physics essay pdf

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Course info.

• Prof. David Kaiser

Departments

• Science, Technology, and Society

As Taught In

• History of Science and Technology
• Modern History

Learning Resource Types

Einstein, oppenheimer, feynman: physics in the 20th century.

There are three essays and one essay revision for STS.042. All papers should be double-spaced, in 12-point font, and have standard margins of standard width (1 to 1.25 inches). Acceptable file formats include .doc, .docx, and .pdf.

Assignment: Write a referee report on Einstein’s 1905 paper on special relativity.

Due date: Friday of Week 5

Length: 4–5 double-spaced pages. 

Grade: Your grade on Paper 1 will contribute 25% of your final course grade.

Due date: Friday of Week 8

Length: 6–7 double-spaced pages. 

Grade : Your grade on Paper 2 will contribute 20% of your final course grade.

Paper 2 Revision Exercise

Assignment: Revise paper 2. Your revised paper should again be 6–7 double-spaced pages.

Due date: Friday of Week 11

Due date: Wednesday of Week 15

Length: 10–12 double-spaced pages. 

Grade: Your grade on Paper 3 will contribute 35% of your final course grade.

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Collection  04 March 2020

Top 100 in Physics

This collection highlights our most downloaded* physics papers published in 2019. Featuring authors from around the world, these papers feature valuable research from an international community.

* Data obtained from SN Insights which is based on Digital Science’s Dimensions.

Arrow of time and its reversal on the IBM quantum computer

• G. B. Lesovik
• I. A. Sadovskyy
• V. M. Vinokur

Room-temperature Operation of Low-voltage, Non-volatile, Compound-semiconductor Memory Cells

• Ofogh Tizno
• Andrew R. J. Marshall
• Manus Hayne

Emergent dynamics of neuromorphic nanowire networks

• Adrian Diaz-Alvarez
• Rintaro Higuchi
• Tomonobu Nakayama

Machine-learning guided discovery of a new thermoelectric material

• Yuma Iwasaki
• Ichiro Takeuchi
• Shinichi Yorozu

Beyond 30% Conversion Efficiency in Silicon Solar Cells: A Numerical Demonstration

• Sayak Bhattacharya
• Sajeev John

QAOA for Max-Cut requires hundreds of qubits for quantum speed-up

• G. G. Guerreschi
• A. Y. Matsuura

How Quantum Mechanics can consistently describe the use of itself

• Dustin Lazarovici
• Mario Hubert

Finding Hadamard Matrices by a Quantum Annealing Machine

• Andriyan Bayu Suksmono
• Yuichiro Minato

Enhanced Grüneisen Parameter in Supercooled Water

• Gabriel O. Gomes
• H. Eugene Stanley
• Mariano de Souza

Laser-wakefield accelerators for high-resolution X-ray imaging of complex microstructures

• A. E. Hussein
• N. Senabulya
• A. G. R. Thomas

QuEST and High Performance Simulation of Quantum Computers

• Tyson Jones
• Simon C. Benjamin

Improving solutions by embedding larger subproblems in a D-Wave quantum annealer

• Shuntaro Okada
• Masayuki Ohzeki
• Shinichiro Taguchi

Electronic and Magnetic Properties of Lanthanum and Strontium Doped Bismuth Ferrite: A First-Principles Study

• Ayana Ghosh
• Dennis P. Trujillo
• Jian-Xin Zhu

Quantum annealing for systems of polynomial equations

• Chia Cheng Chang
• Arjun Gambhir
• Shigetoshi Sota

High-temperature operation of a silicon qubit

• Takahiro Mori
• Satoshi Moriyama

Pore-scale characteristics of multiphase flow in heterogeneous porous media using the lattice Boltzmann method

• Sahar Bakhshian
• Seyyed A. Hosseini
• Nima Shokri

Linear and circular-polarization conversion in X-band using anisotropic metasurface

• M. Ismail Khan
• Zobaria Khalid
• Farooq A. Tahir

Observation of Skyrmions at Room Temperature in Co 2 FeAl Heusler Alloy Ultrathin Film Heterostructures

