Within the field of
physicsPhysics is a natural science that involves the study of matter and its motion through spacetime, 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...
,
experimental physics is the category of disciplines and sub-disciplines concerned with the
observationObservation is either an activity of a living being, such as a human, consisting of receiving knowledge of the outside world through the senses, or the recording of data using scientific instruments. The term may also refer to any data collected during this activity...
of physical phenomena in order to gather
dataThe term data refers to qualitative or quantitative attributes of a variable or set of variables. Data are typically the results of measurements and can be the basis of graphs, images, or observations of a set of variables. Data are often viewed as the lowest level of abstraction from which...
about the
universeThe Universe is commonly defined as the totality of everything that exists, including all matter and energy, the planets, stars, galaxies, and the contents of intergalactic space. Definitions and usage vary and similar terms include the cosmos, the world and nature...
. Methods vary from discipline to discipline, from simple experiments and observations, such as the
Cavendish experimentThe Cavendish experiment, performed in 1797–98 by British scientist Henry Cavendish was the first experiment to measure the force of gravity between masses in the laboratory, and the first to yield accurate values for the gravitational constant. Because of the unit conventions then in use,...
, to more complicated ones, such as the
Large Hadron ColliderThe Large Hadron Collider is the world's largest and highest-energy particle accelerator. It is expected to address some of the most fundamental questions of physics, advancing the understanding of the deepest laws of nature....
.
Overview
Experimental physics regroup all the disciplines of physics that are concerned with data-acquisition, data-acquisition methods, and the detailed conceptualization (beyond simple
thought experimentA thought experiment or Gedankenexperiment considers some hypothesis, theory, or principle for the purpose of thinking through its consequences...
s) and realization of laboratory
experimentAn experiment is a methodical procedure carried out with the goal of verifying, falsifying, or establishing the validity of a hypothesis. Experiments vary greatly in their goal and scale, but always rely on repeatable procedure and logical analysis of the results...
s. It is often put in contrast with
theoretical physicsTheoretical physics is a branch of physics which employs mathematical models and abstractions of physics to rationalize, explain and predict natural phenomena...
, which is more concerned with predicting and explaining the physical behaviour of nature than the acquisition of knowledge about it.
Although experimental and theoretical physics are concerned with different aspects of nature, they both share the same goal of understanding it and have a symbiotic relation. The former provides data about the universe, which can then be analyzed in order to be understood, while the latter provides explanations for the data and thus offers insight on how to better acquire data and on how to set up experiments. Theoretical physics can also offer insight on what data is needed in order to gain a better understanding of the universe, and on what experiments to devise in order to obtain it.
History
As a distinct field, experimental physics was established in
early modern EuropeEarly modern Europe is the term used by historians to refer to a period in the history of Europe which spanned the centuries between the end of the Middle Ages and the beginning of the Industrial Revolution, roughly the late 15th century to the late 18th century...
, during what is known as the
Scientific RevolutionThe Scientific Revolution is an era associated primarily with the 16th and 17th centuries during which new ideas and knowledge in physics, astronomy, biology, medicine and chemistry transformed medieval and ancient views of nature and laid the foundations for modern science...
, by physicists such as
Galileo GalileiGalileo Galilei , was an Italian physicist, mathematician, astronomer, and philosopher who played a major role in the Scientific Revolution. His achievements include improvements to the telescope and consequent astronomical observations and support for Copernicanism...
,
Christiaan Huygens,
Johannes KeplerJohannes Kepler was a German mathematician, astronomer and astrologer. A key figure in the 17th century scientific revolution, he is best known for his eponymous laws of planetary motion, codified by later astronomers, based on his works Astronomia nova, Harmonices Mundi, and Epitome of Copernican...
,
Blaise Pascal Blaise Pascal , was a French mathematician, physicist, inventor, writer and Catholic philosopher. He was a child prodigy who was educated by his father, a tax collector in Rouen...
and Sir
Isaac NewtonSir Isaac Newton PRS was an English physicist, mathematician, astronomer, natural philosopher, alchemist, and theologian, who has been "considered by many to be the greatest and most influential scientist who ever lived."...
. In the early 17th century, Galileo made extensive use of experimentation to validate physical theories, which is the key idea in the modern scientific method. Galileo formulated and successfully tested several results in dynamics, in particular the law of
inertiaInertia is the resistance of any physical object to a change in its state of motion or rest, or the tendency of an object to resist any change in its motion. It is proportional to an object's mass. The principle of inertia is one of the fundamental principles of classical physics which are used to...
, which later became the first law in
Newton's laws of motionNewton's laws of motion are three physical laws that form the basis for classical mechanics. They describe the relationship between the forces acting on a body and its motion due to those forces...
. In Galileo's
Two New SciencesThe Discourses and Mathematical Demonstrations Relating to Two New Sciences was Galileo's final book and a sort of scientific testament covering much of his work in physics over the preceding thirty years.After his Dialogue Concerning the Two Chief World Systems, the Roman Inquisition had banned...
, a dialogue between the characters Simplicio and Salviati discuss the motion of a ship (as a moving frame) and how that ship's cargo is indifferent to its motion. Huygens used the motion of a boat along a Dutch canal to illustrate an early form of the conservation of
momentumIn classical mechanics, linear momentum or translational momentum is the product of the mass and velocity of an object...
.
Experimental physics is considered to have culminated with the publication of the
Philosophiae Naturalis Principia MathematicaPhilosophiæ Naturalis Principia Mathematica, Latin for "Mathematical Principles of Natural Philosophy", often referred to as simply the Principia, is a work in three books by Sir Isaac Newton, first published 5 July 1687. Newton also published two further editions, in 1713 and 1726...
in 1687 by Sir Isaac Newton (1643–1727). In 1687, Newton published the
Principia, detailing two comprehensive and successful physical theories:
Newton's laws of motionNewton's laws of motion are three physical laws that form the basis for classical mechanics. They describe the relationship between the forces acting on a body and its motion due to those forces...
, from which arise
classical mechanicsIn physics, classical mechanics is one of the two major sub-fields of mechanics, which is concerned with the set of physical laws describing the motion of bodies under the action of a system of forces...
; and
Newton's law of universal gravitationNewton's law of universal gravitation states that every point mass in the universe attracts every other point mass with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them...
, which describes the fundamental force of gravity. Both theories agreed well with experiment. The
Principia also included several theories in
fluid dynamicsIn physics, fluid dynamics is a sub-discipline of fluid mechanics that deals with fluid flow—the natural science of fluids in motion. It has several subdisciplines itself, including aerodynamics and hydrodynamics...
.
From the late 17th century onward,
thermodynamicsThermodynamics is a physical science that studies the effects on material bodies, and on radiation in regions of space, of transfer of heat and of work done on or by the bodies or radiation...
was developed by physicist and chemist
BoyleRobert Boyle FRS was a 17th century natural philosopher, chemist, physicist, and inventor, also noted for his writings in theology. He has been variously described as English, Irish, or Anglo-Irish, his father having come to Ireland from England during the time of the English plantations of...
,
YoungThomas Young was an English polymath. He is famous for having partly deciphered Egyptian hieroglyphics before Jean-François Champollion eventually expanded on his work...
, and many others. In 1733,
BernoulliDaniel Bernoulli was a Dutch-Swiss mathematician and was one of the many prominent mathematicians in the Bernoulli family. He is particularly remembered for his applications of mathematics to mechanics, especially fluid mechanics, and for his pioneering work in probability and statistics...
used statistical arguments with classical mechanics to derive thermodynamic results, initiating the field of
statistical mechanicsStatistical mechanics or statistical thermodynamicsThe terms statistical mechanics and statistical thermodynamics are used interchangeably...
. In 1798,
ThompsonSir Benjamin Thompson, Count Rumford , FRS was an American-born British physicist and inventor whose challenges to established physical theory were part of the 19th century revolution in thermodynamics. He also served as a Lieutenant-Colonel in the Loyalist forces in America during the American...
demonstrated the conversion of mechanical work into heat, and in 1847 Joule stated the law of conservation of
energyIn physics, energy is an indirectly observed quantity. It is often understood as the ability a physical system has to do work on other physical systems...
, in the form of heat as well as mechanical energy.
Ludwig BoltzmannLudwig Eduard Boltzmann was an Austrian physicist famous for his founding contributions in the fields of statistical mechanics and statistical thermodynamics...
, in the nineteenth century, is responsible for the modern form of statistical mechanics.
Besides classical mechanics and thermodynamics, another great field of experimental inquiry within physics was the nature of
electricityElectricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning, static electricity, and the flow of electrical current in an electrical wire...
. Observations in the 17th and eighteenth century by scientists such as
Robert BoyleRobert Boyle FRS was a 17th century natural philosopher, chemist, physicist, and inventor, also noted for his writings in theology. He has been variously described as English, Irish, or Anglo-Irish, his father having come to Ireland from England during the time of the English plantations of...
,
Stephen GrayStephen Gray was an English dyer and amateur astronomer, who was the first to systematically experiment with electrical conduction, rather than simple generation of static charges and investigations of the static phenomena....
