String theory (rare documentary) part 2
Δημοσιεύτηκε στις 22 Αυγ 2015
String theory
In
physics, string theory is a theoretical framework in which the
point-like particles of particle physics are replaced by one-dimensional
objects called strings. String theory describes how these strings
propagate through space and interact with each other. On distance scales
larger than the string scale, a string looks just like an ordinary
particle, with its mass, charge, and other properties determined by the
vibrational state of the string. In string theory, one of the
vibrational states of the string corresponds to the graviton, a quantum
mechanical particle that carries gravitational force. Thus string theory
is a theory of quantum gravity.
String theory is a broad and
varied subject that attempts to address a number of deep questions of
fundamental physics. String theory has been applied to a variety of
problems in black hole physics, early universe cosmology, nuclear
physics, and condensed matter physics, and it has stimulated a number of
major developments in pure mathematics. Because string theory
potentially provides a unified description of gravity and particle
physics, it is a candidate for a theory of everything, a self-contained
mathematical model that describes all fundamental forces and forms of
matter. Despite much work on these problems, it is not known to what
extent string theory describes the real world or how much freedom the
theory allows to choose the details.
String theory was first
studied in the late 1960s as a theory of the strong nuclear force,
before being abandoned in favor of quantum chromodynamics. Subsequently,
it was realized that the very properties that made string theory
unsuitable as a theory of nuclear physics made it a promising candidate
for a quantum theory of gravity. The earliest version of string theory,
bosonic string theory, incorporated only the class of particles known as
bosons. It later developed into superstring theory, which posits a
connection called supersymmetry between bosons and the class of
particles called fermions. Five consistent versions of superstring
theory were developed before it was conjectured in the mid-1990s that
they were all different limiting cases of a single theory in eleven
dimensions known as M-theory. In late 1997, theorists discovered an
important relationship called the AdS/CFT correspondence, which relates
string theory to another type of physical theory called a quantum field
theory.
One of the challenges of string theory is that the full
theory does not yet have a satisfactory definition in all circumstances.
Another issue is that the theory is thought to describe an enormous
landscape of possible universes, and this has complicated efforts to
develop theories of particle physics based on string theory. These
issues have led some in the community to criticize these approaches to
physics and question the value of continued research on string theory
unification.
In
physics, string theory is a theoretical framework in which the
point-like particles of particle physics are replaced by one-dimensional
objects called strings. String theory describes how these strings
propagate through space and interact with each other. On distance scales
larger than the string scale, a string looks just like an ordinary
particle, with its mass, charge, and other properties determined by the
vibrational state of the string. In string theory, one of the
vibrational states of the string corresponds to the graviton, a quantum
mechanical particle that carries gravitational force. Thus string theory
is a theory of quantum gravity.
String theory is a broad and
varied subject that attempts to address a number of deep questions of
fundamental physics. String theory has been applied to a variety of
problems in black hole physics, early universe cosmology, nuclear
physics, and condensed matter physics, and it has stimulated a number of
major developments in pure mathematics. Because string theory
potentially provides a unified description of gravity and particle
physics, it is a candidate for a theory of everything, a self-contained
mathematical model that describes all fundamental forces and forms of
matter. Despite much work on these problems, it is not known to what
extent string theory describes the real world or how much freedom the
theory allows to choose the details.
String theory was first
studied in the late 1960s as a theory of the strong nuclear force,
before being abandoned in favor of quantum chromodynamics. Subsequently,
it was realized that the very properties that made string theory
unsuitable as a theory of nuclear physics made it a promising candidate
for a quantum theory of gravity. The earliest version of string theory,
bosonic string theory, incorporated only the class of particles known as
bosons. It later developed into superstring theory, which posits a
connection called supersymmetry between bosons and the class of
particles called fermions. Five consistent versions of superstring
theory were developed before it was conjectured in the mid-1990s that
they were all different limiting cases of a single theory in eleven
dimensions known as M-theory. In late 1997, theorists discovered an
important relationship called the AdS/CFT correspondence, which relates
string theory to another type of physical theory called a quantum field
theory.
One of the challenges of string theory is that the full
theory does not yet have a satisfactory definition in all circumstances.
Another issue is that the theory is thought to describe an enormous
landscape of possible universes, and this has complicated efforts to
develop theories of particle physics based on string theory. These
issues have led some in the community to criticize these approaches to
physics and question the value of continued research on string theory
unification.
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