Scientific Theory and Scientific Law New cells form from existing cells Force is the product of an object’s mass and acceleration

What is a THEORY? An explanation of a natural or physical phenomenon based on proven MULTIPLE hypotheses and verified MULTIPLE times by independent researchers. Often include laws in order to prove points. Subject to changes as new evidence becomes available. Most theories that you will discuss in a middle/high school science class are well-confirmed and are unlikely to be revised in any significant sense. Theories that are less confirmed are abundant in pseudo-science fields like theoretical physics and cosmology, such as String Theory.

Examples of Theories The Theory of Relativity: that the laws of physics are the same for all observers. The Theory of Evolution by Natural Selection: that the observed changes in species occur due to selection of well adapted specimens over less well adapted specimens. The Big Bang Theory explains how the universe arrived at its present state (expansion).

What is a LAW? Concise, factual (based on data) statement meant to prove an observation. Can often be reduced to a mathematical statement, such as E = mc² Its truth is generally confined to a certain set of conditions. For example, in the case of E = mc², c refers to the speed of light in a vacuum. Accepted to be true and universal by scientists. They are used to make predictions. Example: The product of the mass and acceleration of an object are proportional to the force of the object. F = MA

Examples of Laws Newton’s Law of Gravitation states the idea that any two objects, no matter their mass, exert gravitational force toward one another. (**is used to support Einstein’s Theory of Relativity). Newton's Laws of Motion: statements about how large objects made of atoms behave when moving at low speeds relative to each other. The Laws of Thermodynamics: statements about entropy, temperature, and thermal equilibrium. Ohm's Law: the voltage across a purely resistive element is equal to the current through the element times its resistance Hubble's Law of Cosmic Expansion (Hubble's law) established that the universe is made up of many galaxies, whose movements trace back to the big bang (**is used to support the Big Bang Theory).

Very Very Interesting… We know that Newton's Laws of motion are not, in fact, 100% correct, but we still use them! They break down when the objects are very small or moving very fast (relative to other objects). Why, then, do we keep them around? They are EXTREMELY good at predicting. Engineers building skyscrapers need only consider Newton’s Laws. One can even travel throughout the Solar System using only Newton’s Laws. 

Scientific Theories and Laws To summarize: Laws tell us what happens (descriptions; can be math). Theories examine what happens and tell us how and why it happens (explanations). Theories don't become laws; laws don’t become theories. Both are important, but they tell us very different things.

BOTH Scientific Theories and Laws Scientific Laws and Theories depend on basic elements of the scientific method, such as a hypothesis, testing, finding (or not finding) evidence, analyzing data and developing conclusions. *Reminder: Hypothesis: A tentative statement such as ‘if A happens then B must happen because’ that can be tested by direct experiment or observation. A supported hypothesis can be expressed as a law or a theory. A disproven hypothesis can sometimes be re-tested and found correct as measurements improve. Eventually, other scientists must be able to REPLICATE the results if the experiment is destined to become the basis for a widely accepted law or theory. SO, both are accepted after continuous experimentation.

Question: Is this a scientific theory or a scientific law? Mass can come from energy and energy from mass (E= mc2) The speed of light in a vacuum is constant and an absolute physical boundary for motion Is this a scientific theory or a scientific law? Scientific LAW Is this a scientific theory or a scientific law? Part of the THEORY of relativity

Is a scientific theory or a scientific law more correct? Question: Is a scientific theory or a scientific law more correct? Trick question! Both are equally proven to be true through continuous experimentation.

Analyze the statements below. Law or Theory? For every action, there is an equal and opposite reaction. F = ma Light is an electromagnetic phenomenon described by Maxwell’s Laws Earth’s magnetic field is generated by a conducting fluid in its core. Matter cannot be created nor destroyed, only changed. Energy cannot be created nor destroyed, only changed. Momentum is the product of a body’s mass and its velocity. The inverse-square law for gravity and Newton’s laws of motion explain why orbits are ellipses. Any two objects, no matter their mass, exert a gravitational force toward one another that can be calculated. There is a relationship between a planet's orbital period and its distance from the sun. The universe is constantly expanding outward in reaction to a huge initial event producing matter, energy, and gravity.