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Modern physics is a branch of physics that developed in the early 20th century and onward or branches greatly influenced by early 20th century physics. Notable branches of modern physics include quantum mechanics, special relativity and general relativity.
Sep 6, 2023 · Modern Physics. This book is part of a series on Modern Physics: Waves. General Mechanics. Special Relativity. Quantum Mechanics. Electrodynamics. Nuclear Physics. A printable version of Modern Physics is available. ( edit it)
The eighteenth edition of this well-known textbook continues to provide a thorough understanding of the principles of modern physics. It offers a detailed presentation of important topics such...
Contemporary research in physics can be broadly divided into nuclear and particle physics; condensed matter physics; atomic, molecular, and optical physics; astrophysics; and applied physics. Some physics departments also support physics education research and physics outreach .
- Definitions
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- Modern Research
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- Anomalies and Discrepancies
- Alternative Theories
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Gravitation, also known as gravitational attraction, is the mutual attraction between all masses in the universe. Gravity is the gravitational attraction at the surface of a planet or other celestial body; "gravity" may also include, in addition to gravitation, the centrifugal force resulting from the planet's rotation (see #Earth's gravity).
Ancient world
The nature and mechanism of gravity were explored by a wide range of ancient scholars. In Greece, Aristotle believed that objects fell towards the Earth because the Earth was the center of the Universe and attracted all of the mass in the Universe towards it. He also thought that the speed of a falling object should increase with its weight, a conclusion that was later shown to be false. While Aristotle's view was widely accepted throughout Ancient Greece, there were other thinkers such as Pl...
Scientific revolution
In the mid-16th century, various European scientists experimentally disproved the Aristotelian notion that heavier objects fall at a faster rate. In particular, the Spanish Dominican priest Domingo de Soto wrote in 1551 that bodies in free fall uniformly accelerate. De Soto may have been influenced by earlier experiments conducted by other Dominican priests in Italy, including those by Benedetto Varchi, Francesco Beato, Luca Ghini, and Giovan Bellaso which contradicted Aristotle's teachings o...
Newton's theory of gravitation
In 1657, Robert Hooke published his Micrographia, in which he hypothesised that the Moon must have its own gravity.In 1666, he added two further principles: that all bodies move in straight lines until deflected by some force and that the attractive force is stronger for closer bodies. In a communication to the Royal Society in 1666, Hooke wrote Hooke's 1674 Gresham lecture, An Attempt to prove the Annual Motion of the Earth, explained that gravitation applied to "all celestial bodies" In 168...
In modern physics, general relativity remains the framework for the understanding of gravity. Physicists continue to work to find solutions to the Einstein field equationsthat form the basis of general relativity, while some scientists have speculated that general relativity may not be applicable at all in certain scenarios.
Earth's gravity
Every planetary body (including the Earth) is surrounded by its own gravitational field, which can be conceptualized with Newtonian physics as exerting an attractive force on all objects. Assuming a spherically symmetrical planet, the strength of this field at any given point above the surface is proportional to the planetary body's mass and inversely proportional to the square of the distance from the center of the body. The strength of the gravitational field is numerically equal to the acc...
Origin
The earliest gravity (possibly in the form of quantum gravity, supergravity or a gravitational singularity), along with ordinary space and time, developed during the Planck epoch (up to 10−43 seconds after the birth of the Universe), possibly from a primeval state (such as a false vacuum, quantum vacuum or virtual particle), in a currently unknown manner.
Gravitational radiation
General relativity predicts that energy can be transported out of a system through gravitational radiation. The first indirect evidence for gravitational radiation was through measurements of the Hulse–Taylor binary in 1973. This system consists of a pulsar and neutron star in orbit around one another. Its orbital period has decreased since its initial discovery due to a loss of energy, which is consistent for the amount of energy loss due to gravitational radiation. This research was awarded...
There are some observations that are not adequately accounted for, which may point to the need for better theories of gravity or perhaps be explained in other ways. 1. Extra-fast stars: Stars in galaxies follow a distribution of velocities where stars on the outskirts are moving faster than they should according to the observed distributions of nor...
Historical alternative theories
1. Aristotelian theory of gravity 2. Le Sage's theory of gravitation (1784) also called LeSage gravity but originally proposed by Fatio and further elaborated by Georges-Louis Le Sage, based on a fluid-based explanation where a light gas fills the entire Universe. 3. Ritz's theory of gravitation, Ann. Chem. Phys.13, 145, (1908) pp. 267–271, Weber–Gauss electrodynamics applied to gravitation. Classical advancement of perihelia. 4. Nordström's theory of gravitation(1912, 1913), an early competi...
Modern alternative theories
1. Brans–Dicke theoryof gravity (1961) 2. Induced gravity (1967), a proposal by Andrei Sakharov according to which general relativity might arise from quantum field theoriesof matter 3. String theory(late 1960s) 4. ƒ(R) gravity(1970) 5. Horndeski theory(1974) 6. Supergravity(1976) 7. In the modified Newtonian dynamics (MOND) (1981), Mordehai Milgrom proposes a modification of Newton's second lawof motion for small accelerations 8. The self-creation cosmologytheory of gravity (1982) by G.A. Ba...
I. Bernard Cohen (1999) [1687]. "A Guide to Newton's Principia". The Principia : mathematical principles of natural philosophy. By Newton, Isaac. Translated by I. Bernard Cohen. University of Calif...Halliday, David; Robert Resnick; Kenneth S. Krane (2001). Physics v. 1. New York: John Wiley & Sons. ISBN 978-0-471-32057-9.Serway, Raymond A.; Jewett, John W. (2004). Physics for Scientists and Engineers (6th ed.). Brooks/Cole. ISBN 978-0-534-40842-8.Tipler, Paul (2004). Physics for Scientists and Engineers: Mechanics, Oscillations and Waves, Thermodynamics (5th ed.). W.H. Freeman. ISBN 978-0-7167-0809-4."Gravitation", Encyclopedia of Mathematics, EMS Press, 2001 [1994]"Gravitation, theory of", Encyclopedia of Mathematics, EMS Press, 2001 [1994]A number of rules which we use to understand the world no longer apply. These rules include the rule that velocities can be added to each other, the rule that time and space are different things, the rule that matter and energy are separate, the rules for momentum.
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Modern Physics intertwines active learning pedagogy with the material typically covered in an introductory survey, from the basics of relativity and quantum mechanics through recent developments in particle physics and cosmology.
