1. What is Physics 2. Nature Science 3. Science 4. Scientific Method 5. Branches of Science 6. Branches of Physics Einstein Newton 7. Branches of Applied Physics
Bardeen Feynmann
2016-03-05 What is Physics
• Meaning of Physics (from Ancient Greek: φυσική (phusikḗ )) is knowledge of nature (from φύσις phúsis "nature"). • Physics is the natural science that involves the study of matter and its motion through space and time, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves. • Physics is one of the oldest academic disciplines, perhaps the oldest through its inclusion of astronomy. Over the last two millennia, physics was a part of natural philosophy along with chemistry, certain branches of mathematics, and biology, but during the scientific revolution in the 17th century, the natural sciences emerged as unique research programs in their own right. Physics intersects with many interdisciplinary areas of research, such as biophysics and quantum chemistry, and the boundaries of physics are not rigidly defined. • New ideas in physics often explain the fundamental mechanisms of other sciences, while opening new avenues of research in areas such as mathematics and philosophy. 2016-03-05 What is Physics
• Physics also makes significant contributions through advances in new technologies that arise from theoretical breakthroughs. • For example, advances in the understanding of electromagnetism or nuclear physics led directly to the development of new products that have dramatically transformed modern-day society, such as television, computers, domestic appliances, and nuclear weapons; advances in thermodynamics led to the development of industrialization, and advances in mechanics inspired the development of calculus.
2016-03-05 Natural Science
• Natural science is a branch of science concerned with the description, prediction, and understanding of natural phenomena, based on observational and empirical evidence. Validity, accuracy, and social mechanisms ensuring quality control, such as peer review and repeatability of findings, are amongst the criteria and methods used for this purpose. • Natural science can be broken into two main branches: life science (or biological science) and physical science. Physical science is further broken down into branches, including physics, astronomy, chemistry, and earth science. All of these branches of natural science are divided into many further specialized branches (also known as fields), and each of these is known as a "natural science".
2016-03-05 Natural Science
• In Western society's analytic tradition, the empirical and especially natural sciences use tools from formal sciences, such as mathematics and logic, converting information about nature into measurements which can be explained as clear statements about the "laws of nature". The social sciences also use such methods, but rely more on qualitative research, so that they are sometimes called "soft science", whereas natural sciences, insofar as emphasizing quantifiable data produced, tested, and confirmed through the scientific method are sometimes called "hard science". • Modern natural science succeeded more classical approaches to natural philosophy, usually traced to ancient Greece. Galileo, Descartes, Francis Bacon, and Newton debated the benefits of using approaches which were more mathematical and more experimental in a methodical way. Still, philosophical perspectives, conjectures, and presuppositions, often overlooked, remain requisite in natural science. Systematic data collection, including discovery science, succeed natural history, which emerged in the 16th century by describing and classifying plants, animals, minerals, and so on. Yet today, natural history suggests observational descriptions aimed at popular 2016-03-05 audiences. Science
• Science is a systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the universe. In an older and closely related meaning, "science" also refers to this body of knowledge itself, of the type that can be rationally explained and reliably applied. Ever since classical antiquity, science as a type of knowledge has been closely linked to philosophy. • In the West during the early modern period the words "science" and "philosophy of nature" were sometimes used interchangeably, and until the 19th century natural philosophy (which is today called "natural science") was considered a branch of philosophy.
2016-03-05 Science
• In modern usage "science" most often refers to a way of pursuing knowledge, not only the knowledge itself. In the 17th and 18th centuries scientists increasingly sought to formulate knowledge in terms of laws of nature. Over the course of the 19th century, the word "science" became increasingly associated with the scientific method itself, as a disciplined way to study the natural world, including physics, chemistry, geology and biology. It is in the 19th century also that the term scientist began to be applied to those who sought knowledge and understanding of nature. • Modern science is typically subdivided into the natural sciences which study the material world, the social sciences which study people and societies, and the formal sciences like mathematics. The formal sciences are often excluded as they do not depend on empirical observations. Disciplines which use science like engineering and medicine may also be considered to be applied sciences.
2016-03-05 Scientific Method
• The scientific method is a body of techniques for investigating phenomena, acquiring new knowledge, or correcting and integrating previous knowledge. To be termed scientific, a method of inquiry is commonly based on empirical or measurable evidence subject to specific principles of reasoning. • The Oxford English Dictionary defines the scientific method as "a method or procedure that has characterized natural science since the 17th century, consisting in systematic observation, measurement, and experiment, and the formulation, testing, and modification of hypotheses.“ • The purpose of an experiment is to determine whether observations agree with or conflict with the predictions derived from a hypothesis. Experiments can take place in a college lab, on a kitchen table, at CERN, at the bottom of an ocean, on Mars, and so on. There are difficulties in a formulaic statement of method, however. Though the scientific method is often presented as a fixed sequence of steps, it represents rather a set of general principles. Not all steps take place in every scientific inquiry, and are not always in the same order.
