[hyperpape]

I'm not sure I understand the relevance of what Summers is saying. He's talking about a current slowdown in growth, and arguing for expansionary monetary policy. This article is claiming that there's a limited amount of growth that we can expect in the longterm, because we'll run out of sources of energy. But Summers isn't talking about energy as a limit..indeed, he's saying commodity prices are depressed.

Am I missing something?

[uxcn]

The other article isn't entirely arguing that energy is a fundamental limit, although the example it gives is pretty hilarious. It's ultimately arguing that there are fundamentally limited things for capital to invest in and grow.

[hyperpape]

The only argument I see is that energy places a limit on growth. Now, one might think that if energy is one limit, there must be others, but I can't find that argument actually presented.

[uxcn]

    > Economist: But I have to object to the statement that growth must stop once 
    > energy amount/price saturates. There will always be innovations that people 
    > are willing to purchase that do not require additional energy.

...and so on

[hyperpape]

I think you're getting this backwards--this is not an argument that there's more limits, it's an argument over whether limited energy actually implies limits to growth. What the economist says is "even if energy is limited, growth is not" and the physicist goes on to rebut that claim.

[uxcn]

The rebuttal has to do with the definition of economic growth (assuming it isn't connected to energy consumption and gdp), which the economist argues has to do with quality of life. The rebuttal is that quality of life can only objectively improve to a certain point, and that the remaining measures aren't really quantifiable.

So the last, albeit minor, argument is that there would be a point where there isn't anything to invest in to grow, which essentially describes the ultimate form of secular stagnation. I think the economic counter-argument goes something like the money supply isn't inherently finite. I could see that being an interesting argument.