Scientific Laws AND Theories Supported by a large body of experimental data Help unify a particular field of scientific study Widely accepted by the vast majority of scientists within a specific discipline or field. Meant to be questioned and challenged Can be limited, changed or deemed invalid

Scientific Law Describes what nature does under certain conditions - and will predict what will happen as long as those conditions are met. Often mathematically defined

Scientific Theory Explains how nature works Often non-mathematical Can incorporate facts, laws, inferences, and tested hypotheses.

“Proof” "... In science, we never have sufficient reason for the belief that we have attained the truth.... This means that we have no proofs in science (excepting, of course, pure mathematics and logic)… if we mean by 'proof' an argument which establishes once and for ever the truth of a theory." Sir Karl Popper, The Problem of Induction, 1953 "If you thought that science was certain — well, that is just an error on your part." Richard Feynman ( ). "A religious creed differs from a scientific theory in claiming to embody eternal and absolutely certain truth, whereas science is always tentative, expecting that modification in its present theories will sooner or later be found necessary, and aware that its method is one which is logically incapable of arriving at a complete and final demonstration." Bertrand Russell, Grounds of Conflict, Religion and Science, 1953.

“Proof” - continued In truth, science can never establish 'truth' or 'fact' in the sense that a scientific statement can be made that is formally beyond question. All scientific statements and concepts are open to re- evaluation as new data is acquired and novel technologies emerge. That said, we often hear 'proof' mentioned in a scientific context, and there is a sense in which it denotes "strongly supported by scientific means". Even though one may hear 'proof' used like this, it is a careless and inaccurate handling of the term.

Common Sense is Not Science Though science formally cannot establish absolute truth, it can provide overwhelming evidence in favor of certain ideas. Usually these ideas are quite unobvious, and often they clash with common sense.

Common Sense is Not Science Common sense tells us: that the earth is flat that the Sun truly rises and sets that the surface of the Earth is not spinning at over 1000 miles per hour that bowling balls fall faster than marbles that particles don't curve around corners like waves around a floating dock that the continents don't move that objects heavier-than-air can't have sustained flight unless they can flap wings However, science has been used to demonstrate that all these common sense ideas are wrong.

Hypothesis A tentative statement about the natural world, which leads to deductions that can be tested. Can be used to build more complex inferences and explanations. Can be considered the “state of knowledge before experimental work has been performed”

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