2016-03-05 Scientific Method
• The scientific method seeks to explain the events of nature in a reproducible way. An explanatory thought experiment or hypothesis is put forward, as explanation, using principles such as "Occam's Razor" (1.필요하지 않은 경우에까지 많은 것을 가정하면 안 된다. 2.보다 적은 수의 논리로 설명이 가능한 경우, 많은 수의 논리를 세 우지 말라.) and are generally expected to seek consilience—fitting well with other accepted facts related to the phenomena. • This new explanation is used to make falsifiable predictions that are testable by experiment or observation. The predictions are to be posted before a confirming experiment or observation is sought, as proof that no tampering has occurred. Disproof of a prediction is evidence of progress. This is done partly through observation of natural phenomena, but also through experimentation, that tries to simulate natural events under controlled conditions, as appropriate to the discipline (in the observational sciences, such as astronomy or geology, a predicted observation might take the place of a controlled experiment). Experimentation is especially important in science to help establish causal relationships (to avoid the correlation fallacy).
2016-03-05 Scientific Method
2016-03-05 Branches of Science
• Scientific fields are commonly divided into two major groups: natural sciences, which study natural phenomena (including biological life), and social sciences, which study human behavior and societies. These groupings are empirical sciences, which means the knowledge must be based on observable phenomena and capable of being tested for its validity by other researchers working under the same conditions.[39] There are also related disciplines that are grouped into interdisciplinary applied sciences, such as engineering and medicine. Within these categories are specialized scientific fields that can include parts of other scientific disciplines but often possess their own nomenclature and expertise.
2016-03-05 Branches of Science
• Mathematics, which is classified as a formal science, has both similarities and differences with the empirical sciences (the natural and social sciences). It is similar to empirical sciences in that it involves an objective, careful and systematic study of an area of knowledge; it is different because of its method of verifying its knowledge, using a priori rather than empirical methods. The formal sciences, which also include statistics and logic, are vital to the empirical sciences. Major advances in formal science have often led to major advances in the empirical sciences. The formal sciences are essential in the formation of hypotheses, theories, and laws, both in discovering and describing how things work (natural sciences) and how people think and act (social sciences). • Apart from its broad meaning, the word "Science" sometimes may specifically refer to fundamental sciences (maths and natural sciences) alone. Science schools or faculties within many institutions are separate from those for medicine or engineering, which is an applied science.
2016-03-05 Branches of Science
2016-03-05 History of Physics
Ancient astronomy • Astronomy is the oldest of the natural sciences. The earliest civilizations dating back to beyond 3000 BCE, such as the Sumerians, ancient Egyptians, and the Indus Valley Civilization, all had a predictive knowledge and a basic understanding of the motions of the Sun, Moon, and stars. The stars and planets were often a target of worship, believed to represent their gods. While the explanations for these phenomena were often unscientific and lacking in evidence, these early observations laid the foundation for later astronomy.[9] • According to Asger Aaboe, the origins of Western astronomy can be found in Mesopotamia, and all Western efforts in the exact sciences are descended from late Babylonian astronomy. Egyptian astronomers left monuments showing knowledge of the constellations and the motions of the celestial bodies, while Greek poet Homer wrote of various celestial objects in his Iliad and Odyssey; later Greek astronomers provided names, which are still used today, for most constellations visible from the northern hemisphere.[12]
2016-03-05 History of Physics
Natural philosophy • Natural philosophy has its origins in Greece during the Archaic period, (650 BCE – 480 BCE), when Pre-Socratic philosophers like Thales rejected non-naturalistic explanations for natural phenomena and proclaimed that every event had a natural cause. They proposed ideas verified by reason and observation, and many of their hypotheses proved successful in experiment; for example, atomism was found to be correct approximately 2000 years after it was first proposed by Leucippus and his pupil Democritus.