, and
Benjamin FranklinDr. Benjamin Franklin was one of the Founding Fathers of the United States. A noted polymath, Franklin was a leading author, printer, political theorist, politician, postmaster, scientist, musician, inventor, satirist, civic activist, statesman, and diplomat...
created a foundation for later work. These observations also established our basic understanding of electrical charge and
currentElectric current is a flow of electric charge through a medium.This charge is typically carried by moving electrons in a conductor such as wire...
. By 1808
John DaltonJohn Dalton FRS was an English chemist, meteorologist and physicist. He is best known for his pioneering work in the development of modern atomic theory, and his research into colour blindness .-Early life:John Dalton was born into a Quaker family at Eaglesfield, near Cockermouth, Cumberland,...
had discovered that atoms of different elements have different weights and proposed the modern
theory of the atomIn chemistry and physics, atomic theory is a theory of the nature of matter, which states that matter is composed of discrete units called atoms, as opposed to the obsolete notion that matter could be divided into any arbitrarily small quantity...
.
It was
Hans Christian ØrstedHans Christian Ørsted was a Danish physicist and chemist who discovered that electric currents create magnetic fields, an important aspect of electromagnetism...
who first proposed the connection between electricity and magnetism after observing the deflection of a compass needle by a nearby electric current. By the early 1830s
Michael FaradayMichael Faraday, FRS was an English chemist and physicist who contributed to the fields of electromagnetism and electrochemistry....
had demonstrated that magnetic fields and electricity could generate each other. In 1864
James Clerk MaxwellJames Clerk Maxwell of Glenlair was a Scottish physicist and mathematician. His most prominent achievement was formulating classical electromagnetic theory. This united all previously unrelated observations, experiments and equations of electricity, magnetism and optics into a consistent theory...
presented to the
Royal SocietyThe Royal Society of London for Improving Natural Knowledge, known simply as the Royal Society, is a learned society for science, and is possibly the oldest such society in existence. Founded in November 1660, it was granted a Royal Charter by King Charles II as the "Royal Society of London"...
a set of equations that described this relationship between electricity and magnetism.
Maxwell's equationsMaxwell's equations are a set of partial differential equations that, together with the Lorentz force law, form the foundation of classical electrodynamics, classical optics, and electric circuits. These fields in turn underlie modern electrical and communications technologies.Maxwell's equations...
also predicted correctly that
lightLight or visible light is electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight. Visible light has wavelength in a range from about 380 nanometres to about 740 nm, with a frequency range of about 405 THz to 790 THz...
is an
electromagnetic waveElectromagnetic radiation is a form of energy that exhibits wave-like behavior as it travels through space...
. Starting with astronomy, the principles of
natural philosophyNatural philosophy or the philosophy of nature , is a term applied to the study of nature and the physical universe that was dominant before the development of modern science...
crystallized into fundamental laws of physics which were enunciated and improved in the succeeding centuries. By the 19th century, the sciences had segmented into multiple fields with specialized researchers and the field of physics, although logically pre-eminent, no longer could claim sole ownership of the entire field of scientific research.
Current experiments
Some examples of prominent experimental physics projects are:
- Relativistic Heavy Ion Collider
The Relativistic Heavy Ion Collider is one of two existing heavy-ion colliders, and the only spin-polarized proton collider in the world. It is located at Brookhaven National Laboratory in Upton, New York and operated by an international team of researchers...
which collides heavy ionHeavy ion refers to an ionized atom which is usually heavier than helium. Heavy-ion physics is devoted to the study of extremely hot nuclear matter and the collective effects appearing in such systems, differing from particle physics, which studies the interactions between elementary particles...
s such as goldGold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...
ions (it is the first heavy ion collider) and protonThe proton is a subatomic particle with the symbol or and a positive electric charge of 1 elementary charge. One or more protons are present in the nucleus of each atom, along with neutrons. The number of protons in each atom is its atomic number....
s, it is located at Brookhaven National LaboratoryBrookhaven National Laboratory , is a United States national laboratory located in Upton, New York on Long Island, and was formally established in 1947 at the site of Camp Upton, a former U.S. Army base...
, on Long Island, USA.
- HERA
HERA was a particle accelerator at DESY in Hamburg. It began operating in 1992. At HERA, electrons or positrons were collided with protons at a center of mass energy of 318 GeV. It was the only lepton-proton collider in the world while operating...
, which collides electronThe electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...
s or positronThe positron or antielectron is the antiparticle or the antimatter counterpart of the electron. The positron has an electric charge of +1e, a spin of ½, and has the same mass as an electron...
s and protons, and is part of DESYThe DESY is the biggest German research center for particle physics, with sites in Hamburg and Zeuthen....
, located in Hamburg-History:The first historic name for the city was, according to Claudius Ptolemy's reports, Treva.But the city takes its modern name, Hamburg, from the first permanent building on the site, a castle whose construction was ordered by the Emperor Charlemagne in AD 808...
, Germany.
- LHC
The Large Hadron Collider is the world's largest and highest-energy particle accelerator. It is expected to address some of the most fundamental questions of physics, advancing the understanding of the deepest laws of nature....
, or the Large HadronIn particle physics, a hadron is a composite particle made of quarks held together by the strong force...
ColliderA collider is a type of a particle accelerator involving directed beams of particles.Colliders may either be ring accelerators or linear accelerators.-Explanation:...
, which complete construction in 2008 but suffered a series of setbacks. The LHC began operations in 2008, but was shut down for maintenance until the summer of 2009. It is the world's most energetic collider upon completion, it is located at CERNThe European Organization for Nuclear Research , known as CERN , is an international organization whose purpose is to operate the world's largest particle physics laboratory, which is situated in the northwest suburbs of Geneva on the Franco–Swiss border...
, on the French-Swiss border near GenevaGeneva In the national languages of Switzerland the city is known as Genf , Ginevra and Genevra is the second-most-populous city in Switzerland and is the most populous city of Romandie, the French-speaking part of Switzerland...
. The collider became fully operational March 29, 2010 a year and a half later than originally planned.
- JWST
The James Webb Space Telescope , previously known as Next Generation Space Telescope , is a planned next-generation space telescope, optimized for observations in the infrared. The main technical features are a large and very cold 6.5 meter diameter mirror, an observing position far from Earth,...
, or the James WebbJames Edwin Webb was an American government official who served as the second administrator of NASA from February 14, 1961 to October 7, 1968....
Space Telescope, is planned for launch in 2013. It will be the successor to the Hubble Space TelescopeThe Hubble Space Telescope is a space telescope that was carried into orbit by a Space Shuttle in 1990 and remains in operation. A 2.4 meter aperture telescope in low Earth orbit, Hubble's four main instruments observe in the near ultraviolet, visible, and near infrared...
. It will survey the sky in the infrared region. The main goals of the JWST will be in order to understand the initial stages of the universe, galaxy formation as well as the formations of stars and planets, and the origins of life.
Method
Experimental physics uses two main methods of experimental research,
controlled experimentsScientific control allows for comparisons of concepts. It is a part of the scientific method. Scientific control is often used in discussion of natural experiments. For instance, during drug testing, scientists will try to control two groups to keep them as identical and normal as possible, then...
, and
natural experimentA natural experiment is an observational study in which the assignment of treatments to subjects has been haphazard: That is, the assignment of treatments has been made "by nature", but not by experimenters. Thus, a natural experiment is not a controlled experiment...
s. Controlled experiments are often used in laboratories as laboratories can offer a controlled environment. Natural experiments are used, for example, in
astrophysicsAstrophysics is the branch of astronomy that deals with the physics of the universe, including the physical properties of celestial objects, as well as their interactions and behavior...
when observing celestial objects where control of the variables in effect is impossible.
Experimental techniques
Some well-known experimental techniques include:
Prominent experimental physicists
Famous
experimental physicists include:
Within the field of
physicsPhysics is a natural science that involves the study of matter and its motion through spacetime, 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...
,
experimental physics is the category of disciplines and sub-disciplines concerned with the
observationObservation is either an activity of a living being, such as a human, consisting of receiving knowledge of the outside world through the senses, or the recording of data using scientific instruments. The term may also refer to any data collected during this activity...
of physical phenomena in order to gather
dataThe term data refers to qualitative or quantitative attributes of a variable or set of variables. Data are typically the results of measurements and can be the basis of graphs, images, or observations of a set of variables. Data are often viewed as the lowest level of abstraction from which...
about the
universeThe Universe is commonly defined as the totality of everything that exists, including all matter and energy, the planets, stars, galaxies, and the contents of intergalactic space. Definitions and usage vary and similar terms include the cosmos, the world and nature...
. Methods vary from discipline to discipline, from simple experiments and observations, such as the
Cavendish experimentThe Cavendish experiment, performed in 1797–98 by British scientist Henry Cavendish was the first experiment to measure the force of gravity between masses in the laboratory, and the first to yield accurate values for the gravitational constant. Because of the unit conventions then in use,...
