What is Science?

What is Science?

• Know the definition of science, and its strengths and limitations.

• Distinguish between hypotheses and theories.

• Explain the impacts of the scientific contributions of historical and contemporary scientists on scientific thought and on society.

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​Objectives

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• ​science

• qualitative

• quantitative

• hypothesis

• theory

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Terms to Know

• repeatability

• experiment

• scientific method

• uncertainty​

Science is the study of the physical world.

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Science, as defined by the National Academy of Sciences, is the:

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"use of evidence to construct testable explanations and predictions of natural phenomena, as well as the knowledge generated through this process.”

The Nature of Science

​Modern society has a vast and evolving body of knowledge about the natural world. We describe this knowledge through models:

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• physical models:  “The Earth orbits the Sun.”

• mathematical models: “The force of gravity is given by the following equation . . .”

• conceptual models:  “The Sun is surrounded by a gravitational force field.”

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The Nature of Science

• ​Strengths:

  • Science is flexible.

  • Scientific knowledge is subject to constant testing and revision as new knowledge and new technology becomes available. 

  • Changes in science lead to an ever-increasing understanding of the physical world.

• Limitations:

  • Science is limited to the study of the physical, testable, observable world,

  • and is limited to natural explanations of phenomena.

Strengths and limitations of Science

Multiple Select

Identify all of the following that are strengths in science

• subject to constant testing and revision

• testable

• studies must be of physical, testable, and observable world

• explanations must have natural explanations of phenomena

• changes lead to increased understanding of the physical world

Multiple Select

Identify all of the following that are limitations in science

• subject to constant testing and revision

• testable

• studies must be of physical, testable, and observable world

• explanations must have natural explanations of phenomena

• changes lead to increased understanding of the physical world

• ​Physics is both a process and a body of knowledge.

​Scientific Inquiry

• ​Physics is both a process and a body of knowledge.​

  • Knowledge includes facts, like the mass of an electron

​Scientific Inquiry

• ​Physics is both a process and a body of knowledge.

  • Knowledge includes facts, like the mass of an electron

  • This knowledge is gained through a skill-based process known as scientific inquiry.

​Scientific Inquiry

​Scientific inquiry is a process of proposing and testing potential explanations to “discover” which ones are true laws of nature.

​Scientific Inquiry

​Scientific inquiry is a process of proposing and testing potential explanations to “discover” which ones are true laws of nature.

• Example: A scientist might find that when she shines light on a mirror at an angle θ, the light always reflects from the mirror at the same angle.

​Scientific Inquiry

​Scientific inquiry is a process of proposing and testing potential explanations to “discover” which ones are true laws of nature.

• Example: A scientist might find that when she shines light on a mirror at an angle θ, the light always reflects from the mirror at the same angle.

• ​If she tries this for different angles and mirrors, she will discover that it is always true: it is the law of reflection.

​Scientific Inquiry

​What are scientific inquiry skills?

• These are the skills we use to ​DO science.

  • observing

  • inferring

  • ​classifying

  • communicating

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​Scientific Inquiry Skills

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  • hypothesizing

  • Data collection and analysis

  • variable identification

  • experimentation

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• ​observations made using our 5 senses

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​​Qualitative

• observations made using measurements to provide specific information.

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​​Quantitative

​There are 2 types of Observations: Qualitative and Quantitative

Multiple Choice

Observations like the color or texture of an object are ________________ observations.

• quantitative
• qualitative
• operational
• scientific

Multiple Choice

Observations like measurements are ____________ observations

• quantitiative
• qualitative
• operational
• scientific

​Scientific Method

​Scientific Method

The scientific method is the process of proposing theories and rigorously testing them.

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A tentative hypothesis becomes a theory only if the outcome of every single related experiment or observation, made by multiple researchers, agrees with the hypothesis.

A hypothesis is a tentative, testable explanation for an observable physical phenomena.

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Hypothesis

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A hypothesis is a tentative, testable explanation for an observable physical phenomena.

• ​Most hypotheses are incomplete or wrong when first proposed.

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Hypothesis

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A hypothesis is a tentative, testable explanation for an observable physical phenomena.

• ​Most hypotheses are incomplete or wrong when first proposed.

• Hypotheses are still important because they provide something that can be tested and revised.

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Hypothesis

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Multiple Choice

An explanation a scientist makes that we can test to see if it is true or not is a _________.

• hypothesis
• theory
• law
• question

A theory is a comprehensive, well-established and highly reliable explanation of a natural, physical phenomenon.

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Theory

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Example:

• ​Newton hypothesized that light is a particle that bounces off a surface like a billiard ball.

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Hypothesis Vs. Theory

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Example:

• ​Newton hypothesized that light is a particle that bounces off a surface like a billiard ball.

• ​Others proposed that light behaves like a wave

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Hypothesis Vs. Theory

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Example:

• ​Newton hypothesized that light is a particle that bounces off a surface like a billiard ball.

