scope and experiment of physics

• Physics Article
• Scope And Excitement Of Physics

The Scope And Excitement Of Physics

Scope of physics:.

The scope of classical Physics deals with the following branches in Physics

• Classical Mechanics
• Thermodynamics
• Electromagnetism

Modern-day Physics (after the 19th century) deals with concepts of Relativity and Quantum Mechanics. Relativity as we know was something explored by Albert Einstein. The scope of physics grew as the theory of relativity changed the way we used to think about the world and atmosphere. It is most probably the most comprehensive theories which the whole world has acknowledged. The renowned physicist Richard Feynman introduced the world to Quantum Mechanics. It is the study of motion and interaction of subatomic particles, wave-particle duality with the help of a suitable mathematical description.

The diagram given below illustrates the different domains based on speed and size of matter in consideration.

Excitement of Physics:

Do you think teleportation is possible? If your answer is yes, how would that work? I’ll get back to this. If your answer is no, why not? Did people living five hundred years ago know that there will exist a device that can tell you the position of any planet or constellation or such celestial bodies in seconds, should you wish to look for them? I’m talking about Sky Maps of course.

All this has been achieved only because of those people who were curious enough to know why everything exists as it does. The way to teleport is already out there, we just have to find that way how. Where there is a will there is a way, and the will is found through excitement!

Regarding my question on teleportation, we have already achieved the ability of quantum teleportation. In this process, the quantum information (exact information about atom or photon) can be transmitted from one location to another. We may be at this stage now, but who’s to say macroscopic beings like us won’t be able to transport ourselves from one location to another in the future!

Put your understanding of this concept to test by answering a few MCQs. Click ‘Start Quiz’ to begin!

Select the correct answer and click on the “Finish” button Check your score and answers at the end of the quiz

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1 Units and Measurement

1.1 The Scope and Scale of Physics

Learning objectives.

By the end of this section, you will be able to:

• Describe the scope of physics.
• Calculate the order of magnitude of a quantity.
• Compare measurable length, mass, and timescales quantitatively.
• Describe the relationships among models, theories, and laws.

Physics is devoted to the understanding of all natural phenomena. In physics, we try to understand physical phenomena at all scales—from the world of subatomic particles to the entire universe. Despite the breadth of the subject, the various subfields of physics share a common core. The same basic training in physics will prepare you to work in any area of physics and the related areas of science and engineering. In this section, we investigate the scope of physics; the scales of length, mass, and time over which the laws of physics have been shown to be applicable; and the process by which science in general, and physics in particular, operates.

The Scope of Physics

Take another look at the chapter-opening image. The Whirlpool Galaxy contains billions of individual stars as well as huge clouds of gas and dust. Its companion galaxy is also visible to the right. This pair of galaxies lies a staggering billion trillion miles [latex](1.4\times {10}^{21}\text{mi})[/latex] from our own galaxy (which is called the Milky Way ). The stars and planets that make up the Whirlpool Galaxy might seem to be the furthest thing from most people’s everyday lives, but the Whirlpool is a great starting point to think about the forces that hold the universe together. The forces that cause the Whirlpool Galaxy to act as it does are thought to be the same forces we contend with here on Earth, whether we are planning to send a rocket into space or simply planning to raise the walls for a new home. The gravity that causes the stars of the Whirlpool Galaxy to rotate and revolve is thought to be the same as what causes water to flow over hydroelectric dams here on Earth. When you look up at the stars, realize the forces out there are the same as the ones here on Earth. Through a study of physics , you may gain a greater understanding of the interconnectedness of everything we can see and know in this universe.

Think, now, about all the technological devices you use on a regular basis. Computers, smartphones, global positioning systems (GPSs), MP3 players, and satellite radio might come to mind. Then, think about the most exciting modern technologies you have heard about in the news, such as trains that levitate above tracks, “invisibility cloaks” that bend light around them, and microscopic robots that fight cancer cells in our bodies. All these groundbreaking advances, commonplace or unbelievable, rely on the principles of physics. Aside from playing a significant role in technology, professionals such as engineers, pilots, physicians, physical therapists, electricians, and computer programmers apply physics concepts in their daily work. For example, a pilot must understand how wind forces affect a flight path; a physical therapist must understand how the muscles in the body experience forces as they move and bend. As you will learn in this text, the principles of physics are propelling new, exciting technologies, and these principles are applied in a wide range of careers.

The underlying order of nature makes science in general, and physics in particular, interesting and enjoyable to study. For example, what do a bag of chips and a car battery have in common? Both contain energy that can be converted to other forms. The law of conservation of energy (which says that energy can change form but is never lost) ties together such topics as food calories, batteries, heat, light, and watch springs. Understanding this law makes it easier to learn about the various forms energy takes and how they relate to one another. Apparently unrelated topics are connected through broadly applicable physical laws, permitting an understanding beyond just the memorization of lists of facts.

Science consists of theories and laws that are the general truths of nature, as well as the body of knowledge they encompass. Scientists are continuously trying to expand this body of knowledge and to perfect the expression of the laws that describe it. Physics , which comes from the Greek phúsis , meaning “nature,” is concerned with describing the interactions of energy, matter, space, and time to uncover the fundamental mechanisms that underlie every phenomenon. This concern for describing the basic phenomena in nature essentially defines the scope of physics .

Physics aims to understand the world around us at the most basic level. It emphasizes the use of a small number of quantitative laws to do this, which can be useful to other fields pushing the performance boundaries of existing technologies. Consider a smartphone ( Figure ). Physics describes how electricity interacts with the various circuits inside the device. This knowledge helps engineers select the appropriate materials and circuit layout when building a smartphone. Knowledge of the physics underlying these devices is required to shrink their size or increase their processing speed. Or, think about a GPS. Physics describes the relationship between the speed of an object, the distance over which it travels, and the time it takes to travel that distance. When you use a GPS in a vehicle, it relies on physics equations to determine the travel time from one location to another.

Knowledge of physics is useful in everyday situations as well as in nonscientific professions. It can help you understand how microwave ovens work, why metals should not be put into them, and why they might affect pacemakers. Physics allows you to understand the hazards of radiation and to evaluate these hazards rationally and more easily. Physics also explains the reason why a black car radiator helps remove heat in a car engine, and it explains why a white roof helps keep the inside of a house cool. Similarly, the operation of a car’s ignition system as well as the transmission of electrical signals throughout our body’s nervous system are much easier to understand when you think about them in terms of basic physics.

Physics is a key element of many important disciplines and contributes directly to others. Chemistry, for example—since it deals with the interactions of atoms and molecules—has close ties to atomic and molecular physics. Most branches of engineering are concerned with designing new technologies, processes, or structures within the constraints set by the laws of physics. In architecture, physics is at the heart of structural stability and is involved in the acoustics, heating, lighting, and cooling of buildings. Parts of geology rely heavily on physics, such as radioactive dating of rocks, earthquake analysis, and heat transfer within Earth. Some disciplines, such as biophysics and geophysics, are hybrids of physics and other disciplines.

Physics has many applications in the biological sciences. On the microscopic level, it helps describe the properties of cells and their environments. On the macroscopic level, it explains the heat, work, and power associated with the human body and its various organ systems. Physics is involved in medical diagnostics, such as radiographs, magnetic resonance imaging, and ultrasonic blood flow measurements. Medical therapy sometimes involves physics directly; for example, cancer radiotherapy uses ionizing radiation. Physics also explains sensory phenomena, such as how musical instruments make sound, how the eye detects color, and how lasers transmit information.

It is not necessary to study all applications of physics formally. What is most useful is knowing the basic laws of physics and developing skills in the analytical methods for applying them. The study of physics also can improve your problem-solving skills. Furthermore, physics retains the most basic aspects of science, so it is used by all the sciences, and the study of physics makes other sciences easier to understand.

The Scale of Physics

From the discussion so far, it should be clear that to accomplish your goals in any of the various fields within the natural sciences and engineering, a thorough grounding in the laws of physics is necessary. The reason for this is simply that the laws of physics govern everything in the observable universe at all measurable scales of length, mass, and time. Now, that is easy enough to say, but to come to grips with what it really means, we need to get a little bit quantitative. So, before surveying the various scales that physics allows us to explore, let’s first look at the concept of “order of magnitude,” which we use to come to terms with the vast ranges of length, mass, and time that we consider in this text ( Figure ).

Order of magnitude

The order of magnitude of a number is the power of 10 that most closely approximates it. Thus, the order of magnitude refers to the scale (or size) of a value. Each power of 10 represents a different order of magnitude. For example, [latex]{10}^{1},{10}^{2},{10}^{3},[/latex] and so forth, are all different orders of magnitude, as are [latex]{10}^{0}=1,{10}^{-1},{10}^{-2},[/latex] and [latex]{10}^{-3}.[/latex] To find the order of magnitude of a number, take the base-10 logarithm of the number and round it to the nearest integer, then the order of magnitude of the number is simply the resulting power of 10. For example, the order of magnitude of 800 is 10 3 because [latex]{\text{log}}_{10}800\approx 2.903,[/latex] which rounds to 3. Similarly, the order of magnitude of 450 is 10 3 because [latex]{\text{log}}_{10}450\approx 2.653,[/latex] which rounds to 3 as well. Thus, we say the numbers 800 and 450 are of the same order of magnitude: 10 3 . However, the order of magnitude of 250 is 10 2 because [latex]{\text{log}}_{10}250\approx 2.397,[/latex] which rounds to 2.

An equivalent but quicker way to find the order of magnitude of a number is first to write it in scientific notation and then check to see whether the first factor is greater than or less than [latex]\sqrt{10}={10}^{0.5}\approx 3.[/latex] The idea is that [latex]\sqrt{10}={10}^{0.5}[/latex] is halfway between [latex]1={10}^{0}[/latex] and [latex]10={10}^{1}[/latex] on a log base-10 scale. Thus, if the first factor is less than [latex]\sqrt{10},[/latex] then we round it down to 1 and the order of magnitude is simply whatever power of 10 is required to write the number in scientific notation. On the other hand, if the first factor is greater than [latex]\sqrt{10},[/latex] then we round it up to 10 and the order of magnitude is one power of 10 higher than the power needed to write the number in scientific notation. For example, the number 800 can be written in scientific notation as [latex]8\times {10}^{2}.[/latex] Because 8 is bigger than [latex]\sqrt{10}\approx 3,[/latex] we say the order of magnitude of 800 is [latex]{10}^{2+1}={10}^{3}.[/latex] The number 450 can be written as [latex]4.5\times {10}^{2},[/latex] so its order of magnitude is also 10 3 because 4.5 is greater than 3. However, 250 written in scientific notation is [latex]2.5\times {10}^{2}[/latex] and 2.5 is less than 3, so its order of magnitude is [latex]{10}^{2}.[/latex]

The order of magnitude of a number is designed to be a ballpark estimate for the scale (or size) of its value. It is simply a way of rounding numbers consistently to the nearest power of 10. This makes doing rough mental math with very big and very small numbers easier. For example, the diameter of a hydrogen atom is on the order of 10 −10 m, whereas the diameter of the Sun is on the order of 10 9 m, so it would take roughly [latex]{10}^{9}\text{/}{10}^{-10}={10}^{19}[/latex] hydrogen atoms to stretch across the diameter of the Sun. This is much easier to do in your head than using the more precise values of [latex]1.06\times {10}^{-10}\text{m}[/latex] for a hydrogen atom diameter and [latex]1.39\times {10}^{9}\text{m}[/latex] for the Sun’s diameter, to find that it would take [latex]1.31\times {10}^{19}[/latex] hydrogen atoms to stretch across the Sun’s diameter. In addition to being easier, the rough estimate is also nearly as informative as the precise calculation.

Known ranges of length, mass, and time

The vastness of the universe and the breadth over which physics applies are illustrated by the wide range of examples of known lengths, masses, and times (given as orders of magnitude) in Figure . Examining this table will give you a feeling for the range of possible topics in physics and numerical values. A good way to appreciate the vastness of the ranges of values in Figure is to try to answer some simple comparative questions, such as the following:

• How many hydrogen atoms does it take to stretch across the diameter of the Sun?(Answer: 10 9 m/10 –10 m = 10 19 hydrogen atoms)
• How many protons are there in a bacterium?(Answer: 10 –15 kg/10 –27 kg = 10 12 protons)
• How many floating-point operations can a supercomputer do in 1 day?(Answer: 10 5 s/10 –17 s = 10 22 floating-point operations)

In studying Figure , take some time to come up with similar questions that interest you and then try answering them. Doing this can breathe some life into almost any table of numbers.

Visit this site to explore interactively the vast range of length scales in our universe. Scroll down and up the scale to view hundreds of organisms and objects, and click on the individual objects to learn more about each one.

