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The phenomenon of pair
production - Energy conversion to mass
Basic process
The particle and antiparticle
The
particle and the hole
Pair production is a phenomenon of
nature where energy is converted to mass. It provides a conceptual
framework for how our internal world gets translated into the
physical reality we experience. The phenomenon of pair production
can be view two different ways. One way is as a particle and
antiparticle and the other is as a particle and a hole.
Basic
process
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In this phenomenon a wave of
energy or a photon (a packet of energy) interacts with a heavy
nucleus to form an electron - positron pair. Pair production is
observed to occur in nature when a photon or an energy wave packet,
of greater that 1.02 million electron volts passes near the electric
field of a large atom such as lead, uranium or other heavy material
with a large number of protons (around an atomic number of 80 or
90). An electron volt is the amount of energy necessary to
accelerate an electron through a electric potential of one volt. It
is a very small amount of energy.
In the pair production process, as diagramed in the figure below
labeled “Pair Production - Energy Conversion to Mass,” the photon is
literally split into an electron and its anti-particle, called a
positron. Both have a rest mass energy equivalent of 0.511 million
electron volts. (Since mass and energy are equivalent, the mass
energy equivalent is just the amount of energy that it would take to
form the mass of the particle. For an electron that has a mass of
9.11 x 10-24 grams its equivalent energy is 0.511 million electron
volts. For those not familiar with the scientific notation of 10-24,
this symbolism represents a millionth of a millionth of a millionth
of a millionth.)
If the original packet of energy is greater than 1.02 million
electron volts, any energy above 1.02 million electron volts is
split between the kinetic energy of motion of the two particle. The
forward
momentum of the original photon is also preserved in that both
the electron and positron go off at an angle such that their total
momentum and that of the recoiling nucleus equals the momentum of the original photon. It is important
to note the both mass-energy and momentum are conserved in this
interaction. What this means is that when observed from outside the
process, everything that existed before the interaction was retained
and exists afterwards but only in a different form. In the big
picture nothing has changed. In the segments of the process there is
a radical transformation and from an mass point of view,
something is created from nothing. There is creation of mass
from seemingly nothingness.
The positron is the anti-particle of the electron and will be
annihilated if it combines with an electron producing energy
such that mass is converted back into energy. Since all electrons
are equal, any electron can annihilate the positron.
The particle and
antiparticle
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The first view of how energy is
converted to mass is as diagramed above through the formation of
separate and independent particles. This is the view taught in most
physics courses and what you will find in most physics text books
which discuss the topic. In this view, the electron and positron are
see as separate and independent particles. Each goes about its
separate way as it interacts with its environment.
There are two important points about pair production. The first is
that you needed the correct energy to produce the electron-positron
pair. In particular, you need the equivalent rest mass of energy,
that is the amount of energy contained in the both the particle and
antiparticle when at rest. The energy converted to mass is “lost” or
fully “bound” until the particle is annihilated and the energy can
be recovered. The second thing is that it needs a correct
environment. The process does not occur unless certain conditions
are present.
Viewing this phenomenon as a the
creative/creation process, we can say a threshold amount of
energy is sacrificed in a correct context to manifest a pair of
particle with a physical mass. It can also be said something was
created out of nothing. That is, before the interaction, no
particles with mass existed. After the interaction, there were to
particles with mass. Hence something was created out of nothing. But
this can be said only because of the
perspective taken when viewing the process.
The particle and the hole
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What is interesting about the pair
production phenomenon, is that it was predicted using a slightly
different perspective. Another way to view the pair production
phenomena is to create a hole in empty space or release a particle
from a sea of particles below physical matter.
The pair production phenomena was first predicted by a British
physicist P.A.M. Dirac in 1925. His work suggested the existence of
a sea of particles below physical matter which remains unobservable.
Dirac’s concept which predicted the positron, the antielectron, was
rather than two separate particles being produced, an electron is
released from an infinite sea of particles below empty space. In
removing a particle from sea, the remaining particle would act as
the antiparticle. This view is diagramed in the following figure
labeled “Pair Production from the Sea of Negative Mass”.
