Sunday, December 26, 2021

2178 - Light’s Mysteries

 -  2178 - Light’s Mysteries.  The electromagnetic radiation that surrounds us not only allows us to see it is what makes us see.  The energy bundled into each photon strikes the back of the eye and causes a chemical reaction which in turn sends an electrical nerve signal to the brain.  The brain uses these detected signals to create an image and match it with one we have in memory


---------------------------------  2178  -  Light’s Mysteries

-  Half of the human brain and most of its brain power is used in visualization.  The electromagnetic radiation that surrounds us not only allows us to see it is what makes us see.  The energy bundled into each photon strikes the back of the eye and causes a chemical reaction which in turn sends an electrical nerve signal to the brain.  The brain uses these detected signals to create an image and match it with one we have in memory.  We see things.

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-   For the last 400 years science has debated the structure and nature of light.  In the early 1900’s light was first defined as consisting of inter-dependent , mutually perpendicular, transverse oscillations of an electric and magnetic wave.  Light was defined as electromagnetic radiation.  

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-  Visible light is but a very narrow section of the entire electromagnetic spectrum.  Visible light has wavelengths from 390 nanometers (violet colors) to 740 nanometers (red colors).  

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-  The electromagnetic spectrums stretches from power line frequencies of a few cycles per second and 100,000,000 meters wavelength to Gamma Rays that are 1,000,000,000,000,000,000,000,000 cycles per second and 0.000,000,000,000,000,1 meters wavelength.

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-  Each photon of light is an energy bundle.  The amount of energy depends on the frequency of the oscillations.  A constant “unit of action” for each photon, known as Planck’s Constant, times the frequency is the energy that each photon possesses. 

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-   Planck’s Constant unit of Action is 4.136*10^-15 electron volts.  Or, in the metric system, this unit of Action is 6.625*10^-14 kilogram*meters^2 / second.  Both are very small numbers.

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-  Quantum Physics holds that matter, as well as light , exhibit the behaviors of both waves and particles.  It all started in the 1600’s when Christiaan Huygen proposed a wave theory for light.  However, at the same time Isaac Newton proposed the “ corpuscular” or particle theory of light.  

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-  In the 1900’s light diffraction was observed and needed the wave theory to explain it.  Also, Thomas Young’s double-slit experiment with light and the resulting interference patterns needed the wave theory to explain it.

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-  Generally, waves are thought to propagate through some medium.  Huygens called it “aluminiferous aether”.  When James Clerk Maxwell quantified a set of equations for electromagnetic radiation he used “ ether” as the medium for wave propagation.

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-    For 200 years no one could discover what the ether was.  In the 1800’s the Michelson - Morley experiment using a light interferometer failed to detect the ether, and science decided there was none.  

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-  In 1905 Albert Einstein used the particle theory of light to explain the photoelectric effect.  He concluded that light traveled in discrete bundles of energy, called photons.  The energy in photons depended on their frequency of oscillation.

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-  In 1929 de Broglie won the Nobel Prize for his hypothesis that all matter , as well as light, has a wavelength related to its momentum.  Massive particles with much momentum have such small wavelengths as to be undetectable.  But, small objects can have observable wavelengths.  Photons, electron, protons, atoms and even bacteria have been observed to have wavelengths.

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-  Science needed a way to study these wavelengths and developed the mathematics using differential equations to represent the wave-particle duality of light and matter.  Remember, light is energy and energy and matter are the same thing separated by the speed of light squared, E=mc^2.    The Wave Function equation is called the Schrodinger equation.  See note (1) for some description but the math is way over my head.

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-  The Wave Function represents the probability of finding a given particle at a given point.  The probability equations can then be used to describe diffraction, interference and other wave-like properties.  Particles end up distributed according to these probability laws.  The probability of a particle being in any location is a “wave“.  The actual physical appearance of that particle is not a wave.

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-  Back up to the second paragraph where light was defined as a “ transverse wave”.  Waves are a disturbance in a medium around an equilibrium state.  The energy of this disturbance is what causes the wave motion.  A transverse wave has displacements of the medium that are perpendicular ( transverse ) to the direction of the traveling wave.  Ocean waves and vibrating strings are transverse waves.