• Sajid Husain
• Naveen Sisodia
• Sujeet Chaudhary

Successively accelerated ionic wind with integrated dielectric-barrier-discharge plasma actuator for low-voltage operation

• Shintaro Sato
• Haruki Furukawa
• Naofumi Ohnishi

Bulk and surface recombination properties in thin film semiconductors with different surface treatments from time-resolved photoluminescence measurements

• Thomas P. Weiss
• Benjamin Bissig
• Ayodhya N. Tiwari

Probability estimation of a Carrington-like geomagnetic storm

• David Moriña
• Isabel Serra
• Álvaro Corral

Triggering The Birth of New Cycle’s Sunspots by Solar Tsunami

• Mausumi Dikpati
• Scott W. McIntosh
• Abhishek Srivastava

Performance comparison of III–V//Si and III–V//InGaAs multi-junction solar cells fabricated by the combination of mechanical stacking and wire bonding

• Yu-Cheng Kao
• Hao-Ming Chou
• Ray-Hua Horng

Electron-Phonon Coupling as the Source of 1/f Noise in Carbon Soot

Evidence for Crystalline Structure in Dynamically-Compressed Polyethylene up to 200 GPa

• N. J. Hartley

Engineering preferentially-aligned nitrogen-vacancy centre ensembles in CVD grown diamond

• Christian Osterkamp
• Martin Mangold
• Fedor Jelezko

The Young-Feynman controlled double-slit electron interference experiment

• Amir H. Tavabi
• Chris B. Boothroyd
• Giulio Pozzi

Control of Multiferroic properties in BiFeO 3 nanoparticles

• Diego Carranza-Celis
• Alexander Cardona-Rodríguez
• Juan Gabriel Ramírez

Visualization of unstained DNA nanostructures with advanced in-focus phase contrast TEM techniques

• Yoones Kabiri
• Raimond B. G. Ravelli
• Henny Zandbergen

Analog Coupled Oscillator Based Weighted Ising Machine

• Jeffrey Chou
• Suraj Bramhavar
• William Herzog

Revisiting the optical bandgap of semiconductors and the proposal of a unified methodology to its determination

• A. R. Zanatta

Field-free Magnetization Switching by Utilizing the Spin Hall Effect and Interlayer Exchange Coupling of Iridium

• Jian-Gang (Jimmy) Zhu

Growth of vanadium dioxide thin films on hexagonal boron nitride flakes as transferrable substrates

• Shingo Genchi
• Mahito Yamamoto
• Hidekazu Tanaka

On Behind the Physics of the Thermoelectricity of Topological Insulators

• Daniel Baldomir
• Daniel Faílde

Zero-reflection acoustic metamaterial with a negative refractive index

• Choon Mahn Park
• Sang Hun Lee

Switchable multifunctional terahertz metasurfaces employing vanadium dioxide

• Shiwei Tang

Entanglement in a 20-Qubit Superconducting Quantum Computer

• Gary J. Mooney
• Charles D. Hill
• Lloyd C. L. Hollenberg

Strong magnetoelectric coupling in mixed ferrimagnetic-multiferroic phases of a double perovskite

Training Optimization for Gate-Model Quantum Neural Networks

• Laszlo Gyongyosi
• Sandor Imre

High-throughput physical vapour deposition flexible thermoelectric generators

• Katrina A. Morgan
• Daniel W. Hewak

The Effect of Surface Roughness on the Contact Line and Splashing Dynamics of Impacting Droplets

• Miguel A. Quetzeri-Santiago
• Alfonso A. Castrejón-Pita
• J. Rafael Castrejón-Pita

Measurement-Device-Independent Twin-Field Quantum Key Distribution

• Hua-Lei Yin

Inkjet Printing of Super Yellow: Ink Formulation, Film Optimization, OLEDs Fabrication, and Transient Electroluminescence

• Marek Zdzislaw Szymański
• Jacek Ulański

Low-frequency perfect sound absorption achieved by a modulus-near-zero metamaterial

