Category of disciplines and sub-disciplines in Physics
Experimental physics
is the category of disciplines and sub-disciplines in the field of
physics
that are concerned with the
observation
of physical
phenomena
and
experiments
. Methods vary from discipline to discipline, from simple experiments and observations, such as
Galileo's experiments
, to more complicated ones, such as the
Large Hadron Collider
.
Overview
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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 simple
thought experiments
) and realization of laboratory experiments. It is often contrasted with
theoretical physics
, which is more concerned with predicting and explaining the physical behaviour of nature than with acquiring empirical data.
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 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.
History
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As a distinct field, experimental physics was established in
early modern Europe
, during what is known as the
Scientific Revolution
, by physicists such as
Galileo Galilei
,
Christiaan Huygens
,
Johannes Kepler
,
Blaise Pascal
and Sir
Isaac 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 of
inertia
, which later became the first law in
Newton's laws of motion
. In Galileo's
Two 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 of
momentum
.
Experimental physics is considered to have reached a high point with the publication of the
Philosophiae Naturalis Principia Mathematica
in 1687 by Sir Isaac Newton (1643?1727). In 1687, Newton published the
Principia
, detailing two comprehensive and successful physical laws:
Newton's laws of motion
, from which arise
classical mechanics
; and
Newton's law of universal gravitation
, which describes the
fundamental force
of
gravity
. Both laws agreed well with experiment. The
Principia
also included several theories in
fluid dynamics
.
From the late 17th century onward,
thermodynamics
was developed by physicist and chemist
Robert Boyle
,
Thomas Young
, and many others. In 1733,
Daniel Bernoulli
used statistical arguments with classical mechanics to derive thermodynamic results, initiating the field of
statistical mechanics
. In 1798,
Benjamin Thompson
(Count Rumford) demonstrated the conversion of mechanical work into heat, and in 1847
James Prescott Joule
stated the law of conservation of
energy
, in the form of heat as well as mechanical energy.
Ludwig Boltzmann
, 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
electricity
. Observations in the 17th and eighteenth century by scientists such as Boyle,
Stephen Gray
, and
Benjamin Franklin
created a foundation for later work. These observations also established our basic understanding of
electrical charge
and
current
. By 1808
John Dalton
had discovered that atoms of different elements have different weights and proposed the modern
theory of the atom
.
It was
Hans 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 1830s
Michael Faraday
had demonstrated that magnetic fields and electricity could generate each other. In 1864
James Clerk Maxwell
presented to the
Royal Society
a set of equations that described this relationship between electricity and magnetism.
Maxwell's equations
also predicted correctly that
light
is an
electromagnetic wave
. Starting with astronomy, the principles of natural philosophy 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
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Some examples of prominent experimental physics projects are:
- Relativistic Heavy Ion Collider
which collides heavy ions such as
gold
ions (it is the first heavy ion collider) and
protons
, it is located at
Brookhaven National Laboratory
, on Long Island, USA.
- HERA
, which collides
electrons
or
positrons
and protons, and is part of
DESY
, located in
Hamburg
, Germany.
- LHC
, or the Large
Hadron
Collider
, which completed 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
CERN
, on the French-Swiss border near
Geneva
. The collider became fully operational March 29, 2010 a year and a half later than originally planned.
[1]
- LIGO
, the Laser Interferometer Gravitational-Wave Observatory, is a large-scale physics experiment and observatory to detect cosmic gravitational waves and to develop gravitational-wave observations as an astronomical tool. Currently two LIGO observatories exist: LIGO Livingston Observatory in
Livingston, Louisiana
, and LIGO Hanford Observatory near
Richland
,
Washington
.
- JWST
, or the
James Webb
Space Telescope, launched in 2021. It will be the successor to the
Hubble Space Telescope
. 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.
- Mississippi State Axion Search
(2016 completion), Light Shining Through a Wall Experiment (LSW); EM Source: .7m, 50W continuous radio wave emitter
[2]
Method
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Experimental physics uses two main methods of experimental research,
controlled experiments
, and
natural experiments
. Controlled experiments are often used in
laboratories
as laboratories can offer a controlled environment. Natural experiments are used, for example, in
astrophysics
when observing
celestial objects
where control of the variables in effect is impossible.
Famous experiments
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Famous experiments include:
Experimental techniques
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Some well-known experimental techniques include:
Prominent experimental physicists
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Famous experimental physicists include:
Timelines
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See the timelines below for listings of physics experiments.
See also
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References
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Further reading
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- Taylor, John R. (1987).
An Introduction to Error Analysis (2nd ed.)
. University Science Books.
ISBN
978-0-935702-75-0
.
External links
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