A Brief History Of Quantum Mechanics
Ανέβηκε στις 24 Δεκ 2009
http://www.facebook.com/ScienceReason ... Quantum Mechanics (Chapter 1): A Brief History Of Quantum Mechanics.
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1. A Brief History Of Quantum Mechanics
http://www.youtube.com/watch?v=B7pACq...
2. The Structure Of Atoms
http://www.youtube.com/watch?v=-YYBCN...
3. Wave Function And Wave-Particle Duality
http://www.youtube.com/watch?v=7GTCus...
4. The Uncertainty Principle
http://www.youtube.com/watch?v=Fw6dI7...
5. The Spin Of Fundamental Particles
6. Quantum Entanglement
---
The
history of quantum mechanics began essentially with the 1838 discovery
of cathode rays by Michael Faraday, the 1859 statement of the black body
radiation problem by Gustav Kirchhoff, the 1877 suggestion by Ludwig
Boltzmann that the energy states of a physical system could be discrete,
and the 1900 quantum hypothesis by Max Planck that any energy is
radiated and absorbed in quantities divisible by discrete energy
elements, E, such that each of these energy elements is proportional to
the frequency ν with which they each individually radiate energy.
Planck
insisted that this was simply an aspect of the processes of absorption
and emission of radiation and had nothing to do with the physical
reality of the radiation itself.
However, at that time, this
appeared not to explain the photoelectric effect (1839), i.e. that
shining light on certain materials can function to eject electrons from
the material.
In 1905, basing his work on Plancks quantum
hypothesis, Albert Einstein postulated that light itself consists of
individual quanta. These later came to be called photons (1926). From
Einstein's simple postulation was born a flurry of debating, theorizing
and testing, and thus, the entire field of quantum physics.
• http://en.wikipedia.org/wiki/Quantum_...
---
Quantum
mechanics (QM) is a set of principles describing the physical reality
at the atomic level of matter (molecules and atoms) and the subatomic
(electrons, protons, and even smaller particles). These descriptions
include the simultaneous wave-like and particle-like behavior of both
matter and radiation ("waveparticle duality").
Quantum Mechanics
is a mathematical description of reality, like any scientific model.
Some of its predictions and implications go against the "common sense"
of how humans see a set of bodies (a system) behave. This isn't
necessarily a failure of Quantum mechanics - it's more of a reflection
of how humans understand space and time on larger scales (e.g.,
centimetres, seconds) rather than much smaller.
Quantum mechanics
says that the most complete description of a system is its
wavefunction, which is just a number varying between time and place. One
can derive things from the wavefunction, such as the position of a
particle, or its momentum. Yet the wavefunction describes probabilities,
and some physical quantities which classical physics would assume are
both fully defined together simultaneously for a system are not
simultaneously given definite values in Quantum mechanics.
It is
not that the experimental equipment is not precise enough - the two
quantities in question just are not defined at the same time by the
Universe. For instance, location and velocity do not exist
simultaneously for a body (this is called the Heisenberg uncertainty
principle)
Certain systems, however, do exhibit quantum
mechanical effects on a larger scale; superfluidity (the frictionless
flow of a liquid at temperatures near absolute zero) is one well-known
example. Quantum theory also provides accurate descriptions for many
previously unexplained phenomena such as black body radiation and the
stability of electron orbitals. It has also given insight into the
workings of many different biological systems, including smell receptors
and protein structures.
Even so, classical physics often can be a
good approximation to results otherwise obtained by quantum physics,
typically in circumstances with large numbers of particles or large
quantum numbers. (However, some open questions remain in the field of
quantum chaos.)
• http://en.wikipedia.org/wiki/Quantum_...
.
---
Please SUBSCRIBE to Science & Reason:
• http://www.youtube.com/Best0fScience
• http://www.youtube.com/ScienceTV
• http://www.youtube.com/FFreeThinker
---
1. A Brief History Of Quantum Mechanics
http://www.youtube.com/watch?v=B7pACq...
2. The Structure Of Atoms
http://www.youtube.com/watch?v=-YYBCN...
3. Wave Function And Wave-Particle Duality
http://www.youtube.com/watch?v=7GTCus...
4. The Uncertainty Principle
http://www.youtube.com/watch?v=Fw6dI7...
5. The Spin Of Fundamental Particles
6. Quantum Entanglement
---
The
history of quantum mechanics began essentially with the 1838 discovery
of cathode rays by Michael Faraday, the 1859 statement of the black body
radiation problem by Gustav Kirchhoff, the 1877 suggestion by Ludwig
Boltzmann that the energy states of a physical system could be discrete,
and the 1900 quantum hypothesis by Max Planck that any energy is
radiated and absorbed in quantities divisible by discrete energy
elements, E, such that each of these energy elements is proportional to
the frequency ν with which they each individually radiate energy.
Planck
insisted that this was simply an aspect of the processes of absorption
and emission of radiation and had nothing to do with the physical
reality of the radiation itself.
However, at that time, this
appeared not to explain the photoelectric effect (1839), i.e. that
shining light on certain materials can function to eject electrons from
the material.
In 1905, basing his work on Plancks quantum
hypothesis, Albert Einstein postulated that light itself consists of
individual quanta. These later came to be called photons (1926). From
Einstein's simple postulation was born a flurry of debating, theorizing
and testing, and thus, the entire field of quantum physics.
• http://en.wikipedia.org/wiki/Quantum_...
---
Quantum
mechanics (QM) is a set of principles describing the physical reality
at the atomic level of matter (molecules and atoms) and the subatomic
(electrons, protons, and even smaller particles). These descriptions
include the simultaneous wave-like and particle-like behavior of both
matter and radiation ("waveparticle duality").
Quantum Mechanics
is a mathematical description of reality, like any scientific model.
Some of its predictions and implications go against the "common sense"
of how humans see a set of bodies (a system) behave. This isn't
necessarily a failure of Quantum mechanics - it's more of a reflection
of how humans understand space and time on larger scales (e.g.,
centimetres, seconds) rather than much smaller.
Quantum mechanics
says that the most complete description of a system is its
wavefunction, which is just a number varying between time and place. One
can derive things from the wavefunction, such as the position of a
particle, or its momentum. Yet the wavefunction describes probabilities,
and some physical quantities which classical physics would assume are
both fully defined together simultaneously for a system are not
simultaneously given definite values in Quantum mechanics.
It is
not that the experimental equipment is not precise enough - the two
quantities in question just are not defined at the same time by the
Universe. For instance, location and velocity do not exist
simultaneously for a body (this is called the Heisenberg uncertainty
principle)
Certain systems, however, do exhibit quantum
mechanical effects on a larger scale; superfluidity (the frictionless
flow of a liquid at temperatures near absolute zero) is one well-known
example. Quantum theory also provides accurate descriptions for many
previously unexplained phenomena such as black body radiation and the
stability of electron orbitals. It has also given insight into the
workings of many different biological systems, including smell receptors
and protein structures.
Even so, classical physics often can be a
good approximation to results otherwise obtained by quantum physics,
typically in circumstances with large numbers of particles or large
quantum numbers. (However, some open questions remain in the field of
quantum chaos.)
• http://en.wikipedia.org/wiki/Quantum_...
.
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