• Houyou Long
• Xiaojun Liu

Blueprint for nanoscale NMR

• Ilai Schwartz
• Joachim Rosskopf
• Martin B. Plenio

Realization of efficient quantum gates with a superconducting qubit-qutrit circuit

• T. Bækkegaard
• L. B. Kristensen
• N. T. Zinner

Circuit-Based Quantum Random Access Memory for Classical Data

• Daniel K. Park
• Francesco Petruccione
• June-Koo Kevin Rhee

Laser- synthesized TiN nanoparticles as promising plasmonic alternative for biomedical applications

• Anton A. Popov
• Gleb Tselikov
• Andrei V. Kabashin

Improvement of Terahertz Photoconductive Antenna using Optical Antenna Array of ZnO Nanorods

• Mohammad Bashirpour
• Matin Forouzmehr
• Mohammad Neshat

Wave attenuation and trapping in 3D printed cantilever-in-mass metamaterials with spatially correlated variability

• Danilo Beli
• Adriano T. Fabro
• José Roberto F. Arruda

Study of CuO Nanowire Growth on Different Copper Surfaces

• Gerhard Fritz-Popovski
• Florentyna Sosada-Ludwikowska
• Günther A. Maier

Second-order topological insulators and loop-nodal semimetals in Transition Metal Dichalcogenides XTe 2 (X = Mo, W)

• Motohiko Ezawa

Positive non-linear capacitance: the origin of the steep subthreshold-slope in ferroelectric FETs

• Md Nur K. Alam
• J. Van Houdt

Employing machine learning for theory validation and identification of experimental conditions in laser-plasma physics

• A. Gonoskov

Enhanced absorption in all-dielectric metasurfaces due to magnetic dipole excitation

• Pavel D. Terekhov
• Kseniia V. Baryshnikova
• Alina Karabchevsky

Origin of ferromagnetism in Cu-doped ZnO

• Budhi Singh
• Subhasis Ghosh

High-throughput Discovery of Topologically Non-trivial Materials using Spin-orbit Spillage

• Kamal Choudhary
• Kevin F. Garrity
• Francesca Tavazza

Frequency and Phase Characteristics of Candle Flame Oscillation

• Jinghua Xiao

Materials Selection and Mechanism of Non-linear Conduction in Chalcogenide Selector Devices

• Huanglong Li
• John Robertson

Enhanced room temperature ferromagnetism and green photoluminescence in Cu doped ZnO thin film synthesised by neutral beam sputtering

• D. C. Agarwal
• U. B. Singh
• D. K. Avasthi

Hybrid quantum linear equation algorithm and its experimental test on IBM Quantum Experience

• Yonghae Lee
• Soojoon Lee

Effect of sodium diffusion on the properties of CIGS solar absorbers prepared using elemental Se in a two-step process

• Selvaraj Venkataraj

Density of bulk trap states of hybrid lead halide perovskite single crystals: temperature modulated space-charge-limited-currents

• Jan Pospisil
• Oldrich Zmeskal
• Alexander Kovalenko

Spin-momentum locked spin manipulation in a two-dimensional Rashba system

• Makoto Kohda
• Takanori Okayasu
• Junsaku Nitta

Carrier Transport and Recombination Mechanism in Blue Phosphorescent Organic Light-Emitting Diode with Hosts Consisting of Cabazole- and Triazole-Moiety

• Tian-You Cheng
• Jiun-Haw Lee
• Chi-Feng Lin

Possible quantum critical behavior revealed by the critical current density of hole doped high- T c cuprates in comparison to heavy fermion superconductors

• S. H. Naqib
• R. S. Islam

Plasmofluidic Microlenses for Label-Free Optical Sorting of Exosomes

• Xiangchao Zhu
• Ahmet Cicek
• Ahmet Ali Yanik

Research on the Hong-Ou-Mandel interference with two independent sources

• Chen-Xi Liu

All semiconductor enhanced high-harmonic generation from a single nanostructured cone

