The Nature of Science - Edl · The Nature of Science ... there an afterlife?”, “what is the...

The Nature of SciencePhysics – 1st Six Weeks

An Appetizer to Start

The Definition of Science

• Science, as defined by the National Academy of Sciences, is the "use of evidence to construct testable explanations and predictions of natural phenomena, as well as the knowledge generated through this process.“

• So what does that mean exactly? Let’s look at the definition piece by piece…

Science deals only with “natural phenomena”

• Sciences, is the "use of evidence to construct testable explanations

and predictions of natural phenomena, as well as the

knowledge generated through this process.“

• Science Cannot Provide Complete Answers to All Questions –• Science studies the Natural World, the atoms, plants, galaxies,

ecosystems, people, and societies around us as well as the natural forces that effect natural things.

• Science can answer such questions as “How old are the oldest rocks on the Earth?”, “By what chemical process do fungi get energy from the nutrients they absorb?”, “What causes Jupiter’s red spot?”, or “How do lion prides operate and function?”.

Science deals only with “natural phenomena”

• Sciences, is the "use of evidence to construct testable explanations

and predictions of natural phenomena, as well as the

knowledge generated through this process.“

• By contrast Science cannot study the supernatural, which by its very definition operates outside the rules that govern the natural world.

• Science therefore cannot address supernatural questions, such as “is there an afterlife?”, “what is the meaning for life?”, or “is there a soul?”.

• Questions that assume a supernatural answer are beyond science to answer.

• Religion and Philosophy exist to address a supernatural aspect of the universe that science is not designed for.

Science and the Natural World, food for thought…

• Regarding the relationship of Science and the natural world, Geologist Dr. Robert Krampf puts it thusly…

• “(The focus of science on the natural world) doesn’t mean science denies the existence of anything supernatural. It simply means that its not in the realm of science.”

• “Sort of like cooking is not in the realm of astronomy. That doesn’t mean astronomers don’t cook their food – it simply means they don’t spend their time looking through a telescope in search of a good salsa recipe.”

• “Scientists are not involved with the study of religions or belief systems, simply because they are not part of science. The tools of science just don’t apply to them.”

The Definition of Science: Science uses available evidence to explain & predict


Science is not only a bank of knowledge…it is an active process of investigation that relies on evidence & repeatability

So then what are the tools of science?

• Science involves observation and experimentation of the natural world in order to learn more about it.

• This observation is through any of the five senses as well as through tools that can be used to extend those senses (telescopes, binoculars, space probes, microscopes, etc.)

• People who are engaged in science collect facts, measurements, and values. Collectively those items are called data.

• Data can be either Quantitative or Qualitative• Quantitative Data are values that involve numbers. Counts and measurements are

quantitative data.• Qualitative Data are values that do not involve numbers. Qualitative data describes

something using non-numeric terms that are characteristic and may be more approximate. If a scientist were to record the color of something or that it was “hairy” that would be qualitative data.

Qualitative vs. Quantitative Data• Quantitative data is numerical information and can take one of two forms, discrete

or continuous:* Discrete – can only take certain values like whole numbers. * Continuous – can take any value within a range * to put it simply Discrete Data is counted and Continuous is measured

• Qualitative data describes something non-numerically (and often approximately)

Qualitative:•He is brown and black•He has long hair•He has lots of energyQuantitative:•Discrete:

• He has 4 legs• He has 2 brothers

•Continuous:• He weighs 25.5 kg• He is 565 mm tall

Example: What do we know about Rufus the Dog?

The tools of science: The 3 Types of Scientific Investigation

• Scientific Investigations can be one of 3 types: descriptive, comparative, or experimental


In Physics many of the investigations we will perform will be comparative (i.e. “distance vs. time”, “force vs. acceleration”, or “velocity vs. distance”


• Often when you ask people on the street “what is a scientific investigation?” they think of a form of an experimental investigation.

• This is the most rigorous form and strictly holds to the steps of the scientific method.

• This is the only type that has a control group

The Scientific Method

Scientific Investigations: Terminology

• Testable Question – a question that can be answered by designing and conducting a scientific investigation

• Hypothesis – an educated guess based upon prior observations and your knowledge of the topic. Often based upon the research that you do after forming a testable question. Usually phrased as an “IF/THEN” statement.

