
Galactic-Scale Energy (2011) - GuiA
https://dothemath.ucsd.edu/2011/07/galactic-scale-energy/
======
dang
Discussed at the time:
[https://news.ycombinator.com/item?id=2840054](https://news.ycombinator.com/item?id=2840054)

------
dredmorbius
The role of energy and technology in economics has been grossly misunderstood
and/or misstated for decades -- it's largely a product of post-WWII economics,
though there are of course older precursors.

A contemporary economist who's demostrated the role of energy in economic
production, and whose work would (and IMO should) revolutionise the study, is
Steve Keen. His 25 minute presentation "The Role of Energy in Production" adds
an additional term, energy, to the standard Cobb-Douglas function, and
explains virtually all of the residual.

[https://invidio.us/watch?v=BAjN6bG7XzM](https://invidio.us/watch?v=BAjN6bG7XzM)

Audio quality is poor, but I cannot recommend this video highly enough.

For those who prefer text, much of the material is in this post:

[http://www.debtdeflation.com/blogs/2016/08/19/incorporating-...](http://www.debtdeflation.com/blogs/2016/08/19/incorporating-
energy-into-production-functions/)

The idea that "technology" is responsible for "efficiency gains" comes from
the work of Robert Solow, and is called the "Solow Residual". It is quite
literally a mathematical (or statistical) artefact: if you study the behaviour
of a dependent variable on the basis of one or more independent (or
_explanatory_ ) variables, whatever change is _not_ explained is the
"residual", or residual variance.

The residual is real. Its attribution to "technology" is wholly arbitrary.
Solow's independent variables were Capital and Labour, using what's called the
Cobb-Douglas production function. They collectively explain only about TK% of
all increase in net productivity.

Solow himself has more modestly described the residual as "the measure of our
ignorance".

[https://en.wikipedia.org/wiki/Solow_residual](https://en.wikipedia.org/wiki/Solow_residual)

The soundness of the Cobb-Douglas function has been questioned by numerous
other economists, though their views have remained outside the mainstream. A
particular challenge has been meeting the economic fashion of the past 75
years or so of "mathiness" \-- being able to express relationships in a
concise mathematical function, which is what Keen's work above does.

This is strongly bolstered by other work, e.g., in Robert J. Gordon's _The
Rise and Fall of American Growth_ [1], US economic output per worker from 1920
- 1970 (and possibly beyond) grew linearaly with additional horsepower or
kilowatts per worker. Growth _since_ roughly 1970 has slowed.

Keen isn't the first to come up with this understanding. If one reads Adam
Smith with the understanding that in his time, labour _was_ power, then
Smith's measure of wealth, "the annual produce and labour of the nation", is
in large part based on energy input.[2] Leslie White formulated an eponymous
law that the level of a civilisation is proportional to its net power
throughput, similar to the Lotka-Darwin power law, that the evolutionary
advantage goes to organisms which maximise energy flow.[3]

Others include Henry Adams[4], Kenneth Boulding[5], Nicholas Georgescu-
Roegen,[6], Herman Daly[7], R.U. Ayres[8], and Charles A.H. Hall[9], as well
as ecologists Howard T. Odum and Eugene Odum[10].

There are also several histories seen through the lens of energy, most
especially Vaclav Smil's _Energy and Civilization_ (2017) and _Energy and
World History_ (1994)[11], and Manfred Weisenbacher's two-volume epic _Sources
of Power_ [12]. Both Smil and Weissenbacher divide human history into the eras
of hunter-gatherer, agriculture, coal, oil, and post-oil. It's a novel and
highly illuminating historical framework.

________________________________

Notes:

1\. [https://www.worldcat.org/title/rise-and-fall-of-american-
gro...](https://www.worldcat.org/title/rise-and-fall-of-american-growth-the-
us-standard-of-living-since-the-civil-war/oclc/1026312328) Gordon's book
divides American economic history since 1870 into roughly three fifty-year
periods: 1870-1919, 1920-1969, and 1970-2015, the book's publication year.
These are roughly accelerating growth, peak growth, and decelerating growth.
It's a remarkable history and marshalling of facts.

2\. White's Law, more precisely: "culture evolves as the amount of energy
harnessed per capita per year is increased, or as the efficiency of the
instrumental means of putting the energy to work is increased."
[https://en.wikipedia.org/wiki/White%27s_law](https://en.wikipedia.org/wiki/White%27s_law)

3\. [http://www.eoht.info/page/Darwin-
Lotka+energy+law](http://www.eoht.info/page/Darwin-Lotka+energy+law)

4\. See especially _The Education of Henry Adams_ , considered one of the most
important books of the 20th century.

