Science by Marilyn: Some Basic Quantum Mechanical Concepts

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Science by Marilyn: Some Basic Quantum Mechanical Concepts

Post by Samantha York »

Some Basic Quantum Mechanical Concepts

Unfortunately the ideas surrounding quantum mechanics is a field that is full of both marvels and bewilderment. However, while one need not be a specialist in a few ideas and terms should be a part of any science officer’s vocabulary.
One important term and concept in quantum mechanics is quantum superposition. The definition is a valid solution to a Schrodinger equation, but in simple terms it basically states that something on the quantum level can be in two states at once. An atom can be both excited and a regular state and until observed that state is not fixed. In a digital computer a bit is either in 0 or 1 state. In a quantum computer a bit called a qbit is in both 1 and 0 at the same time.
Wave function is an equation that describes the probability of the system. It is a bit too complex to delve into, but suffice to say it is an important idea to quantum mechanics.
As a thought experiment Schrodinger’s cat . In this case a cat is in a box in which a single electron or similar is emitted. If the electron’s spin is positive then a vial of poison is broken and the cat dies. If the spin is negative then nothing happens and the cat lives. In the thought experiment then, until it is observed and thus collapsing the wave function, the cat is both alive and dead at the same time and thus its state of existence is in superposition. P


The next idea is one that has been mentioned several times in the Trek universe in relation to the transporter. The uncertainty principle or as it is used, the Heisenberg uncertainty principle and in Trek the compensator. So what is this exactly and how it relates to our Trek world.
The basic idea is that you cannot simultaneously measure the position of a particle and its momentum below a certain level. An example is trying to measure an electron with a beam of light consisting of photons. As the photon hits the electron, the electron absorbs a bit of energy and shifts its momentum. The higher the energy of the photon to give a better idea of the position of the electron, the more the energy transfer and thus the more the momentum of the electron shifts. Thus as we attempt to determine the atoms in our comrades we are beaming to or from the transporter whatever measurement is being used to determine the position of an atom so we can reconstruct our comrades, we are loosing information on how the relationship of the atoms are as each scan disturbs the system by adding energy in.
Finally we get to quantum entanglement. This is a phenomenon in which quantum particles can become connected or entangled such that no matter how far the distance they are separated they continue to act as one. For example take a pair of particles such that combined their total spin is zero. We separate the particles, and move them many light years apart. When we measure one of the particles we know it has a positive spin, however as we learned from above, the other particle could be positive or negative (superimposed) and yet we will always get a negative spin such that there is the conservation of the net spin (zero). It is as if the particles are somehow communicating across vast distances at superluminal (greater then the speed of light) way what the state of one particle was so that the other can be in the appropriate state. Einstein had trouble with this concept and called it Spooky Action at a Distance, however it has been proven over and over.
Once last concept is quantum tunneling. Simply put this is the idea that in classical physics a particle cannot pass through a barrier and yet it appears to ‘tunnel’ through. Again it is a function of the probability of a particle or set of particles.
If we send a packet of electrons toward a barrier as shown below there is a probability that some of the electrons make it through which they do.

This last concept is important because so many things operate on the principle however in real life and applicable to our Trek world, the fusion of hydrogen in main sequence stars, radioactive decay and the formation of molecules in interstellar clouds (astrochemical synthesis) all relies on the phenomenon.
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