, to more complicated ones, such as the
Large Hadron ColliderThe Large Hadron Collider is the world's largest and highest-energy particle accelerator. It is expected to address some of the most fundamental questions of physics, advancing the understanding of the deepest laws of nature....
.
Overview
Experimental physics regroup all the disciplines of physics that are concerned with data-acquisition, data-acquisition methods, and the detailed conceptualization (beyond simple
thought experimentA thought experiment or Gedankenexperiment considers some hypothesis, theory, or principle for the purpose of thinking through its consequences...
s) and realization of laboratory
experimentAn experiment is a methodical procedure carried out with the goal of verifying, falsifying, or establishing the validity of a hypothesis. Experiments vary greatly in their goal and scale, but always rely on repeatable procedure and logical analysis of the results...
s. It is often put in contrast with
theoretical physicsTheoretical physics is a branch of physics which employs mathematical models and abstractions of physics to rationalize, explain and predict natural phenomena...
, which is more concerned with predicting and explaining the physical behaviour of nature than the acquisition of knowledge about it.
Although experimental and theoretical physics are concerned with different aspects of nature, they both share the same goal of understanding it and have a symbiotic relation. The former provides data about the universe, which can then be analyzed in order to be understood, while the latter provides explanations for the data and thus offers insight on how to better acquire data and on how to set up experiments. Theoretical physics can also offer insight on what data is needed in order to gain a better understanding of the universe, and on what experiments to devise in order to obtain it.
History
As a distinct field, experimental physics was established in
early modern EuropeEarly modern Europe is the term used by historians to refer to a period in the history of Europe which spanned the centuries between the end of the Middle Ages and the beginning of the Industrial Revolution, roughly the late 15th century to the late 18th century...
, during what is known as the
Scientific RevolutionThe Scientific Revolution is an era associated primarily with the 16th and 17th centuries during which new ideas and knowledge in physics, astronomy, biology, medicine and chemistry transformed medieval and ancient views of nature and laid the foundations for modern science...
, by physicists such as
Galileo GalileiGalileo Galilei , was an Italian physicist, mathematician, astronomer, and philosopher who played a major role in the Scientific Revolution. His achievements include improvements to the telescope and consequent astronomical observations and support for Copernicanism...
,
Christiaan Huygens,
Johannes KeplerJohannes Kepler was a German mathematician, astronomer and astrologer. A key figure in the 17th century scientific revolution, he is best known for his eponymous laws of planetary motion, codified by later astronomers, based on his works Astronomia nova, Harmonices Mundi, and Epitome of Copernican...
,
Blaise Pascal Blaise Pascal , was a French mathematician, physicist, inventor, writer and Catholic philosopher. He was a child prodigy who was educated by his father, a tax collector in Rouen...
and Sir
Isaac NewtonSir Isaac Newton PRS was an English physicist, mathematician, astronomer, natural philosopher, alchemist, and theologian, who has been "considered by many to be the greatest and most influential scientist who ever lived."...
. In the early 17th century, Galileo made extensive use of experimentation to validate physical theories, which is the key idea in the modern scientific method. Galileo formulated and successfully tested several results in dynamics, in particular the law of
inertiaInertia is the resistance of any physical object to a change in its state of motion or rest, or the tendency of an object to resist any change in its motion. It is proportional to an object's mass. The principle of inertia is one of the fundamental principles of classical physics which are used to...
, which later became the first law in
Newton's laws of motionNewton's laws of motion are three physical laws that form the basis for classical mechanics. They describe the relationship between the forces acting on a body and its motion due to those forces...
. In Galileo's
Two New SciencesThe Discourses and Mathematical Demonstrations Relating to Two New Sciences was Galileo's final book and a sort of scientific testament covering much of his work in physics over the preceding thirty years.After his Dialogue Concerning the Two Chief World Systems, the Roman Inquisition had banned...
, a dialogue between the characters Simplicio and Salviati discuss the motion of a ship (as a moving frame) and how that ship's cargo is indifferent to its motion. Huygens used the motion of a boat along a Dutch canal to illustrate an early form of the conservation of
momentumIn classical mechanics, linear momentum or translational momentum is the product of the mass and velocity of an object...
.
Experimental physics is considered to have culminated with the publication of the
Philosophiae Naturalis Principia MathematicaPhilosophiæ Naturalis Principia Mathematica, Latin for "Mathematical Principles of Natural Philosophy", often referred to as simply the Principia, is a work in three books by Sir Isaac Newton, first published 5 July 1687. Newton also published two further editions, in 1713 and 1726...
in 1687 by Sir Isaac Newton (1643–1727). In 1687, Newton published the
Principia, detailing two comprehensive and successful physical theories:
Newton's laws of motionNewton's laws of motion are three physical laws that form the basis for classical mechanics. They describe the relationship between the forces acting on a body and its motion due to those forces...
, from which arise
classical mechanicsIn physics, classical mechanics is one of the two major sub-fields of mechanics, which is concerned with the set of physical laws describing the motion of bodies under the action of a system of forces...
; and
Newton's law of universal gravitationNewton's law of universal gravitation states that every point mass in the universe attracts every other point mass with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them...
, which describes the fundamental force of gravity. Both theories agreed well with experiment. The
Principia also included several theories in
fluid dynamicsIn physics, fluid dynamics is a sub-discipline of fluid mechanics that deals with fluid flow—the natural science of fluids in motion. It has several subdisciplines itself, including aerodynamics and hydrodynamics...
.
From the late 17th century onward,
thermodynamicsThermodynamics is a physical science that studies the effects on material bodies, and on radiation in regions of space, of transfer of heat and of work done on or by the bodies or radiation...
was developed by physicist and chemist
BoyleRobert Boyle FRS was a 17th century natural philosopher, chemist, physicist, and inventor, also noted for his writings in theology. He has been variously described as English, Irish, or Anglo-Irish, his father having come to Ireland from England during the time of the English plantations of...
,
YoungThomas Young was an English polymath. He is famous for having partly deciphered Egyptian hieroglyphics before Jean-François Champollion eventually expanded on his work...
, and many others. In 1733,
BernoulliDaniel Bernoulli was a Dutch-Swiss mathematician and was one of the many prominent mathematicians in the Bernoulli family. He is particularly remembered for his applications of mathematics to mechanics, especially fluid mechanics, and for his pioneering work in probability and statistics...
used statistical arguments with classical mechanics to derive thermodynamic results, initiating the field of
statistical mechanicsStatistical mechanics or statistical thermodynamicsThe terms statistical mechanics and statistical thermodynamics are used interchangeably...
. In 1798,
ThompsonSir Benjamin Thompson, Count Rumford , FRS was an American-born British physicist and inventor whose challenges to established physical theory were part of the 19th century revolution in thermodynamics. He also served as a Lieutenant-Colonel in the Loyalist forces in America during the American...
demonstrated the conversion of mechanical work into heat, and in 1847 Joule stated the law of conservation of
energyIn physics, energy is an indirectly observed quantity. It is often understood as the ability a physical system has to do work on other physical systems...
, in the form of heat as well as mechanical energy.
Ludwig BoltzmannLudwig Eduard Boltzmann was an Austrian physicist famous for his founding contributions in the fields of statistical mechanics and statistical thermodynamics...
, in the nineteenth century, is responsible for the modern form of statistical mechanics.
Besides classical mechanics and thermodynamics, another great field of experimental inquiry within physics was the nature of
electricityElectricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning, static electricity, and the flow of electrical current in an electrical wire...
. Observations in the 17th and eighteenth century by scientists such as
Robert BoyleRobert Boyle FRS was a 17th century natural philosopher, chemist, physicist, and inventor, also noted for his writings in theology. He has been variously described as English, Irish, or Anglo-Irish, his father having come to Ireland from England during the time of the English plantations of...
,
Stephen GrayStephen Gray was an English dyer and amateur astronomer, who was the first to systematically experiment with electrical conduction, rather than simple generation of static charges and investigations of the static phenomena....
, and
Benjamin FranklinDr. Benjamin Franklin was one of the Founding Fathers of the United States. A noted polymath, Franklin was a leading author, printer, political theorist, politician, postmaster, scientist, musician, inventor, satirist, civic activist, statesman, and diplomat...
created a foundation for later work. These observations also established our basic understanding of electrical charge and
currentElectric current is a flow of electric charge through a medium.This charge is typically carried by moving electrons in a conductor such as wire...
. By 1808
John DaltonJohn Dalton FRS was an English chemist, meteorologist and physicist. He is best known for his pioneering work in the development of modern atomic theory, and his research into colour blindness .-Early life:John Dalton was born into a Quaker family at Eaglesfield, near Cockermouth, Cumberland,...
had discovered that atoms of different elements have different weights and proposed the modern
theory of the atomIn chemistry and physics, atomic theory is a theory of the nature of matter, which states that matter is composed of discrete units called atoms, as opposed to the obsolete notion that matter could be divided into any arbitrarily small quantity...
.