5\. Formulator of the maxim, "anyone who believes in infinite growth on a
finite planet is either mad or an economist".

6\. Georgescu-Roegen's _The Entropy Law and the Economic Process_ is
excellent, but also famously impenetrable. Still recommended. The work is in
many ways similar to Frederick Soddy's, though G-R doesn't cite this, see:
_Wealth, Virtual Wealth, and Debt_
[https://en.wikipedia.org/wiki/Wealth,_Virtual_Wealth_and_Deb...](https://en.wikipedia.org/wiki/Wealth,_Virtual_Wealth_and_Debt)
and _The Role of Money_
[https://archive.org/details/roleofmoney032861mbp](https://archive.org/details/roleofmoney032861mbp)

7\. Daly has a number of less-technical essays included in _Ecological
Economics: Principles and Applications_
([https://www.worldcat.org/title/ecological-economics-
principl...](https://www.worldcat.org/title/ecological-economics-principles-
and-applications/oclc/729975896)) and _Ecological Economics and Sustainable
Development: Selected Essays_ ([https://www.worldcat.org/title/ecological-
economics-and-sust...](https://www.worldcat.org/title/ecological-economics-
and-sustainable-development-selected-essays-of-herman-daly/oclc/195733505)).

8\. R.U. Ayres has published multiple papers and books on this topic. I'd
recommend his bibliography generally:
[https://www.worldcat.org/search?q=au%3Aayres%2C+r.u.&&dblist...](https://www.worldcat.org/search?q=au%3Aayres%2C+r.u.&&dblist=638&fq=)
Keen has been working directly with Ayres in recent years.

9\. See _Energy and the Wealth of Nations_
[https://www.worldcat.org/title/energy-and-the-wealth-of-
nati...](https://www.worldcat.org/title/energy-and-the-wealth-of-nations-an-
introduction-to-biophysical-economics/oclc/1088315973). Hall is also the
origin of the concept of EROEI, energy returned on energy invested.

10\. The Odum brothers, both ecologists, have written or co-written the
leading textbook on ecology, _Fundamentals of Ecology_. Howard came up with an
"energy circuit language" that's remarkably similar to a similar concept of
Aldo Leopold's ( _Sand County Almanac_ ), though both Odum and Leopold sources
claim no mutual awareness at the time.

11\. Smil's books, _Energy and Civilization_
([https://www.worldcat.org/title/energy-and-civilization-a-
his...](https://www.worldcat.org/title/energy-and-civilization-a-
history/oclc/1029804020)), an update to _Energy in World History_
([https://www.worldcat.org/title/energy-in-world-
history/oclc/...](https://www.worldcat.org/title/energy-in-world-
history/oclc/4436805471)). The recent book has been reviewed and recommended
by Bill Gates: [https://www.gatesnotes.com/Books/Energy-and-
Civilization](https://www.gatesnotes.com/Books/Energy-and-Civilization)

12\. Weissenbacher: [https://www.worldcat.org/title/sources-of-power-how-
energy-f...](https://www.worldcat.org/title/sources-of-power-how-energy-
forges-human-history-volume-1-and-volume-2/oclc/712986243) Somewhat unevenly
written, but comprehensive.

~~~
ryacko
I suspect the Solow residual comes mainly from gains through minimizing
inventories and reducing the amount of idleness workers have.

The value of energy and technology is important for societies designed around
nation states which occasionally require the energy and technology to be
repurposed for war. It could be said the history of modern warfare is using
energy and metallurgy to shoot projectiles further and further.

It’s obviously unsustainable, but leaving the arms race requires multilateral
agreements to do so.

~~~
dredmorbius
With a causal mechanism -- "labour without energy is a corpse, capital without
energy is a sculpture" \-- and an r value approaching or above 0.9, I suspect
you're wrong.

~~~
ryacko
Labor without brains is a horse meant for the fields; in times of trouble,
hammers will forge weapons of war.

Economic statistics fail to account for immeasurable and uncountable things,
the immeasurable can only be guessed.

~~~
dredmorbius
What is brains without energy?

What is brains' _relationship_ to energy?

If by "brains" you mean "technology", in the economic sense of "increasing
total factor productivity" or more concisely, _efficiency_ , then the best
that brains are is an _efficiency factor applied to energy input_. That is,
_brains are still a factor multiplier on energy_ , and not an independent
input.

------
lostmsu
My hobby: extrapolating [https://www.xkcd.com/605/](https://www.xkcd.com/605/)

Galaxy-scale energy consumption in 2400 years seems improbable due to the
speed of light limit (Milky Way is 150,000 light-years in diameter).

~~~
vardump
Impossibility was the whole point in this blog post.

Exponential, like say 1% yearly growth, must eventually end.

