By: Tom D. Tamarkin
December 18, 2020
All electromagnetic radiation (hereinafter EMR) is based on “emitted photons.” A photon is an elementary particle or the “quantum” of light and all EMR with no rest mass. It is the “force carrier” of the electromagnetic radiation. Now we get into quantum mechanics but it will be kept simple here.
The effects of this force are observable at the microscopic and at the macroscopic level, because the photon has zero rest mass. This allows long distance interactions. Like all elementary particles, photons are currently best explained by quantum mechanics and exhibit wave–particle duality, exhibiting properties of waves and of particles. For example, a single photon may be refracted by a lens or exhibit wave interference with itself, but also act as a particle giving a definite result when its position is measured. Waves and quanta, being two observable aspects of a single phenomenon, cannot have their true nature described in terms of any mechanical model.
The photon has no rest mass and no electric charge. It is stable and has two possible polarization states. In the momentum representation, which is preferred in quantum field theory, a photon is described by its wave vector, which determines its wavelength, λ, and its direction of propagation. A photon’s wave vector may not be zero and can be represented either as a spatial 3-vector or as a (relativistic) four-vector; in the latter case it belongs to the light cone as illustrated below. Different signs of the four-vector denote different circular polarizations, but in the 3-vector representation one should account for the polarization state separately; it actually is a spin quantum number. In both cases the space of possible wave vectors is three-dimensional.
The photon is the gauge boson for electromagnetism, and the photon does not obey the Pauli Exclusion Principle.
Photons are emitted in many natural processes. During a molecular, atomic, or nuclear transition to a lower energy level, photons of various energy levels will be emitted; from radio waves, to infrared, to light, and up to gamma rays. This is how light is created from the combustion of chemical materials as an example.
The cone shows possible values of wave 4-vector of a photon.
The “time” axis gives the angular frequency (rad⋅s−1) and the “space” axes represent the angular wavenumber (rad⋅m−1).
Green and indigo represent left and right polarization
Remember that electromagnetic radiation starts at the slow rate of holding magnets in your hand and flipping one say twice a second or 2 cycles per second or 2 Hertz. It moves up through the audio range, AM radio, short wave, TV, micro waves, infrared (heat), visible light, ultraviolet radiation (think sun burns), x-rays, and on to nuclear gamma rays and finally cosmic rays coming from the creation of the universe itself ≈13.8 billion years ago. The faster the fields reverse themselves (think magnets North and South poles flipping 180 degrees) the more energy the photons have.
The above graphic depicts the relationship of wavelength and frequency in comparison to familiar objects. The precise relationship between frequency and wavelength is
f = V/λ
f is the frequency
V is the wave velocity or speed (assume C or ≈2.99 X 108 m/s which is the approximate speed of light in a vacuum)
λ is the wavelength of the wave
We do not worry too much about any molecular biological effect radio waves and EMR have until we get to far infrared (heat) and then on to ultra-violate light. The visible light spectrum of red, orange, yellow, green, blue, indigo, and violate is squeezed in-between infrared and ultraviolet. Yes! Heat and light are forms of higher frequency (shorter wave length) higher energy level EMR. Now as said before, emitted EMR consists of the amazing photons, the elementary particle with no rest mass that confounds many people because it has both particle and wave characteristics as described above.
All of this may sound very scientific to many people today, although in the 1960s this was freshman high school physical science curriculum.
We refer to EMR (radiation) which does damage to animal and plant tissue as “ionizing radiation.” This means a level of radiation that causes a chemical change in tissue and/or stimulates nerves to suggest a “sensation” in a well-developed animal species. As stated above the photons comprising EMR are force carriers. The greater the force, the more likely they cause ionizing effects and chemical changes, because chemistry involves moving electrons around and that takes energy. A simple example is the hotter a stove burner, the more damage it does to your finger when you touch it. However if you just “tap” the burner for a fraction of a second with your finger to see if the stove burner is on, no tissue “damage” occurs. There are two things at work here. One is the frequency or wave length of the EMR and the second is the power level; i.e., how many photons are received per square unit of surface area. The second can be a function of instantaneous power or received power integrated over time. An example is the finger “tapping” the stove burner. Do it once and you get the feel of the burner being on. No problem. But do it 20 times over a one minute period and you now have a serious burn. The same holds true with exposure to all high energy EMR. A radiologist can take one x-ray of your arm. No problem. He can take 10 x-rays of your arm over a couple of months. No problem. But if he takes 1,000 x-rays of your arm over a week, you will most likely suffer radiation burns and develop a cancer.
The above graphic shows the energy level of photons as a function of frequency/wavelength
As can be seen above, the ISM band is in the 109 range for frequency (meaning 1 GHz) but its photon energy level is 5 X 10-6 electron volts. That is an extremely small amount of energy; i.e. .0000005 electron volts.
An electron volt, symbol eV, is a unit of energy equal to approximately 160 zeptojoules or 1.6×10−19 joules. A joule is a unit of energy. A simple explanation for the amount of energy comprised by one joule is 1 watt per second. So one electron volt equals .0000000000000000016 watt seconds.
But when you move up to infrared at 1012 range of frequency, the energy is 10-1 electron volt range. That is 105 times or 100,000 times more energy!
That is why you do not want to touch the antenna of a TV station transmitting 100,000 watts at the old analog channel 2 (KCBS in Los Angeles as an example.) You would get a very bad RF burn. But move ten feet away from the antenna and not much happens; a block away and zero effect.
Today we live in a wireless world. At the recent 2016 Consumer Electronics Show (CES) show in Las Vegas most all new consumer products are wireless based. Now the U.S. Department of Transportation is mandating new cars in 2018 to have V to V radio communications (a form of vehicle to vehicle radar) to avoid collisions.
The V2V communications system proposed to be mandated by all automakers selling vehicles in the U.S. operates in the 5.9 GHz range using the DSRC or Dedicated Short Range Communications standards which allow very high data transmissions critical in vehicle safety applications. This frequency range is 5 times higher than the 902-928 MHZ, ISM range used by the smart meter and is squarely in the “microwave” frequency spectrum. Yet it is photon energy level is only 3 X10-5 eV; marginally higher than that of photons in the 902-928 MHz range.
Everything from wireless home PC routers and switches, to cable TV wireless convertors (think AT&T commercials…move your TV anywhere in your house with no wires….), to wireless mice and keyboards, to blue tooth cell phone ear buds, operate in either the 902-928 MHz frequency range or an even higher range of 2.4 GHz. There is no getting away from EMR. There is a huge amount of EMR in space coming from the origin of the Sun and all stars. Happily most of the high energy “cosmic rays” are trapped in the upper atmosphere by the Earth’s magnetic field. EMR is natural coming from the “big bang” and the way atomic theory works. And by the way, The Earth’s magnetic field is created by electro-magnetic forces deep within the inner core and outer core of the Earth which act like a massive electro-magnetic generator based on the solid ferromagnetic inner core surrounded by the molten ferromagnetic outer core traveling at different angular velocities.
We live in a world of 100% duty cycle (constant 24 hours a day 365 days a year) exposure to this background electromagnetic radiation. That is part of life!
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