• ​Others proposed that light behaves like a wave

• ​Neither hypothesis is completely correct;  both were combined to form a modern quantum theory of light.

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Hypothesis Vs. Theory

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Multiple Choice

A broad and comprehensive statement of what is thought to be true; it is supported by much evidence and repeated experimentation.

• hypothesis
• theory
• guess
• fact

In everyday language you might use the word theory to describe a hunch that you have about something.

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A scientific theory is very different from your hunch!

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Theory vs. hunch

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In everyday language you might use the word theory to describe a hunch that you have about something.

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A scientific theory is very different from your hunch!

• A scientific theory has been tested again and again against the harshest criticism and always comes up correct.

• The findings have repeatability – anyone who tests the theory always observes the same results.

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Theory vs. hunch

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Multiple Choice

Repeatability means

• being able to try the same experiment, with the same setup, and produce that exact same result.

• being able to redo an experiment but finding different results

• never being able to reproduce the results of an experiment

Multiple Choice

Before a scientific theory is accepted and supported, it has

• been tested by only one scientist.

• been published in scientific journals.

• been tested many times by different scientists.

• been approved by the International Committee of Scientists.

Match

Identify each of the following adjectives as describing: hypotheses, theories, or both

• tentative

• testable and subject to change

• highly reliable

• based on natural or physical phenomena

• well-established

hypothesis

both

theory

both

Theory

• hypothesis

• both

• theory

• both

• Theory

​Impact of scientists on society

Some findings have broad impact on other scientists and on society.

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Each scientist builds on the results of others and, in the end, deepens our understanding of the universe.

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Let’s look at a few examples.

​Example 1: The Big Bang

​Example 1: The Big Bang

​Example 1: The Big Bang

​Example 1: The Big Bang

​Example 1: The Big Bang

​Scientific theories are subject to change as new areas of science and new technologies are developed.

​Example 2: The Dinosaurs

​A geological team found high concentrations of iridium in rock from the time of dinosaur extinction.

​Example 2: The Dinosaurs

​A geological team found high concentrations of iridium in rock from the time of dinosaur extinction.

• Only asteroids contain that much iridium.

​Example 2: The Dinosaurs

​A geological team found high concentrations of iridium in rock from the time of dinosaur extinction.

• Only asteroids contain that much iridium.

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• Theory:  dinosaur extinction was caused by the impact from a giant asteroid.

​Example 3: Climate Change

Many scientists are currently engaged in research about global temperature changes and rising sea levels.

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​Example 3: Climate Change

Many scientists are currently engaged in research about global temperature changes and rising sea levels.

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Societal impact:​

• These findings have led to broad societal discussions about human impact on Earth’s climate.

​Analyzing Scientific Data

In the process of building scientific theories, scientists must analyze, evaluate and critique scientific explanations.

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​Analyzing Scientific Data

In the process of building scientific theories, scientists must analyze, evaluate and critique scientific explanations.

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• Tools for analyzing a scientific explanation:

  • observational evidence

  • logical reasoning

  • experimental testing

​Observational Evidence

Scientific explanations may be analyzed and evaluated through observational evidence.

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​Observational Evidence

Scientific explanations may be analyzed and evaluated through observational evidence.

Example: 

• Observations of the phases of Venus support the explanation that both Earth and Venus orbit the Sun.

​Observational Evidence

Scientific explanations may be analyzed and evaluated through observational evidence.

Example: 

• Observations of the phases of Venus support the explanation that both Earth and Venus orbit the Sun.

  • The observations of Venus satisfy the criteria for scientific evidence:  they are objective and repeatable.

Multiple Choice

Observations made during an experiment are called:

• data
• problems
• conclusions
• questions

​Logical reasoning

Scientific explanations may be analyzed

and evaluated through logical reasoning.

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Example: 

• The explanation for the seasons is that Earth’s rotational axis is tilted about 23°.

  • How does logical reasoning allow us to analyze this explanation?

​Logical reasoning

Example: 

The explanation for the seasons is that Earth’s rotational axis is tilted about 23^o.

• How does logical reasoning allow us to analyze this explanation?

  • If this explanation for the seasons is true then it logically follows that:

  • An observer at noontime in Austin, Texas (30°N latitude) should see the Sun . . .

    • at 53° from vertical in winter.

    • at 7° from vertical in summer.

      This is exactly what is observed!

​Experimental testing

Scientific explanations may be analyzed and evaluated through

experimental testing.

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• A well-designed experiment allows you to change one variable to determine precisely how other variables respond.

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​Critiquing experimental results

Experimental evidence must be carefully critiqued.

• What are the key questions a researcher should consider when evaluating the quality of experimental results?

​Critiquing experimental results

Experimental evidence must be carefully critiqued.

• What are the key questions a researcher should consider when evaluating the quality of experimental results?

  • Is the experiment objective?

​Critiquing experimental results

Experimental evidence must be carefully critiqued.

• What are the key questions a researcher should consider when evaluating the quality of experimental results?