Building Models

How did we come to know the laws governing natural phenomena? What we refer to as the laws of nature are concise descriptions of the universe around us. They are human statements of the underlying laws or rules that all natural processes follow. Such laws are intrinsic to the universe; humans did not create them and cannot change them. We can only discover and understand them. Their discovery is a very human endeavor, with all the elements of mystery, imagination, struggle, triumph, and disappointment inherent in any creative effort ( Figure ). The cornerstone of discovering natural laws is observation; scientists must describe the universe as it is, not as we imagine it to be.

A model is a representation of something that is often too difficult (or impossible) to display directly. Although a model is justified by experimental tests, it is only accurate in describing certain aspects of a physical system. An example is the Bohr model of single-electron atoms, in which the electron is pictured as orbiting the nucleus, analogous to the way planets orbit the Sun ( Figure ). We cannot observe electron orbits directly, but the mental image helps explain some of the observations we can make, such as the emission of light from hot gases (atomic spectra). However, other observations show that the picture in the Bohr model is not really what atoms look like. The model is “wrong,” but is still useful for some purposes. Physicists use models for a variety of purposes. For example, models can help physicists analyze a scenario and perform a calculation or models can be used to represent a situation in the form of a computer simulation. Ultimately, however, the results of these calculations and simulations need to be double-checked by other means—namely, observation and experimentation.

The word theory means something different to scientists than what is often meant when the word is used in everyday conversation. In particular, to a scientist a theory is not the same as a “guess” or an “idea” or even a “hypothesis.” The phrase “it’s just a theory” seems meaningless and silly to scientists because science is founded on the notion of theories. To a scientist, a theory is a testable explanation for patterns in nature supported by scientific evidence and verified multiple times by various groups of researchers. Some theories include models to help visualize phenomena whereas others do not. Newton’s theory of gravity, for example, does not require a model or mental image, because we can observe the objects directly with our own senses. The kinetic theory of gases, on the other hand, is a model in which a gas is viewed as being composed of atoms and molecules. Atoms and molecules are too small to be observed directly with our senses—thus, we picture them mentally to understand what the instruments tell us about the behavior of gases. Although models are meant only to describe certain aspects of a physical system accurately, a theory should describe all aspects of any system that falls within its domain of applicability. In particular, any experimentally testable implication of a theory should be verified. If an experiment ever shows an implication of a theory to be false, then the theory is either thrown out or modified suitably (for example, by limiting its domain of applicability).

A law uses concise language to describe a generalized pattern in nature supported by scientific evidence and repeated experiments. Often, a law can be expressed in the form of a single mathematical equation. Laws and theories are similar in that they are both scientific statements that result from a tested hypothesis and are supported by scientific evidence. However, the designation law is usually reserved for a concise and very general statement that describes phenomena in nature, such as the law that energy is conserved during any process, or Newton’s second law of motion, which relates force ( F ), mass ( m ), and acceleration ( a ) by the simple equation [latex]F=ma.[/latex] A theory, in contrast, is a less concise statement of observed behavior. For example, the theory of evolution and the theory of relativity cannot be expressed concisely enough to be considered laws. The biggest difference between a law and a theory is that a theory is much more complex and dynamic. A law describes a single action whereas a theory explains an entire group of related phenomena. Less broadly applicable statements are usually called principles (such as Pascal’s principle, which is applicable only in fluids), but the distinction between laws and principles often is not made carefully.

The models, theories, and laws we devise sometimes imply the existence of objects or phenomena that are as yet unobserved. These predictions are remarkable triumphs and tributes to the power of science. It is the underlying order in the universe that enables scientists to make such spectacular predictions. However, if experimentation does not verify our predictions, then the theory or law is wrong, no matter how elegant or convenient it is. Laws can never be known with absolute certainty because it is impossible to perform every imaginable experiment to confirm a law for every possible scenario. Physicists operate under the assumption that all scientific laws and theories are valid until a counterexample is observed. If a good-quality, verifiable experiment contradicts a well-established law or theory, then the law or theory must be modified or overthrown completely.

The study of science in general, and physics in particular, is an adventure much like the exploration of an uncharted ocean. Discoveries are made; models, theories, and laws are formulated; and the beauty of the physical universe is made more sublime for the insights gained.

• Physics is about trying to find the simple laws that describe all natural phenomena.
• Physics operates on a vast range of scales of length, mass, and time. Scientists use the concept of the order of magnitude of a number to track which phenomena occur on which scales. They also use orders of magnitude to compare the various scales.
• Scientists attempt to describe the world by formulating models, theories, and laws.

Conceptual Questions

What is physics?

Physics is the science concerned with describing the interactions of energy, matter, space, and time to uncover the fundamental mechanisms that underlie every phenomenon.

Some have described physics as a “search for simplicity.” Explain why this might be an appropriate description.

If two different theories describe experimental observations equally well, can one be said to be more valid than the other (assuming both use accepted rules of logic)?

No, neither of these two theories is more valid than the other. Experimentation is the ultimate decider. If experimental evidence does not suggest one theory over the other, then both are equally valid. A given physicist might prefer one theory over another on the grounds that one seems more simple, more natural, or more beautiful than the other, but that physicist would quickly acknowledge that he or she cannot say the other theory is invalid. Rather, he or she would be honest about the fact that more experimental evidence is needed to determine which theory is a better description of nature.

What determines the validity of a theory?

Certain criteria must be satisfied if a measurement or observation is to be believed. Will the criteria necessarily be as strict for an expected result as for an unexpected result?

Probably not. As the saying goes, “Extraordinary claims require extraordinary evidence.”

Can the validity of a model be limited or must it be universally valid? How does this compare with the required validity of a theory or a law?

Find the order of magnitude of the following physical quantities. (a) The mass of Earth’s atmosphere: [latex]5.1\times {10}^{18}\text{kg;}[/latex] (b) The mass of the Moon’s atmosphere: 25,000 kg; (c) The mass of Earth’s hydrosphere: [latex]1.4\times {10}^{21}\text{kg;}[/latex] (d) The mass of Earth: [latex]5.97\times {10}^{24}\text{kg;}[/latex] (e) The mass of the Moon: [latex]7.34\times {10}^{22}\text{kg;}[/latex] (f) The Earth–Moon distance (semimajor axis): [latex]3.84\times {10}^{8}\text{m;}[/latex] (g) The mean Earth–Sun distance: [latex]1.5\times {10}^{11}\text{m;}[/latex] (h) The equatorial radius of Earth: [latex]6.38\times {10}^{6}\text{m;}[/latex] (i) The mass of an electron: [latex]9.11\times {10}^{-31}\text{kg;}[/latex] (j) The mass of a proton: [latex]1.67\times {10}^{-27}\text{kg;}[/latex] (k) The mass of the Sun: [latex]1.99\times {10}^{30}\text{kg.}[/latex]

Use the orders of magnitude you found in the previous problem to answer the following questions to within an order of magnitude. (a) How many electrons would it take to equal the mass of a proton? (b) How many Earths would it take to equal the mass of the Sun? (c) How many Earth–Moon distances would it take to cover the distance from Earth to the Sun? (d) How many Moon atmospheres would it take to equal the mass of Earth’s atmosphere? (e) How many moons would it take to equal the mass of Earth? (f) How many protons would it take to equal the mass of the Sun?

a. 10 3 ; b. 10 5 ; c. 10 2 ; d. 10 15 ; e. 10 2 ; f. 10 57

For the remaining questions, you need to use Figure to obtain the necessary orders of magnitude of lengths, masses, and times.

Roughly how many heartbeats are there in a lifetime?

A generation is about one-third of a lifetime. Approximately how many generations have passed since the year 0 AD?

10 2 generations

Roughly how many times longer than the mean life of an extremely unstable atomic nucleus is the lifetime of a human?

Calculate the approximate number of atoms in a bacterium. Assume the average mass of an atom in the bacterium is 10 times the mass of a proton.

10 11 atoms

(a) Calculate the number of cells in a hummingbird assuming the mass of an average cell is 10 times the mass of a bacterium. (b) Making the same assumption, how many cells are there in a human?

Assuming one nerve impulse must end before another can begin, what is the maximum firing rate of a nerve in impulses per second?

10 3 nerve impulses/s

About how many floating-point operations can a supercomputer perform each year?

Roughly how many floating-point operations can a supercomputer perform in a human lifetime?

10 26 floating-point operations per human lifetime

1.1 The Scope and Scale of Physics Copyright © 2016 by OpenStax. All Rights Reserved.

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1.2 The Scientific Methods

Section learning objectives.

By the end of this section, you will be able to do the following:

• Explain how the methods of science are used to make scientific discoveries
• Define a scientific model and describe examples of physical and mathematical models used in physics
• Compare and contrast hypothesis, theory, and law

Teacher Support

The learning objectives in this section will help your students master the following standards:

• (A) know the definition of science and understand that it has limitations, as specified in subsection (b)(2) of this section;
• (B) know that scientific hypotheses are tentative and testable statements that must be capable of being supported or not supported by observational evidence. Hypotheses of durable explanatory power which have been tested over a wide variety of conditions are incorporated into theories;
• (C) know that scientific theories are based on natural and physical phenomena and are capable of being tested by multiple independent researchers. Unlike hypotheses, scientific theories are well-established and highly-reliable explanations, but may be subject to change as new areas of science and new technologies are developed;
• (D) distinguish between scientific hypotheses and scientific theories.

Section Key Terms

[OL] Pre-assessment for this section could involve students sharing or writing down an anecdote about when they used the methods of science. Then, students could label their thought processes in their anecdote with the appropriate scientific methods. The class could also discuss their definitions of theory and law, both outside and within the context of science.

[OL] It should be noted and possibly mentioned that a scientist , as mentioned in this section, does not necessarily mean a trained scientist. It could be anyone using methods of science.

Scientific Methods

Scientists often plan and carry out investigations to answer questions about the universe around us. These investigations may lead to natural laws. Such laws are intrinsic to the universe, meaning that humans did not create them and cannot change them. We can only discover and understand them. Their discovery is a very human endeavor, with all the elements of mystery, imagination, struggle, triumph, and disappointment inherent in any creative effort. The cornerstone of discovering natural laws is observation. Science must describe the universe as it is, not as we imagine or wish it to be.

We all are curious to some extent. We look around, make generalizations, and try to understand what we see. For example, we look up and wonder whether one type of cloud signals an oncoming storm. As we become serious about exploring nature, we become more organized and formal in collecting and analyzing data. We attempt greater precision, perform controlled experiments (if we can), and write down ideas about how data may be organized. We then formulate models, theories, and laws based on the data we have collected, and communicate those results with others. This, in a nutshell, describes the scientific method that scientists employ to decide scientific issues on the basis of evidence from observation and experiment.

An investigation often begins with a scientist making an observation . The scientist observes a pattern or trend within the natural world. Observation may generate questions that the scientist wishes to answer. Next, the scientist may perform some research about the topic and devise a hypothesis . A hypothesis is a testable statement that describes how something in the natural world works. In essence, a hypothesis is an educated guess that explains something about an observation.

[OL] An educated guess is used throughout this section in describing a hypothesis to combat the tendency to think of a theory as an educated guess.

Scientists may test the hypothesis by performing an experiment . During an experiment, the scientist collects data that will help them learn about the phenomenon they are studying. Then the scientists analyze the results of the experiment (that is, the data), often using statistical, mathematical, and/or graphical methods. From the data analysis, they draw conclusions. They may conclude that their experiment either supports or rejects their hypothesis. If the hypothesis is supported, the scientist usually goes on to test another hypothesis related to the first. If their hypothesis is rejected, they will often then test a new and different hypothesis in their effort to learn more about whatever they are studying.

Scientific processes can be applied to many situations. Let’s say that you try to turn on your car, but it will not start. You have just made an observation! You ask yourself, "Why won’t my car start?" You can now use scientific processes to answer this question. First, you generate a hypothesis such as, "The car won’t start because it has no gasoline in the gas tank." To test this hypothesis, you put gasoline in the car and try to start it again. If the car starts, then your hypothesis is supported by the experiment. If the car does not start, then your hypothesis is rejected. You will then need to think up a new hypothesis to test such as, "My car won’t start because the fuel pump is broken." Hopefully, your investigations lead you to discover why the car won’t start and enable you to fix it.

A model is a representation of something that is often too difficult (or impossible) to study directly. Models can take the form of physical models, equations, computer programs, or simulations—computer graphics/animations. Models are tools that are especially useful in modern physics because they let us visualize phenomena that we normally cannot observe with our senses, such as very small objects or objects that move at high speeds. For example, we can understand the structure of an atom using models, without seeing an atom with our own eyes. Although images of single atoms are now possible, these images are extremely difficult to achieve and are only possible due to the success of our models. The existence of these images is a consequence rather than a source of our understanding of atoms. Models are always approximate, so they are simpler to consider than the real situation; the more complete a model is, the more complicated it must be. Models put the intangible or the extremely complex into human terms that we can visualize, discuss, and hypothesize about.

