. It is at a higher potential because there is a lot of it filled to a higher level relative to the bottom of the dam, so there is a potential difference as regards to the height of the water behind the dam compared to the water level below the dam. But here’s the essential point about potential gradients: Unless there is a restoring mechanism (like a river flowing into the dam), the potential differences can be sustained only as long as the two regions remain isolated from each other. As soon as the regions are directly connected, there will be flow from the region of higher potential to the region of lower potential, just as water would flow out if a sluice were opened in the dam.
Figure 5.1 When the sluice gate is opened, water contained by the dam hurtles down the sluice from a region of high gravitational potential (greater height) behind the dam to a region of low gravitational potential (lower height) at the bottom of the dam.
, and that is already happening. For example, if the flow of illegal immigrants continues, it will bring down the wealth and prosperity of the destination nations as their social systems get overburdened. So eventually one of two things will happen: either the flow will continue until the developed countries are reduced to lower socioeconomic levels, reducing the socioeconomic potential differences that are driving the influx of immigrants, or the desperation in the developed countries at losing their way of life will reach a boiling point when they start enacting stronger and inevitably brutal measures that transgress the current moral and legal fabric. I personally believe it will be the latter option, because I can already see more radical viewpoints and measures gaining currency in places like the American Southwest or in parts of Europe. People stay civilized only as long as their personal interests and security are not endangered. It would be a capital mistake to think that we as a species are beyond acts of violence and war—after all, we are only seventy years away from the deadliest war in history, in which 45 million people died in conflicts among “very civilized” countries. Our brains and instincts do not evolve that fast. If we have avoided any major conflict since, it is because people in the strongest nations have been generally well off and happy, and the memory of that last devastating war lingered, but most importantly because nuclear weapons changed the rules by introducing Mutually Assured Destruction (MAD), where there can be no winners. Actually, there are some elements of ironic truth in the cynical point of view that nuclear weapons should get the real credit and several Nobel Peace Prizes to boot for avoiding a Third World War—at least so far.
The principle of how potential differences drive flow is universal and supersedes human emotions and wistful thoughts. Once we remove the barriers, then there will be consequences, some to our liking, some not; for example, outsourcing saves money but bleeds jobs as well. In a global environment, no matter how outraged local workers are, paying someone ten times more for a job here simply cannot be sustained when thousands elsewhere on the planet are happy to do it for ten times less because, for them, even that is far better than the alternatives. In an open global market, we all have to compete harder to survive.
In nature, the sun powers the atmosphere to create the precipitation that makes the rivers flow to sustain the potential difference across a dam. But in the geopolitical and socioeconomic realm, we can’t count on the sun to maintain the potential differences. Therefore, there are only two possible outcomes: reinstate political and economic barriers or come to terms with equilibration where the wealthier countries will have to lower expectations. But as we all know, both options are easier said than done; nature also teaches us that building up potential differences is a much harder and longer process than making use of potential differences.