Experimental physics is the category of disciplines and sub-disciplines in the field ofphysics that are concerned with theobservation of physicalphenomena andexperiments. Methods vary from discipline to discipline, from simple experiments and observations, such as experiments byGalileo Galilei, to more complicated ones, such as theLarge Hadron Collider.
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Experimental physics is a branch of physics that is concerned with data acquisition, data-acquisition methods, and the detailed conceptualization (beyond simplethought experiments) and realization of laboratory experiments. It is often contrasted withtheoretical physics, which is more concerned with predicting and explaining the physical behaviour of nature than with acquiring empirical data.[citation needed]
Although experimental andtheoretical physics are concerned with different aspects of nature, they both share the same goal of understanding it and have asymbiotic relationship. 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 into how to better acquire data and set up experiments. Theoretical physics can also offer insight into what data is needed in order to gain a better understanding of the universe, and into what experiments to devise in order to obtain it.[citation needed]
The tension between experimental and theoretical aspects of physics was expressed byJames Clerk Maxwell as "It is not till we attempt to bring the theoretical part of our training into contact with the practical that we begin to experience the full effect of whatFaraday has called 'mental inertia' - not only the difficulty of recognizing, among the concrete objects before us, the abstract relation which we have learned from books, but the distracting pain of wrenching the mind away from the symbols to the objects, and from the objects back to the symbols. This however is the price we have to pay for new ideas."[1]
As a distinct field, experimental physics was established inearly modern Europe, during what is known as theScientific Revolution, by physicists such asGalileo Galilei,Christiaan Huygens,Johannes Kepler,Blaise Pascal and SirIsaac Newton. 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 ofinertia, which later became the first law inNewton's laws of motion. In Galileo'sTwo New Sciences, 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 ofmomentum.[citation needed]
Experimental physics is considered to have reached a high point with the publication of thePhilosophiae Naturalis Principia Mathematica in 1687 by Sir Isaac Newton (1643–1727). In 1687, Newton published thePrincipia, detailing two comprehensive and successful physical laws:Newton's laws of motion, from which ariseclassical mechanics; andNewton's law of universal gravitation, which describes thefundamental force ofgravity. Both laws agreed well with experiment. ThePrincipia also included several theories influid dynamics.[citation needed]
From the late 17th century onward,thermodynamics was developed by physicist and chemistRobert Boyle,Thomas Young, and many others. In 1733,Daniel Bernoulli used statistical arguments with classical mechanics to derive thermodynamic results, initiating the field ofstatistical mechanics. In 1798,Benjamin Thompson (Count Rumford) demonstrated the conversion of mechanical work into heat, and in 1847James Prescott Joule stated the law of conservation ofenergy, in the form of heat as well as mechanical energy.Ludwig Boltzmann, in the nineteenth century, is responsible for the modern form ofstatistical mechanics.[citation needed]
Besides classical mechanics and thermodynamics, another great field of experimental inquiry within physics was the nature ofelectricity. Observations in the 17th and eighteenth century by scientists such as Boyle,Stephen Gray, andBenjamin Franklin created a foundation for later work. These observations also established our basic understanding ofelectrical charge andcurrent. By 1808John Dalton had discovered that atoms of different elements have different weights and proposed the moderntheory of the atom.[citation needed]
It wasHans Christian Ørsted 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 1830sMichael Faraday had demonstrated that magnetic fields and electricity could generate each other. In 1864James Clerk Maxwell presented to theRoyal Society a set of equations that described this relationship between electricity and magnetism.Maxwell's equations also predicted correctly thatlight is anelectromagnetic wave. Starting with astronomy, the principles of natural philosophy crystallized into fundamentallaws 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.[citation needed]
Some examples of prominent experimental physics projects are:
Experimental physics uses two main methods of experimental research,controlled experiments, andnatural experiments. Controlled experiments are often used inlaboratories as laboratories can offer a controlled environment. Natural experiments are used, for example, inastrophysics when observingcelestial objects where control of the variables in effect is impossible.[citation needed]
Famous experiments include:[citation needed]
Some well-known experimental techniques include:[citation needed]
Famous experimental physicists include:[citation needed]
See the timelines below for listings of physics experiments.
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