It was
Hans Christian ØrstedHans Christian Ørsted was a Danish physicist and chemist who discovered that electric currents create magnetic fields, an important aspect of electromagnetism...
who first proposed the connection between electricity and magnetism after observing the deflection of a compass needle by a nearby electric current. By the early 1830s
Michael FaradayMichael Faraday, FRS was an English chemist and physicist who contributed to the fields of electromagnetism and electrochemistry....
had demonstrated that magnetic fields and electricity could generate each other. In 1864
James Clerk MaxwellJames Clerk Maxwell of Glenlair was a Scottish physicist and mathematician. His most prominent achievement was formulating classical electromagnetic theory. This united all previously unrelated observations, experiments and equations of electricity, magnetism and optics into a consistent theory...
presented to the
Royal SocietyThe Royal Society of London for Improving Natural Knowledge, known simply as the Royal Society, is a learned society for science, and is possibly the oldest such society in existence. Founded in November 1660, it was granted a Royal Charter by King Charles II as the "Royal Society of London"...
a set of equations that described this relationship between electricity and magnetism.
Maxwell's equationsMaxwell's equations are a set of partial differential equations that, together with the Lorentz force law, form the foundation of classical electrodynamics, classical optics, and electric circuits. These fields in turn underlie modern electrical and communications technologies.Maxwell's equations...
also predicted correctly that
lightLight or visible light is electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight. Visible light has wavelength in a range from about 380 nanometres to about 740 nm, with a frequency range of about 405 THz to 790 THz...
is an
electromagnetic waveElectromagnetic radiation is a form of energy that exhibits wave-like behavior as it travels through space...
. Starting with astronomy, the principles of
natural philosophyNatural philosophy or the philosophy of nature , is a term applied to the study of nature and the physical universe that was dominant before the development of modern science...
crystallized into fundamental laws of physics which were enunciated and improved in the succeeding centuries. By the 19th century, the sciences had segmented into multiple fields with specialized researchers and the field of physics, although logically pre-eminent, no longer could claim sole ownership of the entire field of scientific research.
Current experiments
Some examples of prominent experimental physics projects are:
- Relativistic Heavy Ion Collider
The Relativistic Heavy Ion Collider is one of two existing heavy-ion colliders, and the only spin-polarized proton collider in the world. It is located at Brookhaven National Laboratory in Upton, New York and operated by an international team of researchers...
which collides heavy ionHeavy ion refers to an ionized atom which is usually heavier than helium. Heavy-ion physics is devoted to the study of extremely hot nuclear matter and the collective effects appearing in such systems, differing from particle physics, which studies the interactions between elementary particles...
s such as goldGold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...
ions (it is the first heavy ion collider) and protonThe proton is a subatomic particle with the symbol or and a positive electric charge of 1 elementary charge. One or more protons are present in the nucleus of each atom, along with neutrons. The number of protons in each atom is its atomic number....
s, it is located at Brookhaven National LaboratoryBrookhaven National Laboratory , is a United States national laboratory located in Upton, New York on Long Island, and was formally established in 1947 at the site of Camp Upton, a former U.S. Army base...
, on Long Island, USA.
- HERA
HERA was a particle accelerator at DESY in Hamburg. It began operating in 1992. At HERA, electrons or positrons were collided with protons at a center of mass energy of 318 GeV. It was the only lepton-proton collider in the world while operating...
, which collides electronThe electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...
s or positronThe positron or antielectron is the antiparticle or the antimatter counterpart of the electron. The positron has an electric charge of +1e, a spin of ½, and has the same mass as an electron...
s and protons, and is part of DESYThe DESY is the biggest German research center for particle physics, with sites in Hamburg and Zeuthen....
, located in Hamburg-History:The first historic name for the city was, according to Claudius Ptolemy's reports, Treva.But the city takes its modern name, Hamburg, from the first permanent building on the site, a castle whose construction was ordered by the Emperor Charlemagne in AD 808...
, Germany.
- LHC
The Large Hadron Collider is the world's largest and highest-energy particle accelerator. It is expected to address some of the most fundamental questions of physics, advancing the understanding of the deepest laws of nature....
, or the Large HadronIn particle physics, a hadron is a composite particle made of quarks held together by the strong force...
ColliderA collider is a type of a particle accelerator involving directed beams of particles.Colliders may either be ring accelerators or linear accelerators.-Explanation:...
, which complete construction in 2008 but suffered a series of setbacks. The LHC began operations in 2008, but was shut down for maintenance until the summer of 2009. It is the world's most energetic collider upon completion, it is located at CERNThe European Organization for Nuclear Research , known as CERN , is an international organization whose purpose is to operate the world's largest particle physics laboratory, which is situated in the northwest suburbs of Geneva on the Franco–Swiss border...
, on the French-Swiss border near GenevaGeneva In the national languages of Switzerland the city is known as Genf , Ginevra and Genevra is the second-most-populous city in Switzerland and is the most populous city of Romandie, the French-speaking part of Switzerland...
. The collider became fully operational March 29, 2010 a year and a half later than originally planned.
- JWST
The James Webb Space Telescope , previously known as Next Generation Space Telescope , is a planned next-generation space telescope, optimized for observations in the infrared. The main technical features are a large and very cold 6.5 meter diameter mirror, an observing position far from Earth,...
, or the James WebbJames Edwin Webb was an American government official who served as the second administrator of NASA from February 14, 1961 to October 7, 1968....
Space Telescope, is planned for launch in 2013. It will be the successor to the Hubble Space TelescopeThe Hubble Space Telescope is a space telescope that was carried into orbit by a Space Shuttle in 1990 and remains in operation. A 2.4 meter aperture telescope in low Earth orbit, Hubble's four main instruments observe in the near ultraviolet, visible, and near infrared...
. It will survey the sky in the infrared region. The main goals of the JWST will be in order to understand the initial stages of the universe, galaxy formation as well as the formations of stars and planets, and the origins of life.
Method
Experimental physics uses two main methods of experimental research,
controlled experimentsScientific control allows for comparisons of concepts. It is a part of the scientific method. Scientific control is often used in discussion of natural experiments. For instance, during drug testing, scientists will try to control two groups to keep them as identical and normal as possible, then...
, and
natural experimentA natural experiment is an observational study in which the assignment of treatments to subjects has been haphazard: That is, the assignment of treatments has been made "by nature", but not by experimenters. Thus, a natural experiment is not a controlled experiment...
s. Controlled experiments are often used in laboratories as laboratories can offer a controlled environment. Natural experiments are used, for example, in
astrophysicsAstrophysics is the branch of astronomy that deals with the physics of the universe, including the physical properties of celestial objects, as well as their interactions and behavior...
when observing celestial objects where control of the variables in effect is impossible.
Famous experiments
Famous
experiments include:
- 2-degree-Field Galaxy Redshift Survey
In astronomy, the 2dF Galaxy Redshift Survey , 2dF or 2dFGRS is a redshift survey conducted by the Anglo-Australian Observatory with the 3.9m Anglo-Australian Telescope between 1997 and 11 April 2002. The data from this survey were made public on 30 June 2003...
- 2-Micron All-Sky Survey (2MASS)
Observations for the Two Micron All-Sky Survey began in 1997 and were completed in 2001 at two telescopes located one each in the northern and southern hemispheres to ensure coverage of the entire sky...
- Bell test experiments
The Bell test experiments serve to investigate the validity of the entanglement effect in quantum mechanics by using some kind of Bell inequality...
- BOOMERanG experiment
The BOOMERanG experiment measured the cosmic microwave background radiation of a part of the sky during three sub-orbital balloon flights. It was the first experiment to make large, high fidelity images of the CMB temperature anisotropies...
- Camera obscura experiments
- Cavendish experiment
The Cavendish experiment, performed in 1797–98 by British scientist Henry Cavendish was the first experiment to measure the force of gravity between masses in the laboratory, and the first to yield accurate values for the gravitational constant. Because of the unit conventions then in use,...
- Cosmic Background Explorer
- Cowan–Reines neutrino experiment
- Davisson–Germer experiment
- Double-slit experiment
The double-slit experiment, sometimes called Young's experiment, is a demonstration that matter and energy can display characteristics of both waves and particles...
- Foucault pendulum
The Foucault pendulum , or Foucault's pendulum, named after the French physicist Léon Foucault, is a simple device conceived as an experiment to demonstrate the rotation of the Earth. While it had long been known that the Earth rotated, the introduction of the Foucault pendulum in 1851 was the...
- Franck–Hertz experiment
- Geiger–Marsden experiment
- Gravity Probe A
Gravity Probe A was a space-based experiment to test the theory of general relativity, performed jointly by the Smithsonian Astrophysical Observatory and the National Aeronautics and Space Administration...
- Gravity Probe B
Gravity Probe B is a satellite-based mission which launched on 20 April 2004 on a Delta II rocket. The spaceflight phase lasted until 2005; its aim was to measure spacetime curvature near Earth, and thereby the stress–energy tensor in and near Earth...
