Friday, April 13, 2012

Tom Murphy — Exponential Economist Meets Finite Physicist

Humorous as well as informative as physicist Tom Murphy proves that unlimited growth indefinitely over time is physically impossible.

Read it at Do the Math
Exponential Economist Meets Finite Physicist
by Tom Murphy | Associate Professor of Physics, University of California, San Diego


Ryan Harris said...

Dark energy, invisible hands.
Big Bang!, infinite growth.

Kindergarten concepts are hard to shake in any endeavor.

paul meli said...

Interesting read.

Illustrates the wonder-ment any engineer, mathematician or physicist must feel when reading/listening to economists arguments.

Major_Freedom said...

Considering the size of the universe, and considering how our minds are in principle capable of attaining practically unlimited knowledge over the material world, then we're talking billions, probably trillions of years into the future where intelligent life can no longer transform anything in the physical universe into usable resources.

In the future going forward, colonizing the stars will be as science fictional as early human tribes in Africa and Europe contemplating traversing the Atlantic.

Tom Hickey said...

"llustrates the wonder-ment any engineer, mathematician or physicist must feel when reading/listening to economists arguments."

That's on the quantity side. On the quality side, philosophers, psychologists, anthropologists, sociologists, and evolutionary scientists are just as amazed at economists' simplistic ideas about how human beings think, feel, behave, and interact.


Septeus7 said...

First, Tom Murphy is confused by what economic growth is. You don't need increased energy consumption for economic growth.

Economic growth measures the number of ways resources (material and non-material) are used hence resources are like the universe; "finite but unbounded." Tom Murphy is a typical Newtonian in his mindset and this imperial reasoning is so pre-Planck.

Even in a so-called steady state any substitution from one material to another would seen as a kind of economic growth simply because markets the place more value on the newer item.

Second. He assume that exponential economic growth is tied to some physical exponential. It is not. What is the basis for the recent exponential growth of physical consumption. It is growing population. It has been shown that energy growth of consumption doesn't increase much beyond 150k dollars. So once population stabilizes the physical growth model switches from exponential to linear. Tom Murphy never makes a linear growth model and thus his short-term peakerism.

In fact, growth is historically linear not exponential. You have jumping curves that start as exponential and collapse and then another curve starts. The aggregated effect is a line not a curve but mathematicians are confused by this concept because every point matches a point a exponential curve and their simple textbooks say that exponentials can't be linear.

Murphy's growth model is limited to exponential functions where the power is a constant but real growth is a sum of exponential function where the power isn't a constant but time dependent.

Unfortunately, I don't how to write in summation notation on this blog so it is a bit hard explain what errors underlie the mathematical model.


Septeus7 said...

NextBigFuture Blog has had several discussions and other physicist (Sebtal) and mathematician (GoatGuy) disagree.

GoatGuy has utterly destroyed Murphy's argument against low cost space launch ( and and

I'm frankly tired of these 1950s rocket assumptions given JPAerospace is currently building an Airship which gives us LEO with less energy consumption than commercial jet travel.

I've asked where he get get his heat modelling and he seems to assume that we won't actually use any of the heat to do work (we have engine that work at temperatures as low 500 degrees f and nanotech electron trapping get us usuable work below room temp) and he isn't modeling the cooling effect of increased vegetation. He reminds me of the late Bill Smalley saying Nanotech couldn't exist for thermodynamic reasons in the 1990s while having a living body.

All of these arguments are like a hunter gather arguing that a 1 gigawatt economy can't exist on his island because it lacks the the number of trees needed even to sustain that level of output for even a week and the smoke would kill him regardless of the number of trees while he sits on a uranium mine.


Septeus7 said...

To a academic physicist everything looks like a steam engine even when it is not.

Tom Murphy has using this logic has proven that hydras don't exist because as do not undergo senescence and a biological species they grow exhibit cell growth on one kind or another them on a constant basis must not exist. There is no such thing as no growth living system but living systems seems to continue and exhibit negatrophy and have for billions of years despite the physicists and their silly steam engine assumptions.

As recently as 1997 physicists said a physical model of hyperbolic space was impossible. See this video on just how stupid mathematicians and physicists really are!