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-  A longitudinal wave has displacements of the medium that are back and forth along the same direction of the traveling wave.  Sound waves are longitudinal waves.

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-  The math works for waves in a medium.  Electromagnetic radiation travels through empty space with no medium (that we know of).  However, the math for these waves is still the same.  Waves transport energy, but not matter.  The medium itself does not travel.  The individual particles undergo back-and-forth, up-and-down, side-to-side motion around an equilibrium position, but the particles do not travel in the direction that the wave propagates.

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-  To describe wave motion we need to describe the position of a particle in the medium at any point in time.  Mathematically this description is the Wave Function.

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----------------  v  =   the velocity of the wave’s propagation

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----------------  A  =  The maximum amplitude or magnitude of the displacement from equilibrium.

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----------------  T  =  The time for one cycle, the Period, in seconds per cycle.

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-----------------  f  -  the frequency in cycles per second.  The frequency is the reciprocal of the Period.  f  = 1 / T   ,or, T  = 1 / f.

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---------------  2*pi*f  =  angular frequency in radiant per second.  The are 2*pi radians in one cycle.

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----------------  w  =  wavelength is the distance between corresponding points on a successive, repetitive wave.

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--------------  2*pi / w  =  the wave number or propagation constant in radians per meter.

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---------------  v  = f * w  =  velocity = frequency * wavelength.

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---------------  v  =  w / T  =  velocity =  wavelength / Period.

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-  The vertical position of a point on the wave is “y” and the horizontal position is “x”.  The time is “t”.  The mathematical function for the position of a particle is:

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--------------  y  =  A*sin 2*pi*f ( t - x / v)

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--------------  y  =  A*sin 2*pi( t / T - x / v)

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--------------  y  =  A*sin (2*pi*f  t - 2*pi*x / w)

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-  The first derivative of these functions is the rate of change of the particles position with time.  The second derivative of this function is the rate of change of the rate of change.  The second derivative is the Wave Function : 

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-------------  d^2y / dx^2  =  d^2y / v^2  *  dt^2

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-  This equation says that the second derivative of “y” with respect to “x”  =  the second derivative of “y” with respect to “t”, time, divided by the wave velocity squared.  If a function “y” acts as a wave with a velocity, ”v” ,then, it can be described mathematically as a Wave Function. 

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-   These derivatives are not that foreign to us.  The first derivative of distance with respect to time, that is, the rate of change of distance with respect to time is velocity.  The second derivative of distance with respect to time is the rate of change of velocity, or the rate of change of the rate of change of distance with respect to time which is acceleration.  On difference is that this is position in one dimension and the Wave Function is position in 3 dimensions.

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-  That gets us to Schrodinger’s Wave Equation which is much too complicated for me to explain.  It describes the behavior of a particle in a field of force, like the behavior of an electron inside an atom.  Here is Schrodinger’s Wave Equation:

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--------  (Laplace Operation)^2 * Wave Function - 4*pi*mass / (-1)^.5 * Planck’s Constant * (Derivative of the Wave Function with time)  -  8*pi^2 * mass * Potential Energy / (Planck’s Constant)^2 * Wave Function  = 0


--------  where:  the (Laplace Operation )   =  di/dx + dj/dy + dk/dz

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---------  where : “ijk” are unit vectors along the “xyz” axes respectively.  And, these are partial derivatives because they have more than one variable.  To solve them you hold some variables constant and do a “partial derivative” on one variable at a time.

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-  These Wave Equations are usually too difficult to be solved directly.  The math is too hard.  Instead, mathematicians solve an easier equation that is close then use Perturbation Theory to approximate the answer.  Perturbation makes small changes to the easy equation and then characterizes the changes to get to the more difficult equation‘s solution.

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-  How can a simple thing as light get so complex?  

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-  Entropy always increases and minimum entropy is maximum complexity.  So, if entropy always increase the fate of the Universe must be darkness.  Light is radiation, or energy.  Light and matter must be the same thing according to E=mc^2. -

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-   So, your body and soul are made up of a very low energy form of light.  We call it matter. Matter too is very complex.  If entropy always increases the fate of the Universe must also be no matter.  No matter.  That is all I got to say on the subject.

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-   November 21, 2018                   Light’s Mysteries        934       2178

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 --------------------------   Sunday, December 26, 2021  --------------------------

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