- Hafele–Keating experiment
- Homestake experiment
The Homestake experiment was an experiment headed by astrophysicists Raymond Davis, Jr. and John N. Bahcall in the late 1960s. Its purpose was to collect and count neutrinos emitted by nuclear fusion taking place in the Sun. Bahcall did the theoretical calculations and Davis designed the experiment...
- Oil drop experiment
- Michelson–Morley experiment
- Sloan Digital Sky Survey
The Sloan Digital Sky Survey or SDSS is a major multi-filter imaging and spectroscopic redshift survey using a dedicated 2.5-m wide-angle optical telescope at Apache Point Observatory in New Mexico, United States. The project was named after the Alfred P...
- Stern–Gerlach experiment
Important in the field of quantum mechanics, the Stern–Gerlach experiment, named after Otto Stern and Walther Gerlach, is a 1922 experiment on the deflection of particles, often used to illustrate basic principles of quantum mechanics...
- Wilkinson Microwave Anisotropy Probe
The Wilkinson Microwave Anisotropy Probe — also known as the Microwave Anisotropy Probe , and Explorer 80 — is a spacecraft which measures differences in the temperature of the Big Bang's remnant radiant heat — the Cosmic Microwave Background Radiation — across the full sky. Headed by Professor...
Experimental techniques
Some well-known experimental techniques include:
- Crystallography
Crystallography is the experimental science of the arrangement of atoms in solids. The word "crystallography" derives from the Greek words crystallon = cold drop / frozen drop, with its meaning extending to all solids with some degree of transparency, and grapho = write.Before the development of...
- Ellipsometry
Ellipsometry is an optical technique for the investigation of the dielectric properties of thin films....
- Faraday cage
A Faraday cage or Faraday shield is an enclosure formed by conducting material or by a mesh of such material. Such an enclosure blocks out external static and non-static electric fields...
- Interferometry
Interferometry refers to a family of techniques in which electromagnetic waves are superimposed in order to extract information about the waves. An instrument used to interfere waves is called an interferometer. Interferometry is an important investigative technique in the fields of astronomy,...
- Raman spectroscopy
Raman spectroscopy is a spectroscopic technique used to study vibrational, rotational, and other low-frequency modes in a system.It relies on inelastic scattering, or Raman scattering, of monochromatic light, usually from a laser in the visible, near infrared, or near ultraviolet range...
- Signal processing
Signal processing is an area of systems engineering, electrical engineering and applied mathematics that deals with operations on or analysis of signals, in either discrete or continuous time...
- Spectroscopy
Spectroscopy is the study of the interaction between matter and radiated energy. Historically, spectroscopy originated through the study of visible light dispersed according to its wavelength, e.g., by a prism. Later the concept was expanded greatly to comprise any interaction with radiative...
- X-ray spectroscopy
X-ray spectroscopy is a gathering name for several spectroscopic techniques for characterization of materials by using x-ray excitation.-Characteristic X-ray Spectroscopy:...
Prominent experimental physicists
Famous
experimental physicists include:
Within the field of
physicsPhysics is a natural science that involves the study of matter and its motion through spacetime, 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...
,
experimental physics is the category of disciplines and sub-disciplines concerned with the
observationObservation is either an activity of a living being, such as a human, consisting of receiving knowledge of the outside world through the senses, or the recording of data using scientific instruments. The term may also refer to any data collected during this activity...
of physical phenomena in order to gather
dataThe term data refers to qualitative or quantitative attributes of a variable or set of variables. Data are typically the results of measurements and can be the basis of graphs, images, or observations of a set of variables. Data are often viewed as the lowest level of abstraction from which...
about the
universeThe Universe is commonly defined as the totality of everything that exists, including all matter and energy, the planets, stars, galaxies, and the contents of intergalactic space. Definitions and usage vary and similar terms include the cosmos, the world and nature...
. Methods vary from discipline to discipline, from simple experiments and observations, such as the
Cavendish experimentThe Cavendish experiment, performed in 1797–98 by British scientist Henry Cavendish was the first experiment to measure the force of gravity between masses in the laboratory, and the first to yield accurate values for the gravitational constant. Because of the unit conventions then in use,...
, to more complicated ones, such as the
Large Hadron ColliderThe Large Hadron Collider is the world's largest and highest-energy particle accelerator. It is expected to address some of the most fundamental questions of physics, advancing the understanding of the deepest laws of nature....
.
Overview
Experimental physics regroup all the disciplines of physics that are concerned with data-acquisition, data-acquisition methods, and the detailed conceptualization (beyond simple
thought experimentA thought experiment or Gedankenexperiment considers some hypothesis, theory, or principle for the purpose of thinking through its consequences...
s) and realization of laboratory
experimentAn experiment is a methodical procedure carried out with the goal of verifying, falsifying, or establishing the validity of a hypothesis. Experiments vary greatly in their goal and scale, but always rely on repeatable procedure and logical analysis of the results...
s. It is often put in contrast with
theoretical physicsTheoretical physics is a branch of physics which employs mathematical models and abstractions of physics to rationalize, explain and predict natural phenomena...
, which is more concerned with predicting and explaining the physical behaviour of nature than the acquisition of knowledge about it.
Although experimental and theoretical physics are concerned with different aspects of nature, they both share the same goal of understanding it and have a symbiotic relation. The former provides data about the universe, which can then be analyzed in order to be understood, while the latter provides explanations for the data and thus offers insight on how to better acquire data and on how to set up experiments. Theoretical physics can also offer insight on what data is needed in order to gain a better understanding of the universe, and on what experiments to devise in order to obtain it.
History
As a distinct field, experimental physics was established in
early modern EuropeEarly modern Europe is the term used by historians to refer to a period in the history of Europe which spanned the centuries between the end of the Middle Ages and the beginning of the Industrial Revolution, roughly the late 15th century to the late 18th century...
, during what is known as the
Scientific RevolutionThe Scientific Revolution is an era associated primarily with the 16th and 17th centuries during which new ideas and knowledge in physics, astronomy, biology, medicine and chemistry transformed medieval and ancient views of nature and laid the foundations for modern science...
, by physicists such as
Galileo GalileiGalileo Galilei , was an Italian physicist, mathematician, astronomer, and philosopher who played a major role in the Scientific Revolution. His achievements include improvements to the telescope and consequent astronomical observations and support for Copernicanism...
,
Christiaan Huygens,
Johannes KeplerJohannes Kepler was a German mathematician, astronomer and astrologer. A key figure in the 17th century scientific revolution, he is best known for his eponymous laws of planetary motion, codified by later astronomers, based on his works Astronomia nova, Harmonices Mundi, and Epitome of Copernican...
,
Blaise Pascal Blaise Pascal , was a French mathematician, physicist, inventor, writer and Catholic philosopher. He was a child prodigy who was educated by his father, a tax collector in Rouen...
and Sir
Isaac NewtonSir Isaac Newton PRS was an English physicist, mathematician, astronomer, natural philosopher, alchemist, and theologian, who has been "considered by many to be the greatest and most influential scientist who ever lived."...
. In the early 17th century, Galileo made extensive use of experimentation to validate physical theories, which is the key idea in the modern scientific method. Galileo formulated and successfully tested several results in dynamics, in particular the law of
inertiaInertia is the resistance of any physical object to a change in its state of motion or rest, or the tendency of an object to resist any change in its motion. It is proportional to an object's mass. The principle of inertia is one of the fundamental principles of classical physics which are used to...
, which later became the first law in
Newton's laws of motionNewton's laws of motion are three physical laws that form the basis for classical mechanics. They describe the relationship between the forces acting on a body and its motion due to those forces...
. In Galileo's
Two New SciencesThe Discourses and Mathematical Demonstrations Relating to Two New Sciences was Galileo's final book and a sort of scientific testament covering much of his work in physics over the preceding thirty years.After his Dialogue Concerning the Two Chief World Systems, the Roman Inquisition had banned...
, a dialogue between the characters Simplicio and Salviati discuss the motion of a ship (as a moving frame) and how that ship's cargo is indifferent to its motion. Huygens used the motion of a boat along a Dutch canal to illustrate an early form of the conservation of
momentumIn classical mechanics, linear momentum or translational momentum is the product of the mass and velocity of an object...
.
Experimental physics is considered to have culminated with the publication of the
Philosophiae Naturalis Principia MathematicaPhilosophiæ Naturalis Principia Mathematica, Latin for "Mathematical Principles of Natural Philosophy", often referred to as simply the Principia, is a work in three books by Sir Isaac Newton, first published 5 July 1687. Newton also published two further editions, in 1713 and 1726...
in 1687 by Sir Isaac Newton (1643–1727). In 1687, Newton published the
Principia, detailing two comprehensive and successful physical theories:
Newton's laws of motionNewton's laws of motion are three physical laws that form the basis for classical mechanics. They describe the relationship between the forces acting on a body and its motion due to those forces...
, from which arise
classical mechanicsIn physics, classical mechanics is one of the two major sub-fields of mechanics, which is concerned with the set of physical laws describing the motion of bodies under the action of a system of forces...
