Two recent web discussions, based on the questions, “What is the exact definition of a point?” and “what actually creates a dimension?” have brought me to attempt to start to spell out my own precise definitions of the concepts I have been working with and attempting to understand over the last several years. Here is my first (partial) shot at that. I hope you will feel free to comment, clarify, dispute (or denounce) as you see fit.
Objective reality consists of the set of objects, events and phenomena that we perceive directly through our sensory organs as existing in the world outside of our heads, as well as those that we infer indirectly from their perceived effects on the objects, events, and phenomena that we perceive directly.
Perception is the internal process by which we acquire information about the elements of objective reality via our sensory system and the processing of that information in the brain including its comparison with stored mental constructs of prior perceptions.
Dimensions are mental constructs devised to measure, describe, denote, and communicate descriptions of the physical attributes of what we perceive to be objective reality, that is, what we perceive to exist in the world outside of our heads.
Time is a conceptual dimension created by humans in order to measure, describe, denote and communicate the persistence or duration of objects, events, and phenomena in the real world. Time is not and never has been a real physical entity in and of itself. The units we have chosen for the measurement of time are, of course, drawn from our observations of the periodic, rhythmic and recurring successions of natural events, but these are it’s only roots in the physical world.
The common three spatial dimensions, length, breadth, and height, along with theangular dimensions, are of the same heritage as time and what they describe is not the extensive concept we denote as “space.” but rather the size, form, and behavior of objects, events, and phenomena in the real world.
(The use of the neologism “spacetime” in modern physics must be faulted for attributing real physical characteristics to what are, in fact, only mental constructs. This linguistic disconnection is often hidden in the mathematical expressions used in modern physics and has led to extensive misinterpretations of theories proposed and promulgated in the physical sciences.)
The models (theories, cosmologies) that we create as scientists are our attempts to organize those observations and perceptions that are too distant, too short-lived, or too ephemeral for our direct experience or experiment, but that we believe may help to explain the true structure and order of our world and our universe. Such models are, of course always incomplete and many, perhaps most of them, are wrong. It is our job then to continually review, update as new knowledge is acquired or replace them with more complete and, hopefully, more sophisticated and comprehensive models. This is the real work of physics, not to adhere to things like “the standard model” on fear of death.
Wave is a conceptual term devised and adopted for use to represent or describe certain characteristics of phenomena that we have discerned to exist, but waves are not real entities in themselves. We see waves in bodies of water as characteristic motions of the liquid’s surface. they can be periodic, they can vary in frequency and amplitude, they can arise by some external causation, they can dissipate on the removal of that causation. We attribute wave-like behavior, i.e. alternating, oscillating, periodic, etc., to many phenomena. In sound, the waves are seen as variations in the compression of the atmosphere, in electricity we see waves as alternations in direction of flow in alternating current, in sports stadiums we call certain behavior of spectators as a “wave.” So, a wave is a characteristic behavior of something else, so we cannot say a wave is a thing, event, or phenomenon in and of itself, these making up the class of entities we call “reality.”
As the term is used in physics, waves are of two types, mechanical and electromagnetic. The current Wikipedia definition expresses it this way:
There are two main types of waves. Mechanical waves propagate through a medium, and (in the process) the substance of this medium is deformed. The deformation reverses itself owing to restoring forces resulting from its deformation. For example, sound waves propagate via air molecules colliding with their neighbors. When air molecules collide, they also bounce away from each other (a restoring force). This keeps the molecules from continuing to travel in the direction of the wave.
The second main type of wave, electromagnetic waves, do not require a medium. Instead, they consist of periodic oscillations of electrical and magnetic fields generated by charged particles, and can therefore travel through a vacuum. These types of waves vary in wavelength, and include radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays, and gamma rays.
This definition includes an important assumption, that “charged particles” are a necessary source or generator of electromagnetic waves, an assumption that may be subject to question. In fact, electromagnetic waves are also fluctuations in a medium and that medium is the electromagnetic field itself., a medium that fills what we call a vacuum. I think this is where the confusion arises, giving material attributes to a conceptual entity, a wave, which is not a real entity in and of itself. And while electromagnetic waves are generally represented as fluctuations in two dimensions in printed papers and graphics, they actually exist as fluctuations in other characteristics, as in intensity, or polarity, or something like energy density, all of which are difficult to describe except in mathematical terms.