The second and third round of the discussion he fails to mention time frames which makes the entire discussion pointless.

His argument that once the cost of something becomes zero people stop using it is absurd and proven false. Did the music industry collapse because copying music became free on the internet?

Quote: "But if energy became arbitrarily cheap, someone could buy all of it," That is a non-sequitor. Music right now arbitrarily cheap and no have or is going to buy all of it.


Septeus7 said...

Tom Murphy reminds me of these famous prophets of the impossible (mostly British Imperialist see Dr. Hudson's "America' Protectionist Takeoff").

Quote: " Men might as well project a voyage to the Moon as attempt to employ steam navigation against the stormy North Atlantic Ocean."
- Dr. Dionysus Lardner (1793-1859), Professor of Natural Philosophy and Astronomy at University College, London."

Quote: "There is a young madman proposing to light the streets of London—with what do you suppose—with smoke!
- Sir Walter Scott (1771-1832)"

Quote: "This `telephone' has too many shortcomings to be seriously considered as a practical form of communication. The device is inherently of no value to us.
- Western Union internal memo, 1878

Quote: "Rail travel at high speed is not possible because passengers, unable to breathe, would die of asphyxia.
- Dr. Dionysus Lardner (1793-1859), Professor of Natural Philosophy and Astronomy at University College, London.

Quote: "That the automobile has practically reached the limit of its development is suggested by the fact that during the past year no improvements of a radical nature have been introduced.
- Scientific American, Jan. 2, 1909


Septeus7 said...

Quote: There is no likelihood man can ever tap the power of the atom. The glib supposition of utilizing atomic energy when our coal has run out is a completely unscientific Utopian dream, a childish bug-a-boo. Nature has introduced a few fool-proof devices into the great majority of elements that constitute the bulk of the world, and they have no energy to give up in the process of disintegration.
- Robert A. Millikan (1863-1953) [1928 speech to the Chemists' Club (New York)]

Quote: "This foolish idea of shooting at the moon is an example of the absurd length to which vicious specialization will carry scientists working in thought-tight compartments. Let us critically examine the proposal. For a projectile entirely to escape the gravitation of earth, it needs a velocity of 7 miles a second. The thermal energy of a gramme at this speed is 15,180 calories... The energy of our most violent explosive--nitroglycerine--is less than 1,500 calories per gramme. Consequently, even had the explosive nothing to carry, it has only one-tenth of the energy necessary to escape the earth... Hence the proposition appears to be basically impossible.
- W. A. Bickerton, Professor of Physics and Chemistry at Canterbury College (Christchurch, New Zealand), 1926.

Quote: "Space travel is utter bilge."
- Dr. Richard van der Reit Wooley, Astronomer Royal, space advisor to the British government, 1956.

and on and on and on....

Tom Hickey said...

Thanks for the elucidation, Septeus7. Why don't you post it over at his place and see what he has to say. Iam not competent to speak to the physics of it, and apparently the economist was not able to mount an argument. Or you could just provide links this and see if he follows up. I left a comment saying that I had linked to his post.

Anonymous said...

On the subject of heating up the planet. ALL physical processes, no matter how efficient or effective, eventually result in the conversion of energy into heat. So any form of energy generation and utilisation that does not rely on the incoming solar radiation (directly or indirectly) will result in the build up of heat on the Earth. The temperature will rise until the amount of energy radiated into space matches the energy being received. This is basic physics and well understood.

Tom Hickey said...

"The temperature will rise until the amount of energy radiated into space matches the energy being received. This is basic physics and well understood."

That's why I was excited about the scaling up of passive solar architecture. That and conservation are the way to go as a first line of defense.

Anonymous said...

Yes, this the real strength of renewable energy (wind, solar, tidal,etc). It simply captures and diverts energy that is arriving and makes it available for us to utilise. At the end it all eventually becomes heat, as it would anyway, and leaves as radiated energy. So there there is no net increase in energy and therefore no overall temperature change.

Mark Bahner said...

"Interesting read.

Illustrates the wonder-ment any engineer, mathematician or physicist must feel when reading/listening to economists arguments."

Then you'll probably also find this read interesting:

Exponential Engineer meets Finite Physicist