Scientific models are constructed based on the results of previous experiments. Even still, models often only describe a phenomenon partially or in a few limited situations. Some phenomena are so complex that they may be impossible to model them in their entirety, even using computers. An example is the electron cloud model of the atom in which electrons are moving around the atom’s center in distinct clouds ( Figure 1.12 ), that represent the likelihood of finding an electron in different places. This model helps us to visualize the structure of an atom. However, it does not show us exactly where an electron will be within its cloud at any one particular time.

As mentioned previously, physicists use a variety of models including equations, physical models, computer simulations, etc. For example, three-dimensional models are often commonly used in chemistry and physics to model molecules. Properties other than appearance or location are usually modelled using mathematics, where functions are used to show how these properties relate to one another. Processes such as the formation of a star or the planets, can also be modelled using computer simulations. Once a simulation is correctly programmed based on actual experimental data, the simulation can allow us to view processes that happened in the past or happen too quickly or slowly for us to observe directly. In addition, scientists can also run virtual experiments using computer-based models. In a model of planet formation, for example, the scientist could alter the amount or type of rocks present in space and see how it affects planet formation.

Scientists use models and experimental results to construct explanations of observations or design solutions to problems. For example, one way to make a car more fuel efficient is to reduce the friction or drag caused by air flowing around the moving car. This can be done by designing the body shape of the car to be more aerodynamic, such as by using rounded corners instead of sharp ones. Engineers can then construct physical models of the car body, place them in a wind tunnel, and examine the flow of air around the model. This can also be done mathematically in a computer simulation. The air flow pattern can be analyzed for regions smooth air flow and for eddies that indicate drag. The model of the car body may have to be altered slightly to produce the smoothest pattern of air flow (i.e., the least drag). The pattern with the least drag may be the solution to increasing fuel efficiency of the car. This solution might then be incorporated into the car design.

Using Models and the Scientific Processes

Be sure to secure loose items before opening the window or door.

In this activity, you will learn about scientific models by making a model of how air flows through your classroom or a room in your house.

• One room with at least one window or door that can be opened
• Work with a group of four, as directed by your teacher. Close all of the windows and doors in the room you are working in. Your teacher may assign you a specific window or door to study.
• Before opening any windows or doors, draw a to-scale diagram of your room. First, measure the length and width of your room using the tape measure. Then, transform the measurement using a scale that could fit on your paper, such as 5 centimeters = 1 meter.
• Your teacher will assign you a specific window or door to study air flow. On your diagram, add arrows showing your hypothesis (before opening any windows or doors) of how air will flow through the room when your assigned window or door is opened. Use pencil so that you can easily make changes to your diagram.
• On your diagram, mark four locations where you would like to test air flow in your room. To test for airflow, hold a strip of single ply tissue paper between the thumb and index finger. Note the direction that the paper moves when exposed to the airflow. Then, for each location, predict which way the paper will move if your air flow diagram is correct.
• Now, each member of your group will stand in one of the four selected areas. Each member will test the airflow Agree upon an approximate height at which everyone will hold their papers.
• When you teacher tells you to, open your assigned window and/or door. Each person should note the direction that their paper points immediately after the window or door was opened. Record your results on your diagram.
• Did the airflow test data support or refute the hypothetical model of air flow shown in your diagram? Why or why not? Correct your model based on your experimental evidence.
• With your group, discuss how accurate your model is. What limitations did it have? Write down the limitations that your group agreed upon.
• Yes, you could use your model to predict air flow through a new window. The earlier experiment of air flow would help you model the system more accurately.
• Yes, you could use your model to predict air flow through a new window. The earlier experiment of air flow is not useful for modeling the new system.
• No, you cannot model a system to predict the air flow through a new window. The earlier experiment of air flow would help you model the system more accurately.
• No, you cannot model a system to predict the air flow through a new window. The earlier experiment of air flow is not useful for modeling the new system.

This Snap Lab! has students construct a model of how air flows in their classroom. Each group of four students will create a model of air flow in their classroom using a scale drawing of the room. Then, the groups will test the validity of their model by placing weathervanes that they have constructed around the room and opening a window or door. By observing the weather vanes, students will see how air actually flows through the room from a specific window or door. Students will then correct their model based on their experimental evidence. The following material list is given per group:

• One room with at least one window or door that can be opened (An optimal configuration would be one window or door per group.)
• Several pieces of construction paper (at least four per group)
• Strips of single ply tissue paper
• One tape measure (long enough to measure the dimensions of the room)
• Group size can vary depending on the number of windows/doors available and the number of students in the class.
• The room dimensions could be provided by the teacher. Also, students may need a brief introduction in how to make a drawing to scale.
• This is another opportunity to discuss controlled experiments in terms of why the students should hold the strips of tissue paper at the same height and in the same way. One student could also serve as a control and stand far away from the window/door or in another area that will not receive air flow from the window/door.
• You will probably need to coordinate this when multiple windows or doors are used. Only one window or door should be opened at a time for best results. Between openings, allow a short period (5 minutes) when all windows and doors are closed, if possible.

Answers to the Grasp Check will vary, but the air flow in the new window or door should be based on what the students observed in their experiment.

Scientific Laws and Theories

A scientific law is a description of a pattern in nature that is true in all circumstances that have been studied. That is, physical laws are meant to be universal , meaning that they apply throughout the known universe. Laws are often also concise, whereas theories are more complicated. A law can be expressed in the form of a single sentence or mathematical equation. For example, Newton’s second law of motion , which relates the motion of an object to the force applied ( F ), the mass of the object ( m ), and the object’s acceleration ( a ), is simply stated using the equation

Scientific ideas and explanations that are true in many, but not all situations in the universe are usually called principles . An example is Pascal’s principle , which explains properties of liquids, but not solids or gases. However, the distinction between laws and principles is sometimes not carefully made in science.

A theory is an explanation for patterns in nature that is supported by much scientific evidence and verified multiple times by multiple researchers. While many people confuse theories with educated guesses or hypotheses, theories have withstood more rigorous testing and verification than hypotheses.

[OL] Explain to students that in informal, everyday English the word theory can be used to describe an idea that is possibly true but that has not been proven to be true. This use of the word theory often leads people to think that scientific theories are nothing more than educated guesses. This is not just a misconception among students, but among the general public as well.

As a closing idea about scientific processes, we want to point out that scientific laws and theories, even those that have been supported by experiments for centuries, can still be changed by new discoveries. This is especially true when new technologies emerge that allow us to observe things that were formerly unobservable. Imagine how viewing previously invisible objects with a microscope or viewing Earth for the first time from space may have instantly changed our scientific theories and laws! What discoveries still await us in the future? The constant retesting and perfecting of our scientific laws and theories allows our knowledge of nature to progress. For this reason, many scientists are reluctant to say that their studies prove anything. By saying support instead of prove , it keeps the door open for future discoveries, even if they won’t occur for centuries or even millennia.

[OL] With regard to scientists avoiding using the word prove , the general public knows that science has proven certain things such as that the heart pumps blood and the Earth is round. However, scientists should shy away from using prove because it is impossible to test every single instance and every set of conditions in a system to absolutely prove anything. Using support or similar terminology leaves the door open for further discovery.

Check Your Understanding

• Models are simpler to analyze.
• Models give more accurate results.
• Models provide more reliable predictions.
• Models do not require any computer calculations.
• They are the same.
• A hypothesis has been thoroughly tested and found to be true.
• A hypothesis is a tentative assumption based on what is already known.
• A hypothesis is a broad explanation firmly supported by evidence.
• A scientific model is a representation of something that can be easily studied directly. It is useful for studying things that can be easily analyzed by humans.
• A scientific model is a representation of something that is often too difficult to study directly. It is useful for studying a complex system or systems that humans cannot observe directly.
• A scientific model is a representation of scientific equipment. It is useful for studying working principles of scientific equipment.
• A scientific model is a representation of a laboratory where experiments are performed. It is useful for studying requirements needed inside the laboratory.
• The hypothesis must be validated by scientific experiments.
• The hypothesis must not include any physical quantity.
• The hypothesis must be a short and concise statement.
• The hypothesis must apply to all the situations in the universe.
• A scientific theory is an explanation of natural phenomena that is supported by evidence.
• A scientific theory is an explanation of natural phenomena without the support of evidence.
• A scientific theory is an educated guess about the natural phenomena occurring in nature.
• A scientific theory is an uneducated guess about natural phenomena occurring in nature.
• A hypothesis is an explanation of the natural world with experimental support, while a scientific theory is an educated guess about a natural phenomenon.
• A hypothesis is an educated guess about natural phenomenon, while a scientific theory is an explanation of natural world with experimental support.
• A hypothesis is experimental evidence of a natural phenomenon, while a scientific theory is an explanation of the natural world with experimental support.
• A hypothesis is an explanation of the natural world with experimental support, while a scientific theory is experimental evidence of a natural phenomenon.

Use the Check Your Understanding questions to assess students’ achievement of the section’s learning objectives. If students are struggling with a specific objective, the Check Your Understanding will help identify which objective and direct students to the relevant content.

This book may not be used in the training of large language models or otherwise be ingested into large language models or generative AI offerings without OpenStax's permission.

Want to cite, share, or modify this book? This book uses the Creative Commons Attribution License and you must attribute Texas Education Agency (TEA). The original material is available at: https://www.texasgateway.org/book/tea-physics . Changes were made to the original material, including updates to art, structure, and other content updates.

Access for free at https://openstax.org/books/physics/pages/1-introduction

• Authors: Paul Peter Urone, Roger Hinrichs
• Publisher/website: OpenStax
• Book title: Physics
• Publication date: Mar 26, 2020
• Location: Houston, Texas
• Book URL: https://openstax.org/books/physics/pages/1-introduction
• Section URL: https://openstax.org/books/physics/pages/1-2-the-scientific-methods

© Jun 7, 2024 Texas Education Agency (TEA). The OpenStax name, OpenStax logo, OpenStax book covers, OpenStax CNX name, and OpenStax CNX logo are not subject to the Creative Commons license and may not be reproduced without the prior and express written consent of Rice University.

• Scope And Excitement Of Physics

Physics covers an outsized area of study. Its range is extremely vast, from the molecular level to the astronomical level. Thus it’s exciting also. So, during this article, we’ll be discussing the scope and excitement of Physics. Physics is basically the study of energy , matter, and their interactions. It’s a very broad field because it is concerned with matter and energy in the least levels—from the foremost fundamental particles of interest in the whole universe.

                                                                      Scope And Excitement Of Physics

What is the Scope of Physics?

Physics is a very vast subject. The scope of physics deals with the magnitude of physical quantities like energy, mass etc. The scope of physics is best understood under the three disciplines Microscopic, Mesoscopic and Macroscopic phenomena.

Microscopic Phenomena

This phenomenon takes place at the molecular or atomic level.

Mesoscopic Phenomena

It occurs between the microscopic and macroscopic phenomena. This level of physics is applicable once we enforce miniature of the macroscopic level phenomena as wiped out electronic physics.

Macroscopic Phenomena

All the theories related to classical physics is not applicable to microscopic and mesoscopic phenomena. Hence, macroscopic phenomena come into effect. It includes:

• Mechanics – The world of Physics that deals with the behaviour of bodies and their effect on the environment when subjected to external mechanical force is understood as Mechanics. For example, pushing a door or pulling a rope is an example of mechanical force.
• Electrodynamics – The world of Physics that deals with the electrical and magnetic phenomena relating to the charged and magnetic bodies are often known as Electrodynamics. Example – Response of electrical circuits to ac voltage(signal) or working of an antenna.
• Optics – The branch of Physics that deals with light related phenomena is mentioned as Optics. It covers the issues associated with optical phenomena and instruments.
• Thermodynamics – It’s the branch of physics that deals with the situations that consisted of macroscopic equilibrium and takes care of entropy change, temperature, internal energy etc. of the system through external work and warmth transfer. It’s different from mechanics because it doesn’t deal with the motion of particles as an entire. The efficiency of engines and refrigerators, the direction of physical or chemical processes are the issues of interest in Thermodynamics .

Excitement of Physics

Physics may be a very exciting subject. It excites people’s mentality in many ways. Some think that they will pose a huge magnitude of physical quantities with help of a couple of basic principles. For a few, each problem within physics may be a challenge.

Excitement results in Progress – Basically it is the excitement that results in experiment and progress. Excitement to seek out new ways of learning has made physics advance at such rapid speed. Physics is very vast with many variations and the most interesting as well as an exciting subject. Proving its laws may be a thrilling work for the lover of physics. As we move on, we’ll see many interesting parts of physics in future.