; and
Newton's law of universal gravitationNewton's law of universal gravitation states that every point mass in the universe attracts every other point mass with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them...
, which describes the fundamental force of gravity. Both theories agreed well with experiment. The
Principia also included several theories in
fluid dynamicsIn physics, fluid dynamics is a sub-discipline of fluid mechanics that deals with fluid flow—the natural science of fluids in motion. It has several subdisciplines itself, including aerodynamics and hydrodynamics...
.
From the late 17th century onward,
thermodynamicsThermodynamics is a physical science that studies the effects on material bodies, and on radiation in regions of space, of transfer of heat and of work done on or by the bodies or radiation...
was developed by physicist and chemist
BoyleRobert Boyle FRS was a 17th century natural philosopher, chemist, physicist, and inventor, also noted for his writings in theology. He has been variously described as English, Irish, or Anglo-Irish, his father having come to Ireland from England during the time of the English plantations of...
,
YoungThomas Young was an English polymath. He is famous for having partly deciphered Egyptian hieroglyphics before Jean-François Champollion eventually expanded on his work...
, and many others. In 1733,
BernoulliDaniel Bernoulli was a Dutch-Swiss mathematician and was one of the many prominent mathematicians in the Bernoulli family. He is particularly remembered for his applications of mathematics to mechanics, especially fluid mechanics, and for his pioneering work in probability and statistics...
used statistical arguments with classical mechanics to derive thermodynamic results, initiating the field of
statistical mechanicsStatistical mechanics or statistical thermodynamicsThe terms statistical mechanics and statistical thermodynamics are used interchangeably...
. In 1798,
ThompsonSir Benjamin Thompson, Count Rumford , FRS was an American-born British physicist and inventor whose challenges to established physical theory were part of the 19th century revolution in thermodynamics. He also served as a Lieutenant-Colonel in the Loyalist forces in America during the American...
demonstrated the conversion of mechanical work into heat, and in 1847 Joule stated the law of conservation of
energyIn physics, energy is an indirectly observed quantity. It is often understood as the ability a physical system has to do work on other physical systems...
, in the form of heat as well as mechanical energy.
Ludwig BoltzmannLudwig Eduard Boltzmann was an Austrian physicist famous for his founding contributions in the fields of statistical mechanics and statistical thermodynamics...
, in the nineteenth century, is responsible for the modern form of statistical mechanics.
Besides classical mechanics and thermodynamics, another great field of experimental inquiry within physics was the nature of
electricityElectricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning, static electricity, and the flow of electrical current in an electrical wire...
. Observations in the 17th and eighteenth century by scientists such as
Robert BoyleRobert Boyle FRS was a 17th century natural philosopher, chemist, physicist, and inventor, also noted for his writings in theology. He has been variously described as English, Irish, or Anglo-Irish, his father having come to Ireland from England during the time of the English plantations of...
,
Stephen GrayStephen Gray was an English dyer and amateur astronomer, who was the first to systematically experiment with electrical conduction, rather than simple generation of static charges and investigations of the static phenomena....
, and
Benjamin FranklinDr. Benjamin Franklin was one of the Founding Fathers of the United States. A noted polymath, Franklin was a leading author, printer, political theorist, politician, postmaster, scientist, musician, inventor, satirist, civic activist, statesman, and diplomat...
created a foundation for later work. These observations also established our basic understanding of electrical charge and
currentElectric current is a flow of electric charge through a medium.This charge is typically carried by moving electrons in a conductor such as wire...
. By 1808
John DaltonJohn Dalton FRS was an English chemist, meteorologist and physicist. He is best known for his pioneering work in the development of modern atomic theory, and his research into colour blindness .-Early life:John Dalton was born into a Quaker family at Eaglesfield, near Cockermouth, Cumberland,...
had discovered that atoms of different elements have different weights and proposed the modern
theory of the atomIn chemistry and physics, atomic theory is a theory of the nature of matter, which states that matter is composed of discrete units called atoms, as opposed to the obsolete notion that matter could be divided into any arbitrarily small quantity...
.
It was
Hans Christian ØrstedHans Christian Ørsted was a Danish physicist and chemist who discovered that electric currents create magnetic fields, an important aspect of electromagnetism...
who first proposed the connection between electricity and magnetism after observing the deflection of a compass needle by a nearby electric current. By the early 1830s
Michael FaradayMichael Faraday, FRS was an English chemist and physicist who contributed to the fields of electromagnetism and electrochemistry....
had demonstrated that magnetic fields and electricity could generate each other. In 1864
James Clerk MaxwellJames Clerk Maxwell of Glenlair was a Scottish physicist and mathematician. His most prominent achievement was formulating classical electromagnetic theory. This united all previously unrelated observations, experiments and equations of electricity, magnetism and optics into a consistent theory...
presented to the
Royal SocietyThe Royal Society of London for Improving Natural Knowledge, known simply as the Royal Society, is a learned society for science, and is possibly the oldest such society in existence. Founded in November 1660, it was granted a Royal Charter by King Charles II as the "Royal Society of London"...
a set of equations that described this relationship between electricity and magnetism.
Maxwell's equationsMaxwell's equations are a set of partial differential equations that, together with the Lorentz force law, form the foundation of classical electrodynamics, classical optics, and electric circuits. These fields in turn underlie modern electrical and communications technologies.Maxwell's equations...
also predicted correctly that
lightLight or visible light is electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight. Visible light has wavelength in a range from about 380 nanometres to about 740 nm, with a frequency range of about 405 THz to 790 THz...
is an
electromagnetic waveElectromagnetic radiation is a form of energy that exhibits wave-like behavior as it travels through space...
. Starting with astronomy, the principles of
natural philosophyNatural philosophy or the philosophy of nature , is a term applied to the study of nature and the physical universe that was dominant before the development of modern science...
crystallized into fundamental laws of physics which were enunciated and improved in the succeeding centuries. By the 19th century, the sciences had segmented into multiple fields with specialized researchers and the field of physics, although logically pre-eminent, no longer could claim sole ownership of the entire field of scientific research.
Current experiments
Some examples of prominent experimental physics projects are:
- Relativistic Heavy Ion Collider
The Relativistic Heavy Ion Collider is one of two existing heavy-ion colliders, and the only spin-polarized proton collider in the world. It is located at Brookhaven National Laboratory in Upton, New York and operated by an international team of researchers...
which collides heavy ionHeavy ion refers to an ionized atom which is usually heavier than helium. Heavy-ion physics is devoted to the study of extremely hot nuclear matter and the collective effects appearing in such systems, differing from particle physics, which studies the interactions between elementary particles...
s such as goldGold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...
ions (it is the first heavy ion collider) and protonThe proton is a subatomic particle with the symbol or and a positive electric charge of 1 elementary charge. One or more protons are present in the nucleus of each atom, along with neutrons. The number of protons in each atom is its atomic number....
s, it is located at Brookhaven National LaboratoryBrookhaven National Laboratory , is a United States national laboratory located in Upton, New York on Long Island, and was formally established in 1947 at the site of Camp Upton, a former U.S. Army base...
, on Long Island, USA.
- HERA
HERA was a particle accelerator at DESY in Hamburg. It began operating in 1992. At HERA, electrons or positrons were collided with protons at a center of mass energy of 318 GeV. It was the only lepton-proton collider in the world while operating...
, which collides electronThe electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...
s or positronThe positron or antielectron is the antiparticle or the antimatter counterpart of the electron. The positron has an electric charge of +1e, a spin of ½, and has the same mass as an electron...
s and protons, and is part of DESYThe DESY is the biggest German research center for particle physics, with sites in Hamburg and Zeuthen....
, located in Hamburg-History:The first historic name for the city was, according to Claudius Ptolemy's reports, Treva.But the city takes its modern name, Hamburg, from the first permanent building on the site, a castle whose construction was ordered by the Emperor Charlemagne in AD 808...
, Germany.
- LHC
The Large Hadron Collider is the world's largest and highest-energy particle accelerator. It is expected to address some of the most fundamental questions of physics, advancing the understanding of the deepest laws of nature....
, or the Large HadronIn particle physics, a hadron is a composite particle made of quarks held together by the strong force...
ColliderA collider is a type of a particle accelerator involving directed beams of particles.Colliders may either be ring accelerators or linear accelerators.-Explanation:...
, which complete construction in 2008 but suffered a series of setbacks. The LHC began operations in 2008, but was shut down for maintenance until the summer of 2009. It is the world's most energetic collider upon completion, it is located at CERNThe European Organization for Nuclear Research , known as CERN , is an international organization whose purpose is to operate the world's largest particle physics laboratory, which is situated in the northwest suburbs of Geneva on the Franco–Swiss border...
, on the French-Swiss border near GenevaGeneva In the national languages of Switzerland the city is known as Genf , Ginevra and Genevra is the second-most-populous city in Switzerland and is the most populous city of Romandie, the French-speaking part of Switzerland...
. The collider became fully operational March 29, 2010 a year and a half later than originally planned.