• Dominik Franz
• Shatha Kaassamani
• Hamed Merdji

p -wave superconductivity in iron-based superconductors

• E. F. Talantsev

Lattice Discontinuities of 1T-TaS 2 across First Order Charge Density Wave Phase Transitions

• Dirk Dietzel
• André Schirmeisen

Weak localization and small anomalous Hall conductivity in ferromagnetic Weyl semimetal Co 2 TiGe

• Rajendra P. Dulal
• Bishnu R. Dahal
• John Philip

Dirac gap opening and Dirac-fermion-mediated magnetic coupling in antiferromagnetic Gd-doped topological insulators and their manipulation by synchrotron radiation

• A. M. Shikin
• D. A. Estyunin

Continuously Frequency-Tuneable Plasmonic Structures for Terahertz Bio-sensing and Spectroscopy

• Xiangying Deng
• Yukio Kawano

Silver nanowires with optimized silica coating as versatile plasmonic resonators

• Martin Rothe
• Yuhang Zhao
• Oliver Benson

Full-surface emission of graphene-based vertical-type organic light-emitting transistors with high on/off contrast ratios and enhanced efficiencies

• Byoungchoo Park
• Won Seok Lee

Fe-Sn nanocrystalline films for flexible magnetic sensors with high thermal stability

• K. Fujiwara
• A. Tsukazaki

Light-emitting diodes with surface gallium nitride p–n homojunction structure formed by selective area regrowth

• Ming-Lun Lee
• Shih-Sian Wang
• Jinn-Kong Sheu

How a ferromagnet drives an antiferromagnet in exchange biased CoO/Fe(110) bilayers

Efficient visible light modulation based on electrically tunable all dielectric metasurfaces embedded in thin-layer nematic liquid crystals

• Arseniy I. Kuznetsov

How to measure the local Dzyaloshinskii-Moriya Interaction in Skyrmion Thin-Film Multilayers

• Mirko Baćani
• Miguel A. Marioni
• Hans J. Hug

Simulation and design of folded perovskite x-ray detectors

• Henning Mescher
• Elias Hamann

High-Electrical-Conductivity Multilayer Graphene Formed by Layer Exchange with Controlled Thickness and Interlayer

• Hiromasa Murata
• Yoshiki Nakajima

Tunable Superconducting Cavity using Superconducting Quantum Interference Device Metamaterials

• David Shrekenhamer
• Jacob Alldredge

RGB Magnetophotonic Crystals for High-contrast Magnetooptical Spatial Light Modulators

• Soheila Kharratian
• Mehmet C. Onbaşlı

The actual electronic band structure of a rubrene single crystal

• Kazumoto Miwa
• Kazuyuki Sakamoto

Three-dimensional resonating metamaterials for low-frequency vibration attenuation

• D. Chronopoulos
• R. K. Leach

Ultra-high sensitive 1D porous silicon photonic crystal sensor based on the coupling of Tamm/Fano resonances in the mid-infrared region

• Ashour M. Ahmed
• Ahmed Mehaney

The Transition to Paschen’s Law for Microscale Gas Breakdown at Subatmospheric Pressure

• Amanda M. Loveless
• Guodong Meng
• Allen L. Garner

Ferroelectrics with a controlled oxygen-vacancy distribution by design

• Yuji Noguchi
• Hiroki Matsuo
• Masaru Miyayama

The paradoxes of the Late Hesperian Mars ocean

A universal constant for dark matter-baryon interplay

• Man Ho Chan

Superconducting Diamond on Silicon Nitride for Device Applications

• Henry A. Bland
• Evan L. H. Thomas
• Oliver A. Williams

Perovskite ferroelectric tuned by thermal strain

• O. Pacherova

Radiation Tolerance of Nanopore Sequencing Technology for Life Detection on Mars and Europa

• Mark A. Sutton
• Aaron S. Burton
• Sarah Stewart Johnson

Laser-driven shock compression of “synthetic planetary mixtures” of water, ethanol, and ammonia

• M. Guarguaglini
• J.-A. Hernandez

Detecting dynamic spatial correlation patterns with generalized wavelet coherence and non-stationary surrogate data