FAQs about Scope And Excitement Of Physics

Q.1. What is the two scopes of physics?

Answer – The two scopes of physics are – Classical Physics and Modern Physics. Classical physics principle works with the macroscopic phenomena while the modern physics principle works upon the microscopic phenomena.

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Chapter 1: Units, Dimensions, and Measurements

Back to chapter, the scope of physics, next video 1.2: orders of magnitude.

Physics is the study of nature and the laws that help us in understanding all natural phenomena. This is because everything consists of matter and energy and interacts in space and time.

Principles of physics are key elements in many scientific disciplines. In chemistry, they are applied to study the interactions of atoms and molecules. In many engineering branches, we use the laws of physics in designing new technologies and devices.

Physics also describes the chemical processes that take place in the human body, making possible the development of techniques and devices used in biological and medical sciences.

The laws of physics are used by all the disciplines, and the study of physics greatly contributes to our understanding of other sciences.

Many physical quantities that are defined by the laws of physics can be expressed as a combination of length, mass, and time quantities.

Length is a physical measurement of distance that is measured in the SI unit of the meter, mass with the unit of the kilogram, and time with the unit seconds.

Physics is concerned with the interactions of energy, matter, space, and time, in order to discover the underlying mechanisms that underpin all phenomena. The word "physics" comes from the Greek word "phúsis", which means nature. Physics seeks to comprehend the natural world around us at its most fundamental level. It emphasizes the use of quantitative laws to do this, which could be valuable in other fields that want to push the performance boundaries of present technologies.

Physics knowledge is vital, not only in scientific careers, but in everyday settings too. For instance, physics can help us understand how microwave ovens work, and why they might affect pacemakers. Many disciplines rely on physics, and it contributes directly to several more. For example, chemistry deals with the interactions of atoms and molecules, and so it has close ties to atomic and molecular physics. Similarly, most branches of engineering are concerned with designing new technologies, processes, or structures within the constraints set by the laws of physics.

It is not necessary to formally learn all applications of physics. Knowing the fundamental rules and having the analytical skills to apply them is the most valuable thing you can do. Physics can also help you enhance your problem-solving abilities. Furthermore, because physics preserves the most fundamental components of science, it is used by all sciences.

This text is adapted from Openstax, University Physics Volume 1, Chapter 1: Units and Measurements.

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What is physics?

Physics is the branch of science that deals with the structure of matter and how the fundamental constituents of the universe interact. It studies objects ranging from the very small using quantum mechanics to the entire universe using general relativity .

Physicists and other scientists use the International System of Units (SI) in their work because they wish to use a system that is agreed upon by scientists worldwide. Since 2019 the SI units have been defined in terms of fundamental physical constants, which means that scientists anywhere using SI can agree upon the units they use to measure physical phenomena.

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physics , science that deals with the structure of matter and the interactions between the fundamental constituents of the observable universe . In the broadest sense, physics (from the Greek physikos ) is concerned with all aspects of nature on both the macroscopic and submicroscopic levels. Its scope of study encompasses not only the behaviour of objects under the action of given forces but also the nature and origin of gravitational, electromagnetic, and nuclear force fields. Its ultimate objective is the formulation of a few comprehensive principles that bring together and explain all such disparate phenomena.

(Read Einstein’s 1926 Britannica essay on space-time.)

Physics is the basic physical science . Until rather recent times physics and natural philosophy were used interchangeably for the science whose aim is the discovery and formulation of the fundamental laws of nature. As the modern sciences developed and became increasingly specialized, physics came to denote that part of physical science not included in astronomy , chemistry , geology , and engineering . Physics plays an important role in all the natural sciences, however, and all such fields have branches in which physical laws and measurements receive special emphasis, bearing such names as astrophysics , geophysics , biophysics , and even psychophysics . Physics can, at base, be defined as the science of matter , motion , and energy . Its laws are typically expressed with economy and precision in the language of mathematics .

Both experiment, the observation of phenomena under conditions that are controlled as precisely as possible, and theory, the formulation of a unified conceptual framework, play essential and complementary roles in the advancement of physics. Physical experiments result in measurements, which are compared with the outcome predicted by theory. A theory that reliably predicts the results of experiments to which it is applicable is said to embody a law of physics. However, a law is always subject to modification, replacement, or restriction to a more limited domain, if a later experiment makes it necessary.

The ultimate aim of physics is to find a unified set of laws governing matter, motion, and energy at small (microscopic) subatomic distances, at the human (macroscopic) scale of everyday life, and out to the largest distances (e.g., those on the extragalactic scale). This ambitious goal has been realized to a notable extent. Although a completely unified theory of physical phenomena has not yet been achieved (and possibly never will be), a remarkably small set of fundamental physical laws appears able to account for all known phenomena. The body of physics developed up to about the turn of the 20th century, known as classical physics, can largely account for the motions of macroscopic objects that move slowly with respect to the speed of light and for such phenomena as heat , sound , electricity , magnetism , and light . The modern developments of relativity and quantum mechanics modify these laws insofar as they apply to higher speeds, very massive objects, and to the tiny elementary constituents of matter, such as electrons , protons , and neutrons .

The scope of physics

The traditionally organized branches or fields of classical and modern physics are delineated below.

Mechanics is generally taken to mean the study of the motion of objects (or their lack of motion) under the action of given forces. Classical mechanics is sometimes considered a branch of applied mathematics. It consists of kinematics , the description of motion, and dynamics , the study of the action of forces in producing either motion or static equilibrium (the latter constituting the science of statics ). The 20th-century subjects of quantum mechanics, crucial to treating the structure of matter, subatomic particles , superfluidity , superconductivity , neutron stars , and other major phenomena, and relativistic mechanics , important when speeds approach that of light, are forms of mechanics that will be discussed later in this section.

In classical mechanics the laws are initially formulated for point particles in which the dimensions, shapes, and other intrinsic properties of bodies are ignored. Thus in the first approximation even objects as large as Earth and the Sun are treated as pointlike—e.g., in calculating planetary orbital motion. In rigid-body dynamics , the extension of bodies and their mass distributions are considered as well, but they are imagined to be incapable of deformation . The mechanics of deformable solids is elasticity ; hydrostatics and hydrodynamics treat, respectively, fluids at rest and in motion.

The three laws of motion set forth by Isaac Newton form the foundation of classical mechanics, together with the recognition that forces are directed quantities ( vectors ) and combine accordingly. The first law, also called the law of inertia , states that, unless acted upon by an external force , an object at rest remains at rest, or if in motion, it continues to move in a straight line with constant speed . Uniform motion therefore does not require a cause. Accordingly, mechanics concentrates not on motion as such but on the change in the state of motion of an object that results from the net force acting upon it. Newton’s second law equates the net force on an object to the rate of change of its momentum, the latter being the product of the mass of a body and its velocity. Newton’s third law, that of action and reaction, states that when two particles interact, the forces each exerts on the other are equal in magnitude and opposite in direction. Taken together, these mechanical laws in principle permit the determination of the future motions of a set of particles, providing their state of motion is known at some instant, as well as the forces that act between them and upon them from the outside. From this deterministic character of the laws of classical mechanics, profound (and probably incorrect) philosophical conclusions have been drawn in the past and even applied to human history.

Lying at the most basic level of physics, the laws of mechanics are characterized by certain symmetry properties, as exemplified in the aforementioned symmetry between action and reaction forces. Other symmetries, such as the invariance (i.e., unchanging form) of the laws under reflections and rotations carried out in space , reversal of time, or transformation to a different part of space or to a different epoch of time, are present both in classical mechanics and in relativistic mechanics, and with certain restrictions, also in quantum mechanics. The symmetry properties of the theory can be shown to have as mathematical consequences basic principles known as conservation laws , which assert the constancy in time of the values of certain physical quantities under prescribed conditions. The conserved quantities are the most important ones in physics; included among them are mass and energy (in relativity theory, mass and energy are equivalent and are conserved together), momentum , angular momentum , and electric charge .

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From theory to experiment, share this:.

Special Feature

A view of the types of physics research

Jess McIver, Graduate Student, University of Massachusetts Amherst

University of Massachusetts-Amherst

Physics research can usually be classified as theory, experiment, computation, or somewhere in between. Each type of research has its own challenges and rewards.

Theorists use mathematics and models to explain current phenomena, predict new ones, and describe the laws of the universe. Often these researchers tackle specific problems limited in scope, such as modeling nuanced particle interactions or predicting the amplitude of gravitational waves propogating from shortly after the big bang.

Experimentalists test theoretical predictions as well as investigate observable interactions and physical behavior. This generally involves constructing and operating instrumentation used for measurement or observation, on a scale from the rather small (equipment that fits easily inside a small room) to the very large (e.g., the Large Hadron Collider, which has a 27-km circumference). Experimental physics often leads theory, as when a new unpredicted particle is discovered. Likewise, theory often leads experimental activities. 

Computation

Computational physics is increasingly becoming a field unto itself. These researchers apply numerical analysis and other computational techniques to physics problems, including large-scale weather simulations, investigations of the properties of semiconductors, or models of protein folding. Computation has deep connections to both theory and experiment. 

Introducing LIGO

The Laser Interferometer Gravitational-Wave Observatory (LIGO) is a great example of a project that draws on different types of physics. LIGO consists of two state-of-the-art interferometers, one in Hanford, Washington, and the other in Livingston, Louisiana. They are designed to measure gravitational waves, tiny perturbations in the fabric of space-time emitted by astrophysical events great distances away.

Using strain measured by LIGO’s giant Michelson interferometers, we should be able to reconstruct the signal of a passing gravitational wave created by, for example, a neutron star merger, a galactic supernova, or a pulsar. If detected, gravitational waves would be especially interesting for probing astrophysical objects and events that are difficult to observe via telescopes. 

Experimental physicists from around the world design, test, and install the cutting-edge technology that makes the interferometers work, from optic cavities and coatings to systems that isolate the optics from the constantly moving ground. Reading out the data that LIGO produces, calibrating it correctly, transmitting it for immediate analysis, and storing it all for future use requires an enormous amount of computing power. To search for small signals in that noisy data, data analysts blend theory, experiment, and computation techniques to build algorithms that search for different types of gravitational-wave signals. An especially powerful method compares the data with gravitational-wave templates generated with known astrophysical models, supplied by theorists and computational theorists called numerical relativists. It’s an enormously complicated project with many different specialties.

The scientists of the LIGO Scientific Collaboration are a diverse group at different stages of their careers, based at institutions big and small, focusing on many types of physics research that are all integral to the goal of observing new astrophysics from gravitational waves. //

MORE INFORMATION

Learn more about LIGO at www.ligo.org .

Apply for the LIGO Summer Undergraduate Research Fellowship at www.ligo.caltech.edu/LIGO_web/students/SURF/ .

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• Scope and Excitement of Physics

Scope and Excitement of Physics in Detail

Physics is a universal truth that guides the existence of all animate and inanimate objects in nature. It is not a subject that is only bound inside a book but a vast truth spoken in the language of mathematics. The excitement of physics is so immense that many people have dedicated their whole lives to physics. The excitement of physics ranges from simple joyful science experiments and magic tricks to large hadron colliders sprawling across countries. Scope of physics includes dealing with fast moving racing cars to infinitesimally slow decaying carbon. Even for  a beating heart, expanding lungs and rushing blood inside vessels, physics has an answer, a lucid mathematical one.

Scope And Excitement of Physics in Detail

Physics is one of the important branches of science. It details the matter, how it changes, how it forms. It considers very tiny particles to the whole universe. Physics plays a predominant role in our day-to-day life. Most of the activities can be identified using Physics. So let us understand what the scope and excitement of physics are.

Scope and Excitement of Physics Class 11

For the Class 11th students, it is imperative to discuss the scope and excitement of physics. Because after Class 12, the student needs to choose their career option. Many of the young generations have several scientists in them. So with the proper understanding and prior knowledge of the scope and excitement of physics only, the students get interested in the subject and try to enrich their learning according to that. Physics for Class 11 is not a subject of interest and excitement but a foundation for securing a much coveted dream career for them. Physics can open the door for an aspiring engineer or a scientist and this is very clear to a Class 11-12 student who focuses on this subject with such an aim in future.

Define Scope and Excitement of Physics

The Scope and Excitement of Physics in the Modern world can be defined as the threading or involving physics to a particular extent and how this spreading will be happening is called the scope and excitement of physics. But we cannot define the scope of physics Particularly in one or two sentences. Its scope is very vast and can be seen in day-to-day life.

The Scope of physics can be categorized into two disciplines for the convenience of better understanding. They are:

Microscopic.

Macroscopic.

