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 (Top) 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 (Top) 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 (Top) 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

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