Chapter 3: Science, Systems, Matter and Energy “Science is an adventure of the human spirit. It is essentially an artistic enterprise, stimulated largely by curiosity, served largely by disciplined imagination, and based largely on faith in the reasonableness, order, and beauty of the universe.” Warren Weaver

Science and Critical Thinking What is science? Science is an attempt to discover order in nature and use that knowledge to make predictions about what is likely to happen in nature.

What scientists do Ask a question Do experiments and collect data Formulate hypothesis to explain data Do more experiments to test hypothesis Revise hypothesis if necessary Interpret data Well-tested and accepted patterns in data become scientific laws Well-tested and accepted hypotheses become scientific theories.

Models and Behavior of Systems A system is a set of components that Function and interact in some regular and theoretically predictable manner Can be isolated for the purposes of observation and study. The environment consists of a vast number of interacting systems and have the following key components. Inputs Flows or throughputs Stores or storage areas Outputs

Why are models useful? Find out how systems work Evaluate which ideas or hypotheses word Mathematical models consist of one or more equations to describe the behavior of a system and to make predictions about the behavior of the system. Use mathematical models to answer if-then questions: “If we do such and such, then what is likely to happen now and in the future?”

Feedback Loops A feedback loop occurs when an output of matter, energy, or information is fed back into the system as an input that changes the system. Positive feedback loop – change in a certain direction provides information that causes a system to change further in the same direction. Negative feedback loop – one change leads to a lessening of that change.

Feedback Loops - Examples

Environmental Surprises One of the basic principles of environmental science is that we can never do one thing. Any action in a complex system has multiple and often unpredictable effects. Surprises are the result of: Discontinuities – abrupt shifts when some environmental threshold is crossed. Synergistic interactions – two or more factors interact to produce effects greater than the sum of their effects acting separately Unpredictable or chaotic events such as hurricanes, earthquakes, invasions of ecosystems by nonnative species, slowly building

Strategies to deal with surprises: Increase research on environmental thresholds and synergistic interactions Developing better models to understand the behavior of complex living systems and our economic and political systems. Formulating scenarios of possible environmental surprises and developing a range of strategies for dealing with them. Acting to prevent or lesson the effects of possible surprises through pollution prevention, more efficient and environmentally benign use of resources, and reduced population growth.

Matter: Forms, Structure, and Quality Elements – make up every material substance Compounds – two or more elements Atoms – smallest unit of matter Protons + Neutrons uncharged Electrons - Ions – electrically charged atoms Molecules – combination of two or more atoms of the same or different elements

Organic and Inorganic Organic compounds contain carbon atoms combined with each other and with atoms of one or more other elements. Examples are table sugar, vitamins, plastics, aspirin, penicillin Categories: Hydrocarbons – carbon and hydrogen (methane CH 4 ) Chlorinated hydrocarbons – carbon, hydrogen, and chlorine (DDT) Chlorofluorocarbons – carbon, chlorine, fluorine (Freon-12) Simple carbohydrates – carbon, hydrogen, and oxygen (Glucose)

Energy: Forms and Quality Energy is the capacity to do work and transfer heat. Two major types of energy: Kinetic – energy of motion Potential – stored and potentially available for use. Potential can be changed to kinetic

pH Scale pH is a measure of the concentration of H + in a water solution.

Heat Transfer Temperature is the average speed of motion of the atoms, ions, or molecules in a sample of matter at any give moment. There are three ways in which heat can be transferred from one place to another: Convection – transfer of heat by the movement of heated material Conduction – transfer of heat by collisions of atoms or molecules Radiation – transfer of heat by wave motion

Electromagnetic Spectrum

Energy Quality Energy quality is a measure of an energy source’s ability to do useful work.

Physical and Chemical Changes A physical change involves no change in chemical composition A chemical change, or chemical reaction, involves a change in the chemical compositions of the elements or compounds are altered.

Law of Conservation of Matter “We may change various elements and compounds from one physical or chemical form to another, but in no physical and chemical change can we crate or destroy any of the atoms involved.” There is now “away” in “to throw away”

Pollutants We can make the environment cleaner and convert some potentially harmful chemicals into less harmful physical or chemical forms. Factors determining the severity of a pollutant’s harmful effects are: Chemical nature Concentration – ppm, ppt Persistence – how long it stays in the environment Degradable pollutants (non-persistent) – human sewage Slowly degradable (persistent) – DDT and most plastic Nondegradable pollutants – lead, mercury, and arsenic

Ionizing Radiation Each year people are exposed to some ionizing radiation from natural or background sources and from human Effects: Genetic damage – mutations to DNA Somatic – burns, miscarriages, eye cataracts and certain cancers Variances: Type of radiation Penetrating Power Sources Half-life of the radioisotope

Two Laws Governing Energy Changes First Law of Thermodynamics: (Low of conservation of energy) “In all physical and chemical changes, energy is neither created nor destroyed, but it may be converted from one form to another.” – we can’t get something for nothing Second Law of Thermodynamics: “When energy is changed from one form to another, some of the useful energy is always degraded to lower quality, more dispersed, less useful energy.” – we end up with less usable energy than we started: often heat

Second Law of Thermodynamics - Visual

High-Throughput Economy A high-throughput economy – sustaining ever-increasing economic growth by increasing the flow of matter and energy resources through their economic systems.

Matter-Recycling Economy Economic growth continues without depleting matter resources or producing excessive pollution and environmental degradation.

Low-Throughput Economy