Exploring Theories and Laws

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Exploring Theories and Laws
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Theories
Laws
How are these four concepts related to each other?
Facts
Hypotheses
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Common Descriptions

• Facts are indisputable, proven, known to have
  happened
• Hypotheses are educated guesses, hunches,
  unsubstantiated claims
• Theories are unsubstantiated ideas, opinions,
  unproven explanations
• Laws are proven theories that have withstood
  repeated testing over time, rules that must be
  followed, a piece of enacted legislation

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L A W (fact)
When proven that it always works
THEORY
HYPOTHESIS
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From Where Do These Ideas Originate?
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Theories in Media
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Laws in Media
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Explicit Instruction
Answer A law is something that can be measured
or observed to be true. A theory is something
that can only be assumed to be true based on the
best available knowledge. A theory can
eventually, though not necessarily, become a law
after time and scrutiny.
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Student Teacher Ideas

• A scientific law is a theory that has been proven
  over and over by different scientists.
• A scientific law is definite, and nothing is
  named a law unless scientists agree that there is
  no question to its being true. For example,
  scientists are open to finding new information
  about the atomic theory, but Newtons law of
  motion has been tested enough times that
  scientists are certain it is true.
• Newtons 1st Law is proven and through various
  testing and experiments it has come to be known
  as a proven law. Theories, however, have not been
  proved enough to be changed into laws.

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Jigsaw Activity

• Read your article.
• Discuss the authors definitions and examples of
  scientific fact, theory, law, and hypothesis.
• How are these similar/different from the commonly
  used/Helen Curtis definitions of these terms?
• Be prepared to briefly share with the class.

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List examples of scientific theories and laws.
Theories Laws
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Theories Laws
Theory of Special Relativity The speed of light in a vacuum is constant regardless of the motion of the observer or the motion of the light source. Explains the relationship between mass and energy. Newtons Laws of Motion Describes the relationship between the forces acting on a body and its motion due to those forces.
Atomic Theory All matter is composed of elements made up of atoms. Explains why matter is conserved in chemical reactions. Ideal Gas Law PVnRT Describes the relationship between pressure, volume, moles, and temperature of a gas.
Electromagnetic Field Theory A change in an electric field produces a perpendicular magnetic field. A change in a electric field produces a perpendicular electric field. Explains the way in which charges and currents interact. Ohms Law V IR Describes the relationship between the voltage (V), current (I), and resistance (R).
Theory of Plate Tectonics Earths crust is divided into plates that move. Explains why earthquakes and volcanoes occur in certain zones. Law of Superposition Describes the general principle that in undeformed layers of rock, the oldest rock will be at the bottom.
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Theories Laws
Theory of Special Relativity The speed of light in a vacuum is constant regardless of the motion of the observer or the motion of the light source. Explains the relationship between mass and energy. Newtons Laws of Motion Describes the relationship between the forces acting on a body and its motion due to those forces.
Atomic Theory All matter is composed of elements made up of atoms. Explains why matter is conserved in chemical reactions. Ideal Gas Law PVnRT Describes the relationship between pressure, volume, moles, and temperature of a gas.
Electromagnetic Field Theory A change in an electric field produces a perpendicular magnetic field. A change in a electric field produces a perpendicular electric field. Explains the way in which charges and currents interact. Ohms Law V IR Describes the relationship between the voltage (V), current (I), and resistance (R).
Theory of Plate Tectonics Earths crust is divided into plates that move. Explains why earthquakes and volcanoes occur in certain zones. Law of Superposition Describes the general principle that in undeformed layers of rock, the oldest rock will be at the bottom.
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Theories Explain Observations
Theory of Plate Tectonics Earths crust is divided into plates that move. Explains why earthquakes and volcanoes occur in certain zones.
Electromagnetic Field Theory A change in an electric field produces a perpendicular magnetic field. A change in a magnetic field produces a perpendicular electric field. Explains the way in which charges and currents interact.
Darwins theory of natural selection Explains the diversity of life in terms of competition, survival, and inherited traits. Explains the fossil record and how species can change over time.
Atomic Theory Matter is composed of discrete units called atoms, as opposed to the obsolete notion that matter could be divided into any arbitrarily small quantity Explains why matter is conserved in chemical reactions.
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Theories Explain Laws
Einsteins General Theory of Relativity Explains gravity in terms of space-time curvature and that space-time is curved by matter. Law of universal gravitation Describes the relationship between mass, distance, and the force of gravity.
Chromosome Theory chromosomes are the basis for all genetic inheritance. Explains the mechanism underlying Mendels laws. The law of independent assortment Describes the principle that traits are passed on to offspring independent of each other .
Kinetic Molecular Theory Matter consists of tiny particles in constant motion, whose speed is proportional to the absolute temperature. Explains gas laws. Boyles Law Describes the relationship between pressure and volume of a gas when temperature is held constant.
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Which Came First?
General Theory of Relativity Law of Universal Gravitation
Chromosome Theory Law of Independent Assortment
Kinetic Molecular Theory Boyles Law
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Which Came First?
General Theory of Relativity Einstein 1916 Law of Universal Gravitation Newton 1687
Kinetic Molecular Theory Bernoulli, Clausius 1738, 1857 Boyles Law Boyle 1662
Chromosome Theory Thomas Hunt 1910 Law of Independent Assortment Mendel 1866
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Boyles Law