  • Is the experiment objective?

  • Are the observations unbiased?

​Critiquing experimental results

Experimental evidence must be carefully critiqued.

• What are the key questions a researcher should consider when evaluating the quality of experimental results?

  • Is the experiment objective?

  • Are the observations unbiased?

  • Could other variables have caused the observed effects?

​Critiquing experimental results

Experimental evidence must be carefully critiqued.

• What are the key questions a researcher should consider when evaluating the quality of experimental results?

  • Is the experiment objective?

  • Are the observations unbiased?

  • Could other variables have caused the observed effects?

  • Do other researchers observe the same result?

​Critiquing experimental results

Experimental evidence must be carefully critiqued.

• What are the key questions a researcher should consider when evaluating the quality of experimental results?

  • Is the experiment objective?

  • Are the observations unbiased?

  • Could other variables have caused the observed effects?

  • Do other researchers observe the same result?

  • Has the data been analyzed to understand the uncertainties in measurement?

​Critiquing experimental results

Experimental evidence must be carefully critiqued.

• What are the key questions a researcher should consider when evaluating the quality of experimental results?

  • Is the experiment objective?

  • Are the observations unbiased?

  • Could other variables have caused the observed effects?

  • Do other researchers observe the same result?

  • Has the data been analyzed to understand the uncertainties in measurement?

  • Are the observed effects greater than the uncertainties in measurement?

Uncertainty

ALL measured data contains some degree of uncertainty.

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This uncertainty, or error - is the unavoidable difference between a

measurement and the true value of the quantity being measured.​

Uncertainty

ALL measured data contains some degree of uncertainty.

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This uncertainty, or error - is the unavoidable difference between a

measurement and the true value of the quantity being measured.

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But if physics is based on measurement, and all measurements contain uncertainty, then how can we ever be confident about scientific explanations based on experimental evidence?

A test case

Let’s say a student wants to test this scientific explanation:​

heavy objects fall faster than light objects.

He drops a heavy stone and a light stone and collects this data on the time to fall.

The student argues that this data supports his explanation. His friend says he’s wrong. 

• What is the evidence for each view?

• Who is right?

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A test case

​Ask yourself:​

• What is the observed “effect”?

• What is the uncertainty in the data?

• What caused the uncertainty?

• Is the observed “effect” significant compared to the uncertainty in the data?

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A test case

This experiment does not support the explanation because the experiment finds no significant difference between the heavy stone and the lighter stone.

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•The values for the heavy rock vary by more than a tenth of a second.

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•The average value for the two rocks differs by only two hundredths of a second.

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Uncertainty

• Uncertainty can never be eliminated.

• Taking lots of data allows you to quantify the uncertainty.

• Empirical evidence must always be evaluated with respect to uncertainties before any conclusion can be made.

Multiple Choice

You see an icicle hanging from a branch or roof and notice that the ice forms in ripples on the surface of the icicle. 

Which of the following is a valid way to test a hypothesis about these ripples?

• Do research for information on the internet.

• Look for information in textbooks or at a library.

• Ask a teacher or another knowledgeable person.

• Do an experiment by creating icicles at different temperatures.

Multiple Select

Which of the following could be scientific evidence?

• The speedometer on a car reads 57 miles per hour.

• A photograph shows the planet Venus at a specific position in the evening sky.

• You notice that the temperature outside is 27º

• A teacher tells you that the atomic mass of carbon is

  12.0 grams per mole.

• A newspaper headline announces the discovery of a

  previously unknown fundamental particle

Multiple Choice

Johnny heard that he can show the way the Earth is tilted by studying the length of daylight. Every day Johnny would calculate the time of the sunrise and the sunset to determine the length of the day. After collecting this information every day for a year, what would be his next step?

• Form his hypothesis

• Write his conclusion

• Analyze the data he collected

• Create a question

Multiple Choice

Brian was flying to Orlando. When he took off in his hometown it was raining. Brian noticed the clouds were dark when the plane was taking off the ground. But, once the plane got above the cloud cover, he noticed the clouds were white. If Brian was to create an experiment about this observation, what would be his next step?

• Form a question

• Create an experiment

• Analyze data

• Create a conclusion

Multiple Choice

The first classification of life was presented by Aristotle who indicated that all life was either Plant or Animal. Now in science we have 7 levels of classification. Why was science allowed to change?

• Science is unchangable

• Science is always changing as new technology and information is presented.

• Original science was bad science

• Science cannot be disproven

Multiple Choice

The past couple years, there has been many that believe, once again, that the Earth is flat. Which of the following has prevented this new idea from being accepted by the science community?

• It is accepted by the science community

• Certain political figures want to prevent it from being accepted

• There has not been enough new data and/or experimentation to cause a change in science.

• They did not use a control group

Multiple Choice

Which is not a characteristic of science?

• Conserved to data and facts

• Open to change

• conclusions are first created then support is made

• Open to criticism