In this concept, a hole created in this sea of particles existing
below empty space. The pair would act as a matter anti-matter pair.
When the particle is released, a hole is produced and that hole acts
as an antiparticle. The antiparticle is a direct reflection of the
particle produced. It was predicted that when an electron, the
smallest particle know to exist at that time with mass, was released
from this sea the hole created by the removal of the electron acted
as the opposite of an electron or what was called a positron or an
anti-electron. Hence the formation of a electron-positron pair.
To create this pair one only need to supply the correct amount of
energy under the correct conditions equivalent to twice the rest
mass of the particle. It is to be noted that in this case the same
amount of energy is needed as to form the particle - antiparticle
pair but the energy is not seen as being split between the particle
and the antiparticle but rather it is the energy necessary to free
the particle or “cut it out” from its “bound” state in the sea of
particle. This phenomenon was predicted by Dirac to occur when there
was sufficient energy (greater than 1.02 million electron volts to
remove a particle from this sea.
Any remaining energy would be the energy kinetic energy of the
particle split between the sea of particles and the particle that is
form. Since the formed particle would be much lighter than the
massive sea of particles out of which it came, the particle would be
seen as taking the energy and the sea of particles would appear
stationary much the way a ball moves in the gravitation field of the
earth. Although both the earth and the ball move, the earth is too
large to observe its movement relative to the ball. The hole however
would move as the reflection of the particle and give all the
appearance as an equal and opposite particle moving in the opposite
direction.
There is a simply way to understand how the energy could remain in
the particle that is created and not split between the particle and
its hole, yet the hole appears to move. Think of the way the shadow
of a cloud or airplane moves across the ground with no energy of its
own but only follows the object producing the shadow. In many ways
the shadow is in fact the sunlight that has been “cut out” of the
sun shining on earth by the object casting the shadow. As the
airplane flies higher, the shadow seems to move away and get
smaller. As the airplane flies lower, the shadow grows as if it is
coming closer.
This prediction by Dirac caused an upset to physicists at this time.
What this prediction by Dirac did was it implied a return to an all
penetrating world ether that has been discarded by physicists at the
turn of the century but it came back in a new fashion in that there
was something out of which all reality formed given sufficient
energy. As one might suspect, when Dirac’s theory was proposed, it
was not readily accepted since it seemed to resurrect a concept that
physicists had believed was dispelled with the Michelson experiment
of 1887. The negative results of this experiment were subsequently
explained by Einstein in 1905 by his rejection of the entire
idea of a world ether and returned to the idea of a completely empty
space. Dirac’s premise was proven correct in 1931 when Carl Anderson
confirmed the existence of the positron particle predicted by
Dirac’s theory.
The significant difference in this view is that the hole tracks with
the particle. Of course, this was not what was observed in reality.
The antiparticle did not track the particle. When the electron and
positron were produced in pair production the positron was totally
independent of the electron with which it was created. Naturally,
this view of pair production was discarded.
Because any electron looks like any other electron, we don’t see the
full subtle of the relationship of a particle and its hole. However,
if the particle and antiparticle were totally unique creations this
view would not have to be totally discarded. That is, if there was
no other particle in Creation that look like the particle that was
produced, then only its unique antiparticle could annihilate it. In
this case the hole may not track the particle but it would be needed
to annihilate the particle. The fact that a unique particle would
only be completely annihilated by its unique antiparticle is an
interesting concept. It lies a basic analogy is to understand how we
can each be a unique creation sustained in the physical world and
yet we create the reality of our experiences as discussed in the
topic, "An
energy consciousness and metaphysical application of pair production"
In keeping with the
Bohr Approach to use nature as a guide, the pair production
phenomenon give a way provided by nature to see how energy is
directly converted to a form within an existing creation.
Related topics
Pair annihilation
An energy consciousness and metaphysical application of pair
production
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