About their problems. They try to find answers for their problems together. For example

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LAW OF CONSERVATION OF MATTER:

EVERYTHING MUST GO SOMEWHERE
We always talk about consuming or using up matter resources, but actually we don't consume any matter. We only borrow some of the earth's resources for a while - taking them from the earth, carrying them to another part of the globe, processing them, using them, and then discarding, reusing, or recycling them. In the process of using matter, we may change it to another form. But we can neither create nor destroy any measurable amount of matter. This results from the law of conservation of matter: In any ordinary physical or chemical change, matter is neither created nor destroyed but merely changed from one form to another. This law tells us that we can never really throw any matter away. Everything must go somewhere and all we can do is to recycle some of the matter we think we have thrown away.

We can collect dust and soot from the smokestacks of industrial plants, but these solid wastes must then go somewhere. Cleaning up smoke is a misleading practice, because the invisible gaseous and very tiny particle pollutants left are often more damaging than the large solid particles that are removed. We can collect garbage and remove solid wastes from sewage, but they must either be burned (air pollution), dumped into rivers, lakes, and oceans (water pollution) or deposited on the land (soil pollution and water pollution if they wash away).

We can reduce air pollution from the internal combustion engines in cars by using electric cars. But since electric car batteries must be recharged every day, we will have to build more electric power plants. If these are coal-fired, their smokestacks will add additional and even more dangerous air pollutants to the air; more land will be scarred from strip mining, and more water will be polluted from the acids that tend to leak out of coal mines. We could use nuclear power plants to produce the extra electricity needed. But then we risk greater heat or thermal pollution of rivers and other bodies of water used to cool such plants.

Although we can certainly make the environment cleaner, talk of 'cleaning up the environment and 'pollution free' cars, products, or industries is a scientific absurdity. The law of conservation of matter tells us that we will always be faced with pollution of some sort. Thus, we are also faced with the problem of trade-off. In turn, these frequently involve subjective and controversial scientific, political, economic, and ethical judgments about what is a dangerous pollutant level, to what degree a pollutant must be controlled, and what amount of money we are willing to pay to reduce a pollutant to a harmless level.