- JWST
The James Webb Space Telescope , previously known as Next Generation Space Telescope , is a planned next-generation space telescope, optimized for observations in the infrared. The main technical features are a large and very cold 6.5 meter diameter mirror, an observing position far from Earth,...
, or the James WebbJames Edwin Webb was an American government official who served as the second administrator of NASA from February 14, 1961 to October 7, 1968....
Space Telescope, is planned for launch in 2013. It will be the successor to the Hubble Space TelescopeThe Hubble Space Telescope is a space telescope that was carried into orbit by a Space Shuttle in 1990 and remains in operation. A 2.4 meter aperture telescope in low Earth orbit, Hubble's four main instruments observe in the near ultraviolet, visible, and near infrared...
. It will survey the sky in the infrared region. The main goals of the JWST will be in order to understand the initial stages of the universe, galaxy formation as well as the formations of stars and planets, and the origins of life.
Method
Experimental physics uses two main methods of experimental research,
controlled experimentsScientific control allows for comparisons of concepts. It is a part of the scientific method. Scientific control is often used in discussion of natural experiments. For instance, during drug testing, scientists will try to control two groups to keep them as identical and normal as possible, then...
, and
natural experimentA natural experiment is an observational study in which the assignment of treatments to subjects has been haphazard: That is, the assignment of treatments has been made "by nature", but not by experimenters. Thus, a natural experiment is not a controlled experiment...
s. Controlled experiments are often used in laboratories as laboratories can offer a controlled environment. Natural experiments are used, for example, in
astrophysicsAstrophysics is the branch of astronomy that deals with the physics of the universe, including the physical properties of celestial objects, as well as their interactions and behavior...
when observing celestial objects where control of the variables in effect is impossible.
Famous experiments
Famous
experiments include:
- 2-degree-Field Galaxy Redshift Survey
In astronomy, the 2dF Galaxy Redshift Survey , 2dF or 2dFGRS is a redshift survey conducted by the Anglo-Australian Observatory with the 3.9m Anglo-Australian Telescope between 1997 and 11 April 2002. The data from this survey were made public on 30 June 2003...
- 2-Micron All-Sky Survey (2MASS)
Observations for the Two Micron All-Sky Survey began in 1997 and were completed in 2001 at two telescopes located one each in the northern and southern hemispheres to ensure coverage of the entire sky...
- Bell test experiments
The Bell test experiments serve to investigate the validity of the entanglement effect in quantum mechanics by using some kind of Bell inequality...
- BOOMERanG experiment
The BOOMERanG experiment measured the cosmic microwave background radiation of a part of the sky during three sub-orbital balloon flights. It was the first experiment to make large, high fidelity images of the CMB temperature anisotropies...
- Camera obscura experiments
- Cavendish experiment
The Cavendish experiment, performed in 1797–98 by British scientist Henry Cavendish was the first experiment to measure the force of gravity between masses in the laboratory, and the first to yield accurate values for the gravitational constant. Because of the unit conventions then in use,...
- Cosmic Background Explorer
- Cowan–Reines neutrino experiment
- Davisson–Germer experiment
- Double-slit experiment
The double-slit experiment, sometimes called Young's experiment, is a demonstration that matter and energy can display characteristics of both waves and particles...
- Foucault pendulum
The Foucault pendulum , or Foucault's pendulum, named after the French physicist Léon Foucault, is a simple device conceived as an experiment to demonstrate the rotation of the Earth. While it had long been known that the Earth rotated, the introduction of the Foucault pendulum in 1851 was the...
- Franck–Hertz experiment
- Geiger–Marsden experiment
- Gravity Probe A
Gravity Probe A was a space-based experiment to test the theory of general relativity, performed jointly by the Smithsonian Astrophysical Observatory and the National Aeronautics and Space Administration...
- Gravity Probe B
Gravity Probe B is a satellite-based mission which launched on 20 April 2004 on a Delta II rocket. The spaceflight phase lasted until 2005; its aim was to measure spacetime curvature near Earth, and thereby the stress–energy tensor in and near Earth...
- Hafele–Keating experiment
- Homestake experiment
The Homestake experiment was an experiment headed by astrophysicists Raymond Davis, Jr. and John N. Bahcall in the late 1960s. Its purpose was to collect and count neutrinos emitted by nuclear fusion taking place in the Sun. Bahcall did the theoretical calculations and Davis designed the experiment...
- Oil drop experiment
- Michelson–Morley experiment
- Sloan Digital Sky Survey
The Sloan Digital Sky Survey or SDSS is a major multi-filter imaging and spectroscopic redshift survey using a dedicated 2.5-m wide-angle optical telescope at Apache Point Observatory in New Mexico, United States. The project was named after the Alfred P...
- Stern–Gerlach experiment
Important in the field of quantum mechanics, the Stern–Gerlach experiment, named after Otto Stern and Walther Gerlach, is a 1922 experiment on the deflection of particles, often used to illustrate basic principles of quantum mechanics...
- Wilkinson Microwave Anisotropy Probe
The Wilkinson Microwave Anisotropy Probe — also known as the Microwave Anisotropy Probe , and Explorer 80 — is a spacecraft which measures differences in the temperature of the Big Bang's remnant radiant heat — the Cosmic Microwave Background Radiation — across the full sky. Headed by Professor...
Experimental techniques
Some well-known experimental techniques include:
- Crystallography
Crystallography is the experimental science of the arrangement of atoms in solids. The word "crystallography" derives from the Greek words crystallon = cold drop / frozen drop, with its meaning extending to all solids with some degree of transparency, and grapho = write.Before the development of...
- Ellipsometry
Ellipsometry is an optical technique for the investigation of the dielectric properties of thin films....
- Faraday cage
A Faraday cage or Faraday shield is an enclosure formed by conducting material or by a mesh of such material. Such an enclosure blocks out external static and non-static electric fields...
- Interferometry
Interferometry refers to a family of techniques in which electromagnetic waves are superimposed in order to extract information about the waves. An instrument used to interfere waves is called an interferometer. Interferometry is an important investigative technique in the fields of astronomy,...
- Raman spectroscopy
Raman spectroscopy is a spectroscopic technique used to study vibrational, rotational, and other low-frequency modes in a system.It relies on inelastic scattering, or Raman scattering, of monochromatic light, usually from a laser in the visible, near infrared, or near ultraviolet range...
- Signal processing
Signal processing is an area of systems engineering, electrical engineering and applied mathematics that deals with operations on or analysis of signals, in either discrete or continuous time...
- Spectroscopy
Spectroscopy is the study of the interaction between matter and radiated energy. Historically, spectroscopy originated through the study of visible light dispersed according to its wavelength, e.g., by a prism. Later the concept was expanded greatly to comprise any interaction with radiative...
- X-ray spectroscopy
X-ray spectroscopy is a gathering name for several spectroscopic techniques for characterization of materials by using x-ray excitation.-Characteristic X-ray Spectroscopy:...
Prominent experimental physicists
Famous
experimental physicists include:
- Alhacen (965–1039)
- Carl David Anderson
Carl David Anderson was an American physicist. He is best known for his discovery of the positron in 1932, an achievement for which he received the 1936 Nobel Prize in Physics, and of the muon in 1936.-Biography:...
(1905–1991)
- John Bardeen
John Bardeen was an American physicist and electrical engineer, the only person to have won the Nobel Prize in Physics twice: first in 1956 with William Shockley and Walter Brattain for the invention of the transistor; and again in 1972 with Leon Neil Cooper and John Robert Schrieffer for a...
(1908–1991)
- Antoine Henri Becquerel
Antoine Henri Becquerel was a French physicist, Nobel laureate, and the discoverer of radioactivity along with Marie Curie and Pierre Curie, for which all three won the 1903 Nobel Prize in Physics.-Early life:...
(1852–1908)
- Gerd Binnig
Gerd Binnig is a German physicist, and a Nobel laureate.He was born in Frankfurt am Main and played in the ruins of the city during his childhood. His family lived partly in Frankfurt and partly in Offenbach am Main, and he attended school in both cities. At the age of 10, he decided to become a...
(1947–Present)
- Abū Rayhān al-Bīrūnī (973–1043)
- Patrick Blackett (Baron Blackett)
Patrick Maynard Stuart Blackett, Baron Blackett OM CH FRS was an English experimental physicist known for his work on cloud chambers, cosmic rays, and paleomagnetism. He also made a major contribution in World War II advising on military strategy and developing Operational Research...
(1897–1974)
- Nicolaas Bloembergen
Nicolaas Bloembergen is a Dutch-American physicist and Nobel laureate.He received his Ph.D. degree from University of Leiden in 1948; while pursuing his PhD at Harvard, Bloembergen also worked part-time as a graduate research assistant for Edward Mills Purcell at the MIT Radiation Laboratory...
(1920–Present)
- Jagadish Chandra Bose (1858–1937)
- William Henry Bragg
Sir William Henry Bragg OM, KBE, PRS was a British physicist, chemist, mathematician and active sportsman who uniquely shared a Nobel Prize with his son William Lawrence Bragg - the 1915 Nobel Prize in Physics...