• Variable – A factor in any investigation that can change• Constant Variable – any variable that the investigator keeps the same in an

experimental investigation• Experimental Variable – the variable that the investigator purposely changes in

order to view the results in an experimental investigation• Control – This is a setup in an experimental investigation where the variable is not

tested. The results of the experimental variable are compared to this group.*Ex. if you were testing which brand of fertilizer worked best, the control group would have no fertilizer used on it at all.

Scientific Investigations: Terminology• Independent Variable – (aka the “manipulated variable”) this is the factor or

condition that is changed on purpose by the investigator in order to view its results. *This is a term that is often used with comparative investigations when two variables are compared. * In an experimental investigation, this is the “experimental variable”. * When graphing it is on the X axis. (the bottom)

• Dependent Variable – (aka the “responding variable”) the factor or condition that changes as a result of the independent variable.

* This is a term that is often used with comparative investigations when two variables are being compared.*When graphing it is on the Y axis. (the side)

The Dependent Variable depends upon the Independent Variable to change

Example Research Question: Do people who are taller jump farther?Example Hypothesis: If a person is tall, then they will jump farIV: Height DV: Length of Jump

D = dependent variableR = responding variableY = graph information on the vertical or y-axis

M = manipulated variableI = independent variableX = graph information on the horizontal or x-axis

DRY MIX

Questions that Science cannot answer

• Earlier you learned that science can only answer questions about the natural world, but also has a few other limitations

• Science is limited to addressing only testable questions, those that can be proven wrong by multiple investigators over time.

• Science cannot answer…• Questions concerning personal beliefs or opinions (Ex: “Which tastes better Coke or

Pepsi?”)• Scientists could also answer a more specific question, such as “Which type of soda

is purchased more often by Americans?”. This type of question could be answered by taking a survey, or by looking at existing data on soda sales. Science also cannot answer questions like “What is the meaning of life?” or “Why are we here?” because answers will be different based on personal opinions and beliefs.

• Questions concerning phenomena that cannot be observed with our senses (or any tools that could extend our senses) (Ex: “What do fish think about?” they could spend all day thinking about chess problems – most likely they don’t but we lack technology to read minds – so we can’t prove they don’t)

Questions that Science cannot answer

• Questions that are too general (Ex: “Why do people yawn?” – there is too much to test, we would have to break it down and study aspects like “Does yawning increase the level of oxygen in the blood?”)

• Questions that we cannot answer due to limits on time, technology, or resources• For example, there are limits on the smallest things we can see even with our

strongest microscopes. And although we may have the technology to travel to other planets in our solar system, it would take such a long time to get there, and would be so expensive that it is not practical. However, as our technology advances, more questions will become testable.

• Questions that we cannot answer due for ethical reasons (Ex: “Does eating food containing mercury cause birth defects?” is testable, but perhaps should not be tested because it could put people and their children at risk for serious health problems. )

• Sometimes these questions are answered by observing people who are affected accidentally.

Scientific Questions – in summary

A “Scientifically Testable Question” is… • one that can be objectively proven or disproven through a scientific

investigation or survey (carefully worded of course)• contains a manipulated and a responding variable (though not required for

descriptive investigations)• is centered on items in the natural world• is measurable, should not be too broad • and is not a matter of opinion.

Scientifically testable questions begin with Why, How, Does, Which, What, Is, Can, Would, etc.• Note: avoid using “Why” as it tends to start overly broad questions which

aren’t easily tested and must be pared down.• Insure that the question is as narrowly focused as possible.

Science assumes a rational world that is governed by rules

Science Explains and Predicts:

• Scientists strive to make sense of observations and occurrences by constructing explanations for them that use or are consistent with currently held scientific principles.

• The essence of science is confirmation by observation• Science does not state how or if findings should be used – as those

are the reflection of beliefs and opinion (Ex: science can split the atom and lead to the technology of the atomic bomb – but does not say it should be used. Also science can lead to the ability to splice genes or clone animals and people – but remains mute on how or if that should be utilized)

Science assumes a rational world that is governed by rules

Science Explains and Predicts:

• Science presumes that the things and events in the universe occur in consistent patterns that are knowable through careful study.