Microscopic Physics

If the students are asked to get the scope and excitement of physics assignment download, there they can find a detailed explanation of all disciplines of physics which can be explained below. Microscopic physics deals with the movement of atoms and molecules. It is also known as modern physics. It consists of two.

Quantum Mechanics: - Quantum mechanics is a part of the scope of physics. It majorly deals with the subatomic particles and their movements. The quantization of energy, uncertainty principle, etc. was studied and can be identified in Quantum mechanics.

Theory of Relativity:- This theory was proposed by the father of physics, Albert Einstein. According to Einstein, the moment of inertia and the non-inertial particles and their relation can be studied in relativity theory. All these points are very helpful in the scope and excitement of the physics seminar for the students of Class 11.

Macroscopic Physics

In the scope and excitement of physics assignment, the next segment is about macroscopic physics. It deals with the study and understanding of finite size objects and terrestrial bodies. In contrast to modern physics, it is known as classical physics. The scope and excitement of physics can be explained using measures here. They are:

Mechanics:- The name itself explains that mechanics is a branch of physics that deals with the position and motion of an object. Newton's laws of motion can be formed using these mechanics only.

Thermodynamics:- The next subheading of the scope and excitement of physics is thermodynamics. Thermo means heat. Dynamics means movement or change or conversion. Here it explains the conversion of heat energy into various forms like mechanical energy or electrical energy or any other.

Electrodynamics:- Electro Dynamics is another band branch of physics that deals with the movement and interaction between two charged bodies. Electric field and magnetic field Concepts were explained here by the scientists, Coulomb and Oersted.

Optics:- It is an advanced branch of physics that is the most important segment in the scope and excitement of physics assignment. It deals with light and images. Also, the properties like reflection, refraction, diversification, etc. can be understood in optics.

The Excitement of Physics Class 11

While preparing for the scope and excitement of the physics seminar, it is essential to highlight the excitement of physics for Class 11. Generally, excitement means curiosity to know how it happens or what happens. The ancient people or the older generations may not know the advanced technologies like treadmills, GPS technology, teleportation, etc. Still, those people tried to know and understand the subject to gain in-depth knowledge. Then they think of the utilization of this knowledge. This leads to the inventions of several enhancements. This curiosity of learning physics is nothing but the excitement of physics.

Hence the scope and excitement of physics can be understood and a clear idea. However, the scope of physics can't be restricted here. The scope of physics keeps on changing and expanding its range according to the changes in day-to-day life.

FAQs on Scope and Excitement of Physics

1. What Important Laws are There in Physics?

Physical laws are the last, which can be drawn as a conclusion after conducting several observations and experiments followed by thorough research. These last play a vital role in the field of science, which concise the work or may convert to energy or action.

Archimedes Principle.

Avagadro’s Law.

Newton’s Laws.

Coulomb’s Law.

Stefan’s Law.

Pascal’s Law.

Hooke’s Law.

Bernoulli's Principle.

Boyle's Law.

Charles law.

Kepler's Law.

Graham's law.

Tyndall's law.

Law of conservation of energy.

These are the important physical laws stated by different scientists after their experiments and research.

2. How Physics is Related to Other Subjects?

As physics is a vast subject and has several innovative things, it is used by different subjects. Also, some other subjects are used by physics. For example, if we consider maths, mathematics is a theory of numbers. And explains the numbers and their relationship, calculations, etc. To find out the observations in physics, we need to find the values and calculate the result using the formula after experimenting. This can be done with the help of mathematics.

Similarly, if we take the manufacturing of opticals, it uses several principles derived from physics. And the major concept of optical fiber is very helpful in the manufacturing of opticals. Besides all these, ontology, which involves real-world experiences, reliable experiments. It uses both physics and mathematics to get the output. As mathematics is a set of patterns, hypotheses whereas physics explains various theories and reactions, the moment of internal particles, and external particles. So by combining all these, we can perform activities of ontology.

3. What Are the different branches of Physics?

Physics is a vast subject that encompasses all universal truths in daily life proven and reestablished by great scientists by theories, principles and laws. They touch all the branches of physics. The subject is divided into the following branches:

Thermodynamics

Electromagnetism

Relativistic Mechanics

Quantum mechanics

Molecular physics

Nuclear physics

Condensed matter physics

Astrophysics

Particle physics

Plasma physics.

There are many hybrids of physics to touch and understand many concepts in other subjects like biophysics and geophysics. Physical chemistry is also of much importance.

4. What are the scopes in physics?

The scope of physics is enormous. However, the scope is much more in Applied physics than in theoretical physics. The scope of research is huge in physics. Research in spintronics, low-temperature physics is going in full-fledged in some great institutions of the country like IISc, TIFR and IIT. Important topics for research in physics also include semiconductor physics and crystal physics. Researches in astrophysics are quite fascinating and they have scopes in institutions like IIA and NCRA. Research in physics has huge scope and demand but it is highly competitive at the same time.

5. What are the career prospects in Physics?

Studying physics and mastering it can give you a secured professional life. There are many job prospects in Physics that can be equally interesting and secure. Few job prospects enlisted below:

Engineering

Research scientists.

Robotic engineering

Space scientists

Astronomists

Quality control manager

Academics like professors and lecturers

Physics teacher

Data Scientist

Aerospace engineer

Optical engineer

Medical Physicist

Web developer

Research analyst and associate

There are many more but research in institutions like IISc, TIFR, BARC and a few IITs is the dream of many budding scientists. This field is interesting and gives them a scope to explore the depth of the scientist and contribute further to it.

6. Why is Physics so interesting and exciting?

Physics is not only exciting to a physicist or a scientist exploring different arenas of physics but also interesting to common men. The common man or even a child can relate the facts and theories of physics in day-to-day life. Everything in physics can be mathematically derived and conceptually understood. There is not much to rote-learn in the subject making it more exciting. The concepts in physics govern nature and carry huge importance but again they can be simply derived with a pen and paper. So to understand and decipher the tales of natural physics is a unique quest. It is the greatest tool by which we can express our creativity and hence we find it so exciting.

7. How are physics and other subjects related to each other?

The concepts of physics are so vast that it encompasses many other subjects and science in daily life as well.  All the major theories and derivations need mathematics to explain it thus making an everlasting relationship between the two subjects. Physics is related to chemistry under the branch of Physical chemistry where they both go hand in hand to explain a huge arena of real-world science. Physics of the body is such a deep-rooted concept and such a vast field that new hybrids of biology and physics have been added to the list of subjects. They are biophysics and biotechnology. Physics is also related to geography as well and so is the inclusion of the subject geophysics to understand and predict earthquakes or any other calamity.

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Experimental Physics

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This textbook provides the knowledge and skills needed for thorough understanding of the most important methods and ways of thinking in experimental physics. The reader learns to design, assemble, and debug apparatus, to use it to take meaningful data, and to think carefully about the story told by the data.

Key Features:

• Efficiently helps students grow into independent experimentalists through a combination of structured yet thought-provoking and challenging exercises, student-designed experiments, and guided but open-ended exploration.
• Provides solid coverage of fundamental background information, explained clearly for undergraduates, such as ground loops, optical alignment techniques, scientific communication, and data acquisition using LabVIEW, Python, or Arduino.
• Features carefully designed lab experiences to teach fundamentals, including analog electronics and low noise measurements, digital electronics, microcontrollers, FPGAs, computer interfacing, optics, vacuum techniques, and particle detection methods.
• Offers a broad range of advanced experiments for each major area of physics, from condensed matter to particle physics. Also provides clear guidance for student development of projects not included here.
• Provides a detailed Instructor’s Manual for every lab, so that the instructor can confidently teach labs outside their own research area.

TABLE OF CONTENTS

Part i | 70  pages, fundamentals, chapter 1 | 4  pages, introduction, chapter 2 | 12  pages, planning and carrying out experiments, chapter 3 | 10  pages, presenting your results, chapter 4 | 24  pages, uncertainty and statistics, chapter 5 | 18  pages, scientific ethics, part ii | 216  pages, tools of an experimentalist, chapter 6 | 60  pages, analog electronics, chapter 7 | 10  pages, fundamentals of interfacing experiments with computers, chapter 8 | 52  pages, digital electronics, chapter 9 | 32  pages, data acquisition and experiment control with python, chapter 10 | 20  pages, basic optics techniques and hardware, chapter 11 | 16  pages, laser beams, polarization, and interference, chapter 12 | 4  pages, chapter 13 | 20  pages, particle detection, part iii | 144  pages, fields of physics, chapter 14 | 10  pages, development and supervision of independent projects, chapter 15 | 8  pages, condensed matter physics, chapter 16 | 20  pages, chapter 17 | 14  pages, non-linear, granular, and fluid physics, chapter 18 | 30  pages, atomic and molecular physics, chapter 19 | 6  pages, photonics and fiber optics, chapter 20 | 26  pages, experiments with entangled photons, chapter 21 | 28  pages, nuclear and particle physics.

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1 Units and Measurement

1.1 the scope and scale of physics, learning objectives.

By the end of this section, you will be able to:

• Describe the scope of physics.
• Calculate the order of magnitude of a quantity.
• Compare measurable length, mass, and timescales quantitatively.
• Describe the relationships among models, theories, and laws.

Physics is devoted to the understanding of all natural phenomena. In physics, we try to understand physical phenomena at all scales—from the world of subatomic particles to the entire universe. Despite the breadth of the subject, the various subfields of physics share a common core. The same basic training in physics will prepare you to work in any area of physics and the related areas of science and engineering. In this section, we investigate the scope of physics; the scales of length, mass, and time over which the laws of physics have been shown to be applicable; and the process by which science in general, and physics in particular, operates.

The Scope of Physics

Take another look at the chapter-opening image. The Whirlpool Galaxy contains billions of individual stars as well as huge clouds of gas and dust. Its companion galaxy is also visible to the right. This pair of galaxies lies a staggering billion trillion miles [latex] (1.4\,×\,{10}^{21}\text{mi}) [/latex] from our own galaxy (which is called the Milky Way ). The stars and planets that make up the Whirlpool Galaxy might seem to be the furthest thing from most people’s everyday lives, but the Whirlpool is a great starting point to think about the forces that hold the universe together. The forces that cause the Whirlpool Galaxy to act as it does are thought to be the same forces we contend with here on Earth, whether we are planning to send a rocket into space or simply planning to raise the walls for a new home. The gravity that causes the stars of the Whirlpool Galaxy to rotate and revolve is thought to be the same as what causes water to flow over hydroelectric dams here on Earth. When you look up at the stars, realize the forces out there are the same as the ones here on Earth. Through a study of physics , you may gain a greater understanding of the interconnectedness of everything we can see and know in this universe.

Think, now, about all the technological devices you use on a regular basis. Computers, smartphones, global positioning systems (GPSs), MP3 players, and satellite radio might come to mind. Then, think about the most exciting modern technologies you have heard about in the news, such as trains that levitate above tracks, “invisibility cloaks” that bend light around them, and microscopic robots that fight cancer cells in our bodies. All these groundbreaking advances, commonplace or unbelievable, rely on the principles of physics. Aside from playing a significant role in technology, professionals such as engineers, pilots, physicians, physical therapists, electricians, and computer programmers apply physics concepts in their daily work. For example, a pilot must understand how wind forces affect a flight path; a physical therapist must understand how the muscles in the body experience forces as they move and bend. As you will learn in this text, the principles of physics are propelling new, exciting technologies, and these principles are applied in a wide range of careers.

The underlying order of nature makes science in general, and physics in particular, interesting and enjoyable to study. For example, what do a bag of chips and a car battery have in common? Both contain energy that can be converted to other forms. The law of conservation of energy (which says that energy can change form but is never lost) ties together such topics as food calories, batteries, heat, light, and watch springs. Understanding this law makes it easier to learn about the various forms energy takes and how they relate to one another. Apparently unrelated topics are connected through broadly applicable physical laws, permitting an understanding beyond just the memorization of lists of facts.

Science consists of theories and laws that are the general truths of nature, as well as the body of knowledge they encompass. Scientists are continuously trying to expand this body of knowledge and to perfect the expression of the laws that describe it. Physics , which comes from the Greek phúsis , meaning “nature,” is concerned with describing the interactions of energy, matter, space, and time to uncover the fundamental mechanisms that underlie every phenomenon. This concern for describing the basic phenomena in nature essentially defines the scope of physics .

Physics aims to understand the world around us at the most basic level. It emphasizes the use of a small number of quantitative laws to do this, which can be useful to other fields pushing the performance boundaries of existing technologies. Consider a smartphone ( (Figure) ). Physics describes how electricity interacts with the various circuits inside the device. This knowledge helps engineers select the appropriate materials and circuit layout when building a smartphone. Knowledge of the physics underlying these devices is required to shrink their size or increase their processing speed. Or, think about a GPS. Physics describes the relationship between the speed of an object, the distance over which it travels, and the time it takes to travel that distance. When you use a GPS in a vehicle, it relies on physics equations to determine the travel time from one location to another.

