The word “conservation” is used in our everyday language to mean “proactive prevention of destruction and/or depletion” as in conservation of wildlife, historic buildings, wetlands, etc. Physicists use the word somewhat differently. There are several conservation principles in physics – the most notable being the conservation of energy and conservation of mass.
The word “conservation” in this context implies that the total amount of the substance under consideration remains the same over time as a law of nature. One of my favourite analogies when I tutor physics to high school students is to compare energy with wealth. Energy is the ability to do work and wealth is the ability to spend money. Neither energy nor wealth can be created or destroyed. They can only be transformed from one form to another (and hence “conserved”): from mechanical energy to heat energy or from real estate investment to gold, for example. Whenever someone is losing money, another person (or persons) is gaining an equal amount of money and vice versa.
When a person (or a machine) does work his energy goes down just like a person’s wealth is reduced when he spends money. Using this analogy, it is easy to understand why the rich are getting richer at the expense of the poor people who are getting poorer. Even though it is not a perfect analogy it helps my students understand key concepts like work and energy more quickly. However, I run into a problem when I talk about nuclear energy and more specifically, conversion of mass into energy by that famous E=Mc^2 equation of Einstein. It becomes apparent that energy can, in fact, be created by converting mass into energy. This means that the law of conservation of energy plus the law of conservation of mass must be combined into a single more generalized law of conservation of mass/energy.
Nuclear and atomic bombs and nuclear reactors are three devices that have been invented and used by scientists to convert mass into energy. Use of the first two is virtually nonexistent because of their catastrophic consequences but nuclear reactors provide a significant fraction of our energy consumption throughout the world with no input needed from other forms of energy. With all the recent emphasis on solar energy it seems that we can fulfil all our energy needs by harnessing solar energy and then converting it into other forms.
However, the sun really does not create this energy; it converts mass into energy. We can think of the sun as an entity composed of myriads of nuclear fusion bombs with explosions occurring at every moment. Every second mass of the sun goes down by 4.5 billion kilograms because this lost mass is converted into energy; even at that rate the sun is so huge that it would continue to shine for billions of more years before being gradually reduced to a “white dwarf”. My problem in tutoring sessions arises from the fact that now I must come up with something analogous to mass in our financial life which can be converted into an apparently limitless supply of wealth.
It may not be something immediately recognizable as wealth but could be converted into goods for financial gain. Much to my surprise, I realized that my analogy can be extended; there are indeed such sources, and they are all parts of our solar system. The sun and earth pair not only gives us an unlimited amount of energy, they also give us an endless supply of wealth. To elaborate on this point let me point out that all our wealth eventually comes from natural resources, natural gas and oil, coal, minerals and ores, timber, crops etc. These natural resources are processed by manufacturing and agricultural companies into various functional items which are then traded to generate profit – the ultimate source of financial viability for everyone.
How are these natural resources generated? A key contributing factor is the sun and various geothermal processes in the interior of the earth. The sun causes evaporation from the oceans which then turns into rain and helps crops to grow. All minerals and metallic ores were produced millions of years ago in the deep crust of the earth by various volcanic activities. Natural gas was the result of conversion of biological elements through decomposition over a period of thousands of years. If we dig into the earth’s interior, we will find all kinds of valuable ores and minerals. Just imagine if someone finds a hundred-carat diamond while digging in a diamond mine.
That would be worth millions of dollars. It is not quite as dramatic as transforming one gram of nuclear matter into energy but still makes the point about my analogy. It is no wonder that countries which are rich in natural resources are also the most prosperous ones – Russia because of coal, gold and oil, USA for coal, timber and a variety of other ores, Saudi Arabia for its gas and oil reserve, Australia for bauxite and other ores, South Africa for gold and so on. Countries like Canada, Brazil, Iran and China also rank high by this criterion. Sri Ramkrishna used to say “taka mati, mati taka” (money is dirt, dirt is money). It may not be just a philosophical metaphor, but a profound factual statement about how wealth is generated from mother earth. We must remember that the earth and the sun were both originally parts of the same gaseous cloud after a supernova explosion and gradually grew into spherical orbs when the solar system started to cool down.
The solar system can give us all the energy we need as well as all the wealth we want to spend and enjoy. It seems that conservation of mass/energy and conservation of wealth/natural resources are really two different manifestations of a much more universal and generalized principle of conservation. This principle can be stated by using a slightly different meaning of the word “conservation”. We can say that all the energy and all the wealth we need for our survival (at least, until the sun stops shining) have already been stored or conserved for us within the solar system. All our needed energy on this earth can be harnessed from sunlight and other natural phenomena (wind and waterfalls, for example) caused by the sun, as well as natural gas and oil buried under the earth’s crust. Similarly, this earth, with a little help from the sun, can provide all the wealth needed for survival of the entire mankind. Then why do we always feel that we are running out of energy and running out of natural resources? Why are there millions of people living in poverty and without electricity, heat and other energy?
The only social issue is a fair process for harnessing and distributing what is already stored for us. Lack of fairness is the root cause of all the miseries in the world. As Gandhiji once said “the world has enough for everyone’s need, but not enough for everyone’s greed”. Perhaps the principles of conservation of mass/energy and conservation of wealth/natural resources could be combined into one grand conservation scheme. In any event, it seems that the significance of these conservation laws has been over-emphasized by the physicists. We really need not worry about running out of energy (or wealth for that matter) necessary for our survival!
(The writer, a physicist who worked in academia and industry, is a Bengali settled in America.)