• Scientists understand that through the use of the mind, coupled with instruments that extend the senses, people can discover patterns in all of nature.

• Science assumes that the universe (as its name implies) is a vast single system in which the basic rules are everywhere the same. Knowledge gained from studying one part is applicable to other parts.

• Hypotheses about testable questions are tested, if they are confirmed they can build to form larger explanations made up of large numbers of confirmed hypotheses known as theories.

• Theories can be used to explain the present and predict how the natural world will function in the future.

Science Demands Evidence: “A Few Good Men”

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• Science demands evidence. Science works like the court of law

• Remember the Tom Cruise quote that his character Lt. Kaffee said in A Few Good Men …

“It doesn't matter what I believe. It only matters what I can prove! So please, don't tell me what I know, or don't know; I know the LAW. “

• You can replace “LAW” with “SCIENCE” and the statement works just as well. In science, a hypothesis, theory, or even a law is only as good as the concrete foundation of evidence from the natural world that underpins it.

• Lt. Kaffee suspected that Col. Jessup ordered the victim Pvt. Santiago to be punished and after that punishment resulted in his death – he orchestrated the cover-up of that death.

• Without evidence – beyond reasonable doubt in the courtroom - proving his hypothesis for what happened to Pvt. Santiago, his hypothesis was meaningless and worthless.

Denzel Washington knows…Science demands proof! Needs evidence!

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The Definition of Science: Science uses available evidence to explain & predict


Science is used to explain what we encounter in the natural world and predict its future behavior

Hypothesis vs. Theory

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• In Science, words have meaning, so the terms hypothesis, theory, and law can’t be used interchangeably

• A hypothesis is an educated guess based upon observation and prior knowledge, but has yet to be tested.

• On the other hand, a theory is an extensively tested explanation• A theory summarizes a group of hypotheses that have been proven

upon repeated testing. Theories are explanations of phenomenon that are based upon repeated testing by multiple investigators.

Fact vs. Opinion

• Fact – in science, an observation that has been repeatedly confirmed.

• Facts may be found to be false later on when tested with better instruments.

• Facts (or observations) are the raw materials of science.

• A box is red or it has a mass of 2 kg are facts. That there are 25 desks in this room is a fact.

• Facts may be organized into Scientific Laws.

• Opinion – a belief that a person may have that cannot be proven true (or false) objectively. Personal feelings play a role in opinions.

• If a person said that a box was pretty or if someone said that the class room is too small for 25 students, those would be opinions.

Theories and Scientific Laws

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• Theories can be disproven if enough evidence to the contrary comes to light from multiple investigators. But if you think of a Greek temple that has hundreds of pillars as being akin to a theory that is upheld by hundreds of proven hypotheses, if a single hypotheses or two are disproven but the overall majority remain untouched – the theory can be refined, but stay intact.

• A scientific law ( a.k.a. “natural law”) is a generalization based upon a large number of observations – of things that are universal and always appear to be true.

• Scientific laws are observations condensed into a pattern, and don’t go beyond what was actually observed. Both theories & laws can be used to predict.

• Laws do not attempt to explain why a thing happens. • A key difference between a law and a theory is that a theory will provide an answer

to “why” something occurs while a law will only answer the “what”• Scientific laws can often be stated in a mathematical formula• Ex: Newton could use the Law of Gravity to predict how things would behave, but

he couldn’t explain why.

Hypotheses, Theories, and Laws

• A theory can be though of as an automobile. An automobile has many moving parts which work together to get you from one place to another. You can replace parts or upgrade the design without changing the overall vehicle.

• A theory is like an automobile in that components can be changed or improved upon without changing the overall validity of the theory.

• Examples of theories are, Cell Theory, Germ Theory, Atomic Theory, The Theory of Evolution, the Theory of Plate Tectonics. Theories are often tinkered with, but rarely is there enough evidence to the contrary to completely discard a theory once it has been thoroughly tested.

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Scientific Ideas are subject to change – nothing is carved in marble

• Science is tentative and dynamic – nothing is fixed. Knowledge is based upon what can be substantiated by evidence, but there are no “absolute truths” in Science.

• Change in knowledge is inevitable because new observations may challenge current, prevailing theories.

• In science, the testing and improving and occasional discarding of theories, old or new, goes on all of the time.