Figure 1.2  The Apple iPhone is a common smartphone with a GPS function. Physics describes the way that electricity flows through the circuits of this device. Engineers use their knowledge of physics to construct an iPhone with features that consumers will enjoy. One specific feature of an iPhone is the GPS function. A GPS uses physics equations to determine the drive time between two locations on a map.

Knowledge of physics is useful in everyday situations as well as in nonscientific professions. It can help you understand how microwave ovens work, why metals should not be put into them, and why they might affect pacemakers. Physics allows you to understand the hazards of radiation and to evaluate these hazards rationally and more easily. Physics also explains the reason why a black car radiator helps remove heat in a car engine, and it explains why a white roof helps keep the inside of a house cool. Similarly, the operation of a car’s ignition system as well as the transmission of electrical signals throughout our body’s nervous system are much easier to understand when you think about them in terms of basic physics.

Physics is a key element of many important disciplines and contributes directly to others. Chemistry, for example—since it deals with the interactions of atoms and molecules—has close ties to atomic and molecular physics. Most branches of engineering are concerned with designing new technologies, processes, or structures within the constraints set by the laws of physics. In architecture, physics is at the heart of structural stability and is involved in the acoustics, heating, lighting, and cooling of buildings. Parts of geology rely heavily on physics, such as radioactive dating of rocks, earthquake analysis, and heat transfer within Earth. Some disciplines, such as biophysics and geophysics, are hybrids of physics and other disciplines.

Physics has many applications in the biological sciences. On the microscopic level, it helps describe the properties of cells and their environments. On the macroscopic level, it explains the heat, work, and power associated with the human body and its various organ systems. Physics is involved in medical diagnostics, such as radiographs, magnetic resonance imaging, and ultrasonic blood flow measurements. Medical therapy sometimes involves physics directly; for example, cancer radiotherapy uses ionizing radiation. Physics also explains sensory phenomena, such as how musical instruments make sound, how the eye detects color, and how lasers transmit information.

It is not necessary to study all applications of physics formally. What is most useful is knowing the basic laws of physics and developing skills in the analytical methods for applying them. The study of physics also can improve your problem-solving skills. Furthermore, physics retains the most basic aspects of science, so it is used by all the sciences, and the study of physics makes other sciences easier to understand.

The Scale of Physics

From the discussion so far, it should be clear that to accomplish your goals in any of the various fields within the natural sciences and engineering, a thorough grounding in the laws of physics is necessary. The reason for this is simply that the laws of physics govern everything in the observable universe at all measurable scales of length, mass, and time. Now, that is easy enough to say, but to come to grips with what it really means, we need to get a little bit quantitative. So, before surveying the various scales that physics allows us to explore, let’s first look at the concept of “order of magnitude,” which we use to come to terms with the vast ranges of length, mass, and time that we consider in this text ( (Figure) ).

Figure 1.3 (a) Using a scanning tunneling microscope, scientists can see the individual atoms (diameters around 10–10 m) that compose this sheet of gold. (b) Tiny phytoplankton swim among crystals of ice in the Antarctic Sea. They range from a few micrometers (1 μm is 10–6 m) to as much as 2 mm (1 mm is 10–3 m) in length. (c) These two colliding galaxies, known as NGC 4676A (right) and NGC 4676B (left), are nicknamed “The Mice” because of the tail of gas emanating from each one. They are located 300 million light-years from Earth in the constellation Coma Berenices. Eventually, these two galaxies will merge into one. (credit a: modification of work by Erwinrossen; credit b: modification of work by Prof. Gordon T. Taylor, Stony Brook University; NOAA Corps Collections; credit c: modification of work by NASA, H. Ford (JHU), G. Illingworth (UCSC/LO), M. Clampin (STScI), G. Hartig (STScI), the ACS Science Team, and ESA)

Order of magnitude

The order of magnitude of a number is the power of 10 that most closely approximates it. Thus, the order of magnitude refers to the scale (or size) of a value. Each power of 10 represents a different order of magnitude. For example, [latex] {10}^{1},{10}^{2},{10}^{3}, [/latex] and so forth, are all different orders of magnitude, as are [latex] {10}^{0}=1,{10}^{-1},{10}^{-2}, [/latex] and [latex] {10}^{-3}. [/latex] To find the order of magnitude of a number, take the base-10 logarithm of the number and round it to the nearest integer, then the order of magnitude of the number is simply the resulting power of 10. For example, the order of magnitude of 800 is 10 3 because [latex] {\text{log}}_{10}800\approx 2.903, [/latex] which rounds to 3. Similarly, the order of magnitude of 450 is 10 3 because [latex] {\text{log}}_{10}450\approx 2.653, [/latex] which rounds to 3 as well. Thus, we say the numbers 800 and 450 are of the same order of magnitude: 10 3 . However, the order of magnitude of 250 is 10 2 because [latex] {\text{log}}_{10}250\approx 2.397, [/latex] which rounds to 2.

An equivalent but quicker way to find the order of magnitude of a number is first to write it in scientific notation and then check to see whether the first factor is greater than or less than [latex] \sqrt{10}={10}^{0.5}\approx 3. [/latex] The idea is that [latex] \sqrt{10}={10}^{0.5} [/latex] is halfway between [latex] 1={10}^{0} [/latex] and [latex] 10={10}^{1} [/latex] on a log base-10 scale. Thus, if the first factor is less than [latex] \sqrt{10}, [/latex] then we round it down to 1 and the order of magnitude is simply whatever power of 10 is required to write the number in scientific notation. On the other hand, if the first factor is greater than [latex] \sqrt{10}, [/latex] then we round it up to 10 and the order of magnitude is one power of 10 higher than the power needed to write the number in scientific notation. For example, the number 800 can be written in scientific notation as [latex] 8\,×\,{10}^{2}. [/latex] Because 8 is bigger than [latex] \sqrt{10}\approx 3, [/latex] we say the order of magnitude of 800 is [latex] {10}^{2+1}={10}^{3}. [/latex] The number 450 can be written as [latex] 4.5\,×\,{10}^{2}, [/latex] so its order of magnitude is also 10 3 because 4.5 is greater than 3. However, 250 written in scientific notation is [latex] 2.5\,×\,{10}^{2} [/latex] and 2.5 is less than 3, so its order of magnitude is [latex] {10}^{2}. [/latex]

The order of magnitude of a number is designed to be a ballpark estimate for the scale (or size) of its value. It is simply a way of rounding numbers consistently to the nearest power of 10. This makes doing rough mental math with very big and very small numbers easier. For example, the diameter of a hydrogen atom is on the order of 10 −10 m, whereas the diameter of the Sun is on the order of 10 9 m, so it would take roughly [latex] {10}^{9}\text{/}{10}^{-10}={10}^{19} [/latex] hydrogen atoms to stretch across the diameter of the Sun. This is much easier to do in your head than using the more precise values of [latex] 1.06\,×\,{10}^{-10}\text{m} [/latex] for a hydrogen atom diameter and [latex] 1.39\,×\,{10}^{9}\text{m} [/latex] for the Sun’s diameter, to find that it would take [latex] 1.31\,×\,{10}^{19} [/latex] hydrogen atoms to stretch across the Sun’s diameter. In addition to being easier, the rough estimate is also nearly as informative as the precise calculation.

Known ranges of length, mass, and time

The vastness of the universe and the breadth over which physics applies are illustrated by the wide range of examples of known lengths, masses, and times (given as orders of magnitude) in (Figure) . Examining this table will give you a feeling for the range of possible topics in physics and numerical values. A good way to appreciate the vastness of the ranges of values in (Figure) is to try to answer some simple comparative questions, such as the following:

• How many hydrogen atoms does it take to stretch across the diameter of the Sun?(Answer: 10 9 m/10 –10 m = 10 19 hydrogen atoms)
• How many protons are there in a bacterium?(Answer: 10 –15 kg/10 –27 kg = 10 12 protons)
• How many floating-point operations can a supercomputer do in 1 day?(Answer: 10 5 s/10 –17 s = 10 22 floating-point operations)

In studying (Figure) , take some time to come up with similar questions that interest you and then try answering them. Doing this can breathe some life into almost any table of numbers.

Figure 1.4 This table shows the orders of magnitude of length, mass, and time.

Visit this site to explore interactively the vast range of length scales in our universe. Scroll down and up the scale to view hundreds of organisms and objects, and click on the individual objects to learn more about each one.

Building Models

How did we come to know the laws governing natural phenomena? What we refer to as the laws of nature are concise descriptions of the universe around us. They are human statements of the underlying laws or rules that all natural processes follow. Such laws are intrinsic to the universe; humans did not create them and cannot change them. We can only discover and understand them. Their discovery is a very human endeavor, with all the elements of mystery, imagination, struggle, triumph, and disappointment inherent in any creative effort ( (Figure) ). The cornerstone of discovering natural laws is observation; scientists must describe the universe as it is, not as we imagine it to be.

Figure 1.5 (a) Enrico Fermi (1901–1954) was born in Italy. On accepting the Nobel Prize in Stockholm in 1938 for his work on artificial radioactivity produced by neutrons, he took his family to America rather than return home to the government in power at the time. He became an American citizen and was a leading participant in the Manhattan Project. (b) Marie Curie (1867–1934) sacrificed monetary assets to help finance her early research and damaged her physical well-being with radiation exposure. She is the only person to win Nobel prizes in both physics and chemistry. One of her daughters also won a Nobel Prize. (credit a: United States Department of Energy)

A model is a representation of something that is often too difficult (or impossible) to display directly. Although a model is justified by experimental tests, it is only accurate in describing certain aspects of a physical system. An example is the Bohr model of single-electron atoms, in which the electron is pictured as orbiting the nucleus, analogous to the way planets orbit the Sun ( (Figure) ). We cannot observe electron orbits directly, but the mental image helps explain some of the observations we can make, such as the emission of light from hot gases (atomic spectra). However, other observations show that the picture in the Bohr model is not really what atoms look like. The model is “wrong,” but is still useful for some purposes. Physicists use models for a variety of purposes. For example, models can help physicists analyze a scenario and perform a calculation or models can be used to represent a situation in the form of a computer simulation. Ultimately, however, the results of these calculations and simulations need to be double-checked by other means—namely, observation and experimentation.

Figure 1.6 What is a model? The Bohr model of a single-electron atom shows the electron orbiting the nucleus in one of several possible circular orbits. Like all models, it captures some, but not all, aspects of the physical system.

The word theory means something different to scientists than what is often meant when the word is used in everyday conversation. In particular, to a scientist a theory is not the same as a “guess” or an “idea” or even a “hypothesis.” The phrase “it’s just a theory” seems meaningless and silly to scientists because science is founded on the notion of theories. To a scientist, a theory is a testable explanation for patterns in nature supported by scientific evidence and verified multiple times by various groups of researchers. Some theories include models to help visualize phenomena whereas others do not. Newton’s theory of gravity, for example, does not require a model or mental image, because we can observe the objects directly with our own senses. The kinetic theory of gases, on the other hand, is a model in which a gas is viewed as being composed of atoms and molecules. Atoms and molecules are too small to be observed directly with our senses—thus, we picture them mentally to understand what the instruments tell us about the behavior of gases. Although models are meant only to describe certain aspects of a physical system accurately, a theory should describe all aspects of any system that falls within its domain of applicability. In particular, any experimentally testable implication of a theory should be verified. If an experiment ever shows an implication of a theory to be false, then the theory is either thrown out or modified suitably (for example, by limiting its domain of applicability).

A law uses concise language to describe a generalized pattern in nature supported by scientific evidence and repeated experiments. Often, a law can be expressed in the form of a single mathematical equation. Laws and theories are similar in that they are both scientific statements that result from a tested hypothesis and are supported by scientific evidence. However, the designation law is usually reserved for a concise and very general statement that describes phenomena in nature, such as the law that energy is conserved during any process, or Newton’s second law of motion, which relates force ( F ), mass ( m ), and acceleration ( a ) by the simple equation [latex] F=ma. [/latex] A theory, in contrast, is a less concise statement of observed behavior. For example, the theory of evolution and the theory of relativity cannot be expressed concisely enough to be considered laws. The biggest difference between a law and a theory is that a theory is much more complex and dynamic. A law describes a single action whereas a theory explains an entire group of related phenomena. Less broadly applicable statements are usually called principles (such as Pascal’s principle, which is applicable only in fluids), but the distinction between laws and principles often is not made carefully.