2016-03-05 History of Physics
Classical physics • Physics became a separate science when early modern Europeans used experimental and quantitative methods to discover what are now considered to be the laws of physics. • Major developments in this period include the replacement of the geocentric model of the solar system with the helio-centric Copernican model, the laws governing the motion of planetary bodies determined by Johannes Kepler between 1609 and 1619, pioneering work on telescopes and observational astronomy by Galileo Galilei in the 16th and 17th Centuries, and Isaac Newton's discovery and unification of the laws of motion and universal gravitation that would come to bear his name. Newton also developed calculus, the mathematical study of change, which provided new mathematical methods for solving physical problems.[18]
2016-03-05 History of Physics
Classical physics • The discovery of new laws in thermodynamics, chemistry, and electromagnetics resulted from greater research efforts during the Industrial Revolution as energy needs increased. The laws comprising classical physics remain very widely used for objects on everyday scales travelling at non-relativistic speeds, since they provide a very close approximation in such situations, and theories such as quantum mechanics and the theory of relativity simplify to their classical equivalents at such scales. However, inaccuracies in classical mechanics for very small objects and very high velocities led to the development of modern physics in the 20th century.
Sir Isaac Newton (1643–1727), whose laws of motion and universal gravitation were major milestones in classical physics
2016-03-05 History of Physics
Modern physics • Modern physics began in the early 20th century with the work of Max Planck in quantum theory and Albert Einstein's theory of relativity. Both of these theories came about due to inaccuracies in classical mechanics in certain situations. Classical mechanics predicted a varying speed of light, which could not be resolved with the constant speed predicted by Maxwell's equations of electromagnetism; this discrepancy was corrected by Einstein's theory of special relativity, which replaced classical mechanics for fast- moving bodies and allowed for a constant speed of light. Black body radiation provided another problem for classical physics, which was corrected when Planck proposed that light comes in individual packets known as photons; this, along with the photoelectric effect and a complete theory predicting discrete energy levels of electron orbitals, led to the theory of quantum mechanics taking over from classical physics at very small scales.
2016-03-05 History of Physics
Modern physics • Quantum mechanics would come to be pioneered by Werner Heisenberg, Erwin Schrödinger and Paul Dirac. From this early work, and work in related fields, the Standard Model of particle physics was derived. Following the discovery of a particle with properties consistent with the Higgs boson at CERN in 2012, all fundamental particles predicted by the standard model, and no others, appear to exist; however, physics beyond the Standard Model, with theories such as supersymmetry, is an active area of research. Areas of mathematics in general are important to this field, such as study of probabilities.
Albert Einstein (1879–1955), Max Planck (1858–1947), whose work on the the originator of the photoelectric effect and the theory of quantum theory of relativity led to a mechanics revolution in 20th century physics
2016-03-05 History of Physics
Difference between classical and modern physics While physics aims to discover universal laws, its theories lie in explicit domains of applicability. Loosely speaking, the laws of classical physics accurately describe systems whose important length scales are greater than the atomic scale and whose motions are much slower than the speed of light. Outside of this domain, observations do not match predictions provided by classical mechanics. Albert Einstein contributed the framework of special relativity, which replaced notions of absolute time and space with spacetime and allowed an accurate description of systems whose components have speeds approaching the speed of light. Max Planck, Erwin Schrödinger, and others introduced quantum mechanics, a probabilistic notion of particles and interactions that allowed an accurate description of atomic and subatomic scales. Later, quantum field theory unified quantum mechanics and special relativity. General relativity allowed for a dynamical, curved spacetime, with which highly massive systems and the large-scale structure of the universe can be well-described. General relativity has not yet been unified with the other fundamental descriptions; several candidate theories of quantum gravity are being developed. 2016-03-05 History of Physics
2016-03-05 Branches of Physics
1. Classical mechanics 2. Thermodynamics and statistical mechanics 3. Electromagnetism 4. Relativity 5. Quantum mechanics 6. Interdisciplinary fields • astrophysics, the physics in the universe, including the properties and interactions of celestial bodies in astronomy. • biophysics, studying the physical interactions of biological processes. • chemical physics, the science of physical relations in chemistry. • econophysics, dealing with physical processes and their relations in the science of economy. • geophysics, the sciences of physical relations on our planet. • medical physics, the application of physics to prevention, diagnosis, and treatment. • physical chemistry, dealing with physical processes and their relations in the science of physical chemistry.