• Mario Chavez
• Bernard Cazelles

Bulk superconductivity in a four-layer-type Bi-based compound La 2 O 2 Bi 3 Ag 0.6 Sn 0.4 S 5.7 Se 0.3

• Rajveer Jha
• Yosuke Goto
• Yoshikazu Mizuguchi

All Nonmetal Resistive Random Access Memory

• Andrei Gismatulin
• Albert Chin

Improvements in structural and optical properties of wafer-scale hexagonal boron nitride film by post-growth annealing

• Seung Hee Lee
• Hokyeong Jeong
• Jong Kyu Kim

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1.1 Physics: An Introduction

Learning objectives.

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

• Explain the difference between a principle and a law.
• Explain the difference between a model and a theory.

The physical universe is enormously complex in its detail. Every day, each of us observes a great variety of objects and phenomena. Over the centuries, the curiosity of the human race has led us collectively to explore and catalog a tremendous wealth of information. From the flight of birds to the colors of flowers, from lightning to gravity, from quarks to clusters of galaxies, from the flow of time to the mystery of the creation of the universe, we have asked questions and assembled huge arrays of facts. In the face of all these details, we have discovered that a surprisingly small and unified set of physical laws can explain what we observe. As humans, we make generalizations and seek order. We have found that nature is remarkably cooperative—it exhibits the underlying order and simplicity we so value.

It is the underlying order of nature that makes science in general, and physics in particular, so 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.

The unifying aspect of physical laws and the basic simplicity of nature form the underlying themes of this text. In learning to apply these laws, you will, of course, study the most important topics in physics. More importantly, you will gain analytical abilities that will enable you to apply these laws far beyond the scope of what can be included in a single book. These analytical skills will help you to excel academically, and they will also help you to think critically in any professional career you choose to pursue. This module discusses the realm of physics (to define what physics is), some applications of physics (to illustrate its relevance to other disciplines), and more precisely what constitutes a physical law (to illuminate the importance of experimentation to theory).

Science and the Realm of Physics

Science consists of the theories and laws that are the general truths of nature as well as the body of knowledge they encompass. Scientists are continually trying to expand this body of knowledge and to perfect the expression of the laws that describe it. Physics is concerned with describing the interactions of energy, matter, space, and time, and it is especially interested in what fundamental mechanisms underlie every phenomenon. The concern for describing the basic phenomena in nature essentially defines the realm of physics .

Physics aims to describe the function of everything around us, from the movement of tiny charged particles to the motion of people, cars, and spaceships. In fact, almost everything around you can be described quite accurately by the laws of physics. Consider a smart phone ( Figure 1.3 ). 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 the smart phone. Next, consider a GPS system. 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. GPS relies on precise calculations that account for variations in the Earth's landscapes, the exact distance between orbiting satellites, and even the effect of a complex occurrence of time dilation. Most of these calculations are founded on algorithms developed by Gladys West, a mathematician and computer scientist who programmed the first computers capable of highly accurate remote sensing and positioning. When you use a GPS device, it utilizes these algorithms to recognize where you are and how your position relates to other objects on Earth.

Applications of Physics

You need not be a scientist to use physics. On the contrary, 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. (See Figure 1.4 and Figure 1.5 .) Physics allows you to understand the hazards of radiation and rationally evaluate these hazards 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 through our body’s nervous system are much easier to understand when you think about them in terms of basic physics.

Physics is the foundation of many important disciplines and contributes directly to others. Chemistry, for example—since it deals with the interactions of atoms and molecules—is rooted in atomic and molecular physics. Most branches of engineering are applied 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 in the 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 cell walls and cell membranes ( Figure 1.6 and Figure 1.7 ). On the macroscopic level, it can explain the heat, work, and power associated with the human body. Physics is involved in medical diagnostics, such as x-rays, magnetic resonance imaging (MRI), and ultrasonic blood flow measurements. Medical therapy sometimes directly involves physics; for example, cancer radiotherapy uses ionizing radiation. Physics can also explain sensory phenomena, such as how musical instruments make sound, how the eye detects color, and how lasers can transmit information.

