Nuclear Fission/Fusion And Anti-Matter

Fission/Fusion:

  • since quantum events do not have a “cause”, this also means that all possible quantum events must and will happen
  • without cause and effect, conservation laws can be violated, although only on very short timescales (things have to add up in the end)
  • violation of mass/energy allowed for the understanding of the source of nuclear power in the Universe, fission and fusion
One of the surprising results of quantum physics is that if a physical event is not specifically forbidden by a quantum rule, than it can and will happen. While this may strange, it is a direct result of the uncertainty principle. Things that are strict laws in the macroscopic world, such as the conversation of mass and energy, can be broken in the quantum world with the caveat that they can only broken for very small intervals of time (less than a Planck time). The violation of conservation laws led to the one of the greatest breakthroughs of the early 20th century, the understanding of radioactivity decay (fission) and the source of the power in stars (fusion).Nuclear fission is the breakdown of large atomic nuclei into smaller elements. This can happen spontaneously (radioactive decay) or induced by the collision with a free neutron. Spontaneously fission is due to the fact that the wave function of a large nuclei is ‘fuzzier’ than the wave function of a small particle like the alpha particle. The uncertainty principle states that, sometimes, an alpha particle (2 protons and 2 neutrons) can tunnel outside the nucleus and escape.

  • fission is the splitting of atomic nuclei, either spontaneously or by collision (induced)
  • fusion is the merger of atomic particles to form new particles
Induced fission occurs when a free neutron strikes a nucleus and deforms it. Under classical physics, the nucleus would just reform. However, under quantum physics there is a finite probability that the deformed nucleus will tunnel into two new nuclei and release some neutrons in the process, to produce a chain reaction.Fusion is the production of heavier elements by the fusing of lighter elements. The process requires high temperatures in order to produce sufficiently high velocities for the two light elements to overcome each others electrostatic barriers.

  • quantum tunneling and uncertainty are required for these processes
  • and quantum physics, even though centered on probabilities, is our most accurate science in its predictions
Even for the high temperatures in the center of a star, fusion requires the quantum tunneling of a neutron or proton to overcome the repulsive electrostatic forces of an atomic nuclei. Notice that both fission and fusion release energy by converting some of the nuclear mass into gamma-rays, this is the famous formulation by Einstein that E=mc2.Although it deals with probabilities and uncertainties, the quantum mechanics has been spectacularly successful in explaining otherwise inaccessible atomic phenomena and in meeting every experimental test. Its predictions are the most precise and the best checked of any in physics; some of them have been tested and found accurate to better than one part per billion.

Antimatter:

  • symmetry in quantum physics lead to the prediction of opposite matter, or antimatter
  • matter and antimatter can combine to form pure energy, and the opposite is true, energy can combine to form matter/antimatter pairs
A combination of quantum mechanics and relativity allows us to examine subatomic processes in a new light. Symmetry is very important to physical theories. Thus, the existence of a type of `opposite’ matter was hypothesized soon after the development of quantum physics. `Opposite’ matter is called antimatter. Particles of antimatter has the same mass and characteristics of regular matter, but opposite in charge. When matter and antimatter come in contact they are both instantaneously converted into pure energy, in the form of photons.Antimatter is produced all the time by the collision of high energy photons, a process called pair production, where an electron and its antimatter twin (the positron) are created from energy (E=mc2). A typical spacetime diagram of pair production looks like the following:

  • spacetime diagrams provide a backwards time interpretation for antimatter, symmetry in space and time
Positrons only survive for a short time since they are attracted to other electrons and disintegrate. Since quantum mechanics states that energy, time and space can be violated, another way of looking at pair production is to state that the positron does not exist, but rather it is an electron traveling backwards in time. Since it is going backwards in time, its charge would be reversed and its spacetime diagram would look like the following:

  • the quantum world leads to new ways of looking at existence and reality
In this interpretation, the collision of an electron and two photons causes the electron to go backward in time till it meets another pair of photons, then reverses itself again. The world of quantum physics allows for many such strange views of subatomic interactions.
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