SCHRODINGER'S CAT (2)

That the cat still is a topic of conversation 80 years after Schrödinger's original thought experiment is amazing.

But why?

THOMAS YOUNG

You can put part of the blame on Thomas Young. Thomas Young (13 June 1773 – 10 May 1829) was an English polymath, and dabbled in physiology, language, musical harmony and Egyptology.  Oh yea, and also physics.

In Young's own judgment, of his many achievements the most important was to establish the wave theory of light. To do so, he had to overcome the century-old view, expressed in the venerable Isaac Newton's "Optics", that light is a particle. Isaac Newton, who did many experimental investigations of light, had rejected the wave theory of light and developed his corpuscular (or particle) theory according to which light is emitted from a luminous body in the form of tiny particles.  Nevertheless, in the early 19th century Young put forth a number of theoretical reasons supporting the wave theory of light, and he developed two enduring demonstrations to support this viewpoint. With the ripple tank he demonstrated the idea of interference in the context of water waves. With the two-slit, or double-slit experiment, he demonstrated interference in the context of light as a wave. In a paper entitled "Experiments and Calculations Relative to Physical Optics", published in 1803, Young describes an experiment in which he placed a narrow card (approx. 1/30th in.) in a beam of light from a single opening in a window and observed the fringes of color in the shadow and to the sides of the card. He observed that placing another card before or after the narrow strip so as to prevent light from the beam from striking one of its edges caused the fringes to disappear.  This supported the contention that light is composed of waves.  That the double-slit experiment can also prove the particle theory was not lost on the physicists of the 1927 Solvay conference, both must be versions of the natural world.  A good lay description of the double-slit experiment  is "Dr. Quantum - Double Slit Experiment & Entanglement" by Fred Alan Wolff, or Cassopedia Project's "Double Slit Experiment - The Strangeness Of Quantum Mechanics", both of which are usually available on YouTube.

The nature of quantum physics is such that the old methods of experiment, observe, record, refine, no longer provide valid data.  In the double-slit experiment, the act of observation changes the outcome.  That something can be a particle, and a wave, at the same time is difficult to understand intuitively. But with an overwhelming amount of evidence it needs to be treated as a natural state.

Quantum mechanics differs significantly from classical mechanics in its predictions when the scale of observations becomes comparable to the atomic and sub-atomic scale, the so-called quantum realm. Quantum physics deals with a subject that has several key facets that must be taken at face value.

• The subject is very small.  For example, we cannot directly see an electron, and we don't suspect we ever will (the electron is smaller than the amplitude of visible light). REFERENCE: Standard Model, Atom, Elementary particle.
• Our knowledge of the subject is inferred from behaviors, reactions, and other indirect consequences.  The rules of quantum mechanics are based on statistical math models. REFERENCE: Scanning tunneling microscope, Particle accelerator, Feynman diagram.
• Our methods of observation use tools that also have quantum fussiness and can cause one quantum particle to interact with another.  One of the outcomes of this is that we can never measure a complete set of the subjects attributes. Schrödinger equation, Heisenberg uncertainty principle.
• The subject displays both wave-like and particle-like behavior. REFERENCE: Wave-particle duality, de Broglie wave, Complementarity.
• The subject displays a particle-like behavior when acted upon.  REFERENCE: Wave function collapse Generalized position eigenstate, Measurement in quantum mechanics.
• The subject displays a wave-like behavior when left alone, in that "a quantum state is a set of mathematical variables that fully describes a quantum system".  REFERENCE: Wave packet, Quantum state.
• The subject is fundamentally a product of energy, mass, space, and time. REFERENCE: E = mc2.
• The subject exists as a discrete, unchanging entity (like a movie frame) at point Planck time. REFERENCE: Quantum, Canonical quantization, Max Planck.
• From one Planck time unit to the next, the displacement of the subject in space is limited to the distance of one Planck length (the next movie frame displacement cannot exceed the speed of light). REFERENCE: Displacement operator, Atomic electron transition.

During a 1961 lecture for undergraduate students at the California Institute of Technology, Richard Feynman, said this about the concept of energy:

There is a fact, or if you wish, a law, governing all natural phenomena that are known to date. There is no known exception to this law—it is exact so far as we know. The law is called the conservation of energy. It states that there is a certain quantity, which we call energy, that does not change in manifold changes which nature undergoes. That is a most abstract idea, because it is a mathematical principle; it says that there is a numerical quantity which does not change when something happens. It is not a description of a mechanism, or anything concrete; it is just a strange fact that we can calculate some number and when we finish watching nature go through her tricks and calculate the number again, it is the same.

—The Feynman Lectures on Physics

Since 1918 it has been known that the law of conservation of energy is the direct mathematical consequence of the translational symmetry of the quantity conjugate to energy, namely time. That is, energy is conserved because the laws of physics do not distinguish between different instants of time (see Noether's theorem).

So, if we put the pieces together, and use the old axiom that after all the impossible things are discarded, the remainder, however unlikely, must be considered.  In this case, I swear it doesn't seem like it should warrant being stuck in limbo with Schrödinger's cat.

SIDE NOTES:

The quantum realm is inhabited by very, very small particles, bits of matter.  They translate in space and time in quanta, similar to frames on a movie reel.  When they move, they exhibit a wave pattern.  The term 'wave' is poorly defined in this case, and the mathematics implies a repeating pattern of probable locations.

When we do something to observe the location of the particle, it is like petting the cat with a 710J John Deere Backhoe.  Liable to be some damage to the cat, and you won't be able to determine its location or velocity.

In order to explain the interference pattern, you either; (1) assume that the probability wave is all there is, and that the act of observation brings the particle into reality and collapses the wave. (2) assume that there are hidden variables, 'a unifying theory' or a carrier mechanism that will carry and shape the wave form. (3) assume that each quantum shift spins off a new universe, a global mind, or everyone has their own universe. (4) go all metaphysical with Doctor Quantum and ring up the Dalai Lama.