Physics: Quantum Theory: Quantum Mechanincs
Introduction
Physics is the study of matter and energy, it is an ancient and broad field of
science. The word 'physics' comes from the Greek 'knowledge of nature,' and in
general, the field aims to analyze and understand the natural phenomena of the
universe. .The scope of physics is very wide and vast. It deals with not only the tinniest
particles of atoms, but also natural phenomenon like the galaxy, the milky way, solar
and lunar eclipses, and more. While it is true that physics is a branch of science, there
are many sub-branches within the field of physics. There are 11 branches of physics;
classical physics, modern physics, nuclear physics, atomic physics, geophysics,
biophysics, mechanics, acoustics, optics, thermodynamics, and astrophysics.
Theoretical physicists are trying to solve the most relevant problem of physics
nowadays, combining the relativity and the quantum theory into one single theory that
can explain the universe, you have probably heard of the Theory of Everything. Modern
physics encompasses the theory of relativity and quantum physics. Quantum physics
Discussion
Modern physics is a branch of physics that is mainly concerned with the theory of
relativity and quantum mechanics. Albert Einstein and Max Plank were the pioneers of
modern of physics as the first scientists to introduce the theory of relativity and quantum
mechanics, respectively. Quantum theory is the theoretical basis of modern physics that
explains the nature and behavior of matter and energy on the atomic and subatomic
level. The nature and behavior of matter and energy at that level is sometimes referred
to as quantum physics and quantum mechanics. Physicist Max Planck presented his
quantum theory to the German Physical Society. Planck had sought to discover the
reason that radiation from a glowing body changes in color from red, to orange, and,
finally, to blue as its temperature rises. Planck wrote a mathematical equation involving
a figure to represent these individual units of energy, which he called quanta. According
to the quantum theory, energy is held to be emitted and absorbed in tiny, discrete
amounts. An individual bundle or packet of energy, called a quantum (pl. quanta), thus
behaves in some situations much like particles of matter; particles are found to exhibit
certain wavelike properties when in motion and are no longer viewed as localized in a
given region but rather as spread out to some degree. The quantum theory shows that
those frequencies correspond to definite energies of the light quanta, or photons, and
result from the fact that the electrons of the atom can have only certain allowed energy
values, or levels; when an electron changes from one allowed level to another, a
quantum of energy is emitted or absorbed whose frequency is directly proportional to
the energy difference between the two levels. Aspects of the quantum theory have
provoked vigorous philosophical debates.
The Development of Quantum Theory

In 1900, Planck made the assumption that energy was made of individual units, or
quanta.

In 1905, Albert Einstein theorized that not just the energy, but the radiation itself
was quantized in the same manner.

In 1924, Louis de Broglie proposed that there is no fundamental difference in the
makeup and behavior of energy and matter; on the atomic and subatomic level
either may behave as if made of either particles or waves. This theory became
known as the principle of wave-particle duality: elementary particles of both energy
and matter behave, depending on the conditions, like either particles or waves.

In 1927, Werner Heisenberg proposed that precise, simultaneous measurement of
two complementary values - such as the position and momentum of a subatomic
particle - is impossible. Contrary to the principles of classical physics, their
simultaneous measurement is inescapably flawed; the more precisely one value is
measured, the more flawed will be the measurement of the other value. This theory
became known as the uncertainty principle, which prompted Albert Einstein's
famous comment, "God does not play dice."
The Copenhagen Interpretation and the Many-Worlds Theory
The two major interpretations of quantum theory's implications for the nature of
reality are the Copenhagen interpretation and the many-worlds theory. Niels Bohr
proposed the Copenhagen interpretation of quantum theory, which asserts that a
particle is whatever it is measured to be (for example, a wave or a particle), but that
it cannot be assumed to have specific properties, or even to exist, until it is
measured. To illustrate this theory, we can use the famous and somewhat cruel
analogy of Schrodinger's Cat. The second interpretation of quantum theory is
the many-worlds (or multiverse theory. It holds that as soon as a potential exists for
any object to be in any state, the universe of that object transmutes into a series of
parallel universes equal to the number of possible states in which that the object can
exist, with each universe containing a unique single possible state of that object.
Furthermore, there is a mechanism for interaction between these universes that
somehow permits all states to be accessible in some way and for all possible states
to be affected in some manner. Stephen Hawking and the late Richard Feynman are
among the scientists who have expressed a preference for the many-worlds theory.
Quantum Mechanics and Later Developments
Quantum mechanics, the final mathematical formulation of the quantum theory, was
developed during the 1920s. In 1924, Louis de Broglie proposed that not only do
light waves sometimes exhibit particlelike properties, as in the photoelectric
effect and atomic spectra, but particles may also exhibit wavelike properties. This
hypothesis was confirmed experimentally in 1927 by C. J. Davisson and L. H.
Germer, who observed diffraction of a beam of electrons analogous to the diffraction
of a beam of light.. The wave mechanics of Erwin Schrödinger (1926) involves the
use of a mathematical entity, the wave function, which is related to the probability of
finding a particle at a given point in space. The matrix mechanics of Werner
Heisenberg (1925) makes no mention of wave functions or similar concepts but was
shown to be mathematically equivalent to Schrödinger's theory.
Quantum Physics Applications
The principles of quantum physics are being applied in an increasing number of areas,
including quantum optics, quantum chemistry, quantum computing, and quantum
cryptography. The quantum theory has been successful in explaining microscopic
phenomena. The success of quantum physics has been well-known because of its wide
range of applications.
Desktops, laptops, tablets, smartphones, small household
appliances, and kids’ toys are driven by computer chips. All in all, these computer chips
would not possible to make without the principles of quantum physics. Another
application of quantum physics are;
quantum voltage standard, lasers and
telecommunications, GPS Servers, Magnetic resonance MRI,holography, X-rays,
fluorescence, improved microscopes and cesium clocks.
Conclusion
Quantum physics is almost essential to the modern life. Semiconductor electronics,
lasers, atomic clocks, GPS servers, the cesium clock and magnetic resonance scanners
all fundamentally depend on our understanding of the quantum nature of light and
matter.