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

Models, Theories, and Laws; The Role of Experimentation

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 so 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. (See Figure 1.8 and Figure 1.9 .) The cornerstone of discovering natural laws is observation; science must describe the universe as it is, not as we may imagine 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 the data may be organized and unified. We then formulate models, theories, and laws based on the data we have collected and analyzed to generalize and communicate the results of these experiments.

A model is a representation of something that is often too difficult (or impossible) to display directly. While a model is justified with experimental proof, it is only accurate under limited situations. An example is the planetary model of the atom in which electrons are pictured as orbiting the nucleus, analogous to the way planets orbit the Sun. (See Figure 1.10 .) We cannot observe electron orbits directly, but the mental image helps explain the observations we can make, such as the emission of light from hot gases (atomic spectra). Physicists use models for a variety of purposes. For example, models can help physicists analyze a scenario and perform a calculation, or they can be used to represent a situation in the form of a computer simulation. A theory is an explanation for patterns in nature that is 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 our instruments tell us about the behavior of gases.

A law uses concise language to describe a generalized pattern in nature that is 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 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, mass, and acceleration by the simple equation F = m a F = m a . A theory, in contrast, is a less concise statement of observed phenomena. For example, the Theory of Evolution and the Theory of Relativity cannot be expressed concisely enough to be considered a law. 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. And, whereas a law is a postulate that forms the foundation of the scientific method, a theory is the end result of that process.

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 carefully made.

Models, Theories, and Laws

Models, theories, and laws are used to help scientists analyze the data they have already collected. However, often after a model, theory, or law has been developed, it points scientists toward new discoveries they would not otherwise have made.

The models, theories, and laws we devise sometimes imply the existence of objects or phenomena 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 experiment 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 in order to confirm a law in 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, then the law must be modified or overthrown completely.

The study of science in general and physics in particular is an adventure much like the exploration of 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.

The Scientific Method

Ibn al-Haytham (sometimes referred to as Alhazen), a 10th-11th century scientist working in Cairo, significantly advanced the understanding of optics and vision. But his contributions go much further. In demonstrating that previous approaches were incorrect, he emphasized that scientists must be ready to reject existing knowledge and become "the enemy" of everything they read; he expressed that scientists must trust only objective evidence. Al-Haytham emphasized repeated experimentation and validation, and acknowledged that senses and predisposition could lead to poor conclusions. His work was a precursor to the scientific method that we use today.

As scientists inquire and gather information about the world, they follow a process called the scientific method . This process typically begins with an observation and question that the scientist will research. Next, the scientist typically performs some research about the topic and then devises a hypothesis. Then, the scientist will test the hypothesis by performing an experiment. Finally, the scientist analyzes the results of the experiment and draws a conclusion. Note that the scientific method can be applied to many situations that are not limited to science, and this method can be modified to suit the situation.

Consider an example. Let us say that you try to turn on your car, but it will not start. You undoubtedly wonder: Why will the car not start? You can follow a scientific method to answer this question. First off, you may perform some research to determine a variety of reasons why the car will not start. Next, you will state a hypothesis. For example, you may believe that the car is not starting because it has no engine oil. To test this, you open the hood of the car and examine the oil level. You observe that the oil is at an acceptable level, and you thus conclude that the oil level is not contributing to your car issue. To troubleshoot the issue further, you may devise a new hypothesis to test and then repeat the process again.

The Evolution of Natural Philosophy into Modern Physics

Physics was not always a separate and distinct discipline. It remains connected to other sciences to this day. The word physics comes from Greek, meaning nature. The study of nature came to be called “natural philosophy.” From ancient times through the Renaissance, natural philosophy encompassed many fields, including astronomy, biology, chemistry, physics, mathematics, and medicine. Over the last few centuries, the growth of knowledge has resulted in ever-increasing specialization and branching of natural philosophy into separate fields, with physics retaining the most basic facets. (See Figure 1.11 , Figure 1.12 , and Figure 1.13 .) Physics as it developed from the Renaissance to the end of the 19th century is called classical physics . It was transformed into modern physics by revolutionary discoveries made starting at the beginning of the 20th century.