The models, theories, and laws we devise sometimes imply the existence of objects or phenomena that are as yet unobserved. These predictions are remarkable triumphs and tributes to the power of science. It is the underlying order in the universe that enables scientists to make such spectacular predictions. However, if experimentation does not verify our predictions, then the theory or law is wrong, no matter how elegant or convenient it is. Laws can never be known with absolute certainty because it is impossible to perform every imaginable experiment to confirm a law for every possible scenario. Physicists operate under the assumption that all scientific laws and theories are valid until a counterexample is observed. If a good-quality, verifiable experiment contradicts a well-established law or theory, then the law or theory must be modified or overthrown completely.

The study of science in general, and physics in particular, is an adventure much like the exploration of an uncharted ocean. Discoveries are made; models, theories, and laws are formulated; and the beauty of the physical universe is made more sublime for the insights gained.

• Physics is about trying to find the simple laws that describe all natural phenomena.
• Physics operates on a vast range of scales of length, mass, and time. Scientists use the concept of the order of magnitude of a number to track which phenomena occur on which scales. They also use orders of magnitude to compare the various scales.
• Scientists attempt to describe the world by formulating models, theories, and laws.

Conceptual Questions

What is physics?

Physics is the science concerned with describing the interactions of energy, matter, space, and time to uncover the fundamental mechanisms that underlie every phenomenon.

Some have described physics as a “search for simplicity.” Explain why this might be an appropriate description.

If two different theories describe experimental observations equally well, can one be said to be more valid than the other (assuming both use accepted rules of logic)?

No, neither of these two theories is more valid than the other. Experimentation is the ultimate decider. If experimental evidence does not suggest one theory over the other, then both are equally valid. A given physicist might prefer one theory over another on the grounds that one seems more simple, more natural, or more beautiful than the other, but that physicist would quickly acknowledge that he or she cannot say the other theory is invalid. Rather, he or she would be honest about the fact that more experimental evidence is needed to determine which theory is a better description of nature.

What determines the validity of a theory?

Certain criteria must be satisfied if a measurement or observation is to be believed. Will the criteria necessarily be as strict for an expected result as for an unexpected result?

Probably not. As the saying goes, “Extraordinary claims require extraordinary evidence.”

Can the validity of a model be limited or must it be universally valid? How does this compare with the required validity of a theory or a law?

Find the order of magnitude of the following physical quantities. (a) The mass of Earth’s atmosphere: [latex] 5.1\,×\,{10}^{18}\text{kg;} [/latex] (b) The mass of the Moon’s atmosphere: 25,000 kg; (c) The mass of Earth’s hydrosphere: [latex] 1.4\,×\,{10}^{21}\text{kg;} [/latex] (d) The mass of Earth: [latex] 5.97\,×\,{10}^{24}\text{kg;} [/latex] (e) The mass of the Moon: [latex] 7.34\,×\,{10}^{22}\text{kg;} [/latex] (f) The Earth–Moon distance (semimajor axis): [latex] 3.84\,×\,{10}^{8}\text{m;} [/latex] (g) The mean Earth–Sun distance: [latex] 1.5\,×\,{10}^{11}\text{m;} [/latex] (h) The equatorial radius of Earth: [latex] 6.38\,×\,{10}^{6}\text{m;} [/latex] (i) The mass of an electron: [latex] 9.11\,×\,{10}^{-31}\text{kg;} [/latex] (j) The mass of a proton: [latex] 1.67\,×\,{10}^{-27}\text{kg;} [/latex] (k) The mass of the Sun: [latex] 1.99\,×\,{10}^{30}\text{kg.} [/latex]

Use the orders of magnitude you found in the previous problem to answer the following questions to within an order of magnitude. (a) How many electrons would it take to equal the mass of a proton? (b) How many Earths would it take to equal the mass of the Sun? (c) How many Earth–Moon distances would it take to cover the distance from Earth to the Sun? (d) How many Moon atmospheres would it take to equal the mass of Earth’s atmosphere? (e) How many moons would it take to equal the mass of Earth? (f) How many protons would it take to equal the mass of the Sun?

a. 10 3 ; b. 10 5 ; c. 10 2 ; d. 10 15 ; e. 10 2 ; f. 10 57

For the remaining questions, you need to use (Figure) to obtain the necessary orders of magnitude of lengths, masses, and times.

Roughly how many heartbeats are there in a lifetime?

A generation is about one-third of a lifetime. Approximately how many generations have passed since the year 0 AD?

10 2 generations

Roughly how many times longer than the mean life of an extremely unstable atomic nucleus is the lifetime of a human?

Calculate the approximate number of atoms in a bacterium. Assume the average mass of an atom in the bacterium is 10 times the mass of a proton.

10 11 atoms

(a) Calculate the number of cells in a hummingbird assuming the mass of an average cell is 10 times the mass of a bacterium. (b) Making the same assumption, how many cells are there in a human?

Assuming one nerve impulse must end before another can begin, what is the maximum firing rate of a nerve in impulses per second?

10 3 nerve impulses/s

About how many floating-point operations can a supercomputer perform each year?

Roughly how many floating-point operations can a supercomputer perform in a human lifetime?

10 26 floating-point operations per human lifetime

• OpenStax University Physics. Authored by : OpenStax CNX. Located at : https://cnx.org/contents/[email protected]:Gofkr9Oy@15 . License : CC BY: Attribution . License Terms : Download for free at http://cnx.org/contents/[email protected]

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Science News

Mayo is weirdly great for understanding nuclear fusion experiments.

A schmear campaign aims to understand how materials transition from elastic to plastic behavior 

Connoisseurs call it “creamy,” haters call it “slimy,” and mechanical engineers call it a “soft solid.” Mayonnaise could help scientists better design nuclear fusion experiments.

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By Emily Conover

19 hours ago

Mayonnaise’s texture inspires love and loathing. Either way, it’s perfect for physics experiments. 

The classic condiment is useful for understanding how materials behave, not only when smeared on sandwiches or plopped in potato salads, but also when deployed in nuclear fusion experiments. Mechanical engineer Arindam Banerjee of Lehigh University in Bethlehem, Pa., and colleagues are studying phenomena that occur in both mayonnaise and in fusion experiments.

Mayonnaise’s behavior sits on the border between elastic and plastic. If jiggled gently, it returns to its original shape. That’s elastic behavior. But fling it forcefully and it goes plastic, meaning it changes shape permanently or breaks apart. 

This elastic-to-plastic transition can also occur in experiments that use lasers to kick off nuclear fusion. In such experiments, lasers blast a metal capsule containing the fuel,  raising pressures and temperatures  so high that atomic nuclei in the fuel fuse together, releasing energy ( SN: 2/16/24 ). Scientists hope to eventually use nuclear fusion as a source of power.

But it’s difficult to study how materials behave under the extreme conditions required for fusion. So in their latest experiment, the scientists looked at how mayo mixed with a gas — air — as they rotated a wheel that they’d dolloped the mayonnaise into. The centrifugal force of the spinning wheel accelerated the mayo into the gas. 

After the wheel stopped spinning, the scientists observed whether the glob returned to its original shape, changed shape or broke apart. This determined the  border between the elastic and plastic behavior , they reported in the May  Physical Review E . 

The mayo and air are akin to the molten metal of a fusion fuel capsule and the gas it contains. The molten capsule has some properties of a solid — like gloopy mayo, it doesn’t flow on its own — but it can break apart under enough force. If the metal becomes plastic before fusion occurs, the gas could escape, spoiling the fusion attempt.

Working with mayo does have one drawback. When you show up in the supermarket checkout line with 48 containers of mayo, you’re bound to attract attention. “We sometimes get a lot of questions from the grocery stores,” Banerjee says, “why we are buying that much mayonnaise.”

More Stories from Science News on Physics

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Dark matter experiments get a first peek at the ‘neutrino fog’ 

A new element on the periodic table might be within reach 

Can light spark superconductivity? A new study reignites debate

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Facility for Rare Isotope Beams

At michigan state university, user community focuses on the future of the field and fostering a diverse and equitable workforce.

The 2024 Low Energy Community Meeting (LECM) took place 7-9 August on the campus of the University of Tennessee Knoxville. LECM brings together members of the worldwide low-energy nuclear physics community to interact and discuss future plans, initiatives, and instruments. Over the course of the three days, 250 participants attended the meeting from 65 institutions and eight countries.

The LECM organizing committee includes representatives from FRIB, Argonne National Laboratory (ANL), the Association for Research at University Nuclear Accelerators (ARUNA), the Argonne Tandem Linac Accelerator System (ATLAS), the Center for Nuclear Astrophysics across Messengers (CeNAM), Lawrence Berkeley National Laboratory (LBNL), Lawrence Livermore National Laboratory (LLNL), Oak Ridge National Laboratory (ORNL), the FRIB Theory Alliance (FRIB-TA), and the FRIB Users Organization Executive Committee. FRIB hosted the meeting last year, and ORNL hosted this year. Texas A&M University will host next year.

LECM included plenary sessions, four working group sessions, and four workshops: Modular Neutron Array (MoNA) collaboration, Fission studies with rare isotope beams, early careers, and public engagement. 

The LECM plenary sessions featured presentations from the FRIB Achievement Awards for Early Career Researchers; a presentation on diversity and inclusion; Kairos Power’s Hermes demonstration reactor; and comments from representatives from the Department of Energy and the National Science Foundation. The meeting highlighted the status at major user facilities—FRIB, ATLAS, and ARUNA.

The 2024 LECM affirmation and resolutions stated:

Affirmation: Our community affirms in the strongest possible terms its commitment to foster a diverse and equitable workforce and to support and respect diversity in all its forms. Individually and collectively we commit to ensuring an inclusive and accessible environment for all and taking action if these values are not being upheld.

Resolution 1: The highest priority for low-energy nuclear physics and nuclear astrophysics research is to maintain U.S. world leadership in nuclear science by capitalizing on recent investments. To this end, we strongly support: 

• Robust theoretical and experimental research programs and the development and retention of a diverse and equitable workforce; 
• The optimal operation of the FRIB and ATLAS national user facilities;
• Investments in the ARUNA facilities, and key national laboratory facilities; 
• The FRIB Theory Alliance and all its initiatives.

All are critical to fully realize the scientific potential of the field and foster future breakthroughs.

Resolution 2: The science case for an energy upgrade of FRIB to 400 MeV/u is compelling. FRIB400 greatly expands the opportunities in the field. We strongly endorse starting the upgrade during the upcoming Long Range Plan period to harness its significant discovery potential. We support instrument developments, including the FDS and ISLA, now that GRETA and HRS are underway. These community devices are important to realize the full scope of scientific opportunities

Resolution 3: Computing is essential to advance all fields of nuclear science. We strongly support enhancing opportunities in computational nuclear science to accelerate discoveries and maintain U.S. leadership by: 

• Strengthening programs and partnerships to ensure the efficient utilization of new high-performance computing (HPC) hardware and new capabilities and approaches offered by artificial intelligence/machine learning (AI/ML) and quantum computing (QC); 
• Establishing programs that support the education, training of, and professional pathways for a diverse and multidisciplinary workforce with cross-disciplinary collaborations in HPC, AI/ML, and QC; 
• Expanding access to dedicated hardware and resources for HPC and new emerging computational technologies, as well as capacity computing essential for many research efforts.

Resolution 4: Research centers are important for low-energy nuclear science. They facilitate strong national and international communications and collaborations across disciplines and across theory and experiment. Interdisciplinary centers are particularly essential for nuclear astrophysics to seize new scientific opportunities in this area. We strongly endorse a nuclear astrophysics center that builds on the success of JINA, fulfills this vital role, and propels innovation in the multi-messenger era.

Resolution 5: Nuclear data play an essential role in all facets of nuclear science. Access to reliable, complete and up-to-date nuclear structure and reaction data is crucial for the fundamental nuclear physics research enterprise, as well as for the successes of applied missions in the areas of defense and security, nuclear energy, space exploration, isotope production, and medical applications. It is thus imperative to maintain an effective US role in the stewardship of nuclear data. 

• We endorse support for the compilation, evaluation, dissemination and preservation of nuclear data and efforts to build a diverse, equitable and inclusive workforce that maintains reliable and up-to-date nuclear databases through national and international partnerships. 
• We recommend prioritizing opportunities that enhance the prompt availability and quality of nuclear data and its utility for propelling scientific progress in nuclear structure, reactions and astrophysics and other fundamental physics research programs.
• We endorse identifying interagency-supported crosscutting opportunities for nuclear data with other programs, that enrich the utility of nuclear data in both science and society.

The community also presented a statement on isotopes and applications:

Applied Nuclear Science offers many tangible benefits to the United States and to the world. The Low Energy Nuclear Physics Community recognizes the societal importance of applied research, and strongly encourages support for this exciting and growing field with funding and beam time allocations that enable critical discovery science that will improve our lives and make us all safer.

Rare isotopes are necessary for research and innovation and must be available.  

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Units and Measurement

The Scope and Scale of Physics

Learning objectives.