2016-03-05 Branches of Physics
Theory Major subtopics Concepts
Newton's laws of motion, Density, dimension, gravity, space, time, motion, length, position, velocity, Classical kinematics, statics, dynamics, acceleration, Galilean invariance, mass, momentum, impulse, force, energy, mechanics acoustics, fluid dynamics, angular velocity, angular momentum, moment of inertia, torque, continuum mechanics conservation law, harmonic oscillator, wave, work, power, Euler angles Electrostatics, electrodynamics, Capacitance, electric charge, current, electrical conductivity, electric field, Electro electricity, magnetism, electric permittivity, electric potential, electrical resistance, electromagnetic magnetism magnetostatics, Maxwell's field, electromagnetic induction, electromagnetic radiation, Gaussian surface, equations, optics magnetic field, magnetic flux, magnetic monopole, magnetic permeability Boltzmann's constant, conjugate variables, enthalpy, entropy, equation of state, equipartition theorem, thermodynamic free energy, heat, ideal gas law, Thermodynamics internal energy, laws of thermodynamics, irreversible process, pressure, and statistical Heat engine, kinetic theory reversible process, spontaneous process, state function, statistical ensemble, mechanics temperature, thermodynamic equilibrium, thermodynamic potential, thermodynamic processes, thermodynamic state, thermodynamic system, viscosity, volume, work, Adiabatic approximation, black-body radiation, correspondence principle, Path integral formulation, free particle, Hamiltonian, Hilbert space, identical particles, matrix mechanics, scattering theory, Schrödinger Quantum Planck's constant, operators, quanta, quantization, quantum harmonic equation, quantum field oscillator, quantum number, quantum tunneling, Schrödinger's cat, Dirac mechanics theory, quantum statistical equation, spin, wave function, wave mechanics, wave–particle duality, zero- mechanics point energy, Pauli exclusion principle, Heisenberg uncertainty principle Covariance, equivalence principle, four-momentum, four-vector, principle of relativity, gravity, inertial frame of reference, invariance, length contraction, Special relativity, general Lorentz transformation, mass–energy equivalence, metric, Minkowski space, relativity, Einstein field Relativity principle of relativity, proper length, proper time, reference frame, rest equations energy, rest mass, relativity of simultaneity, spacetime, speed of light, time 2016-03-05 dilation, twin paradox, world line Branches of Physics
Branches f Physics Divisions Applied, Experimental, Theoretical Thermodynamics, Mechanics (Classical (Lagrangian, Hamiltonian) Energy, Motion Continuum, Celestial, Statistical, Fluid, Quantum) Gravitation, Electromagnetism, Quantum field theory, Waves, Fields Relativity (Special, General) Accelerator, Acoustics, Astrophysics (Nuclear, Stellar, Heliophysics (Solar), Space, Astroparticle), Atomic–molecular–optical (AMO), Communication, Computational, Condensed matter (Solid-state, Soft) By specialty Digital, Engineering, Material, Mathematical, Nuclear, Optics (Geometrical, Physical, Nonlinear, Quantum), Particle (Phenomenology) Plasma, Polymer, Statistical Biophysics (Virophysics, Biomechanics), Medical physics Physics in life (Cardiophysics, Health physics, Laser medicine, Medical science imaging, Nuclear medicine, Neurophysics (Psychophysics) Physics with Agrophysics (Soil), Atmospheric, Chemical, Econophysics, Geophysics other sciences
2016-03-05 Applied Physics
• Applied physics is physics which is intended for a particular technological or practical use. It is usually considered as a bridge or a connection between physics and engineering. • "Applied" is distinguished from "pure" by a subtle combination of factors such as the motivation and attitude of researchers and the nature of the relationship to the technology or science that may be affected by the work. It usually differs from engineering in that an applied physicist may not be designing something in particular, but rather is using physics or conducting physics research with the aim of developing new technologies or solving an engineering problem. This approach is similar to that of applied mathematics. In other words, applied physics is rooted in the fundamental truths and basic concepts of the physical sciences but is concerned with the utilization of these scientific principles in practical devices and systems. • Applied physicists can also be interested in the use of physics for scientific research. For instance, the field of accelerator physics can contribute to research in theoretical physics by enabling design and construction of high-energy colliders.
2016-03-05 Applied Physics
Examples of Research Areas • The transistor, which was first invented by physicists John Bardeen, Walter Brattain and William Shockley in 1947 • Lasers, such as Vertical-cavity surface-emitting lasers • Photonic Crystals and Quantum Optics • Semiconductors A magnetic resonance image • Accelerator Physics
Experiment using a laser 2016-03-05 Applied Physics
• Accelerator physics, Acoustics, Agrophysics, Analog electronics, Astrophysics, Ballistics, Biophysics, Communication physics, Computational physics, Condensed matter physics, Control theory, Digital electronics, Econophysics, Experimental physics, Engineering physics, Fiber optics, Fluid dynamics, Force microscopy and imaging, Geophysics, Laser physics, Medical physics, Metrological physics, Microfluidics, Nanotechnology, Nondestructive testing, Nuclear engineering, Nuclear technology, Optics, Optoelectronics, Photonics, Photovoltaics, Plasma physics, Quantum electronics, Semiconductor physics and devices, Soil physics, Solid state physics, Space physics, Spintronics, Superconductors, Vehicle dynamics. Etc.
2016-03-05