• New Experiments Physico-Mechanicall, Touching the
  Spring of the Air, and its Effects... (1662)

7 investigations deal with changes in pressure as
a result of changes in volume
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Boyles Law 1662
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Kinetic Molecular Theory (Early Ideas about
Molecular Motion)

• Bernoulli (1738) Hydrodynamica
• Gases consist of great numbers of molecules
  moving in all directions
• Impact on a surface causes gas pressure
• Heat is the kinetic energy of their motion
• Herapath (1821)
• Gas particle momentum is a measure of the
  absolute temperature of the gas
• Waterston (1843)
• Gas pressure is a function of the number of
  molecules per unit volume, molecular mass, and
  molecular mean-squared velocity
• Note both Herapath and Waterston initially
  failed peer review when attempting to get their
  ideas published by the Royal Society of London

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Kinetic Molecular Theory

• Clausius (1857)
• Included translational, rotational, and
  vibrational particle motion
• The size of a particle is negligibly small
  relative to its container
• The duration of impact is infinitesimal as
  compared to the time between two successive
  collisions.
• Others continued working on theory for the next
  50 years
• Maxwell (1859)
• Boltzmann (1890s)
• Einstein (1905) and Smoluchowski (1906) Brownian
  motion

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Timeline of Gas Laws and KMT
Boyles Law
Clausius first complete version of Kinetic
Molecular Theory
Bernoulli (initial ideas about particle motion)
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Scientific Fact In science fact can only
mean confirmed to such a degree that it would be
perverse to withhold provisional consent.
Stephen J. Gould

• Scientific Hypothesis
• A proposed answer to a research question
• A tentative explanation for an observation or
  phenomena that can be tested through
  experimentation.

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Scientific Theory A general principle supported
by a substantial body of evidence offered to
provide an explanation of observed facts and as a
basis for future discussion or investigation.
Lincoln, Boxshall, and Clark (1990)
Scientific Law A scientific law is a
description of a natural relationship or
principle, often expressed in mathematical terms.
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• Is there a hierarchy among the four original
  concepts?
• Facts
• Theories
• Laws
• Hypotheses

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More absolute
Laws
And, eventually proven, become
Theories
Which, when supported by experiments, become
Less absolute
Hypotheses
Lead scientists to develop
Facts
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More absolute
Laws
And, eventually proven, become
Theories
Which, when supported by experiments, become
Less absolute
Hypotheses
Lead scientists to develop
Facts
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THEORY
L A W
HYPOTHESIS
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THEORY
L A W

• Concise, descriptive principal
• Based more on observation

• Explanatory principal
• Based more on inference

HYPOTHESIS
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So How Do We Teach This?
Mystery Tube
Law of Strings When any short string is pulled,
the long string shortens by an equivalent amount.
String Theory ?
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So How Do We Teach This?
Mystery Tube
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Post-InstructionQuotes from Students Teachers

• Scientific theories never turn into laws.
• A scientific law is often mathematical and is
  used to describe a pattern found in nature. A
  theory is used to try and explain the why of a
  pattern or occurrence.
• A scientific law is a statement describing how
  something works. A scientific theory attempts to
  explain something that cannot be directly
  observed. Laws are usually something that is
  observable. Theories are based on inference, an
  effort to explain something.

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Laws and Theories
Laws
Theories

• Based on evidence
• Can change with new evidence
• Cannot
• change into
• each other

• Based primarily on observations
• Holds for specific conditions
• More descriptive
• Answers what happens?

• Relies heavily on inferences
• Generalizations
• More explanatory
• Answers How does it happen?