Classical physics is not an exact description of the universe, but it is an excellent approximation under the following conditions: Matter must be moving at speeds less than about 1% of the speed of light, the objects dealt with must be large enough to be seen with a microscope, and only weak gravitational fields, such as the field generated by the Earth, can be involved. Because humans live under such circumstances, classical physics seems intuitively reasonable, while many aspects of modern physics seem bizarre. This is why models are so useful in modern physics—they let us conceptualize phenomena we do not ordinarily experience. We can relate to models in human terms and visualize what happens when objects move at high speeds or imagine what objects too small to observe with our senses might be like. For example, we can understand an atom’s properties because we can picture it in our minds, although we have never seen an atom with our eyes. New tools, of course, allow us to better picture phenomena we cannot see. In fact, new instrumentation has allowed us in recent years to actually “picture” the atom.

Limits on the Laws of Classical Physics

For the laws of classical physics to apply, the following criteria must be met: Matter must be moving at speeds less than about 1% of the speed of light, the objects dealt with must be large enough to be seen with a microscope, and only weak gravitational fields (such as the field generated by the Earth) can be involved.

Some of the most spectacular advances in science have been made in modern physics. Many of the laws of classical physics have been modified or rejected, and revolutionary changes in technology, society, and our view of the universe have resulted. Like science fiction, modern physics is filled with fascinating objects beyond our normal experiences, but it has the advantage over science fiction of being very real. Why, then, is the majority of this text devoted to topics of classical physics? There are two main reasons: Classical physics gives an extremely accurate description of the universe under a wide range of everyday circumstances, and knowledge of classical physics is necessary to understand modern physics.

Modern physics itself consists of the two revolutionary theories, relativity and quantum mechanics. These theories deal with the very fast and the very small, respectively. Relativity must be used whenever an object is traveling at greater than about 1% of the speed of light or experiences a strong gravitational field such as that near the Sun. Quantum mechanics must be used for objects smaller than can be seen with a microscope. The combination of these two theories is relativistic quantum mechanics, and it describes the behavior of small objects traveling at high speeds or experiencing a strong gravitational field. Relativistic quantum mechanics is the best universally applicable theory we have. Because of its mathematical complexity, it is used only when necessary, and the other theories are used whenever they will produce sufficiently accurate results. We will find, however, that we can do a great deal of modern physics with the algebra and trigonometry used in this text.

Check Your Understanding

A friend tells you they have learned about a new law of nature. What can you know about the information even before your friend describes the law? How would the information be different if your friend told you they had learned about a scientific theory rather than a law?

Without knowing the details of the law, you can still infer that the information your friend has learned conforms to the requirements of all laws of nature: it will be a concise description of the universe around us; a statement of the underlying rules that all natural processes follow. If the information had been a theory, you would be able to infer that the information will be a large-scale, broadly applicable generalization.

PhET Explorations

Equation grapher.

Learn about graphing polynomials. The shape of the curve changes as the constants are adjusted. View the curves for the individual terms (e.g. y = bx y = bx ) to see how they add to generate the polynomial curve.

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• Authors: Paul Peter Urone, Roger Hinrichs
• Publisher/website: OpenStax
• Book title: College Physics 2e
• Publication date: Jul 13, 2022
• Location: Houston, Texas
• Book URL: https://openstax.org/books/college-physics-2e/pages/1-introduction-to-science-and-the-realm-of-physics-physical-quantities-and-units
• Section URL: https://openstax.org/books/college-physics-2e/pages/1-1-physics-an-introduction

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[Niels Bohr] Essays 1958-1962 Atomic Physics And human knowledge