(1862–1942)
- William Lawrence Bragg
Sir William Lawrence Bragg CH OBE MC FRS was an Australian-born British physicist and X-ray crystallographer, discoverer of the Bragg law of X-ray diffraction, which is basic for the determination of crystal structure. He was joint winner of the Nobel Prize for Physics in 1915. He was knighted...
(1890–1971)
- Walter Houser Brattain
Walter Houser Brattain was an American physicist at Bell Labs who, along with John Bardeen and William Shockley, invented the transistor. They shared the 1956 Nobel Prize in Physics for their invention. He devoted much of his life to research on surface states.- Early life and education :He was...
(1902–1987)
- Karl Ferdinand Braun
Karl Ferdinand Braun was a German inventor, physicist and Nobel laureate in physics. Braun contributed significantly to the development of the radio and television technology: he shared with Guglielmo Marconi the 1909 Nobel Prize in Physics.-Biography:Braun was born in Fulda, Germany, and...
(1850–1918)
- James Chadwick
Sir James Chadwick CH FRS was an English Nobel laureate in physics awarded for his discovery of the neutron....
(1891–1974)
- Owen Chamberlain
Owen Chamberlain was an American physicist, and Nobel laureate in physics for his discovery, with collaborator Emilio Segrè, of antiprotons, a sub-atomic antiparticle.-Biography:...
(1920–2006)
- Pavel Alekseyevich Cherenkov
Pavel Alekseyevich Cherenkov was a Soviet physicist who shared the Nobel Prize in physics in 1958 with Ilya Frank and Igor Tamm for the discovery of Cherenkov radiation, made in 1934.-Biography:...
(1904–1990)
- Steven Chu
Steven Chu is an American physicist and the 12th United States Secretary of Energy. Chu is known for his research at Bell Labs in cooling and trapping of atoms with laser light, which won him the Nobel Prize in Physics in 1997, along with his scientific colleagues Claude Cohen-Tannoudji and...
(1948–Present)
- John Cockcroft
Sir John Douglas Cockcroft OM KCB CBE FRS was a British physicist. He shared the Nobel Prize in Physics for splitting the atomic nucleus with Ernest Walton, and was instrumental in the development of nuclear power....
(1897–1967)
- Marie Curie
Marie Skłodowska-Curie was a physicist and chemist famous for her pioneering research on radioactivity. She was the first person honored with two Nobel Prizes—in physics and chemistry...
(1867–1934)
- Clinton Davisson
Clinton Joseph Davisson , was an American physicist who won the 1937 Nobel Prize in Physics for his discovery of electron diffraction. Davisson shared the Nobel Prize with George Paget Thomson, who independently discovered electron diffraction at about the same time as Davisson.-Early...
(1881–1958)
- Charles Drummond Ellis
Sir Charles Drummond Ellis was a physicist and scientific administrator. His work on the magnetic spectrum of the beta-rays helped to develop a better understanding of nuclear structure....
(1895–1980)
- Michael Faraday
Michael Faraday, FRS was an English chemist and physicist who contributed to the fields of electromagnetism and electrochemistry....
(1791–1867)
- Enrico Fermi
Enrico Fermi was an Italian-born, naturalized American physicist particularly known for his work on the development of the first nuclear reactor, Chicago Pile-1, and for his contributions to the development of quantum theory, nuclear and particle physics, and statistical mechanics...
(1901–1954)
- Galileo Galilei
Galileo Galilei , was an Italian physicist, mathematician, astronomer, and philosopher who played a major role in the Scientific Revolution. His achievements include improvements to the telescope and consequent astronomical observations and support for Copernicanism...
(1564–1642)
- Al-Khazini
Abu al-Fath Abd al-Rahman Mansour al-Khāzini or simply Abu al-Fath Khāzini was a Muslim astronomer of Greek ethnicity from Merv, then in the Khorasan province of Persia .-References:...
(fl. 1115-1130)
- Max von Laue
Max Theodor Felix von Laue was a German physicist who won the Nobel Prize in Physics in 1914 for his discovery of the diffraction of X-rays by crystals...
(1879–1960)
- Ernest Orlando Lawrence
Ernest Orlando Lawrence was an American physicist and Nobel Laureate, known for his invention, utilization, and improvement of the cyclotron atom-smasher beginning in 1929, based on his studies of the works of Rolf Widerøe, and his later work in uranium-isotope separation for the Manhattan Project...
(1901–1958)
- Ernst Mach
Ernst Mach was an Austrian physicist and philosopher, noted for his contributions to physics such as the Mach number and the study of shock waves...
(1838–1916)
- Albert Abraham Michelson
Albert Abraham Michelson was an American physicist known for his work on the measurement of the speed of light and especially for the Michelson-Morley experiment. In 1907 he received the Nobel Prize in Physics...
(1852–1931)
- Robert Andrews Millikan (1868–1953)
- Ukichiro Nakaya
was a Japanese physicist and science essayist known for his work in glaciology and low-temperature sciences. He is credited with making the first artificial snowflakes.-Life and research:...
(1900–1962)
- Isaac Newton
Sir Isaac Newton PRS was an English physicist, mathematician, astronomer, natural philosopher, alchemist, and theologian, who has been "considered by many to be the greatest and most influential scientist who ever lived."...
(1643–1727)
- Chandrasekhara Venkata Raman (1888–1970)
- John William Strutt (3rd Baron Rayleigh) (1842–1919)
- Wilhelm Conrad Röntgen
Wilhelm Conrad Röntgen was a German physicist, who, on 8 November 1895, produced and detected electromagnetic radiation in a wavelength range today known as X-rays or Röntgen rays, an achievement that earned him the first Nobel Prize in Physics in 1901....
(1845–1923)
- Ernest Rutherford
Ernest Rutherford, 1st Baron Rutherford of Nelson OM, FRS was a New Zealand-born British chemist and physicist who became known as the father of nuclear physics...
(1871–1937)
- William Bradford Shockley (1910–1989)
- Nikola Tesla
Nikola Tesla was a Serbian-American inventor, mechanical engineer, and electrical engineer...
(1856–1943)
- Joseph John Thomson
Sir Joseph John "J. J." Thomson, OM, FRS was a British physicist and Nobel laureate. He is credited for the discovery of the electron and of isotopes, and the invention of the mass spectrometer...
(1856–1940)
Timelines
See the timelines below for listings of physics experiments.
- Timeline of classical mechanics
-Early history:* 300s BC - Aristotle founds the system of Aristotelian physics* 260 BC - Archimedes mathematically works out the principle of the lever and discovers the principle of buoyancy...
- Timeline of electromagnetism and classical optics
Timeline of electromagnetism and classical optics*424 BC Aristophanes "lens" is a glass globe filled with water....
- Timeline of gravitational physics and relativity
Timeline of gravitational physics and general relativity* 3rd century BC - Aristarchus of Samos proposes heliocentric model, measures the distance to the moon and its size...
- Timeline of nuclear fusion
Timeline of significant events in the study and use of nuclear fusion:*1929 - Atkinson and Houtermans used the measured masses of low-mass elements and applied Einstein's discovery that E=mc2 to predict that large amounts of energy could be released by fusing small nuclei together .*1932 - Mark...
- Timeline of other background radiation fields
Timeline of other background radiation fields* 1912 - Victor Hess discovers that the ionization of air increases with altitude indicating the existence of cosmic radiation* 1949 - Herbert Friedman detects evidence for extrasolar X-rays...
- Timeline of particle physics technology
Timeline of particle physics technology* 1896 - Charles Wilson discovers that energetic particles produce droplet tracks in supersaturated gases* 1908 - Hans Geiger and Ernest Rutherford invent the Geiger counter...
- Timeline of atomic and subatomic physics
- Timeline of states of matter and phase transitions
Timeline of states of matter and phase transitions* 1895 – Pierre Curie discovers that induced magnetization is proportional to magnetic field strength* 1911 – Heike Kamerlingh Onnes discloses his research on superconductivity...
- Timeline of thermodynamics, statistical mechanics, and random processes
A timeline of events related to thermodynamics.- Before 1800 :* 1650 – Otto von Guericke builds the first vacuum pump* 1660 – Robert Boyle experimentally discovers Boyle's Law, relating the pressure and volume of a gas...
- Timeline of particle discoveries
This is a timeline of subatomic particle discoveries, including all particles thus far discovered which appear to be elementary given the best available evidence...
See also
- Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, 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...
- Engineering
Engineering is the discipline, art, skill and profession of acquiring and applying scientific, mathematical, economic, social, and practical knowledge, in order to design and build structures, machines, devices, systems, materials and processes that safely realize improvements to the lives of...
- Experimental science
- Measuring instrument
In the physical sciences, quality assurance, and engineering, measurement is the activity of obtaining and comparing physical quantities of real-world objects and events. Established standard objects and events are used as units, and the process of measurement gives a number relating the item...