Because of the mortal dangers of ignoring the laws of physics, I will draw attention to a powerful group of people with huge followings in our culture who essentially believe that "Barry Bonds is in Space." It behooves us to quickly ignore much of what these folks say and listen to some others who agree with Einstein and his brethren.
I'll reveal these "space cadets" by contrasting the law of gravity with one of their "laws." Okum's Law is used to predict the ebb and flow of economic growth based on the ebb and flow of unemployment rates [Change in GDP = 3% - 2(Change in unemployment rate)]. It basically says that as more people are unemployed the economy grows less because fewer workers are actually producing, and vice versa. Okay, that makes sense, but look at that 3% baseline for GDP based on the historical trend in GDP growth. They, meaning the economists, are essentially saying "Barry Bonds is in Space" by assuming that the upward trend of the ball (by analogy GDP) simply continues. It is time to bring them down to Earth.
The upward movement of the baseball, and our economy, is made possible by energy applied to a certain task. In our economy, energy is often used to take raw materials from the Earth and transform them into products that we consume. These transformation and consumption processes make wastes that either we clean up at a cost (e.g., sewage treatment plants) or accumulate in our surroundings (e.g., greenhouse gases). Picture this as a flow from the Earth into human-made goods and services and back to the Earth again. The laws of physics and ecology tell us that there are limits to this flow. First, the sources of flow are not infinite; forests only grow so fast, oil wells and ancient aquifers can be pumped dry. Second, pollution interferes with the sources we rely upon; acid rain kills forests, ozone depletion damages crops, and heavy metals poison fish. But search the text of any introductory economics text used widely today and you will likely find no mention of physical or ecological constraints on economic growth. The index will probably be devoid of the words "thermodynamics," "carrying capacity," "environment," "resources," and "pollution." Instead, you will find a circular flow diagram between households and industry that is the standard model for how our economy works. This circular flow diagram ignores the resource inputs and pollution outputs of the human economy, making it dangerously incomplete.
How can economists (actually a particular, now dominant, brand of economics called neoclassical) be so misguided? I am not sure, but propose that the shortcomings of neoclassical economics result from (1) academic specialization, (2) personal isolation from nature, and (3) political expediency. Professors in different departments rarely talk to each other anymore as each discipline has become more complex, so cross-disciplinary fertilization and reality checking may not happen. As individuals in advanced techno-industrial civilizations, many of us have lost contact with the natural processes that actually sustain our lives, so our personal experience may blind our conceptual models. An economy that is portrayed as perpetually growing relieves class tensions, as economic competition is not considered a zero sum game and thus Barry Bonds' extravagant salary and lifestyle is not seen as impinging upon the needs of others.
I believe the human economy is more like a real Barry Bonds homer, up then down, not just because the laws of physics and ecology dictate it must come down, but because of how we are behaving. If baseballs were designed to sprout glider wings made of solar panels and a small propeller on the front, then maybe the homer would keep going up, or at least level off and fly at some altitude. But we aren't using fossil fuels and concentrated mineral ores to make our economy something that can keep flying. If we were worried about falling back to Earth we'd be building wind turbines instead of Humvees, and investing in solar panels instead of exotic vacations. Okum and his ilk are very dangerous indeed. They have given us a false sense of security and hubris that promotes actions precipitating our own downfall. So if these are false gods, who should we listen to instead?
A good place to start is the book "Limits to Growth: The 30-Year Update" by Donella Meadows, Jorgen Randers and Dennis Meadows. Thirty years ago the original work caused quite a stir, but has largely been forgotten by most people. Too bad, because data now support the thesis of this work and we have squandered our opportunity--the gift of insight they provided decades ago. Read about Ecological Economics, perhaps a book by Herman Daly, and see what an economic theory looks like when the laws of physics and ecology are included. Then consider what this all means for yourself, your family, your community and the future. What choices do you make about how you spend your time and income: Season tickets to the Giants or a set of solar panels on the roof?