choice, generally, even if it were available. (Agricultural pack animals were solar-powered machines all along. But, it takes no human work to build or maintain the fields of grass that they graze off).

There's an essay and a large HN thread about a related idea—why ancient Romans did not develop (combustion-powered) steam engines, what technological barriers prevented that,

https://news.ycombinator.com/item?id=32607187 (Why no Roman industrial revolution? (acoup.blog)", 519 comments)

Iron-age solar engines may have been impossible twice-over: impossible because of the lack of mirrors, and impossible again because of a lack of metallurgy for building high-pressure steam vessels.

Another interesting analytical lens is the Kondratiev wave, https://en.wikipedia.org/wiki/Kondratiev_wave , sometimes applied by Immanuel Wallerstein in his world-systems theory, https://en.wikipedia.org/wiki/World-systems_theory .

I hate the Kardashev scale. How is it useful in describing technological advancement? A civilization that technically had the ability to capture all the energy output from a star may not decide to do so. There's also the fact capturing the energy of a star and capturing the energy of a galaxy is the exact same level of technology, given galaxies are made of stars. "Capturing the energy of a planet" isn't even a coherent concept.

'"Capturing the energy of a planet" isn't even a coherent concept.'

Galactus would like a word.

It's an arbitrary and flawed scale, but necessarily so given the only space-faring civilisation we can see is the one in the mirror.

It does, however, give us a common point of reference for conversation about what may yet come.

The sun is pretty near, so it would be much easier to capture all of its energy, when compared to capture all of the energy of millions objects scattered over thousands of light years.

> capturing the energy of a star and capturing the energy of a galaxy is the exact same level of technology, given galaxies are made of stars

That's like saying that building a house and building a metropolis is the same level of technology because cities are made of houses.

Exactly. Houses do not predate cities by any appreciable margin.

- "Capturing the energy of a planet" isn't even a coherent concept."

There's a perfectly cogent definition: it's the technological level where you can scale out solar photovoltaics (or equivalents) to within an order of magnitude of the solar energy incident on a planet. It's a useful framework of thinking. Human civilization in particular does not possess this technology level. We're four orders of magnitude short of this energy output, and we don't have the technical ability to reach it even if we really wanted to—i.e. today's manufacturing methods are too primitive, not automated, rely too heavily on manual labor.

It's a framework to measure and then think about this technology gap. What's the difference between that imaginary civilization, and ours? We don't have advanced AI automation: we simply can't print O(100 trillion meter^2) of solar PV at any price. (The automation fraction is too low: human labor is the finite, limiting resource). Nor can we cover oceans with solar panels: we don't have the raw infrastructure power to build megastructures on that scale (again, some sort of an "automation" gap). And another: our (cheap) photovoltaics are an order of magnitude short of theoretical efficiency limits, waste most of the light that's incident on them. This one's a technology gap, and there's presumably a giant amount of physics understanding, computational power, and engineering ability that separates us from that end-game technology level. That separates our civilization from a hypothetical reference one.

It's a framework to contemplate these kinds of questions.

> And another: our (cheap) photovoltaics are an order of magnitude short of theoretical efficiency limits, waste most of the light that's incident on them.

I believe this is your only error: the cheap ones are about 20% efficient, the best are about 45%, and the theoretical maximum is about 69%.

https://en.wikipedia.org/wiki/Solar-cell_efficiency#Thermody...

A completely normal theory for a culture that determines the degree of development by the amount of available hydrocarbon mixtures (natural gas and oil).

There is no point in hating such nonsense, but it is worth fearing.

It's a catch-all for the tech capabilities of a civilization. Expressed in terms of energy harvesting.

Eg. capturing all energy output of a star, includes the ability to move (vehicles, robots etc) through space, build star-sized infrastructure, and so on.

Personally I prefer the magnitude of energy production/consumption. MWatt → GW → TW etc.

Or how advanced (or energy-dense) its source is:

Burning stuff → electric power → nuclear fission → nuclear fusion → antimatter

How amazing it would be to be able to harness the power of a star... to mine crypto.

Just remember that it's exactly the same total amount of crypto as if everyone didn't bother.

And then the crypto miners weeped, for there was no more crypto left to mine.

Von Neumann crypto probes.

This is interesting, but it’s essentially defining advancement as an increase in energy spending

I think a sufficiently advanced civilization won’t need to use that much energy

> I think a sufficiently advanced civilization won’t need to use that much energy

https://en.m.wikipedia.org/wiki/Jevons_paradox

Interesting

That means that some civilizations figure out how to be more efficient for real and others just keep increasing their energy use

So “advancing” could mean either, and we might find very advanced civilizations on a range of two opposites of a spectrum

Nice

A Type N civilization may have up to 21e6^(N+1) bitcoins ;)

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