How to measure by ElementaryParticle?
Description of ElementaryParticle/Light;
||The laws of physics describe light and matter, and the
quantum revolution rewrote both descriptions. Radioactivity was good example of
matter's behaving in a way that was inconsistent with classical physics, but if
we want to get under the hood and understand how non-classical things happen it
will be easier to focus on light rather than matter. A radioactive atom such as
uranium 235 is after all an extremely complex system, consisting of 92 protons,
143 neutrons, and 92 electrons. Light, however, can be a simple sine wave.
However successful the classical wave theory of light had
been allowing the creation of radio and radar, for example, it still failed to
describe many important phenomena. An example that is currently of great
interest is the way the ozone layer protects us from the dangerous
short-wavelength ultraviolet part of the sun's spectrum. In the classical
description, light is a wave. When a wave passes into and back out of a medium,
its frequency is unchanged, and although its wavelength is altered while it is
in the medium, it returns to its original value when the wave reemerges.
For a long time, physicists tried to explain away the problems
with the classical theory of light as arising from an imperfect understanding
of atoms and the interaction of light with individual atoms and molecules. The
ozone paradox, for example, could have been attributed to the incorrect
assumption that the ozone layer was a smooth, continuous substance, when in
reality it was made of individual ozone molecules. It wasn't until 1905 that
Albert Einstein threw down the gauntlet, proposing that the problem had nothing
to do with the details of light's interaction with atoms and everything to do
with the fundamental nature of light itself.
In those days the data were sketchy, the ideas vague, and
the experiments difficult to interpret; it took a genius like Einstein to cut
through the thicket of confusion and find a simple solution. Although Einstein was interpreting different
observations, this is the conclusion he reached in his 1905 paper: that the
pure wave theory of light is an oversimplification, and that the energy of a
beam of light comes in finite chunks rather than being spread smoothly
throughout a region of space.
We now think of these chunks as particles of light, and call
them photons, although Einstein avoided the word particle, and the word photon
was invented later. Regardless of words, the trouble was that waves and
particles seemed like inconsistent categories. The reaction to Einstein's paper
could be kindly described as vigorously skeptical. Even twenty years later,
Einstein wrote, there are therefore now two theories of light, both indispensable,
and as one must admit today despite twenty years of tremendous effort on the
part of theoretical physicists without any logical connection.
We have seen evidence that light energy comes in little
chunks, so the next question to be asked is naturally how much energy is in one
chunk. The most straightforward experimental avenue for addressing this
question is a phenomenon known as the photoelectric effect. The photoelectric
effect occurs when a photon strikes the surface of a solid object and knocks out
an electron. It occurs continually all around you. It is happening right now at
the surface of your skin and on the paper or computer screen from which you are
reading these words.
The photoelectric effect was discovered serendipitously by
Heinrich Hertz in 1887, as he was experimenting with radio waves. He was not
particularly interested in the phenomenon, but he did notice that the effect
was produced strongly by ultraviolet light and more weakly by lower
frequencies. Light whose frequency was lower than a certain critical value did
not eject any electrons at all. This dependence on frequency didn't make any
sense in terms of the classical wave theory of light. A light wave consists of
electric and magnetic fields. The stronger the fields, i.e., the greater the
wave's amplitude, the greater the forces that would be exerted on electrons
that found themselves bathed in the light. It should have been amplitude
(brightness) that was relevant, not frequency. The dependence on frequency not
only proves that the wave model of light needs modifying, but with the proper
interpretation it allows us to determine how much energy is in one photon, and
it also leads to a connection between the wave and particle models that we need
in order to reconcile them, therefore, light must be both a particle and a
wave. It is a wave because it exhibits interference effects. At the same time,
the fact that the photographs contain discrete dots is a direct demonstration
that light refuses to be split into units of less than a single photon.
One possible interpretation of wave-particle duality that
occurred to physicists early in the game was that perhaps the interference
effects came from photons interacting with each other. By analogy, a water wave
consists of moving water molecules and interference of water wave results
ultimately from all the mutual pushes and pulls of the molecules, if
interference effects came from photons interacting with each other, a bare
minimum of two photons would have to be present at the same time to produce
interference. By making the light source extremely dim, we can be virtually
certain that there are never two photons in the box at the same time.
