The Physics of Sustainability

Here is a key paragraph from  President Obama’s inauguration speech on Monday, January 21^st. 2013:

For now decisions are upon us, and we cannot afford delay. We cannot mistake absolutism for principle, or substitute spectacle for politics, or treat name-calling as reasoned debate. We must act, knowing that our work will be imperfect. We must act, knowing that today’s victories will be only partial, and that it will be up to those who stand here in four years, and forty years, and four hundred years hence to advance the timeless spirit once conferred to us in a spare Philadelphia hall.

The President was making a pledge, and was calling on all of us to join him, to act now for the benefit of future generations. The President was urging all of us to act now, to make the world a better place so that in four years, forty years or four hundred years, future generations can improve on what we are doing. In his short speech, he made a specific reference to climate change as an “obvious” place to start. In this and future blogs I would like to try and quantify this concept, as well as describe what, in my opinion, is involved. In my background, we call this effort sustainability.

There is a standing effort (including by my school and my students) to define sustainability, especially since the word is so often used in conjunction with environmental issues.

An article by Johnston, Everard, Santillo and Robèrt with the title “Reclaiming the Definition of Sustainability” (Env Sci Pollut Res 14 (1) 60 – 66 (2007)) starts with the following paragraph:

The idea of ‘sustainable development’ was first widely articulated in 1987’s Brundtland Report (World Commission on Environment and Development) from the United Nations. The ‘Brundtland definition’ of sustainable development was framed as “…development that meets the needs of the present without compromising the ability of future generations to meet their own needs”. It posits that the only truly sustainable form of progress is that which simultaneously addresses the interlinked aspects of economy, environment and social well-being.

In the subsequent two years, around 140 alternative and variously-modified definitions of ‘sustainable development’ emerged. Currently, it has been estimated that some three hundred definitions of ‘sustainability’ and ‘sustainable development’ exist broadly within the domain of environmental management and the associated disciplines which link with it, either directly or indirectly.

Let me try here to add my own definition:

I will start with a story that over the years became a concept. The concept is called the Fermi Paradox. Enrico Fermi is considered to be one of the greatest physicists, ever. He was born in Italy and immigrated to the United States in 1938 (his wife was Jewish). In 1950, while working at the Los Alamos National Laboratory, Fermi had a casual lunch conversation with other physicists, among them Edward Teller. The topic was the recent spate of claimed UFO (Unidentified Flying Objects) sightings and the likelihood of the existence of extraterrestrial life capable of reaching us from outer space. According to some accounts, Fermi did some quick calculations that resulted in a conclusion in the form of a question – if they are there – where are they?

The question was later formalized in the following form:

The Fermi paradox (or Fermi’s paradox) is the apparent contradiction between high estimates of the probability of the existence of extraterrestrial civilization and humanity’s lack of contact with, or evidence for, such civilizations. The basic points of the argument, made by physicists Enrico Fermi and Michael H. Hart, are:

• The Sun is a young star. There are billions of stars in the galaxy that are billions of years older;
• Some of these stars likely have Earth-like planets which, if the Earth is typical, may develop intelligent life;
• Presumably some of these civilizations will develop interstellar travel, as Earth seems likely to do;
• At any practical pace of interstellar travel, the galaxy can be completely colonized in just a few tens of millions of years.

According to this line of thinking, the Earth should have already been colonized, or at least visited. But no convincing evidence of this exists. Furthermore, no confirmed signs of intelligence elsewhere have been spotted, either in our galaxy or the more than 80 billion other galaxies of the observable universe. Hence Fermi’s question “Where is everybody?”

There is much more in the Wikipedia article that describes the efforts to resolve this paradox. There are concerted efforts to search for extraterrestrial life: These efforts include The SETI Institute (Search for Extraterrestrial Intelligence), the Kepler space observatory to search for Earth-like planets and the search and life forms on Earth that develop in extreme environments. The only effort that directly relates to the Fermi Paradox is the SETI effort; they should be coming to look for us and not the other way around. We have yet to develop interstellar travel capabilities (the movie Avatar was not filmed on site 🙂 ). By the most optimistic estimates – if everything goes well (no self inflicted destruction of any kind) it will take us a few hundred years of technological development to accomplish this. Assuming that our civilization can last long enough to develop these capabilities, we must therefore necessarily be sustainable for at least that long.

We can reverse this scenario and imagine that a SETI institute, or something similar, exists somewhere in our galaxy (further away it gets really complicated) and is waiting for us to show up. I define sustainability as the condition that we have to develop here to flourish until we develop the technology for extraterrestrial travel that will allow us to move to another planet once we ruin our own.

In my opinion, the conditions to achieve this are very “straightforward”. They have to be able to answer two “simple” questions:

• For how long? – Forever! To repeat President Obama’s language – We must act, knowing that today’s victories will be only partial, and that it will be up to those who stand here in four years, and forty years, and four hundred years hence to advance the timeless spirit once conferred to us in a spare Philadelphia hall
• How to do it? – To achieve the sustainable objectives on this time scale, we will have to establish equilibrium with the physical environment and at the same time maximize individual opportunities for everybody on this planet.

“Forever” can be considered as an unrealistic requirement. Actually, Physics tells us that nothing in the Universe is sustainable forever. Under normal conditions, in about 5 billion years our Sun will exhaust its fuel and convert to a giant fireball that will reach us. On a somewhat shorter time scale, our brightest star, Sirius, (which is actually a binary star that rotates with a corps [White Dwarf] around their mutual center of gravity), could lose enough mass to the White Dwarf to cause a massive explosion in the form of a supernova that would evaporate our Solar system. Other cosmological collisions within this time scale are obviously also possible. On a more human time scale, however, we can consider a few hundred years as forever.

It reminds me of the days that I had a contract with an industry to help dispose of radioactive waste that was accumulating at the Hanford Nuclear facility in Washington State. The effort was guided by the requirement of the surrounding community to have a guarantee that whatever disposal method is being used, it would remain stable for at least 100,000 years. Everybody with even a minimal technical background regarded a guarantee over such a time scale to be completely unrealistic. But, through the interpretation of “forever” through President Obama’s statement, the “forever” becomes doable. We just have to try hard, not be perfect. Keep our eyes at the target and correct as we go along and hope that future generations will continue with the effort.

With the current global population at 7 billion, estimated to stabilize at 9 billion toward the end of the century, the requirement to establish and maintain equilibrium with the physical environment and at the same time maximize individual opportunities for everybody on this planet, rules out “back to the cave” scenarios.

In future blogs, I will try to argue that we need the economists to be our social engineers who will show us how to achieve a sustainable world here.  Hopefully, they will be able to shift the emphasis from trying to understand the economy to trying to lead us how to optimize the way we live in order to achieve these long-term objectives. The first step will probably be to move away from a perpetual growth desire to a flexible, productive, equilibrium.