Science. Models, systems

1. Science. Models, systems “Scientific knowledge is a body of statements of varying degrees of certainty – some most unsure, some nearly sure, and none absolutely certain” – Richard Feynman

2. Science and Technology • Science – knowledge of how the world works • Technology – creation of new processes intended to improve the quality of life

3. Scientific method • HYPOTHESIS – proposed to explain observed patterns • Critical experiments • Analysis and conclusions

4. Scientific law and Theory • Law – certain phenomena always act in a predictable manner • Theory – rational explanation for numerous observations of a certain phenomena – global warming due to greenhouse effect

5. Accuracy Vs Precision Accuracy – measurement agrees with the accepted correct value Precision – measure of reproducibility

6. Types of reasoning • Inductive - using observations and facts to arrive at generalizations • Deductive - using logic to arrive at a specific conclusion

7. Models • Mental models –perception , unreliable • Conceptual – general relationships among components of a system • Graphic – display data • Physical – miniatures • Mathematical – use of equations

8. Feedback loop • Change in one part of a system influences another part of the system

9. Positive feedback loop • Exponential growth of population – more individuals lead to increased number of births

10. Negative feedback loop • Temperature regulation in humans – increased temperature leads to decrease in temperature by sweating

11. Complex systems • Time lags – change in a system leads to other changes after a delay – lung cancer • Resistance to change – built in resistance – political, economic • Synergy-when two or more processes interact so that the combined effect is greater • Chaos – unpredictable behavior in a system

12. Gaia Hypothesis (1970) • James Lovelock and Lynn Marguilis • proposes that organisms interact with their inorganic surroundings on Earth to form a self-regulating, complex system that contributes to maintaining the conditions for life on the planet

13. Important Terms • Inputs - matter, energy, information • Throughput - flow of input • Output - matter, energy, information flowing out

15. Matter and Energy Resources Nature’s Building Blocks anything that has mass and takes up space

16. Forms of matter • elements – single type of atoms • 110 elements – 92 natural +18 synthesized • compounds - 2 or more elements, held together by chemical bonds

17. Building Blocks • atoms - smallest units of matter- protons,neutrons,electrons • ion - electrically charged atoms • molecules - combinations of atoms of the same or different elements

18. Definitions • Atomic Number - number of protons • Isotopes - same atomic number, different mass number • Ions - atoms can gain or lose one or more electrons • Mass Number - protons + neutrons

19. Isotope • Elements with same atomic number but a different mass number

20. Some Important elements- composition by weight – only 8 elements make up 98.5% of the Earth’s crust

21. Organic Compounds • with carbon • sugar, vitamins, plastics, aspirin

22. Environmental Organic Compounds • Hydrocarbons = methane gas • Chlorinated hydrocarbons =. DDT, PCB • Chlorofluorocarbons (CFC)- Freon 12

23. Polymers • larger and more complex organic compounds made up of monomers • complex carbohydrates • proteins - 20 amino acids • nucleic acids - nucleotides

24. Inorganic compounds • no carbon,not originating from a living source • Earth’s crust – minerals,water • water, nitrous oxide, nitric oxide, carbon monoxide, carbon dioxide, sodium chloride, ammonia

25. Matter quality • Measure of how useful a matter is for humans based on availability and concentration

26. Energy • capacity to do work and transfer heat • Kinetic Energy -energy in action • electromagnetic radiation, heat, temperature • Potential energy - stored energy that is potentially available

27. Electromagnetic radiation • different wave lengths shorter – high energy, disrupts cells with long term exposure

28. Energy sources • 97% solar • without it earth’s temperature - 240 C • 1% - non commercial(wood, dung, crops) + commercial ( burning mineral resources)

29. Energy quality • Measure of how useful an energy source is in terms of concentration and ability to perform useful work

30. Law of Conservation of Matter • elements and compounds changed from one form to another, can never be destroyed • no “away” in “throw away”

31. Nuclear Changes • nuclei of certain isotopes spontaneously change (radioisotopes) or made to change into one or more different isotopes • Alpha particles – fast moving (2 protons+2neutrons); Beta particles – high speed electrons ; Gamma particles - high energy electromagnetic radiation • radioactive decay, nuclear fission, nuclear fusion

32. Use….radioisotopes • Estimate age of rocks and fossils • Tracers in pollution detection and medicine • Genetic control of insects

33. Half - Life • time needed for one-half of the nuclei in a radioisotope to decay and emit their radiation. • Goes through 10 half –lives before it becomes a non-radioactive form

34. Nuclear Fission • certain isotopes (uranium 235) split apart into lighter nuclei when struck by neutrons • chain reaction releases energy • needs critical mass of fissionable nuclei

35. Nuclear fusion • two isotopes (hydrogen) forced together at extremely high temperatures (100 million C) • uncontrolled nuclear fusion thermonuclear weapons

36. 1st Law of Energy or 1st Law of Thermodynamics • in all physical and chemical changes energy is neither created or destroyed • energy input always equal to energy output

37. 2nd Law of Energy or 2nd 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(heat)

38. Implications for the environment – High waste society

39. Implications for the environment – Low waste society