By the end of this section, you will be able to:

• Describe the scope of physics.
• Calculate the order of magnitude of a quantity.
• Compare measurable length, mass, and timescales quantitatively.
• Describe the relationships among models, theories, and laws.

Physics is devoted to the understanding of all natural phenomena. In physics, we try to understand physical phenomena at all scales—from the world of subatomic particles to the entire universe. Despite the breadth of the subject, the various subfields of physics share a common core. The same basic training in physics will prepare you to work in any area of physics and the related areas of science and engineering. In this section, we investigate the scope of physics; the scales of length, mass, and time over which the laws of physics have been shown to be applicable; and the process by which science in general, and physics in particular, operates.

The Scope of Physics

Think, now, about all the technological devices you use on a regular basis. Computers, smartphones, global positioning systems (GPSs), MP3 players, and satellite radio might come to mind. Then, think about the most exciting modern technologies you have heard about in the news, such as trains that levitate above tracks, “invisibility cloaks” that bend light around them, and microscopic robots that fight cancer cells in our bodies. All these groundbreaking advances, commonplace or unbelievable, rely on the principles of physics. Aside from playing a significant role in technology, professionals such as engineers, pilots, physicians, physical therapists, electricians, and computer programmers apply physics concepts in their daily work. For example, a pilot must understand how wind forces affect a flight path; a physical therapist must understand how the muscles in the body experience forces as they move and bend. As you will learn in this text, the principles of physics are propelling new, exciting technologies, and these principles are applied in a wide range of careers.

The underlying order of nature makes science in general, and physics in particular, interesting and enjoyable to study. For example, what do a bag of chips and a car battery have in common? Both contain energy that can be converted to other forms. The law of conservation of energy (which says that energy can change form but is never lost) ties together such topics as food calories, batteries, heat, light, and watch springs. Understanding this law makes it easier to learn about the various forms energy takes and how they relate to one another. Apparently unrelated topics are connected through broadly applicable physical laws, permitting an understanding beyond just the memorization of lists of facts.

Science consists of theories and laws that are the general truths of nature, as well as the body of knowledge they encompass. Scientists are continuously trying to expand this body of knowledge and to perfect the expression of the laws that describe it. Physics , which comes from the Greek phúsis , meaning “nature,” is concerned with describing the interactions of energy, matter, space, and time to uncover the fundamental mechanisms that underlie every phenomenon. This concern for describing the basic phenomena in nature essentially defines the scope of physics .

Physics aims to understand the world around us at the most basic level. It emphasizes the use of a small number of quantitative laws to do this, which can be useful to other fields pushing the performance boundaries of existing technologies. Consider a smartphone ( (Figure) ). Physics describes how electricity interacts with the various circuits inside the device. This knowledge helps engineers select the appropriate materials and circuit layout when building a smartphone. Knowledge of the physics underlying these devices is required to shrink their size or increase their processing speed. Or, think about a GPS. Physics describes the relationship between the speed of an object, the distance over which it travels, and the time it takes to travel that distance. When you use a GPS in a vehicle, it relies on physics equations to determine the travel time from one location to another.

Knowledge of physics is useful in everyday situations as well as in nonscientific professions. It can help you understand how microwave ovens work, why metals should not be put into them, and why they might affect pacemakers. Physics allows you to understand the hazards of radiation and to evaluate these hazards rationally and more easily. Physics also explains the reason why a black car radiator helps remove heat in a car engine, and it explains why a white roof helps keep the inside of a house cool. Similarly, the operation of a car’s ignition system as well as the transmission of electrical signals throughout our body’s nervous system are much easier to understand when you think about them in terms of basic physics.

Physics is a key element of many important disciplines and contributes directly to others. Chemistry, for example—since it deals with the interactions of atoms and molecules—has close ties to atomic and molecular physics. Most branches of engineering are concerned with designing new technologies, processes, or structures within the constraints set by the laws of physics. In architecture, physics is at the heart of structural stability and is involved in the acoustics, heating, lighting, and cooling of buildings. Parts of geology rely heavily on physics, such as radioactive dating of rocks, earthquake analysis, and heat transfer within Earth. Some disciplines, such as biophysics and geophysics, are hybrids of physics and other disciplines.

Physics has many applications in the biological sciences. On the microscopic level, it helps describe the properties of cells and their environments. On the macroscopic level, it explains the heat, work, and power associated with the human body and its various organ systems. Physics is involved in medical diagnostics, such as radiographs, magnetic resonance imaging, and ultrasonic blood flow measurements. Medical therapy sometimes involves physics directly; for example, cancer radiotherapy uses ionizing radiation. Physics also explains sensory phenomena, such as how musical instruments make sound, how the eye detects color, and how lasers transmit information.

It is not necessary to study all applications of physics formally. What is most useful is knowing the basic laws of physics and developing skills in the analytical methods for applying them. The study of physics also can improve your problem-solving skills. Furthermore, physics retains the most basic aspects of science, so it is used by all the sciences, and the study of physics makes other sciences easier to understand.

The Scale of Physics

From the discussion so far, it should be clear that to accomplish your goals in any of the various fields within the natural sciences and engineering, a thorough grounding in the laws of physics is necessary. The reason for this is simply that the laws of physics govern everything in the observable universe at all measurable scales of length, mass, and time. Now, that is easy enough to say, but to come to grips with what it really means, we need to get a little bit quantitative. So, before surveying the various scales that physics allows us to explore, let’s first look at the concept of “order of magnitude,” which we use to come to terms with the vast ranges of length, mass, and time that we consider in this text ( (Figure) ).

Order of magnitude

Known ranges of length, mass, and time

The vastness of the universe and the breadth over which physics applies are illustrated by the wide range of examples of known lengths, masses, and times (given as orders of magnitude) in (Figure) . Examining this table will give you a feeling for the range of possible topics in physics and numerical values. A good way to appreciate the vastness of the ranges of values in (Figure) is to try to answer some simple comparative questions, such as the following:

(Answer: 10 9 m/10 –10 m = 10 19 hydrogen atoms)

(Answer: 10 –15 kg/10 –27 kg = 10 12 protons)

(Answer: 10 5 s/10 –17 s = 10 22 floating-point operations)

In studying (Figure) , take some time to come up with similar questions that interest you and then try answering them. Doing this can breathe some life into almost any table of numbers.

Visit this site to explore interactively the vast range of length scales in our universe. Scroll down and up the scale to view hundreds of organisms and objects, and click on the individual objects to learn more about each one.

Building Models

How did we come to know the laws governing natural phenomena? What we refer to as the laws of nature are concise descriptions of the universe around us. They are human statements of the underlying laws or rules that all natural processes follow. Such laws are intrinsic to the universe; humans did not create them and cannot change them. We can only discover and understand them. Their discovery is a very human endeavor, with all the elements of mystery, imagination, struggle, triumph, and disappointment inherent in any creative effort ( (Figure) ). The cornerstone of discovering natural laws is observation; scientists must describe the universe as it is, not as we imagine it to be.

A model is a representation of something that is often too difficult (or impossible) to display directly. Although a model is justified by experimental tests, it is only accurate in describing certain aspects of a physical system. An example is the Bohr model of single-electron atoms, in which the electron is pictured as orbiting the nucleus, analogous to the way planets orbit the Sun ( (Figure) ). We cannot observe electron orbits directly, but the mental image helps explain some of the observations we can make, such as the emission of light from hot gases (atomic spectra). However, other observations show that the picture in the Bohr model is not really what atoms look like. The model is “wrong,” but is still useful for some purposes. Physicists use models for a variety of purposes. For example, models can help physicists analyze a scenario and perform a calculation or models can be used to represent a situation in the form of a computer simulation. Ultimately, however, the results of these calculations and simulations need to be double-checked by other means—namely, observation and experimentation.

The word theory means something different to scientists than what is often meant when the word is used in everyday conversation. In particular, to a scientist a theory is not the same as a “guess” or an “idea” or even a “hypothesis.” The phrase “it’s just a theory” seems meaningless and silly to scientists because science is founded on the notion of theories. To a scientist, a theory is a testable explanation for patterns in nature supported by scientific evidence and verified multiple times by various groups of researchers. Some theories include models to help visualize phenomena whereas others do not. Newton’s theory of gravity, for example, does not require a model or mental image, because we can observe the objects directly with our own senses. The kinetic theory of gases, on the other hand, is a model in which a gas is viewed as being composed of atoms and molecules. Atoms and molecules are too small to be observed directly with our senses—thus, we picture them mentally to understand what the instruments tell us about the behavior of gases. Although models are meant only to describe certain aspects of a physical system accurately, a theory should describe all aspects of any system that falls within its domain of applicability. In particular, any experimentally testable implication of a theory should be verified. If an experiment ever shows an implication of a theory to be false, then the theory is either thrown out or modified suitably (for example, by limiting its domain of applicability).

The models, theories, and laws we devise sometimes imply the existence of objects or phenomena that are as yet unobserved. These predictions are remarkable triumphs and tributes to the power of science. It is the underlying order in the universe that enables scientists to make such spectacular predictions. However, if experimentation does not verify our predictions, then the theory or law is wrong, no matter how elegant or convenient it is. Laws can never be known with absolute certainty because it is impossible to perform every imaginable experiment to confirm a law for every possible scenario. Physicists operate under the assumption that all scientific laws and theories are valid until a counterexample is observed. If a good-quality, verifiable experiment contradicts a well-established law or theory, then the law or theory must be modified or overthrown completely.

The study of science in general, and physics in particular, is an adventure much like the exploration of an uncharted ocean. Discoveries are made; models, theories, and laws are formulated; and the beauty of the physical universe is made more sublime for the insights gained.

• Physics is about trying to find the simple laws that describe all natural phenomena.
• Physics operates on a vast range of scales of length, mass, and time. Scientists use the concept of the order of magnitude of a number to track which phenomena occur on which scales. They also use orders of magnitude to compare the various scales.
• Scientists attempt to describe the world by formulating models, theories, and laws.

Conceptual Questions

What is physics?

Physics is the science concerned with describing the interactions of energy, matter, space, and time to uncover the fundamental mechanisms that underlie every phenomenon.

Some have described physics as a “search for simplicity.” Explain why this might be an appropriate description.

If two different theories describe experimental observations equally well, can one be said to be more valid than the other (assuming both use accepted rules of logic)?

No, neither of these two theories is more valid than the other. Experimentation is the ultimate decider. If experimental evidence does not suggest one theory over the other, then both are equally valid. A given physicist might prefer one theory over another on the grounds that one seems more simple, more natural, or more beautiful than the other, but that physicist would quickly acknowledge that he or she cannot say the other theory is invalid. Rather, he or she would be honest about the fact that more experimental evidence is needed to determine which theory is a better description of nature.

What determines the validity of a theory?

Certain criteria must be satisfied if a measurement or observation is to be believed. Will the criteria necessarily be as strict for an expected result as for an unexpected result?

Probably not. As the saying goes, “Extraordinary claims require extraordinary evidence.”

Can the validity of a model be limited or must it be universally valid? How does this compare with the required validity of a theory or a law?

Use the orders of magnitude you found in the previous problem to answer the following questions to within an order of magnitude. (a) How many electrons would it take to equal the mass of a proton? (b) How many Earths would it take to equal the mass of the Sun? (c) How many Earth–Moon distances would it take to cover the distance from Earth to the Sun? (d) How many Moon atmospheres would it take to equal the mass of Earth’s atmosphere? (e) How many moons would it take to equal the mass of Earth? (f) How many protons would it take to equal the mass of the Sun?

a. 10 3 ; b. 10 5 ; c. 10 2 ; d. 10 15 ; e. 10 2 ; f. 10 57

For the remaining questions, you need to use (Figure) to obtain the necessary orders of magnitude of lengths, masses, and times.

Roughly how many heartbeats are there in a lifetime?

A generation is about one-third of a lifetime. Approximately how many generations have passed since the year 0 AD?

10 2 generations

Roughly how many times longer than the mean life of an extremely unstable atomic nucleus is the lifetime of a human?

Calculate the approximate number of atoms in a bacterium. Assume the average mass of an atom in the bacterium is 10 times the mass of a proton.

10 11 atoms

(a) Calculate the number of cells in a hummingbird assuming the mass of an average cell is 10 times the mass of a bacterium. (b) Making the same assumption, how many cells are there in a human?

Assuming one nerve impulse must end before another can begin, what is the maximum firing rate of a nerve in impulses per second?

10 3 nerve impulses/s

About how many floating-point operations can a supercomputer perform each year?

Roughly how many floating-point operations can a supercomputer perform in a human lifetime?

10 26 floating-point operations per human lifetime

The Scope and Scale of Physics Copyright © 2016 by cnxuniphysics. All Rights Reserved.