If a single photon can demonstrate double-slit interference,
then which slit did it pass through? The unavoidable answer must be that it
passes through both! This might not seem so strange if we think of the photon
as a wave, but it is highly counterintuitive if we try to visualize it as a
particle.
If a photon had a well defined path, then it would not
demonstrate wave superposition and interference effects, contradicting its wave
nature.
A second possible explanation of wave-particle duality was
taken seriously in the early history of quantum mechanics. What if the photon
particle is like a surfer riding on top of its accompanying wave? As the wave
travels along, the particle is pushed, or piloted by it. Imagining the particle
and the wave as two separate entities allows us to avoid the seemingly
paradoxical idea that a photon is both at once. The wave happily does its wave
tricks, like superposition and interference, and the particle acts like a
respectable particle, resolutely refusing to be in two different places at
once. If the wave, for instance, undergoes destructive interference, becoming
nearly zero in a particular region of space, then the particle simply is not
guided into that region.
Around the turn of the twentieth century, experiments began
to show problems with the classical wave theory of light. In any experiment
sensitive enough to detect very small amounts of light energy it becomes clear
that light energy cannot be divided into chunks smaller than a certain amount.
Measurements involving the photoelectric effect demonstrate that this smallest
unit of light energy equals hf, where f is the frequency of the light
and h is a number known as Planck's constant. We say that light energy is
quantized in units of hf, and we interpret this quantization as evidence
that light has particle properties as well as wave properties.
The only method of reconciling the wave and particle natures
of light that has stood the test of experiment is the probability
interpretation: the probability that the particle is at a given location is
proportional to the square of the amplitude of the wave at that location.
One important consequence of wave-particle duality is that
we must abandon the concept of the path the particle takes through space. To
hold on to this concept, we would have to contradict the well established wave
nature of light, since a wave can spread out in every direction simultaneously.
To conclude it, during 2012 many physicists were hoping that
photons particles of light could help us
to piece together the nature of the mysterious stuff thought to make up 85 per
cent of the universe's matter.
Some theories had hinted that heavy photons, hypothetical
versions of the more familiar mass-less particles, might be dark matter.
According to that idea, the heavy photon would have a small amount of mass and
might carry an unknown fundamental force that allows it to interact only with
ordinary photons effectively hiding it from the visible world.
When most particles with mass get too near to a black hole,
they fall in, never to be seen again. Photons with no mass can skirt past
danger if they are on the right trajectory. But a photon with a very tiny in
between mass can enter into an orbit of the spinning black hole and steal some
of its angular momentum. If conditions are right, this process can continue
until orbiting particles slow the hole down so much that it stops spinning.
Some scientist have calculated how long photons of given
masses would take to sap a black hole's spin. Then they examined data on the
ages and rotation speeds of eight super-massive black holes.
||
(QED; QuantumElectroDynamics: Angle of Incidence is not
equal to angle of reflection.)
One of the best devices to download information is eye that
sometimes cannot work correctly because holographic structure of our brain, but
for weak mind without enough concentration. Weak mind cannot process
information fast & correct.
Anyway eyes are not just measuring device. We can measure by
touching or hearing & etc directly but still we have another tools to
measure; Measuring by others. Like measuring attributes & properties of
black-holes, dark-matters and dark energy by effects of them on others so it is
indirect measuring. We can use it to measure elementary particles
specifications like spin so we can use Quantum Effects to measure something we
cannot directly get information about it. Like Quantum Tunneling to measure
what happen inside Black-Holes. That because if we send Entangled Bits to
Black-Holes we can observe effect of them on Entangled Bits in our labs so we
decode the behavior and analysis to understand what happened for those
entangled Bits inside black-holes; how their spin change and how fast it
happened & etc. And it s exactly the mechanism of nature is measuring.
See also;
-To be Continue…
.jpg)
No comments:
Post a Comment