• Science assumes that there is no way to obtain the complete and absolute truth – uncertainty always exists. (Other ways of knowing that are outside the natural world such as religion and philosophy can offer absolute truths).

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Scientific Ideas are subject to change – nothing is carved in marble

• Scientists can begin all claims with “the evidence seems to suggest”• Even though absolute truth cannot be known, increasingly accurate

approximations can be made to explain how the world works.

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Occam’s Razor

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• William of Occam was an English friar and philosopher who lived from 1285 to 1349.

• His vow of poverty may have led him to formulate the “Principal of Parsimony” also known as “Occam’s Razor”

• It is a philosophical guide or suggestion that influences much of scientific thought

• Occam’s Razor states: “when given two explanations for the same thing, the simpler one is usually the correct one”

• or in modern terms: "Our explanations of things should minimize unsupported assumptions."

• Simple explanations come from evidence we know to be true and don’t need scores of assumptions to make them work.

• You always have to look for the simplest, testable explanation

• An example of Occam’s Razor is the saying: “When you hear hoof beats behind you, think horses not zebras”.

• Scientists make generalizations based upon the data from investigations that require the fewest number of assumptions to be true.

ex: a large rock inthe middle of a dryfield, most likely wasn’t left by giantswhich there is no evidence but probably result of melting glaciers which we do have evidence for

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Although there is no absolute certainty in science, theories and scientific laws thathave withstood a myriad of testing are very reliable for making predictions of futureresults

Some Discarded Theories in History• The Geocentric Universe: the concept that the Earth was the center of all the universe and

all celestial objects orbited it. Galileo added observations to the earlier work of Copernicus to begin to disprove this theory.

• Miasmatic Theory of Disease: The long held concept that diseases were caused by “miasmas” or “polluted air”. The name for the disease malaria reflects this as malaria means “bad air” in Latin. The Germ Theory replaced this theory.

• The Stress Theory of Ulcers: In the 1980’s Australian Barry Marshal discovered that the bacteria H. pylori caused ulcers, not stressful situations, and they could be cured with antibiotics.

• Phlogistan Theory: prior to modern chemistry and our knowledge of how chemical reactions take place on the atomic level, people used this theory to explain why some things burned. Flammable items contained a “fire-like” substance called phlogistan that was consumed in burning. Items like coal left little residue because they must have been nearly all phlogistan.

• The Four Humours Theory of Human Physiology: From the ancient Greek doctor Hippocrates through the early 19th century, medical professionals contributed illness to an imbalance of the four humours of the body. The four humours were thought to be: black bile, yellow bile, phlegm and blood. Attempts to restore the balance of the humours and cure the patient included bleeding treatments. President Washington most likely died from this treatment (and another – laxatives) than his actual disease.

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The Definition of Science: A bank of knowledge


• Science comes from the Latin word “scientia” which means “knowledge”• Not only does science refer to the process by which new knowledge of the natural

world is accrued, it also refers to the bank of testable knowledge about the natural world that has been passed down from generation to generation.

Pure Science vs. Applied Science

• Pure Science– research that adds to the body of scientific knowledge – has no practical use– Example: Scientists use a super-collider to study Quarks,

small sub-atomic particles that make up Protons & Neutrons.

• Applied Science (Technology)– the practical application of scientific knowledge– Atomic Clocks use the vibration of Cesium atoms as the

“ticks” to accurately measure time, so accurately that they lose a second every 3.7 billion years.

Pure Science vs Applied Science Examples

PURE

• human genetics

• polymer science

• atomic theory

• study of the human ear

APPLIED

• DNA fingerprinting

• Lycra® spandex

• nuclear weapons

• hearing aids

Basic Branches of Science

• Life Science– the study of living organisms

• Earth Science– the study of Earth and space

• Physical Science– the study of matter and energy– chemistry & physics

What is Physics?

What is Physics?

• Physics is often described as being the most fundamental of all sciences

• Physics is defined as the study of how & why things move.• Physics could be defined as being the study of the forces

and energy that lay behind the composition of all matter as well as how the matter interacts with one another.

• Math is a vital tool used to describe concepts in Physics• As a recent graduate from EHS (Nolan Watson) once

described the course to his Dad – “Physics is like math & science had a baby”

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