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As part of an attempt to establish a new understanding of the earliest applications of quantum mechanics and their importance to the overall development of quantum theory, this paper reexamines the role of research on molecular structure in the transition from the so-called old quantum theory to quantum mechanics and in the two years immediately following this shift (1926–1928). We argue on two bases against the common tendency to marginalize the contribution of these researches. First, because these applications addressed issues of longstanding interest to physicists, which they hoped, if not expected, a complete quantum theory to address, and for which they had already developed methods under the old quantum theory that would remain valid under the new mechanics. Second, because generating these applications was one of, if not the, principal means by which physicists clarified the unity, generality, and physical meaning of quantum mechanics, thereby reworking the theory into its now commonly recognized form, as well as developing an understanding of the kinds of predictions it generated and the ways in which these differed from those of the earlier classical mechanics. More broadly, we hope with this article to provide a new viewpoint on the importance of problem solving to scientific research and theory construction, one that might complement recent work on its role in science pedagogy.

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IB Physics EE examples

Filter exemplars, fluid’s density effect on falling objects, how is the lift at various angles of attack affected by flap deflection angles, want to get full marks for your ee allow us to review it for you 🎯, what effect does the difference in radius at the top and bottom of the roller coaster loop have on the maximum change in g-force that a passenger experiences, what is the relationship between the height of the siphon and the flow velocity out of the siphon, how does the total energy supplied during ultrasonic cavitation of benzene affect the integrated photoluminescence intensity and quantum yield of graphene quantum dots (gqds), fast track your coursework with mark schemes moderated by ib examiners. upgrade now 🚀, how does increasing the angle of a simple pendulum affect its time period, how do changes in viscosity of fluid affect the speed and amplitude of surface waves that are generated by an impact of spherical object, how do the angular momentum and orbital velocity affect the eccentricities of planetary orbits, how does the velocity of a bicycle on a flat horizontal surface affect its stability, investigación sobre el movimiento giroscópico de una peonza y su estabilidad dependiendo de la velocidad de rotación., what effect do mass, radius and length have on the moment of inertia of a cylinder being rotated about its central diameter, what is the critical reynolds number for water flow through a pipe, can the relationship between drag and velocity, r=bv^2, be proved experimentally by finding the constant of proportionality (25/34), can the technology currently under development for wireless power transfer provide a viable and efficient method for delivering electrical power to a wide range of home and industrial applications, “how does the length of a u folded metallic chain with one end fixed affect the time taken for it to unfold under the influence of gravity”, quel est l'effet de la masse et de la pression initiale sur la portée d'une fusée à eau, can we validate the conclusions from the 1919 dyson & eddington total solar eclipse expedition through data analysis of succeeding total eclipse expeditions, how does the phase of argon crystal (density, volume, length and msd) change as the crystal is monotonically heated in the temperature range from 50 to 150 kelvins, to what extent does the bend radius of a silicone tube affect the loss in light intensity for different incoming wavelengths, to what extent do cloud chambers effectively display subatomic particles and the fundamental interactions in the surrounding environment, what is the relationship between the critical air speed required to blow a bubble and the radius of the wand forming it, how does altering the curvature of an aircraft wing function to reduce aerodynamic drag and thus aircraft greenhouse emissions, what is the effect of manipulating the coefficient ’a’ of the parabolic function ax2 on the intensity of the light reflecting off a parabolic object, emitted from set different angles (0°, 15°, and 30°), how does strain rate affect the true stress and true strain of aluminium, steel and polystyrene subject to uniaxial tension, an investigation into the physics of toroidal banked turns, ee physics - what are the requirements for an underwater structure to maintain its structural integrity, to what extent does the backward motion of a human foot impacts the rebound distance of a soccer ball after they collide, how does the maximum height that the water rocket can reach change with the variation of the initially filled amount of water, evidence for the existence of dark matter, when powering a home-built bobbin- tractor, how does the stored energy of a rubber band change depending on the number of twists and the number of elastic bands used, the relationship between the salinity of water and the refractive index of water, what is the effect of inclination of open drainage channels on the rate of flow of water and silt-retention in channels, investigating the effect of changing the distance between the magnets (distance between the stages in a gaussian gun) and the velocity of the ejected metal marble., to what extent do the properties of delta cephei compare to those of the sun.

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